^^•^jriifii-.;;-:'.:^-^;^-;^': ^s.r^£ti*v,^"^t;*)'u>:^xJ? *•%?.!*' - n * 1l"r5^iT*Wt*r ..: H32SE ,•-' "X*isS^ UNITED STATES OF AMERICA. * ♦ . FOUNDED 1836 WASHINGTON, D.C. GPO 16—67244-1 * HUMAN PHYSIOLOGY. ROBLEY DUNGLISON, M. D., PROFESSOR OF THE INSTITUTES OF MEDICINE IN JEFFERSON MEDICAL COLLEGE, PHILADELPHIA j VICE-PRESIDENT OF THE SYDENHAM SOCIETY OF LONDON J SECRETARY TO THE AMERICAN PHILOSOPHICAL SOCIETY, ETC. ETC. : Vastissimi studii primas quasi lineas circumscripsi."—Haller. NEARLY FIVE HUNDRED ILLUSTRATIONS. SEVENTH EDITION, THOROUGHLY REVISED, AND EXTENSIVELY MODIFIED AND ENLARGED. IN TWO VOLUMES. VOL. I. IBRARY j ON GENERALS OFFICE j fjUN.--; 4.-1904; ■I PHILADELPHIA: LEA AND BLANCHARD. 1850. / v. I Entered according to the Act of Congress, in the year 1841, By ROBLEY DUNGLISON, In the Clerk's Office of the District Court for the Eastern District of Pennsylvania. 0 PHILADELPHIA : T. K. AND P. G. COLLINS, PRINTERS. JDebkation to tf*e JFirst avib Qccorib (Editions. TO JAMES MADISON, EX-PRESIDENT OF THE UNITED STATES, ETC., ETC., ALIKE DISTINGUISHED AS AN ILLUSTRIOUS BENEFACTOR OF HIS COUNTRY, A ZEALOUS PROMOTER OF SCIENCE AND LITERATURE, AND THE FRIEND OF MANKIND, &f)ts tDork, INTENDED TO ILLUSTRATE THE FUNCTIONS EXECUTED BY THAT BEING, WHOSE MORAL AND POLITICAL CONDITION HAS BEEN WITH HIM AN OBJECT OF ARDENT AND SUCCESSFUL STUDY, IS, WITH HIS PERMISSION, INSCRIBED, IN TESTIMONY OF UNFEIGNED RESPECT FOR HIS TALENTS AND PHILANTHROPY, AND OF GRATITUDE FOR NUMEROUS EVIDENCES OF FRIENDSHIP, BY HIS OBEDIENT AND OBLIGED SERVANT, THE AUTHOR. DIRECTION TO THE BINDER,. The Plates of the System of Respiratory Nerves, and of the Regular or Symmetrical Nerves between pages 88 and 89, PREFACE TO THE SEVENTH EDITION. On no previous revision of this work has the author bestowed more care than on the present. In the successive editions, it was, of course, necessary to incorporate the different facts and principles, which had been added from time to time, to the science; and this rendered it difficult to preserve throughout the evenness of style, which is so desir- able in every treatise, and more especially in one that is placed in the hands of so many of the younger portion of scientific inquirers. To accomplish this object, the present edition has been subjected to an entire scrutiny, not cmly as regards the important matters of which it tVeats, but the language in which they are conveyed. Perhaps, at no time in the history of the science have observers been more numerous, energetic, and discriminating than in the last few years. Many modifications of fact and inference have consequently taken place, which it has been necessary for the author to record, and to express his views in relation thereto. Especially has he endeavoured to note the phenomena that have presented themselves to the most accurate observers, and to deduce from them laws which may tend to enlarge the boundaries of the science : he has not, however, felt himself at liberty to discard the results of the observations of all former anthro- pologists, or the opinions they had embraced in regard to the various functions. It not unfrequently, indeed, happens, that in ignorance of the history of the science, views are esteemed new, which had been pro- mulged by earlier investigators. He has, therefore, in an encyclopsediac work like the present, retained many of those opinions, whilst he has laboured to do especial justice to such as have emanated from more recent inquirers. In this respect, his work differs from valuable phy- siological treatises that are before the public. Whilst, too, he has inserted the main results of the labours of recent histologists, espe- cially such as are directly applicable to physiology, he has not considered it advisable to pursue the subject to such an extent as if the work were on general anatomy, to which histology properly belongs. vi PREFACE. On the whole subject of physiology proper, as it applies to the func- tions executed by the different organs, the present edition, the author flatters himself, will be found to contain the views of the most distin- guished physiologists of all periods. The contributions to the science of life have, of late years, been rich and varied ; and to collate and weigh them, and to separate the most trustworthy and valued, has been a work of no little discriminating labour,—but to the author a labour of love, inasmuch as they are subjects which he has been long accus- tomed to investigate : and on which he has annually to treat before the class of Institutes of Medicine of the Jefferson Medical College. The Bibliography, prefixed to the first volume, will exhibit the number and variety of sources of information at home and abroad, which he has had to consult, and will afford a coup d'oeil of the chief biological investigations, undertaken since the appearance of the last edition more especially, which have so changed the face of the science in regard to certain subjects as to require that they should be re-written. The rich collection of materials in the possession of his publishers has enabled him to increase greatly the list of illustrations, and to substitute in many cases better; whilst new cuts have been added so as to make the whole number four hundred and seventy-four, in place of three hundred and sixty-eight, as in the last edition. It has been difficult in all cases to assign these to the original projectors ; but an effort has been made so to do. On no former occasion has the author felt as satisfied with his endea- vours to have the work on a level with the existing state of the science ; and, for the seventh time, he ventures to place it before a profession, which has already done too much honor to his efforts to be useful. His crowning desire, in all his literary undertakings, has been to faci- litate the onward course of those who are pressing forward to distinction in a truly learned and difficult profession, and the reception these un- dertakings have met with has satisfied him, that his labours have been far from fruitless. ROBLEY DUNGLISON. 18 Girard Street, August, 1850. AUTHORS REFERRED TO IN THE PREPARATION OF THIS EDITION. Abercrombie, J., Pathological and Practical Researches on Diseases of the Brain and the Spinal Cord, Amer. edit., Philada., 1843. Agassiz, L., Geographical Distribution of Animals, in Christian Examiner, March, 1850. --------Lake Superior; its Physical Characters, Vegetation, and Animals, com- pared with those of other and similar regions, Boston, 1850. --------The Diversity of Origin of the Human Races, in Christian Examiner, July, 1850. Agassiz & Gould, Principles of Zoology, &c, pt. i., Comparative Physiology, Bos- ton, 1848. Albert, On the Colour of the Vagina in Pregnancy, cited in British and Foreign Medico-Chirurgical Review, July, 1848. Amringe. (See Van Amringe.) Ashwell, S., A Practical Treatise on the Diseases peculiar to "Women, third edit. Lond., 1848. Baly, W., On the Glands of Peyer, in London Medical Gazette for March, 1847. -------- and Kirkes, William Senhouse, Recent Advances in the Physiology of Motion, the Senses, Generation, and Development, London, 1848. Barrow, Sir John, An Autobiographical Memoir, Lond., 1847. Barry, W. J., Case of Doubtful Sex, in New York Journal of Medicine, January, 1847. Beck, Mr., Nerves of the Uterus, in Philosophical Transactions, pt. ii. for 1846. Beclard, M., Blood of the Portal Vein, in Annales de Chimie et de Physique, Paris, 1847. Bendz, 'Haandbog i den Almindenige Anatomie, Kiobenhavn, 1847, cited by Kirkes & Paget. B6rard, P., On Gelatin as a Nutriment; Archives Generates de Medecine, Fevrier, 1850. ---------- Cours de Physiologie fait a la Faculte de Medecine de Paris, Paris, 1848-9. --------P. H., Art. Olfaction, Dictionnaire de Medecine, 2de 6dit., Paris, 1840. Bernard, C, On the Communication of Veins and Lymphatics, in Union Medicate, No. 116, and Brit, and For. Medico-Chir. Rev., Jan., 1850. ----------On the Formation of Sugar by the Liver, in Archives Generates de Medecine, Nov., 1848. ----------On Insalivation of Food, in Archives Generates de Medecine, 4e s6rie, torn. xiii. ----------Action of Pancreatic Fluid on Oil, in Archives Generates de Medecine, vol. xix. p. 60. ----------On the Pancreatic Juice, in Archives Generates de MMecine, vol. xiv., and in Provincial Med. and Surgical Journal, March, 1849, and in Gazette Me- dicate, No. 9, Paris, 1849. ------,----, On the Transformation of Starch into Sugar, in Canstatt und Eisen- mann's Jahresbericht liber die Fortschritte in der Biologie im Jahre 1847. viii AUTHORS REFERRED TO, Berthold, Cause of Parturition, Comptes Rendus, Paris, 1844; and Archives Gen. de MMecine, Juin, 1844. --------, A. A., Lehrbuch der Physiologie, 3te Auflage, Getting., 1848. Bertholet, P. G., Weight of Twins, Medical Examiner, Aug., 1848. Bidder, Prof. F., Versuche zur Bestimmung der Chylusmenge, in Miiller s Archiv. fur Anatomie, Jahrgang 1845. . ---:--------, Art. Schmecken, in Wagner's Handworterbuch der Physiologie, 13te Lieferung, Braunschweig, 1846. ■ . Bischoff, T. L. W., On the Amount of Chyle Formed, in Muller's Archiv., Jahr- gang 1846. ---------------, Art. Entwickelungsgeschichte mit besonderer Berucksichtigung der Missbildungen, in Wagner's Handworterbuch der Physiologie, 6te Lieferung, Braunschweig, 1843. Theorie der Befruchtung und iiber die Rolle welchedie Sper- matozo'iden dabei spielen, in Muller's Archiv. der Anatomie, u. s. w., Jahrgang 1847. , Ueber die Glandulae Utriculares des Uterus des Menschen, und Ihren Antheil an der Bildung der Decidua, in Muller's Archiv. fiir Anatomie, Jahrgang 1846. Bishop, J., On the Voice, in Proceedings of the Royal Society, No. 65, 1847. Blake, J., On the Quantity of Blood in the Body, in Medical Examiner, Aug., 1849. -----, Velocity of the Circulation in Edinb. 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Medical and Surgical Journal, Oct. 1846. Brillat-Savarin, Physiologie du Gout, Paris, 1843. Brinton, Wm., Art. Serous and Synovial Membranes, in Todd's Cyclopaedia of Anatomy and Physiology, Pt. xxxiv., Lond., Jan., 1849. Browne, P. A., The Classification of Mankind by the Hair and Wool of their Heads, with an answerto Dr. Prichard's assertion, " that the covering of the head of the Negro is hair properly so termed, and not wool," Philad., 1850. Buckingham, J. S., Travels in France, Piedmont, &c.,Lond., 1849. Budge, J., Art. Sympathischer Nerv mit besonderer Riicksicht auf die Herzbewe- gung, in Wagner's Handworterbuch, u. s. w. 17te Lieferung, Braunschweig, 1847. S & Burrows, G. M., On Disorders of the Cerebral Circulation, Amer. edit., Philad., 1848. Cammann, Dr., On the Capillaries of the Lungs, in New York Journal of Medicine Jan., 1848. Campbell, Lord, The Lives of the Lord Chancellors and Keepers of the Great Seal of England, Amer. edit., Philad., 1847. Carpenter, W. B., Principles of Human Physiology, with their chief applications to Pathology, Hygiene and Forensic Medicine, 4th Amer. edit., Philad., 1850. ---------, Art. Sensation, in Todd's Cyclopaedia of Anatomy and Physiology Pt. xxxiv., Lond., Jan., 1849. ---------, Art. Sleep, in Cyclopaedia of Anatomy and Physiology, Pt. xxxv., Mar., 1849. AUTHORS REFERRED TO. ix Carpenter, Art. Smell, Cyclopaedia of Anatomy and Physiology, Pt. xxxvi., London, June, 1849. Carter, R., Case of Superfoetation, Medical Examiner, Sept., 1849. Cazeaux, M., Hydroaemia in Pregnancy, in Archives Generates de Medecine, Mars, 1850. --------, Traite Theoriquc et Pratique de l'Art des Accouchements, Paris, 1840. Chelius, J. M., System of Surgery, translated by Mr. South, Amer. edit., Philad., Churchill, F., On the Theory and Practice of Midwifery, 3d Amer. edit., by Dr. Huston, Philad., 1848. Clendinning, Dr., in Medico-Chirurgical Transactions, vol. xix. Clutterbuck, H., Art. Apoplexy, in Cyclopaedia of Practical Medicine, Amer. edit., by the Author, Philad., 1844. Cooper, B. B., Life of Sir Astley Cooper, Bart., 8vo., London, 1843. Coste, M., Histoire Generate et Particuliere du D6veloppement des Corps organises, publiee sous les Auspices de M. Villemain, Ministre de l'Instruction publique, Tom. ler., ler et 2de Fascicule, Paris, 1847—1849. Courtz, M., Archives d'Anatomie Generate et de Physiologie, Sept., 1846. Craigie, D., on Obliteration of the Vena Portae, in Edinb. Medical and Surgical Journal, April, 1850. Curling, T. B., Descent of the Testicle, in Lancet, April 10, 1841. ------------, Practical Treatise on the Diseases of the Testis, London, 1843. ------------, on Spermatozoids in Hydrocele, in Edinb. Monthly Journal of Medi- cal Science, May, 1843. ------------, Art. Testicle, Cyclopaedia of Anatomy and Physiology, Pt. xxxviii., Feb. 7, 1850. Darwin, Charles, Journal of Researches into the Natural History and Geology of the countries visited during the voyage of H. M. S. Beagle round the World, Amer. edit., New York, 1846. De Lamartine. (See Lamartine.) De Serres, Marcel, On the Ethiopian as the original type of man, in L'Institut, 13 Fevr. 1850. De Strzelecki, P. E., Physical Description of New South Wales and Van Diemen's Land, Lond., 1845. Donne\ A., Cours de Microscopie, Paris, 1845. Dowler, B., Contributions to Physiology, No. 3, Experiments, &c, on decapitated alligators, New Orleans, 1849, from New Orleans Journal of Medicine. ----------Experimental Researches on the post mortem contractility of the Muscles, with observations on the reflex theory, reprinted from New York Jour- nal of Medicine, May, 1846. ----------Researches, Clinical and Experimental, on the Capillary Circulation; reprinted from New Orleans Medical and Surgical Journal, Jan., 1849. ----------on the Heart's Action, in Contributions to Physiology, New Orleans, 1849. Draper, J. W., A Text Book on Chemistry, New York,_1846. -------------on the Forces which produce the Organization of Plants. Dujardin, M., on Spermatozoids, in Annates des Sciences Natur., Zoologie, viii. 291, and in Manuel de l'Observateur au Microscope, Paris, 1843. Ecker, A., Art. Blutgefassdrusen in Wagner's Handworterbuch der Physiologie, 23te Lieferung, Braunschweig, 1849. --------, On the Spleen, in Schmidt's Jahrbiicher, u. s. w., No. 5, Jahrgang 1848. Emerson, G., The Effect of Depressing Influences on the Number of Mate Concep- tions, in American Journal of the Medical Sciences, July, 1848. Erman, A., Travels in Siberia, translated from the German by W. D. Cooley, Lond., 1848; Philad., 1850. Flint, T. M., Case in which the Stomach had Separated from the CEsophagus, in Medical Examiner, for Decern., 1848. Frerichs, F. F., Art. Synovia, in Wagner's Handworterbuch der Physiologie, 18te Lieferung, Braunschweig, 1848. X AUTHORS REFERRED TO. Frerichs, F. F., Art. Thranensecretion, in Wagner's Handworterbuch der Physio- logie, 19te Lieferung, Braunschweig, 1848. . . . -----------, Art. Verdauung, in Wagner's Handworterbuch der Physiologie, 19te Lieferung, Braunschweig, 1848. . T . Frick, Chas., On the Organic Constituents of the Blood, in American Journal of the Medical Sciences, Jan., 1848. Gerlach, J., Handbuch der Allgemeinen und Speciellen Gewebelehre des Mensch- lichen Kb'rpers, Mainz., 1849. ---------, On the Kidney, in Mailer's Archiv. far Anatomie u. s. w., Jahrgang 1848. Gibbs, J., Wound of Abdomen, in American Journal of the Medical Sciences, Oct., 1846. Girou de Buzareingues, Pr6cis Elementaire de Physiologie Agricole, Paris, 1849. Goodsir, J., Anatomical and Pathological Observations, Edinb., 1845. ----------, Development of the Teeth, Edinb. Med. and Surg. Journal, vol. i. Gorup-Besanez. (See Von Gorup-Besanez.) Gould, A. A. (See Agassiz and Gould.) Ganther, A. F., Lehrbuch der Physiologie des Menschen, Leipz., 1848. Gulliver. (See Hewson.) Guy, W. A., Art. Pulse, Cyclopaedia of Anatomy and Physiology, Pt. xxxi., Lond., May, 1848. Hamernjk, Prager Vierteljahrschrift, 1847, cited in Schmidt's Jahrbacher, Jahr- gang. 1848 and 1849, and in Edinburgh Monthly Journal, Jan., 1849. Harless, E., Experimente zur Lehre von der Muskelirritabilit'at, Muller's Archiv., H. ii. Jahrgang 1847. Harris, S. H., Case of Doubtful Sex, in American Journal of the Medical Sciences, July, 1847. ■ Harrison, J., Coagulation of the Blood, in New Orleans Medical and Surgical Journal, July, 1847. Harvey, A., On llybridity, in Monthly Journal of the Medical Sciences, Oct., 1849. Hassall, A., The Microscopic Anatomy of the Human Body in Health and Dis- ease, Pt. xii., London, 1848. Helmholtz, H., Ueber die Warmentwickelung bei der Muskelaction, in Mailer's Archiv, Jahrgang 1848. Henle, J., Handbuch der rationellen Pathologie, Braunschweig, 1849—50. Hewson, W., Works of, Sydenham Society's edition, by Gulliver, London, 1846. Horlbeck, E., Case of Superfoetation, Charleston Medical Journal, and Review, Jan., 1848. Hornor, C. W., Secretion of milk in a male, in Medical Examiner, August, 1850. Horsford, E. N., On the Proportion of Nitrogen in Aliments, in Philosophical Magazine for Nov., 1845. Humboldt, Baron von, Ansichten der Natur, or Aspects of Nature, translated by Mrs. Sabine, Amer. edit., Philad., 1849. Hutchinson, J., On Respiration, in Medico-Chirurgical Transactions, vol. xxix., Lond., 1846. ---------, On the Spirometer, in Medico-Chirurgical Review, vol. xxix., Lond., 1846. Hyrtl, Jos., M.D., Lehrbuch der Anatomie des Menschen, Prag., 1846. Jackson, J. B. S., A Descriptive Catalogue of the Anatomical Museum of the Bos- ton Society for Medical Improvement, Boston, 1847. Jacubowitsch, De Saliva, dissert, inaugural. Med. Univers. Dorpat. cited by Scherer in Constatt und Eisenmann's Jahresbericht, u. s. w. im Jahre 1848. Jobert, M., Nerves of the Uterus, in Comptes Rendus, Paris, 1841. Johnson, Geo., Art. Ren., Cyclopaedia of Anatomy and Physiology, Pt. xxxii., Lond Aug., 1848. 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Tastsinn und das Gemeingefahl, in Wagner's Handworterbuch der Physiologie, u. s. w., 22ste Lieferung, Braunschweig, 1849. xvi AUTHORS REFERRED TO. Weber, E. H., Zusatze zur Lehre von Baue und von den Verrichtungen der Ge- schlechtsorgane, in Mailer's Archiv. fur Anatomie, Jahrgang 1846. ------, E. and E. H., Ueber die Wirkungen, welche die magneto-elektrische Reizung der Blutgefasse bei lebenden Thieren hemorbringt, in Muller's Archiv. far Ana- tomie, Jahrgang 1847. Whitehead, Jas., On the Causes and Treatment of Abortion and Sterility, Amer. edit, Philad., 1848. Williams, C. J. B., Principles of Medicine, comprising general Pathology and The- rapeutics, &c, 3d Amer. edit., by Dr. Clymer, Philad., 1848. Wilson, E., On Diseases of the Skin, 2d Amer. edit., Philad., 1847. Wyman, Jeffries, A Description of two additional Crania of the Enge-ana, in American Journal of Science and Arts, second series, vol. ix. Zimmermann, on Kyestein, cited in London Medical Gazette, Sept., 1846. CONTENTS OF VOL. I. PRELIMINARY OBSERVATIONS. Prolegomena. I. Of Natural Bodies ..... 1. Difference between Inorganic and Organized Bodies 2. Difference between Animals and Vegetables 33 34 39 GENERAL PHYSIOLOGY OF MAN. I. Material Composition of Man .... a. Organic Elements that contain Nitrogen b. Organic Elements that do not contain Nitrogen c. Solid parts of the Human Body d. Fluids of the Human Body . e. Physical Properties of the Tissues . II. Functions of Man ..... 43 47 53 56 61 63 69 BOOK I. ANIMAL FUNCTIONS, OR FUNCTIONS OF RELATION. Chap. I. Sensibility ....... . 72 1. Nervous System ..... " 72 2. Physiology of Sensibility ..... . 110 a. Sensations ...... 110 a. External Sensations ..... . 119 Sense of Tact or Touch—Palpation 121 1. Anatomy of the Skin, Hair, Nails, &c. . 122 2. Physiology of Tact and Touch 133 Sense of Taste or Gustation ..... . 144 1. Anatomy of the Organs of Taste 144 2. Savours ...... . 147 3. Physiology of Taste .... 150 Sense of Smell or Olfaction ..... . 157 1. Anatomy of the Organ of Smell 157 2. Odours ...... . 161 3. Physiology of Olfaction 167 Sense of Hearing or Audition ... . 174 1. Anatomy of the Organ of Hearing 174 2. Sound ...... . 184 VOL. I.—2 XV111 CONTENTS. 3. Physiology of Audition Sense of Sight or Vision 1. Light .... 2. Anatomy of the Organ of Vision 3. Accessory Organs 4. Physiology of Vision 5. Phenomena of Vision . Additional Senses 6. Internal Sensations Mental Faculties, &c. ...... 1. Physiology of the Intellectual and Moral Faculties Chap. II. Of Muscular Motion, especially of Locomotility or Voluntary Motion 1. Anatomy of the Motory Apparatus 2. Muscles .... 3. Bones .... 4. Physiology of Muscular Motion . 5. Attitudes 6. Movements 7. Locomotive Movements a. Walking b. Leaping c. Running d. Swimming e. Flying .... /. Other varieties of Muscular Action 8. Function of Expression or of Language a. Of the Voice 1. Anatomy of the Vocal Apparatus 2. Physiology of the Voice 1. Intensity or Strength of Voice 2. Tone of Voice , 3. Timbre or Quality of Voice 3. Natural or Inarticulate Language 4. Artificial or Articulate Language 5. Singing b. Gestures Ciliary Motion BOOK II. NUTRITIVE FUNCTIONS. Chap. I. Digestion 1. Anatomy of the Digestive Organs 2. Food of Man 3. Physiology of Digestion 4. Digestion of Solid Food a. Hunger 6. Prehension of Food c. Oral or Buccal Digestion d. Deglutition .512 512 . 540 553 . 554 554 . 561 563 . 568 CONTENTS. xix e. Chymification . /. Action of the Small Intestine . g. Action of the Large Intestine 5. Digestion of Liquids 6. Of Eructation, Regurgitation, and Rumination Chap. II. Absorption ..... I. Digestive Absorption . a. Absorption of Chyle or Chylosis 1. Anatomy of the Chyliferous Apparatus . 2. Chyle .... 3. Physiology of Chylosis 6. Absorption of Drinks . II. Absorption of Lymph or Lymphosis . 1. Anatomy of the Lymphatic Apparatus 2. Lymph . 3. Physiology of Lymphosis III. Venous Absorption 1. Physiology of Venous Absorption IV. Internal Absorption ... V. Accidental Absorption a. Cutaneous Absorption b. Other Accidental Absorptions . 572 . 607 615 . 623 626 . 635 636 . 636 636 . 643 647 . 656 662 . 663 669 . 672 677 . 678 684 . 686 687 . 691 LIST OF ILLUSTEATIONS IN VOL. I. FIG. 1. Endosmometer, ..... 2. Anterior view of the brain and spinal marrow, 3. Front view of the skull, .... 4. Falx cerebri and sinuses of upper and back part of skull, 5. Lateral view of the spinal column, 6. Longitudinal section of the brain on the mesial line, 7. The convolutions of one side of the cerebrum, as seen from above, 8. Superior part of the lateral ventricles, corpora striata, septum lucidum, fornix, &c, as given by a transverse section of the cerebrum, 9. Section of the cerebrum, displaying the surfaces of the corpora striata, and optic thalami, the cavity of the third ventricle, and the upper surface of the cerebellum, ...... 10. An under view of the cerebellum, seen from behind, . 11. Posterior superior view of the pons Varolii, cerebellum, and medulla oblongata and M. spinalis, ...... 12. Analytical diagram of the encephalon—in a vertical section, after Mayo, 13. Anterior view of the medulla oblongata, showing the decussation of the pyramids, and of the upper part of the spinal cord, after Mayo, 14. Transverse sections of the spinal cord, Todd and Bowman, 15. Shows the under surface or base of the encephalon freed from its membranes, ....... 16. Terminal nerves, on the sac of the second molar tooth of the lower jaw in the sheep; showing the arrangement in loops, after Valentin, 17, 18. Pacinian corpuscles, after Todd and Bowman, 19. Represents a nerve consisting of many smaller cords or funiculi wrapped up in a common cellular sheath, 20. A portion of the spinal marrow, showing the origin of some of the spinal nerves, .... 21. Plans in outline, showing the front a, and the sides b, of the spinal cord, with the fissures upon it; also sections of the gray and white matter, and the roots of the spinal nerves, .... 22. Roots of a dorsal spinal nerve, and its union with sympathetic, Todd and Bowman, ..... 23. Great sympathetic nerve, 24. Structure of the spinal cord, according to Stilling, 25. Transverse section of the medulla, after Stilling, 26. Tubular nerve-fibres, .... 2* PAGE 67 73 75 76 77 78 78 79 80 81 81 82 83 84 85 86 87 91 92 100 101 103 xxu LIST OF ILLUSTRATIONS. FIG. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36, 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. after Gelatinous nerve-fibres, . Ganglion corpuscles, after Valentin, Stellate or caudate nerve-corpuscles, after Hannover, Circle of Willis, ..... Sinuses of the base of the skull, Capillary net-work of nervous centres, after Berres, Distribution of capillaries at the surface of the skin of the fing< Berres, ...... Brain of squirrel, laid open, after Solly, Brain of turtle, after Solly, .... 37. Brains of fishes, after Leuret, Vertical section of epidermis, from the palm of the hand, after Wilson, Surface of the skin of the palm, showing the ridges, furrows, cross- grooves, and orifices of the sweat-ducts, Todd and Bowman, Vertical section of the cuticle from the scrotum of a negro, Todd and Bowman, ....... Section of the skin, ...... Papillae of the palm, the cuticle being detached, magnified 35 diameters Sections of hair, ...... Thin layer from the scalp, ..... Magnified view of the root of the hair, Kohlrausch, Section of the skin on the end of the finger, Todd and Bowman, a. Separated epithelium cells from mucous membrane of the mouth b. Pavement-epithelium of the mucous membrane of the smaller bron- chial tubes, ...... Tesselated epithelium, ..... Scales of tesselated epithelium, after Henle, Diagram of the structure of an involuted mucous membrane, showing the continuation of its elements in the follicles and villi, Todd, Cylinders of intestinal epithelium, after Henle, Capillary net-work at margin of lips, after Berres, Front view of the upper surface of the tongue, as well as of the pala- tine arch, Wilson, • •....- View of a papilla of the smallest class, magnified 25 diameters, Todd and Bowman, ........ Vertical section of one'of the gustatory papillae of the largest class, showing its conical form, its sides, and the fissure between the dif- ferent papillae, Todd and Bowman, .... The hypoglossal; lingual branch of fifth pair; glosso-pharyngeal and deep-seated nerves of the neck, Papillae of the tongue, Todd and Bowman, Vertical section of the middle part of the nasal fossae, giving a poste- rior view of the arrangement of the ethmoidal cells, &c, View of the olfactory nerve, with its distribution on the septum nasi • the nares divided by a longitudinal section made immediately to the left of the septum, the right nares being preserved entire, A portion of the pituitary membrane of the nasal septum, magnified 9 times, showing the number, size, and arrangement of the mucous crypts, ....... PAGE 103 104 104 106 108 108 113 115 115 115 123 123 124 124 125 126 127 127 130 131 132 132 133 133 139 145 145 146 146 147 158 159 160 LIST OF ILLUSTRATIONS. xxiii FIG. 61. 62. 63. 64. 65. 66. 67. 68. 69. 70. 71. 72. 73. 74. 75. 76. 77. 78. 79. 80. 81. 82. 83. 84. 85. 86. 87. 88. 89. 90. 91. 92. 93, 94. A portion of the pituitary membrane, with its arteries and veins inject- ed, magnified 15 diameters, ...... Olfactory filaments of the dog, Todd and Bowman, View of, the left ear in its natural state, .... General view of the external, middle, and internal ear, as seen in a prepared section, from Scarpa, ..... Anterior view of the external ear, as well as of the meatus auditorius, labyrinth, &c, ....... Membrana tympani from the outer (a) and from the inner (b) sides, Ossicles of the left ear articulated, and seen from the outside and below, Labyrinth separated from the solid bone in which it lies embedded, Cochlea divided parallel with its axis, through the centre of the mo diolus, Breschet, ...... Osseous labyrinth laid open to show especially the membranous labyrinth, Auditory nerve,. . Ampulla of the external semicircular membranous canal, showing the mode of termination of its nerve, Auditory nerve taken out of the cochlea, Papillae of the auditory nerve, on a segment of the spiral lamina of the cochlea of a young mouse, Reflection of sound, Vertical section of the head and neck, through the mesial line, to show the opening of the Eustachian tube and its relations to the pharynx, Reflection and refraction of light, Prism, .... Double convex lens, Double concave lens, Prismatic spectrum, Aberration of sphericity, Aberration of refrangibility, Front view of the left eye—moderately opened, Side view of the same eye, as in fig. 84, showing that the cilia of the upper lid are concave upwards, and those of the lower lid concave downwards. The general convexity of the eyeball is seen, . Choroid coat of the eye, ....... Pigmentum nigrum, after Todd and Bowman, .... Retina, ......... a. An enlarged plan of the retina, in section, b. The outer surface of Jacob's membrane, from Hannover, ..... Part of the retina of a frog seen from the outer surface, Vertical section of the human retina and hyaloid membrane, after Todd and Bowman, ........ Papillae of the retina of the frog, seen from the side turned towards the vitreous humour, . ...... Plan of the structures in the fore part of the eye, seen in section, Posterior segment of transverse section of the globe of the eye seen from within, ........ PAGE 160 160 175 175 176 177 178 180 180 181 182 182 183 183 186 194 208 210 211 211 212 213 214 214 215 215 216 216 217 218 218 219 219 220 xxiv LIST OF ILLUSTRATIONS. FIG. 95. Vertical section of the sclerotic and cornea, showing the continuity of their tissue between the dotted lines, after Todd and Bowman, 96. Longitudinal section of the globe of the eye, . . • ■ 97. Lens, hardened in spirit and' partially divided along the three interior planes, as well as into lamellae.—Magnified three and a quarter diameters, after Arnold, .... 98. Front view of the crystalline humour or lens, in the adult, 99. Side view of the adult lens, .... 100. Internal view of the iris, 101. External view of the iris, .... 102. A representation of some of the nerves of the orbit, especially to show the lenticular ganglion, after Arnold, 103. Segment of the anterior face of the iris with its vessels injected. Mag nified twenty-five diameters, after Todd and Bowman, 104. An enlarged view of the arteries of the iris, from Arnold, 105. Anterior segment of a transverse section of the globe of the eye seen from within, ...... 106. Choroid and iris, exposed by turning aside the sclerotica, 107. Optic nerves, with the origin of seven other pairs of nerves, 108. Muscles of the eyeball, ..... 109. Meibomian glands seen from the inner or ocular surface of the eyelids with the lachrymal gland—the right side, 110. View of the third, fourth, and sixth pairs of nerves, 111. Posterior view of the eyelids and lachrymal gland, 112. Lachrymal canals, 113. Progress of luminous rays through the eye, 114. Camera obscura, . 115. Experiment of Mariotte, . 116. Muscae volitantes, after T. W. Jones 117. Lines of visible direction, 118, Accidental colours, 119. Myopic vision, 120. Presbyopic vision, 121. Binocular vision.—Professor Wheatstone's experiments 122, 123. Binocular vision, 124. Do. do. 125. Multiple vision with one eye, 126. Do. do. 127. Visual angle, 128. Foreshortening, 129. Perspective, 130. Concave mirror, 131. Convex mirror, 132, 133. Thaumatrope 134. Facial line and angle of man, after Sir C. Bell, 135. Facial line and angle of orang-outang, 136. Old phrenological head, . 137. Phrenological head by Dolci, A. D. 1562, 138,139, 140. Phrenological organs according to Gall, PAGE 220 221 LIST OF ILLUSTRATIONS. XXV FIG. pAGE 141, 142, 143. Phrenological organs according to Spurzheim, . . 348 144, 145. Non-striated muscular fibre, after Bowman and Wilson, . 363 146, 147. Striated muscular fibres, ...... 365 148. Fragments of an elementary fibre of the skate, held together by the untorn but twisted sarcolemma, after Todd and Bowman, . . 366 149. Transverse section of fibres from the pectoral muscle of a teal, after Bowman, ........ 366 150. Transverse section of ultimate fibres of biceps, after Bowman, . 366 151. Fragment of muscular fibre from macerated heart of ox, showing for- mation of striae by aggregation of beaded fibrillae, after Bowman, . 367 152. Portion of human muscular fibre, separating* into disks, by cleavage in . direction of transverse striae, after Bowman, . . . 367 153. Fragments of striated elementary fibres, showing a cleavage in oppo- site directions.—Magnified 300 diameters, . •.' . . 367 154. Mass of ultimate fibres from the pectoralis major of the human foetus, at nine months, after Wilson, . . . . . 369 155. Muscular fibrils of the pig, after Sharpey, .... 369 156. Attachment of tendon to muscular fibre, in skate, after Bowman, . 370 157. Capillary net-work of muscle, after Berres, .... 371 158. Loop-like termination of the nerves in voluntary muscle, after Burdach, 372 159. Compound ventriform muscle, ...... 373 160. Penniform muscle, ....... 373 161. Double penniform muscle, ...... 373 162. Sections of a bone, ....... 379 163. Haversian canals, seen on a longitudinal section of the compact tissue « of the shaft of one of the long bones, after Todd and Bowman, . 381 164. Transverse section of compact tissue of humerus magnified about 150 diameters, ........ 381 165. Direction of encephalic impulses, ..... 393 166. Muscular fibre of dytiscus in contraction, after Bowman, . . 398 167. Muscular fibre of skate, . . . . • 399 168. Centre of gravity, ....... 419 169. Do. do........420 170. Condition of equilibrium, ...... 420 171, 172. Composition of forces, ...... 421 173. Do. do.......422 174. Lever of the first kind, ....... 422 175. Lever of the second kind, ...... 422 176. Lever of the third kind, . . . . . .423 177, 178. Action of the deltoid,......425 179. Action of the biceps, ....... 426 180. Insertion of fibres into tendon, ..... 426 181. Tendon of the great toe, ...... 428 182, 183. Action of intercostal muscles, ..... 428 184, 185. Action of intercostals ...... 429 186. Do. do........430 187. Action of biceps, . . . . . . .430 188. Combined muscular movements in rising, .... 431 189. Ligamentum nuchae, ....... 438 XXVI LIST OF ILLUSTRATIONS. FIG. PAGE 190. Lateral view of a dorsal vertebra, . *° 191. Lateral view of a lumbar vertebra, . *^y 192. Upper portion of thigh-bone, ..••■• 440 193. Movement of the foot in walking, . 445 194. Lateral view of the larynx, ..•••• 455 195. View of the interior of the left half of the larynx, to show the ventricle and laryngeal pouch, after Hilton, ..... 456 196. Larynx from above, after Willis, . 456 197. Scheme of the larynx, ....••• 457 198. Origin and distribution of the eighth pair of nerves, . . 458 199. Scheme of a bird-call, ....... 468 200. Do. do........469 201. Muscles of the head and face, . . . . . . 494 202. Distribution of the facial nerve, ..... 496 203. Plan of the branches of the fifth nerve, modified from a sketch by Sir C.Bell,........497 204. Paralysis of the facial nerve, after Marshall Hall, . . . 498 205. Broad laughter, after Sir Charles Bell, . . . .500 206. Faun weeping, after Sir Charles Bell, ..... 500 207. Physiognomy of melancholy, after Sir Charles Bell, . . . 505 208. Cilia, ........510 209. Vibratile or ciliated epithelium, ..... 510 210. Diagram of the stomach and intestines to show their course, . 513 211. Skull of the Polar bear, ...... 514 212. Skull of the cow........ 515 213. Salivary glands in situ, . . . . . .517 214. Cavity of the mouth, as shown by dividing the angles and turning off the lips, ........ 518 215. Pharynx seen from behind, ...... 518 216. Longitudinal section of oesophagus, near the pharynx, seen on its inside, 518 217. Section of the oesophagus, ...... 518 218. Stomach seen externally, ...... 520 219. Vertical and longitudinal section of stomach and duodenum, . 521 220. Section of a piece of stomach not far from pylorus, . . . 521 221. Tubular follicle of pig's stomach, after Wasmann, . . . 522 222. Vertical section of a stomach cell with its tubes, after Todd and Bow- man- ......... 522 223. Mucous membrane of the stomach, Todd and Bowman, . . 522 224. Front view of stomach, distended by flatus, with peritoneal coat turned ?ff*..........523 225. Distribution of the glossopharyngeal, pneumogastric and spinal acces- sory nerves, or the eighth pair, 226. Stomach of the ox, . 227. Section of the stomach of the ruminant animal, 228. Gastric apparatus of the turkey, 229. Interior of the gastric apparatus of the turkey, 230. Portion of the stomach and duodenum laid open to show their interior 529 231. Longitudinal section of the upper part of the jejunum extended under water*.........529 524 525 525 526 527 LIST OF ILLUSTRATIONS. xxvii FIG. PAGE 232. Muscular coat of the ileum, ...... 530 233. Distribution of capillaries in the villi of the intestine, after Berres, . 530 234. Distribution of capillaries around follicles of mucous membrane, after Berres, ........ 530 235. Bloodvessels of villi of the hare, after Dollinger, . . .531 236. Longitudinal section of the jejunum, showing the villi as seen under the microscope, ....... 531 237. One of the glandulae majores simplices of the large intestine, as seen from above, and also in a section, after Boehm, . . . 531 238. Follicles of Lieberklihn filled with tenacious white secretion in fever, after Boehm, ........ 532 239. Conglomerate gland of Brunner, magnified 100 times, after Boehm, . 532 240. Portion of one of the patches of Peyer's glands from the end of the ileum: highly magnified. The villi are also shown, after Boehm, . 533 241. Section of small intestine, containing some of the glands of Peyer, as shown under the microscope, ..... 533 242. Side view of intestinal mucous membrane of a cat, after Bendz, . 533 243. Muscular coat of the colon, as seen after the removal of the peritoneum, 535 244. Longitudinal section of the end of the ileum, and of the beginning of the large intestine, ....... 535 245. View of external parietes of abdomen, with the position of the lines drawn to mark off its regions, ..... 537 246. Reflections of the peritoneum, as shown in a vertical section of the body, . . . . . . . . . 539 247. Action of the lower jaw in prehension, .... 562 248. Gastric glands of the oesophagus magnified fifteen times, after Sir E. Home, ......... 591 249. Chyliferous vessels, ....... 637 250. Chyliferous apparatus, ....... 638 251. Section of intestinal villus, after Gerlach, .... 639 252. Intestinal villus with the commencement of a lacteal, after Krause, 639 253. Thoracic duct, after Wilson, ...... 641 254. Diagram of a lymphatic gland, showing the intra-glandular net-work, and the transition from the scale-like epithelia of the extra-glandular lymphatics, to the nucleated cells of the intra-glandular, after Good- sir, ......... 642 255. Portion of the intra-glandular lymphatic, showing along the lower edge the thickness of the germinal membrane, and upon it, the thick layer of glandular epithelial cells, after Goodsir, .... 642 256. Vessels and lymphatic glands of axilla, .... 663 257. Lymphatic vessels and glands of the groin of the right side, . 664 258. Lymphatics, ........ 666 259. Bloodvessels and lymphatics from the tail of the tadpole, . . 667 260. Termination of thoracic duct, ...... 673 261. Lymph heart of python bivittatus, after Weber, . . . 675 HUMAN PHYSIOLOGY. PROLEGOMENA. I. NATURAL BODIES. The extensive domain of Nature is divisible into three great classes: —Minerals, Vegetables, and Animals. This division was universally adopted by the ancients, and still prevails, especially amongst the un- scientific. When, however, we carefully examine their respective cha- racteristics, we discover, that the animal and the vegetable resemble each other in many essential particulars. This resemblance has given occasion to the partition of all bodies into two classes: the Inorganic, or those not possessing organs or instruments adapted for the perform- ance of special actions or functions, and the Organized, or such as possess this arrangement. In all ages, philosophers have attempted to point out a "Vast chain of being, which from God began, Nature's ethereal, human, angel, man, Beast, bird, fish, insect, what no eye can see, No glass can reach—" the links of which chain they have considered to be constituted of all natural bodies; passing by insensible gradations through the inorganic and the organized, and forming a rigid and unbroken series; and in which, they have conceived, "------Each moss, Each shell, each crawling insect, holds a rank, Important in the plan of Him who framed This scale of beings—holds a rank which, lost, Would break the chain, and leave behind a gap Which Nature's self would rue." Crystallization has been esteemed by them as the highest link of the inorganic kingdom; the lichen, which encrusts the stone, as but one link higher than the stone itself; the mushroom and the coral as the connecting links between the vegetable and the animal; and the immense space, which separates man—the highest of the mammalia— from his Maker, they have conceived to be occupied in succession by beings of gradually increasing intelligence. If, however, we investi- gate the matter minutely, we discover that many links of the chain appear widely separated from each other; and that, in the existing vol. I.—3 34 NATURAL BODIES. state of our knowledge, the catenation cannot be esteemed rigidly maintained.1 Let us inquire into the great characteristics of the dif- ferent kingdoms, and endeavour to describe the chief points in which living bodies differ from those that have never possessed vitality, and into the distinctions between organized bodies themselves. 1. DIFFEREXCE BETWEEN IXORGANIC AND ORGANIZED BODIES. Inorganic bodies possess the common properties of matter. Their elements are fixed under ordinary circumstances. Their study con- stitutes Physics, in its enlarged sense, or Natural Science. Organized bodies have properties in common with inorganic, but they have like- wise others superadded, which control the first in a singular manner. They are beings, whose elements are undergoing constant mutation, and the sciences treating of their structure and functions are Anatomy and Physiology. They differ from each other in— 1. Origin.—Inorganic bodies are not born: they do not arise from a parent: they spring from the general forces of matter,—the parti- cles being merely in a state of aggregation, and their motions regulated by certain fixed and invariable laws. The animal and the vegetable, on the other hand, are products of generation; they must spring from beings similar to themselves; and they possess the force of life, which controls the ordinary forces of matter. Yet it has been sup- posed, that they are capable of creating life; in other words, that a particular organization presupposes life. This is not the place for entering into the question of generation. It will be sufficient at present to remark, that in the upper classes of animals, the necessity of a pa- rent cannot be contested; the only difficulty that can possibly arise regards the very lowest classes; and analogy warrants the conclusion, that every living being must spring from an egg or a seed. 2. Shape.—The shape of inorganic bodies is not fixed in a deter- minate manner. It is true, that by proper management every mineral can be reduced to a primitive nucleus, which is the same in all minerals of like composition; still, the shape of the mineral, as it presents itself to us, differs. Carbonate of lime, for example, although it may always be reduced to the same primitive nucleus, assumes various appearances; —being sometimes rhomboidal; at others, in regular hexahedral prisms; —in solids, terminated by twelve scalene triangles, or in dodecahedrons, whose surfaces are pentagons. In organized bodies, on the contrary, the shape is constant. Each animal and vegetable has the one that characterizes its species, so that no possible mistake can be indulged; and this applies not only to the whole body, but to every one of its parts, numerous as they are. 3. Size.—The size of an inorganic body is by no means fixed. It may be great, or small, according to the quantity present of the parti- cles that have to form it. A crystal, for example, may be minute or the contrary, according to the number of saline particles in the solu- tion. On the other hand, organized bodies attain a certain size__at 1 Fleming's Philosophy of Zoology, i. 4. Edinburgh, 1822. INORGANIC AND ORGANIZED. 35 times by a slow, at others by a more rapid growth,—but in all cases the due proportion is preserved between the various parts,—between the stem and the root, the limb and the trunk. Each vegetable and each animal has its own size, by which it is known; and although we occasionally meet with dwarf or gigantic varieties, these are unfrequent, and mere exceptions establishing the position. 4. Chemical character.—Great difference exists between inorganic and organized bodies in this respect. In the mineral kingdom are found all the elementary substances, or those which chemistry, at pre- sent, considers simple; amounting to at least sixty-three. They are as follows:—Non-metallic bodies. Oxygen, hydrogen, nitrogen, sulphur, selenium, phosphorus, chlorine, iodine, bromine, fluorine, carbon, boron, silicon. Metals. Potassium, sodium, lithium, calcium, magnesium, barium, strontium, aluminium, glucinium, zirconium, yttrium, thorium, iron, manganese, zinc, cadmium, lead, tin, copper, bismuth, mercury, silver, gold, platinum, rhodium, palladium, osmium, iridium, nickel, cobalt, uranium, cerium, antimony, arsenic, chromium, molybdenum, tungsten, columbium, tellurium, titanium, vanadium, lantanium, didy- mium, erbium, terbium, pelopium, niobium, ruthenium, norium, and ilmenium. In the organized, a few only of these elements of matter are met with, viz., oxygen, hydrogen, azote, carbon, sulphur, phosphorus, chlorine, fluorine, potassium, sodium, calcium, silicium, aluminium, iron, manganese, titanium, and arsenic. The composition of inorganic bodies is more simple; several consist of but one element; and, when composed of more, the combination is rarely higher than ternary. Organized bodies, on the other hand, are never simple, nor even binary. They are always at least ternary or quaternary. The simplest vegetable consists of a union of oxygen, carbon, and hydrogen; the simplest animal, of oxygen, hydrogen, carbon, and nitrogen. The composition of the mineral, again, is constant. Its elements have entirely satisfied their affinities; and all remains at rest. In the organized kingdom, the affinities are not satisfied; compounds are formed to be again decomposed; and this happens from the earliest period of foetal formation till the cessation of life : all is in commotion, and the chemical character of the corporeal fabric incessantly undergoing modification. This applies to every organized body; and, accordingly, change of some kind is essential to our idea of active life. In the case of the seed, which has remained unaltered for centuries, and subse- quently vegetates under favourable circumstances, life may be considered to be dormant or suspended. It possesses vitality, or the power of being excited to active life under favouring influences. In chemical nomenclature, the term element has a different accepta- tion, according as it is applied to inorganic or organic chemistry. In the former, it means a substance, which, in the present state of science, does not admit of decomposition. We say, "in the present state of the science," for several bodies, now esteemed compound, were, not many years ago, classed amongst the simple or elementary. It is not much more than thirty years since the alkalies were found to be com- posed of two elements. Previously, they were considered simple. In 36 NATURAL BODIES. the animal and the vegetable, we find substances, also called elements, but with the epithet organic prefixed, because they are only found in organized bodies; and are therefore the exclusive products ot organi- zation and life. For example, in both animals and vegetables we meet with oxygen, hydrogen, carbon, nitrogen, and different metallic sub- stances : these are chemical or inorganic elements. We further meet with albumen, gelatin, fibrin, osmazome, &c, substances which consti- tute the various organs, and have, therefore, been termed organic ele- ments or compounds of organization; yet they are capable of decom- position ; and in one sense, therefore, not elementary. In the inorganic body, all the elements, that constitute it, are formed by the agency of general chemical affinities; but, in the organized, the formation is produced by the force that presides over the formation of the organic elements themselves,—the force of life. Hence, the chemist is able to recompose many inorganic bodies; whilst the products of organization and life set his art at defiance. The different parts of an inorganic body enjoy an existence inde- pendent of each other; whilst those of the organized are materially dependent. No part can, indeed, be injured without the mass and the separated portion being more or less affected. If we take a piece of marble, which is composed of carbonic acid and lime, and break it into a thousand fragments, each portion will be found to consist of carbonic acid and lime. The mass will be destroyed; but the pieces will not suffer from the disjunction. They will continue as fixed and unmodified as at first. Not so with an organized body. If we tear the branch from a tree, the stem itself participates more or less in the injury; the detached branch speedily undergoes striking changes; it withers; becomes shrivelled; and, in the case of the succulent vege- table, undergoes decomposition; certain of its constituents, no longer held in control by vital agency, enter into new combinations, are given off in the form of gas, and the remainder sinks to earth. Changes, no less impressive, occur in the animal when a limb is separated from the body. The parent trunk suffers ; the system recoils at the first infliction of the injury, but subsequently arouses itself to a reparatory effort,—at times with such energy as to destroy its own vitality. The separated limb, like the branch, is given up, uncontrolled, to new affinities; and putrefaction soon reduces the mass to a state in which its previously admirable organization is no longer perceptible. Some of the lower classes of animals may, indeed, be divided with im- punity; and with no other effect than that of multiplying the animal in proportion to the number of sections ; but these cases are exceptions; and we may regard the destructive process,—set up when parts of organized bodies are separated,—as one of the best modes of distinction between the inorganic and organized classes. 5. Texture.—In this respect the inorganic and organized differ con- siderably,—a difference which has given rise to their respective appel- lations. To the structure of the latter class only can the term texture be with propriety applied. If we examine a vegetable or animal sub- stance with attention, we find, that it has a regular and determinate arrangement or structure; and readily discover, that it consists of va- INORGANIC AND ORGANIZED. 37 rious parts;—in the vegetable, of wood, bark, leaves, roots, flowers, &c.; and in the animal, of muscles, nerves, vessels, &c.; all of which appear to be instruments or organs for special purposes in the economy. Hence, the body is said to be organized, and the result, as well as the process, is often called organization. Properly, organization means the process by which an organized being is formed; organism, the result of such process, or organic structure. The particles of matter in an organized body, in many instances, constitute fibres, which interlace and intersect each other in all direc- tions, and form a spongy areolar texture or tissue, of which the various organs of the body are composed. These fibres, and indeed every or- ganized structure, are considered by modern histologists to be formed originally from cellgerms or cytoblasts: the resulting cells assuming an arrangement appropriate to the particular tissue. " A texture," says Mr. Goodsir,1 " maybe considered either by itself, or in connexion with the parts which usually accompany it. These subsidiary parts may be entirely removed without interfering with the anatomical constitution of the texture. It is essentially non-vascular;—neither vessels nor nerves entering into its intimate structure. It possesses in itself those powers by which it is nourished, produces its kind, and performs the actions for which it is destined, the subsidiary or superadded parts sup- plying it with materials, which it appropriates by its own inherent powers, or connecting it in sympathetic and harmonious action with other parts of the organism to which it belongs. In none of the tex- tures are these characters more distinctly seen than in the osseous. A well-macerated bone is one of the most easily made, and at the same time one of the most curious of anatomical preparations. It is a per- fect example of a texture completely isolated; the vessels, nerves, mem- branes, and fat, are all separated; and nothing is left but the non- vascular osseous substance." In the inorganic substance the mass is homogeneous; the smallest particle of marble consists of carbonic acid and lime; and all the par- ticles concur alike in its formation and preservation. Lastly, while an inorganic body, of a determinate species, has always a fixed composition, the living being, although constituting a particular species, may present individual differences, which give rise in the animal, to various temperaments, constitutions, $c. 6. Mode of preservation.—Preservation of the species is, in organ- ized bodies, the effect of reproduction. As regards individual preser- vation, that of the mineral is dependent upon the same actions that effected its formation; on the persistence of the affinities of cohesion and combination that united its various particles. The animal and the vegetable, on the other hand, are maintained by a mechanism peculiar to themselves. From the bodies surrounding them they lay hold of nutritious matter, which, by a process of elaboration, they assimilate to their own composition; at the same time, they are constantly absorbing 1 Anatomical and Pathological Observations, p. 64, Edinburgh, 1845. See also Schwann, Microscopical Researches into the Accordance in the Structure and Growth of Animals and Plants; translated by Henry Smith. Sydenham Society edit. Lond. 1847. 38 NATURAL BODIES. or taking up particles of their own structure, and throwing them off. The actions of composition and decomposition are constant whilst life persists; although subject to particular modifications at different pe- riods of existence, and under different circumstances. Again:—the inorganic and organized are alike subject to changes during their existence; but the character of these changes, in the two classes, differs essentially. The mineral retains its form, unless acted upon by some mechanical or chemical force. Within, all the particles are at rest, and no internal force exists, which can subject them to modification. There is no succession of conditions that can be termed ages. How different is the case with organized bodies! Internally, there is no rest; from birth to death all is in a state of activity. The plant and the animal are subject to incessant changes. Each runs through a succession of conditions or ages. We see it successively de- velope its structure and functions, attain maturity, and finally decay. Characteristic differences likewise exist in the external conformation of the beings of the two divisions, as well as in their mode of increase. Inorganic bodies have no covering to defend them; no exterior enve- lope to preserve their form; a stone is the same at its centre as at its circumference; whilst organized bodies are protected by an elastic and extensible covering, differing from the parts beneath, and inservient to valuable purposes in the economy. Every change to which an inorganic body is liable must occur at its surface. It is there that the particles are added or abstracted when it experiences increase or diminution. Increase—for growth it can scarcely be termed—takes place by accretion or juxtaposition, that is, by the successive application of fresh particles upon those that form the nucleus ; and diminution in bulk is produced by the removal of the external layers or particles. In organized substances, increase or growth is caused by particles deposited internally, and diminution by particles subtracted from within. We see them, likewise, under two conditions, to which there is nothing similar in the mineral kingdom— health, and disease. In the former, the functions are executed with freedom and energy; in the latter, with oppression and restraint. 7. Termination.—Every body, inorganic or organized, may cease to exist, but the mode of cessation varies greatly in the two classes. The mineral is broken down by mechanical violence; or it ceases to exist in consequence of modifications in the affinities, which held it concrete. It has no fixed duration; and its existence may be terminated at any moment, when the circumstances, that retained it in aggregation, are destroyed. The vegetable and the animal, on the other hand, carry on their functions for a period only which is fixed and determinate for each species. For a time, new particles are deposited internally. The bulk is augmented, and the external envelope distended, until maturity or full developement is attained ; but, after this, decay commences * the functions are exerted with gradually diminishing energy; the fluids decrease in quantity; and the solids become more rigid,—circumstances premonitory of the cessation of vitality. This term of duration is different in different species. Whilst many of the lower classes of ani- ANIMALS AND VEGETABLES. 39 mals and vegetables have but an ephemeral existence, some of the more elevated individuals of the two kingdoms outlive a century. 8. Motive forces.—Lastly, observation has satisfactorily proved, that there are certain forces, which affect matter in general, inorganic as well as organized; and that, in addition to these, organized bodies possess a peculiar force or forces, which modify them in a remarkable manner. Hence, we have general forces; and special or vital; the first acting upon all matter, the dead and the living, and including the forces of gravitation, cohesion, chemical affinity, &c.; the latter appertaining exclusively to living beings. Such are the chief distinctions to be drawn between the two great divisions of natural bodies; the inorganic and the organized. By the comparison which has been instituted, the objects of physiology have been indicated. To inquire into the mode in which a living being is born, nourished, reproduced, and dies, is the legitimate object of the science. We have, however, entered only into a comparison between the inorganic and the organized. The two divisions constituting the latter class differ also materially from each other. Into these differ- ences we shall now inquire. 2. DIFFERENCE BETWEEN ANIMALS AND VEGETABLES. The distinctions between the divisions of organized bodies are not so rigidly fixed, or so readily appreciated, as those between the inorganic and the organized. There are certain functions possessed by both; hence called vegetative, plastic, or organic,—nutrition and reproduction, for example ; but vegetables are endowed with these only. All organ- ized bodies must have the power of assimilating foreign matters to their own substance, and of producing a living being similar to themselves; otherwise, the species, having a limited duration, would perish. In addition to these common functions, animals have sensation and volun- tary motion; by the possession of which they are said to be animated. Hence, they are termed animals, and the condition is called animality. This division of the functions into animal and organic has been adopted, with more or less modification, by most physiologists. Between animals and vegetables, situate high in their respective scales, no confusion can exist. The characters are obvious at sight. No one can confound the horse with the oak; the butterfly with the potato. It is on the lower confines of the two kingdoms, that we are liable to be deceived. Many of the zoophytes have alternately been considered vegetable and animal; but we are generally able to classify any doubtful substance with accuracy; and the following are the prin- cipal points of difference. 1. Composition.—It was long supposed, that the essential difference between animal and vegetable substances consists in the former con- taining nitrogen; whilst the latter do not. Modern researches have, however, satisfactorily shown, that the organized portions of animals and vegetables are essentially alike; and consist of the four elements, —carbon, oxygen, hydrogen, and nitrogen; whilst the unorganized— as the fat of the animal, and the starch of the vegetable—are composed of three elements only—carbon, oxygen, and hydrogen. Still, their 40 NATURAL BODIES. intimate composition must vary greatly; for, when burning, the animal substance is readily known from the vegetable;—a fact, which, as Dr. Fleming1 has remarked, is interesting to the young naturalist, if un- certain to which kingdom to refer any substance met with in his re- searches. The smell of a burnt sponge, of coral, or other zoophytic animal, is so peculiar, that it can scarcely be mistaken for that of a vegetable body in combustion. According to Mulder,2 there is this real difference between plants and animals in composition, that cellulose (C24H21021) forms the principal part of the cellular mass in plants; whilst in animals the primary material is gelatin (C13H10N2Os); and to this rule, he says, no exception has yet been discovered either among animals or plants. 2. Texture.—In this respect, important differences are observable. Both animals and vegetables consist of solid and fluid parts. In the former, however, the fluids bear a large proportion: in the latter, the solids. This is the cause, why decomposition occurs so much more rapidly in the animal than in the vegetable; and in the succulent more than in the dry vegetable. If we analyze the structure of the vege- table, we cannot succeed in detecting more than one elementary tissue, which is vesicular or areolar, or arranged in vesicles or areolae, and appears to form every organ of the body; whilst, in the animal, we discover at least three of these anatomical elements, the areolar— analogous to that of the vegetable;—the muscular, and the nervous. The vegetable again has no great splanchnic cavities containing the chief organs of the body. It has a smaller number of organs, and none that are destined for sensation or volition; in other words, no brain, no nerves, no muscular system ; and the organs of which it con- sists are simple, and readily convertible into each other. But these differences in organization, striking as they may appear, are not sufficient for rigid discrimination, as they are applicable only to the upper classes of each kingdom. In many vegetables, the fluids appear to preponderate over the solids; numerous animals are devoid of muscular and nervous tissues, and apparently of vessels and distinct organs; whilst MM. Dutrochet,3 Brachet,4 and others,5 admit the existence of a rudimental nervous system even in vegetables. # 3. Sensation and voluntary motion.—There is one manifest distinc- tion between animals and vegetables. Whilst the latter receive their nutrition from the objects around them—irresistibly and without voli- tion, or the participation of mind; and whilst the function of repro- duction is effected without the union of the sexes, both volition and sen- sation are necessary for the nutrition of the former, and for acts that are requisite for the reproduction of the species. Hence, the necessity 1 Philosophy of Zoology, i. 41. Edinburgh, 1822. 2 The Chemistry of Animal and Vegetable Physiology; translated by Fromber* n 01 Edinburgh and London, 1849. . ' ^wmDerg, p. yi. 3 Recherches Anatomiques et Physiologiques sur la Structure Intime des A™,™ . j Vegetaux, et sur leur Motilite. Paris, 1824? Ammaux, et des * Recherches Experimentales sur les Fonctions du Systeme Nervemr f}*r,„r~ • o 2d edit. Paris et Lyons, 1837. ^anghonnaire, &c. 1833ir J' R Smhh' Intr°duCli0n t0 BotaDJr» 7th edit' hy Sir W- J- Hooker, p. 40. Lond. ANIMALS AND VEGETABLES. 41 of two faculties or functions in the animal, that are wanting in the vegetable,—sensibility, or the faculty of consciousness and feeling ; and motility, or the power of moving at will the whole body or any of its parts. Vegetables are possessed of spontaneous, but not of voluntary motion. Of the former we have numerous examples in the direction of the branches and upper surfaces of the leaves, although repeatedly disturbed, to the light; and in the unfolding and closing of flowers at stated periods of the day. This, however, is distinct from the sensi- bility and motility that characterize the animal. By sensibility man feels his own existence,—becomes acquainted with the universe,—ap- preciates the bodies that compose it; and experiences all the desires and inward feelings that solicit him to the performance of those ex- ternal actions, which are requisite for his preservation as an individual, and as a species; and by motility he executes those external actions which his sensibility may suggest to him. By some naturalists it has been maintained, that those plants, which are borne about on the waves, and fructify in that situation, exhibit examples of the locomotility, which is described as characteristic of the animal. One of the most interesting novelties in the monotonous occurrences of a voyage across the Atlantic towards the Gulf of Flo- rida is the almost interminable quantity of Fucus natans, Florida weed or Gulf weed, with which the surface of the ocean is covered. But how different is this from the locomotion of animals! It is a subtlety to conceive them identical. The weed is passively and uncon- sciously borne whithersoever the winds and the waves may urge it; whilst animal locomotion requires the direct agency of volition, of a nervous system that can excite, and of muscles that can act under such excitement. The spontaneity and perceptivity of plants must also be explained in a different manner from the elevated function of sensibility on which we shall have to dwell. These properties must be referred to the fact of certain vegetables being possessed of the faculty of contracting on the application of a stimulus, independently of sensation or conscious- ness. If we touch the leaf of the sensitive plant. Mimosa pudica, the various leaflets collapse in rapid succession. In the barberry bush, Berberis vulgaris, we have another example of the possession of this faculty. In the flower, the six stamens, spreading moderately, are shel- tered under the concave tips of the petals, till some extraneous body, as the feet or trunk of an insect in search of honey, touches the inner part of each filament, near the bottom. The susceptibility of this part is such, that the filament immediately contracts, and strikes its anther, full of pollen, against the stigma. Any other part of the filament may be touched without this result, provided no concussion be given to the whole. After a while, the filament retires gradually, and may be again stimulated ; and when each petal, with its annexed filament, has fallen to the ground, the latter, on being touched, shows as much sensibility as ever.1 These singular effects are produced by the power of contractility or 1 Sir J. E. Smith's Introduction to Botany, p. 325. 42. NATURAL BODIES. irritability, the nature of which will fall under consideration here- after. It is possessed equally by animals and vegetables, and is essen- tially organic and vital. This power, we shall see, needs not the intervention of volition: it is constantly exerted in the animal without consciousness, and therefore necessarily without volition. Its existence in vegetables does not, consequently, demonstrate that they are pos- sessed of consciousness. 4. Nutrition.—A great difference exists between plants and animals in this respect. The plant, being fixed to the soil, cannot search after food. It must be passive ; and obtain its supplies from the materials around, and in contact with it; and the absorbing vessels of nutrition must necessarily open on its exterior. In the animal, on the other hand, the aliment is scarcely ever found in a state fit for absorption: it is crude, and in general—Ehrenberg1 thinks always—requires to be received into a central organ or stomach, for the purpose of under- going changes, by a process termed digestion, which adapts it for the nutrition of the individual. The absorbing vessels of nutrition arise, in this case, from the internal or lining membrane of the alimentary tube. The analogy that exists between these two kinds of absorption is great, and had not escaped the attention of the ancients:—Quem- admodum terra arboribus, ita animalibus ventriculus sicut humus," was an aphoristic expression of universal reception. With similar feelings, Boerhaave asserts, that animals have their roots of nutrition in their intestines; and Dr. Alston2 has fancifully termed a plant an inverted animal. After all, however, the most essential difference consists in the steps that are preliminary to the reception of food. These, in the animal, are voluntary,—requiring prehension; often locomotion; and always consciousness. 5. Reproduction.—In this function we find a striking analogy be- tween animals and vegetables; but differences exist, which must be referred to the same cause that produced many of the distinctions already pointed out,—the possession, by the animal, of sensibility and locomotility. For example, every part of the generative act, as before remarked, is, in the vegetable, without the perception or volition of the being:—the union of the sexes, fecundation, and the birth of the new individual are alike automatic. In the animal, on the other hand, the approximation of the sexes is always voluntary and effected consciously: —the birth of the new individual being not only perceived, but some- what aided by volition. Fecundation alone is involuntary and irre- sistible. Again, in the vegetable the sexual organs do not exist at an early period; and are not developed until reproduction is practicable. They are capable of acting for once only, and perish after fecundation; and if the plant be vivacious, they fall off after each reproduction, and are annually renewed. In the animal, on the contrary, they exist from the earliest period of foetal development, survive repeated fecundations and continue during the life of the individual. 1 Edinb. New Philosophical Journal, for Sept. 1831; and Jan. 1838, p. 232. * Tirocinium Botanicum Edinburgense, 8vo., Edinb. 1753. MATERIAL COMPOSITION OF MAN. 43 Lastly, the possession of sensibility and locomotility leads to other characteristics of animated beings. These functions are incapable of constant, unremitting exertion. Sleep, therefore, becomes necessary. The animal is also capable of expression, or of language, in a degree proportionate to the extent of his sensibility, and of his power over the beings that surround him. But these differences in function are not so discriminate as they may appear at first. There are many animals, that are as irresistibly at- tached to the soil as the vegetables themselves. Like the latter, they must, of necessity, be compelled to absorb their food in the state in which it is presented to them. Sensibility and locomotility appear, in the zoophyte, to be no more necessary than in the vegetable. No nervous, no muscular system is required; and, accordingly, none can be traced in them; whilst many of those spontaneous motions of the vegetable, to which allusion has been made, have been considered by some to indicate the first rudiments of sensibility and locomotility; and Linnaeus1 has regarded the closure of the flowers towards night as the sleep, and the movements of vegetables, for the approximation of the sexual organs, as the marriage, of plants. II. GENERAL PHYSIOLOGY OF MAN. The observations made on the differences between animals and vege- tables have anticipated many topics, that would require consideration under this head. These general properties, which man possesses along with other animals, have been referred to in a cursory manner. They will now demand a more special investigation. 1. MATERIAL COMPOSITION OF MAN. The detailed study of human organization is the province of the anatomist,—of its intimate composition, that of the chemist. In ex- plaining the functions executed by the various organs, the physiologist will frequently have occasion to trench upon both. The bones, in the aggregate, form the skeleton. The base of the skeleton is a series of vertebrae, with the skull as a capital,—itself re- garded as a vertebra. This base is situate on the median line through the whole trunk, and contains a cavity, in which are lodged the brain and spinal marrow. On each side of this, other bones, which by some have been called appendices, are arranged in pairs. Upon the skeleton are placed muscles, for moving the different parts of the body; and for changing its situation with regard to the soil. The body is divided into trunk and limbs. The trunk, which is the principal portion, is composed of three splanchnic cavities, the abdomen, thorax, and head, situate one above the other. They contain the most important organs of the body,—those that effect the functions of sensibility, digestion, respiration, circulation, &c. The head comprises the face, in which are the organs of four of the senses—sight, hearing, smell, and taste,— and the cranium, which lodges the brain—the organ of the mental manifestations, and the most elevated part of the nervous system. The 1 Amcenit. Academ., torn. iv. 44 MATERIAL COMPOSITION OF MAN. thorax or chest contains the lungs—organs of respiration—and the heart, the central organ of the circulation. The abdomen contains the principal organs of digestion, and (if we include in it the pelvis), those of the urinary secretion and of generation. Of the limbs, the upper, suspended on each side of the thorax, are instruments of prehension; and are terminated by the hand, the great organ of touch. The lower are beneath the trunk; and are agents for supporting the body, and for locomotion. Vessels, emanating from the heart, are distributed to every part,—conveying to them the blood necessary for their life and nutrition: these are the arteries. Other vessels communicate with them, and convey the blood back to the heart—the veins; whilst a third set arise in the tissues, and convey into the circulation, by a particular channel, a fluid called lymph—whence they derive the name lymphatics. Nerves, communicating with the great central masses of the nervous system, are distributed to every part; and lastly, a membrane or layer, possessed of acute sensibility—the skin.—serves as an outer envelope to the whole body. It was before observed, that two kinds of elements enter into the composition of the body—the chemical or inorganic; and the organic, which are compound, and formed only under the force of life. The chief Chemical or Inorganic Elements, met with, are—oxygen, hydrogen, carbon, nitrogen, phosphorus, calcium; and, in smaller quan- tity, sulphur, iron, manganese, calcium, silicium, aluminium, chlorine; also, sodium, magnesium, &c. &c. 1. Oxygen.—This is widely distributed in the solids and fluids ; and a constant supply of it from the atmosphere is indispensable to animal life. It is almost always found combined with other bodies; often in the form of carbonic acid,—that is, united with carbon. In a separate state it is met with in the air-bag of fishes, in which it is found varying in quantity, according to the species, and the depth at which the fish has been caught. 2. Hydrogen.—This gas occurs universally in the animal kingdom. It is a constituent of all the fluids, and of many of the solids; and is generally in a state of combination with carbon. In the human intes- tines it has been found pure, as well as combined with carbon and sul- phur. 3. Carbon.—This substance is met with under various forms, in both fluids and solids. It is. most frequently found under that of carbonic acid. Carbonic acid has been detected in an uncombined state in urine by Prout; and in the blood by Vogel.1 It exists in the intestines of animals; but is chiefly met with in animal bodies, in combination with the alkalies or earths; and is emitted by all animals in the act of re- spiration. 4. Nitrogen.—This gas is likewise widely distributed as a component of animal substances, and especially of the tissues. It occurs in an uncombined state, in the swimming-bladder of certain fishes. 5. Phosphorus is an essential constituent of neurine; and is found united with oxygen, in the state of phosphoric acid, in many of the ' Annals of Philosophy, vii. 56. MATERIAL COMPOSITION OF MAN. 45 solids and fluids. It is this acid that is combined with the earthy mat- ter of bones; and with potassa, soda, ammonia, and magnesia, in other parts. It is supposed to give rise to the luminousness of certain ani- mals—as of the firefly, Pyrosoma Atlanticum, &c.—but nothing pre- cise is known on this subject. 6. Calcium.—This metal is found in the animal economy only in the state of oxide—lime ; and it is generally united with phosphoric or car- bonic acid. It is the earth, of which the hard parts of animals are constituted. 7. Sulphur is not met with extensively in animal solids or fluids; nor is it often found free, but usually in combination with oxygen united to soda, potassa, or lime. It seems to be an invariable concomitant of albumen; and is found in the intestines, in the form of sulphuretted hydrogen; and as an emanation from fetid ulcers. 8. Iron.—This metal has been detected in the colouring matter of the blood; in bile, and in milk. In the first of these fluids it was, for a long time, considered to be in the state of phosphate or sub-phosphate. Berzelius1 showed, that this was not the case; that the ashes of the colouring matter always yielded oxide of iron in the proportion of l-200th of the original mass. That distinguished chemist was, how- ever, unable to detect the condition in which the metal exists in the blood; and could not discover its presence by any of the liquid tests. Subsequently, Engelhart showed, that the fibrin and albumen of the blood, when carefully separated from colouring particles, do not contain a trace of iron; whilst he could procure it from the red corpuscles by incineration. He also succeeded in proving its existence in the red corpuscles by liquid tests ; and his experiments were repeated, with the same results, by Rose of Berlin.2 In milk, iron seems to be in the state of phosphate. 9. Manganesium has been found in the state of oxide, along with iron, in the ashes of the hair; in bones, and blood, and also in gall- stones, and in the blood. 10. Copper and lead.—It was conceived by M. Devergie, that copper and lead may exist naturally in the tissues ;3 but MM. Flandin and Danger, and a commission of the Acadernie Royale de Me'decine of Paris, were unable to confirm the existence of copper; and the results of the investigations of Professor F. de Cattanei di Momo,4 of Pavia, seem to prove the non-existence of lead also. M. Barse, however, in a paper read before the Royal Academy of Sciences of Paris, in August, 1843, states, that he found both metals in the bodies of two persons, to whom they could not have been given for poisons. The researches of Signor Cattanei di Momo appeared to prove that these metals do not exist in the bodies of new-born children or infants; and M. J. Rossignon has offered a solution as to the probable source of the copper, as he found it not only in the blood and muscles of the dog, but in 1 Medico Chirurgical Transact., vol. iii. 3 Turner's Chemistry, fifth ed., p. 963. London, 1834. 3 Bullet, de l'Academ. Royale de Medecine, 19 Fevr., 1839. 4 Annali Universal! di Medicina, Aprile, 1840; cited in British and Foreign Medical Re- view, Jan., 1841, p. 226. 46 MATERIAL COMPOSITION OF MAN. many articles of vegetable and animal food; in gelatin from bones, for example, in sorrel, chocolate, bread, coffee, succory, madder, and sugar. The ashes obtained from starch sugar yielded 4 per cent, of copper; those of gelatin, 0*03 per cent.; and those of bread, 0-005 to 0*008 per cent.1 It is now generally considered to be present in the human liver,2 and M. E. Millon3 asserts, that human blood invariably contains lead, copper, silica, and manganese. 11. Silicium.—Silica is found in the hair, bones, blood, urine, and in urinary calculi. 12. Chlorine.—In combination with hydrogen, and forming chloro- hydric acid, chlorine is met with in most of the animal fluids. It is generally united with soda. Free chlorohydric acid has also been found by Dr. Prout4 in the stomach of the rabbit, hare, horse, calf, and dog; and he has discovered the same acid in the sour matter ejected from the stomachs of those labouring under indigestion. Mr. Children, and Messrs. Tiedemann and Gmelin,5 made similar observations; and Pro- fessor Emmet and the author6 found it in considerable quantity in the healthy gastric secretions of man. 13. Fluorine.—This simple substance has been found combined with calcium—fluoride of calcium—in the enamel of the teeth, bones, and urine. 14. Sodium.—Oxide of sodium, soda, forms part of all the fluids. It has never been discovered in a free state; but is united (without an acid), to albumen. Most frequently, it is combined with chlorine, and phosphoric acid; less frequently, with lactic, carbonic, and sulphuric acids. Chloride of sodium is contained in most of the animal secre- tions ; and from its decomposition may result the chlorohydric acid of the gastric juice, and a part the soda of the bile and other fluids. 15. Potassium.—The oxide, potassa, is found in many animal fluids, but always united with acids—sulphuric, chlorohydric, phosphoric, &c. It is much more common in the vegetable kingdom; and hence one of its names—vegetable alkali. 16. Magnesium.—The oxide, magnesia, exists sparingly in bones, and in some other parts; but always in combination with phosphoric acid, and appears to be always associated with calcium. 17. Aluminium.—Alumina is said by Morichini to exist in the ena- mel of the teeth. Fourcroy and Vauquelin found it in the bones ; and John, in white hairs. According to Schlossberger, it is in the flesh of fishes.7 18. Titanium.—Dr. Rees affirms, that he detected it in salts ob- tained from the supra-renal capsules. 1 Lond. Med. Gaz., Dec. 1, 1843, from Gazette Medicale de Paris, and Mr. Paget, Rep. on Anatomy and Physiology, 1843-4, in Brit, and For. Med. Rev., Jan., 1845, p. 249. 2 Kirkes and Paget, Manual of Physiology, Amer. edit., p. 29, Philad., 1849. 3 Comptes Rendus, Paris, 1848. 4 Philosoph. Transact, for 1824, p. 45. s Recherches Experimentales, &c, sur la Digestion, trad, par A. G. L. Jourdan Art 4 r> 94, Paris, 1827. ' * ■ > P* 6 See under the head of " Digestion," and the author's Human Health, p. 191, Philadelphia 1844. 7 Henle, Allgemeine Anatomie, s. 4. Leipz., 1841, or Jourdan"s translation i 2 Pnr;a ORGANIC ELEMENTS. 47 19. Arsenic.—It was asserted by M. Orfila, that arsenic exists natu- rally in the human body; and that it is a normal constituent of human bones. Subsequent experiments, however, performed by M. Orfila himself, have shown that there was fallacy in his first observations.1 Organic Elements, proximate principles or compounds of organ- ization, are combinations of two or more of the elementary substances, in definite proportions. Formerly, four only were admitted—gelatin, fibrin, albumen, and oil. Of late, however, organic chemistry has pointed out others, which are divided into two classes,—first, those that contain nitrogen, as albumen, gelatin, fibrin, osmazome, mucus, casein, urea, uric acid, red colouring principle of the blood, yellow colouring principle of the bile, &c; and secondly, those that do not contain azote, —as olein, stearin, the fatty matter of the brain and nerves, acetic, oxalic, benzoic, and lactic acids, sugar of milk, sugar of diabetes, pi- cromel, colouring principle of the bile, and that of other solids and liquids, kc. a. Organic Elements that contain Nitrogen. 1. Protein.—Modern researches appear to have shown, that the chief proximate principles of animal tissues, and those that have been regarded as highly nutritious among vegetables, have almost identically the same composition ; and are modifications of a principle to which Mulder—its discoverer—gave the name Protein. If animal albumen, fibrin, or casein, be dissolved in a moderately strong solution of caust'c potassa, and the solution be exposed for some time to a high tempera- ture, these substances are decomposed. The addition of acetic acid to the solution causes, in all three, the separation of a gelatinous trans- lucent precipitate, which has exactly the same character and composi- tion, from whichsoever of the solutions it is obtained. It may be pro- cured, too, from globulin of blood, and from vegetable albumen.2 The chemical relations of protein, especially in regard to oxygen, are full of interest. The products of its oxidation, binoxide and trit- oxide of protein, occur constantly in the blood. They are formed in the lungs from fibrin; which, in a moist state, possesses the property of absorbing oxygen. Fibrin, oxidized in the lungs, is, according to Mulder, the principal—if not the only—carrier of the oxygen of the air in the blood to the tissues; and it is from this substance especially, • that the secretions are formed. In inflammatory conditions, a much larger quantity of protein in an oxidized state is contained in the blood than in health; and this, according to Mulder, gives occasion to the buffy coat.3 The following substances may be regarded as modifications or com- binations of protein. They are composed of it and of a small quantity of phosphorus, or of sulphur, or both.4 1 Rapport de l'Academie Royale de Medecine, Juillet, 1841; Taylor's Medical Jurispru- dence, by Dr. Griffith, p. 133, Philad., 1845; and Simou, Animal Chemistry, Sydenham Soc. edit., p. 4, Lond., 1845, or Amer. edit., Philad., 1845. ' Liebig, Animal Chemistry, Gregory's and Webster's edit., p. 100. Cambridge, 1842. 3 Simon's Animal Chemistry, Sydenham Soc. edit., p. 12, London, 1845; or American edit., Philadelphia, 1845. 4 Henle, op. cit., p. 31. 48 MATERIAL COMPOSITION OF MAN. a. Albumen.—This is one of the most common organic constituents; and appears under two forms—liquid and concrete. In its purest state, the former is met with in white of egg—whence its name; in the serum of the blood; the lymph of the absorbents; the serous fluid of the great splanchnic cavities and of the areolar membrane; and in the synovial secretion. It is colourless and transparent; without smell or taste; and is coagulated by acids, alcohol, ether, metallic solutions, infusion of galls, and by a temperature of 158° Fahrenheit. ^ A very dilute solution, however, does not become turbid until it is boiled. It is excreted by the kidneys in large quantities, in the disease, which, owing to its presence in the urine, has been called Albuminuria. Concrete, coagulated, or solid albumen, is white; tasteless; and elastic; insoluble in water, alcohol, or oil; but readily soluble in alkalies. Albumen is always combined with soda. It exists, in abundance— both the liquid and concrete—in different parts of the animal body. Hair, nails, and horn consist of it; and it is, in some form or other, a constituent of many tumours. In the advanced chyliferous vessels albumen is found in quantity; and it is probable, that every proteinaceous aliment, and perhaps those that are not proteinaceous, is reduced to the form of albumen in the process of digestion, so that it becomes the nutritious constituent of whatever fluid is absorbed for the formation of tissue. It is not, of itself, organizable; requiring first to be converted into fibrin. b. Fibrin.—This proximate principle exists in the chyle ; enters into the composition of the blood; forms the chief part of muscular flesh; and may be looked upon as one of the most abundant animal substances. It is obtained by beating the blood with a,rod, as it issues from a vein. The fibrin attaches itself to each twig in the form of red filaments, which may be deprived of their colour by repeated washing with cold water. Fibrin is solid; white ; flexible ; slightly elastic ; insipid; in- odorous ; and heavier than water. It is neither soluble in water, alco- hol, nor acids; dissolves in liquid potassa or soda, in the cold, without much change; and when warm, becomes decomposed. Fibrin constitutes the buffy coat of blood; it is thrown out from the blood-vessels, as a secretion, in many cases of inflammation; and be- comes subsequently organized. There is no mode of distinguishing liquid fibrin from liquid albumen, except by the spontaneous coagulation of the former. Consequently, according to Henle,1 if a liquid does not coagulate of itself, it does not * contain fibrin. A very small quantity, however, of fibrin may be so dissolved in serous fluid, that it will not coagulate.2 The change of albumen to fibrin has been regarded as the first important step in the process of assimilation, fibrin being endowed with much higher organ- izable properties than albumen. This has been attributed to some influence exerted upon albuminous fluids by the living surfaces over which they pass. The correspondence of fibrin with albumen is shown by the circum- 1 Op. cit., p. 38. 5 Dr. Buchanan, Lond. Med. Gaz. for 1836, pp. 52 and 90, and ibid, for 1845, p. 617. ORGANIC ELEMENTS. 49 stance, that it may be wholly dissolved in a solution of nitrate of po- tassa, and that this solution greatly resembles a solution of albumen, and is coagulated by heat. This happens, however, only to the ordi- nary fibrin of venous blood. That which is obtained from arterial blood or from the buffy coat; or which has been exposed for some time to the air, is not thus soluble, the difference appearing to depend upon the larger quantity of oxygen contained in the latter; for a solution of venous fibrin in nitre, contained in a deep cylindrical jar, allows a pre- cipitate in fine flocks to fall gradually, provided the air has access to the surface; but not if its access be prevented. This precipitate is insoluble in the solution of nitre, and possesses the properties of arterial fibrin.1 Hence, as Dr. Carpenter2 has remarked, it may be inferred, that the fibrin of venous blood most nearly resembles albumen; whilst that of arterial blood, and of the buffy c«at, contains more oxygen, and is more highly animalized; and that the matter of the red corpuscles is not the only constituent of the blood, which undergoes a change in the respiratory process. c. Casein, Caseum, Caseous matter.—This substance exists in great- est abundance in milk; and is the basis of cheese. It is found also in blood, saliva, bile, pancreatic juice ; in pus, tubercular matter, &c. To obtain it, milk must be left at rest, at the ordinary temperature, until it is coagulated: the cream that collects on the surface must be taken off; the clot well washed with water, drained upon a filter, and dried. The residuum is pure casein. It is a white, insipid, inodorous sub- stance, insoluble in water, but readily soluble in the alkalies, especially in ammonia. It possesses considerable analogy with albumen. Prout ascribes the characteristic flavour of cheese to the presence of caseate of ammonia. Until recently, it was believed that vegetable albumen and fibrin differ from animal albumen and fibrin; but Mulder showed that this is not the case; and casein, which agrees with the others in composi- tion, has been found by Liebig in the vegetable. Legumin is vegetable casein. Of late, the views of Mulder as to the very existence of pro- tein have been combated by Liebig and Th. Fleitmann ;3 but still—as Messrs. Kirkes and Paget4 have remarked—there seems sufficient proba- bility in those views to justify the received use of the term "protein compounds," in speaking of the class, including fibrin, albumen, and others, to which the name of "albuminous compounds" was formerly applied. 2. Globulin.—The globulin of Berzelius consists of the envelopes of the blood corpuscles, and of the .part of their contents that remains after the extraction of the hsematosin. The two constitute hsemato- globulin. M. Lecanu regards globulin as identical with albumen; accord- ing to Mulder, it belongs to the combinations of protein. Simon terms 1 Scherer, Chemisch-physiologische Untersuchungen, Annalen der Chemie, &c, Oct. 1841, cited in Graham's Chemistry, Amer. edit., p. 692. Philad., 1843. a Principles of Human Physiology, 2d edit., p. 479, Philad., 1845. 3 Scherer, in Canstatt und Eisenmann's Jahresbericht iiber die Fortschritte in der Biologie im Jahre, 1847, s. 82. Erlangen, 1S48. * Manual of Physiology, Amer. edit., p. 24, Philad, 1S49. VOL. I.—4 50 MATERIAL COMPOSITION OF MAN. it blood casein, and Henle1 thinks it probable, that it is in reality only albumen with the membranes of the blood corpuscles. Berzelius con- siders the crystalline lens to be composed of the same substance. 3. Pepsin.—This substance, to which Eberle gave the name, was dis- covered by Schwann. It seems to be a modification of protein, but has not been much examined. It is contained in the gastric juice ; and its physiological properties will be described under the head of Digestion. It greatly resembles albumen ; coagulates by heat and alcohol; and loses its solvent virtues. It is best procured by digesting portions of the mucous membrane of the stomach in cold water, after they have been macerated for some time in water at a temperature between 80° and 100° of Fahrenheit. The warm water dissolves various substances as well as some of the pepsin ; but the cold water takes up little more than the pepsin, which is obtained by evaporating the cold solution in the form of a grayish-brown viscid fluid. The addition of alcohol throws down the pepsin in grayish-white flocculi; and one part of the principle thus prepared? when dissolved in even 60,000 parts of water, will digest meat and other alimentary substances. Liebig doubts the existence of pepsin as a distinct compound. According to him—as explained here- after—the solvent power of the gastric juice is owing to the gradual decomposition of a matter dissolved from the lining membrane of the stomach, aided by oxygen introduced into the saliva. 4. Gelatin.—This is the chief constituent of cellular tissue, skin, tendons, ligaments, and cartilages. The membranes and bones also contain a large quantity of it. It is obtained by boiling these sub- stances for some time in water; clarifying the concentrated solution; allowing it to cool, and drying the substance, thus obtained, in the air. In this state it is called glue; in a more liquid form, jelly. Gelatin dissolves readily in hot water; is soluble in acids and alkalies ; insolu- ble in alcohol, ether, and in fixed and volatile oils. Alcohol precipi- tates it from its solution in water. It is not a compound of protein: hence it has been concluded, that it cannot yield albumen, fibrin, or casein; and, therefore, that blood cannot be formed of it. The animal system, it has been maintained, can convert one form of protein into another, but cannot form protein from compounds that do not contain it. This deduction—as stated hereafter—is probably too hasty. It is admitted, that gelatin may be produced from fibrin and albumen ; since, in animals that are fed on these alone, the nutrition of the gelatinous tissues does not seem to be impaired ; and it is as easy to conceive that gelatin may go to the formation of the proteinaceous tissues. Gelatin, nearly in a pure state, forms the air-bag of different fishes, and is well known under the name of isinglass. It is used extensively in the arts, on account of its adhesive quality, under the forms of glue and size. What is called portable soup is dried jelly, seasoned with various spices. 5. Chondrin.—This was first discovered by J. Miiller. It is obtained by boiling the cornea, the permanent cartilages, and the bones before ossification. It is a variety of gelatin. 1 Op. cit., p. 53. ORGANIC ELEMENTS. 51 6. Osmazome.—This is the matiSre extractive du bouillon, extractive, and saponaceous extract of meat.—When flesh, cut into small frag- ments, is macerated in successive portions of cold water, the albumen, osmazome, and salts are dissolved; and, on boiling the solution, the albumen is coagulated. From the liquid remaining, the osmazome may be procured in a separate state, by evaporating to the consistence of an extract, and treating with cold alcohol. This substance is of a reddish-brown colour; and is distinguished from the other animal prin- ciples by solubility in water and alcohol—whether cold or at the boil- ing point—and by not forming a jelly when its solution is concentrated by evaporation. Osmazome exists in the muscles of animals, the blood, and the brain. It gives the peculiar flavour of meat to soups; and, according to Four- croy, the brown crust of roast meat consists of it. Kreatin and Kreatinin are two principles which were formerly in- cluded among the extractive or ill-defined matters of muscular tissue. They have been investigated by Liebig,1 who discovered them also in urine. They appear to be like urea, mere products of the decomposition of muscle. 7. Mucus.—This term has been applied to various substances; and hence the discordant characters ascribed to it. Applying it to the fluid secreted by mucous surfaces, it varies somewhat according to the source whence it is derived. Its leading characters may be exemplified in that derived from the nostrils, which has the following properties. It is insoluble in alcohol and water, but imbibes a little of the latter, and becomes transparent; it is neither coagulated by heat, nor rendered horny; but is coagulated by tannic acid. Mucus, in a liquid state, serves as a protecting covering to different parts. Hence it varies somewhat in its characters, according to the office it has to fulfil. When inspissated, it forms, according to some, the minute scales that are detached from the surface of the body by friction, corns, and the thick layers of the soles of the feet, nails, and horny parts; and it is contained in considerable quantity in hair, wool, feathers, scales of fishes, &c. 8. Urea.—This proximate principle exists in the urine of the mam- malia when they are in a state of health. In human urine it is less abundant after a meal, and it may nearly disappear in diabetes, and affections of the liver. It is obtained by evaporating urine to the con- sistence of syrup. The syrup is then treated with four parts of alco- hol, which are afterwards volatilized by heating the alcoholic extract. The mass that remains is dissolved in water, or rather in alcohol, and crystallized. The purest urea that has been obtained assumes the shape of acicu- lar prisms similar to those of the muriate of strontian. It is colourless, devoid of smell, or of action on blue vegetable colours, transparent, and somewhat hard. Its taste is cool, slightly sharp, and its specific gra- vity is greater than that of water. Urea is supposed by Dr. Prout to be chiefly derived from the de- 1 Chemistry of Food, London, 1847. 52 MATERIAL COMPOSITION OF MAN. composition of the gelatinous tissues; but, as Dr. Carpenter has re- marked,1 there seems to be no valid reason thus to limit the mode of its production. 9. Uric or lithic acid.—This acid is found in the urine of man, birds, serpents, tortoises, crocodiles, lizards; in the excrements _of the silk- worm, and very frequently in urinary calculi. It is obtained by dis- solving any urinary calculus which contains it, or the sediment of hu- man urine, in warm liquid potassa, and precipitating the uric acid by the chlorohydric. Pure uric acid is white, tasteless, and inodorous. It is insoluble in alcohol, and is dissolved very sparingly by cold or hot water, requiring about 10,000 times its weight of that fluid, at 60° of Fahrenheit, for solution. According to Dr. Prout, this acid is not free, but is commonly combined with ammonia; the reddening of litmus paper being not altogether owing to it, but to the super-phosphate of ammonia, which is likewise present in urine. In the herbivora, this acid is replaced by the hippuric. Xanthic acid, found by Marcet in urinary calculi, seems to have been uric acid. 10. Red colouring principles of the blood.—It has been already ob- served that Engelhart and Rose, German chemists, had detected iron in the red corpuscles of the blood, but had not found it in the other principles of that fluid. It has been considered probable, therefore, that it has something to do with the colour. Engelhart's experiments did not, however, determine the manner in which it acts, nor in what state it exists in the blood. The sulphocyanic acid which is found in the saliva, forms, with peroxide of iron, a colour exactly like that of venous blood; and it is possible, that the colouring matter may be a sulpho- cyanate of iron. To obtain the red colouring matter, haematin or haematosin, allow the crassamentum or clot, cut into thin pieces, to drain as much as possible on bibulous paper, triturating it with water, and then evapo- rating the solution at a temperature not exceeding 122° of Fahren- heit. When thus prepared, the colouring particles are no longer of a bright red colour, and their nature is somewhat modified, in conse- quence of which they are insoluble in water. When half dried, they form a brownish-red, granular, friable mass; and, when completely dried at a temperature between 167° and 190°, the mass is tough, hard, and brilliant. The mode in which the haematosin is concerned in the coloration of the blood, will be inquired into under the head of Respiration. A brown colouring matter, hsemaphsein, and a blue colouring matter, haemacyanin, have been described. The former, however, it has been suggested, is nothing more than haematin modified by an alkali; and Simon2 never succeeded in detecting the latter. 11. Yellow colouring principle of the bile;—cholepyrrhin of Berze- lius, biliphsein of Simon.—This substance is present in the bile of nearly all animals. It enters into the composition of almost all gall- stones, and is deposited in the gall-bladder under the form of magma. • Human Physiology, § 673, Lond. 1842. a Op. cit., p. 42. ORGANIC ELEMENTS. 53 It is solid; pulverulent; when dry, insipid, inodorous, and heavier than water. When decomposed by heat, it yields carbonate of ammonia, charcoal, &c. It is insoluble in water, alcohol, and the oils; but solu- ble in alkalies. On the gradual addition of nitric acid to a fluid, which contains this substance in solution, a very characteristic series of tints is evolved. The fluid becomes first blue, then green, afterwards vio- let and red, and ultimately assumes a yellow or yellowish-brown colour. On adding an acid to a solution of biliphsein, a precipitation of green flocculi takes place : these possess all the properties of chlorophyll, or the green colouring matter of leaves. In this state it is termed bili- verdin by Berzelius; and is a product of the metamorphosis of bili- phsein.1 These are the chief nitrogenized organic elements. b. Organic Elements that do not contain Nitrogen. 1. Olein and Stearin.—Fixed oils and fats are not pure proximate principles, as was at one time supposed. They were long presumed to consist of two substances, one of which is solid at the ordinary tem- perature of the atmosphere, and the other fluid: the former of these was called Stearin, from at tap, suet; the latter Ela'in or Olein, from t%aiov, oil. Stearin is the chief ingredient of vegetable and animal suet; of fat and butter; and is found, although in small quantity, in fixed oils. In suety bodies, it is the cause of their solidity. Elain and stearin may be separated from each other by exposing fixed oil to a low temperature; and pressing it, when congealed, between folds of bibulous paper. The stearin is thus obtained in a separate form ; and by pressing the bibulous paper under water, an oily matter is procured, which is elain in a state of purity. Modern chemistry has shown, however, that fat contained in the cells of adipose tissue is composed of a base termed glycerin—itself hydrated oxide of glyceryl—with stearic and margaric acids. Stearin is a bi-stearate of glycerin:— olein, or elain, an oleate of glycerin. 2. Fatty matter of the Brain and Nerves.—Vauquelin2 found two varieties of fatty matter in the brain,—the one white, the other red, the properties of which have not been fully investigated. Both give rise to phosphoric acid by calcination, without there being any evidence of an acid, or phosphate in their composition. They may be obtained by repeatedly boiling the cerebral substance in alcohol; filtering each time; mixing the various liquors, and suffering them to cool:—a lamel- lated substance is deposited, which is the white fatty matter. By eva- porating the alcohol, which still contains red fatty matter and osmazome, to the consistence of bouillie; and exposing this, when cold, to the action of alcohol, the osmazome is entirely dissolved, whilst the alcohol takes up scarcely any red fatty matter. 3. Acetic acid.—This acid exists in a very sensible manner in sweat, urine, and milk—even when entirely sweet. It, or lactic acid, is formed in the stomach in indigestion; was found by the author and his late friend, Professor Emmet, contained in the gastric secretions in health, 1 Simon, op. cit., p. 44. ' Annales de Chim., lxxxi. 37. 54 MATERIAL COMPOSITION OF MAN. and is one of the constant products of the putrid fermentation of ani- mal or vegetable substances. It is the most prevalent of the vegetable acids, and most easily formed artificially. 4. Oxalic acid.—This acid,—which exists extensively in the vege- table kingdom, but always united with lime, potassa, soda, or oxide of iron,—is only found, combined with lime, as an animal constituent in certain urinary calculi. 5. Benzoic acid.—This acid, found in many individuals of the vege- table kingdom, is likewise met with in the urine of the horse, cow, camel, and rhinoceros; and sometimes in that of man, especially of children. When benzoic acid is swallowed, hippuric acid is observed in the urine; and it was supposed by Mr. A. Ure and others, that this was owing to the conversion of uric acid into hippuric; and as the hippurates are more soluble, it was suggested by him, that benzoic acid might be advantageously exhibited in lithuria, and in cases of gouty depositions of lithate of soda. It has been found, however, by Drs. Keller and Garrod,1 and by Professor Booth, and Mr. Boyd, of Phila- delphia,2 that the administration of benzoic acid exerts no influence on the amount of uric acid in the urine. 6. Lactic acid.—Acid of milk is met with in blood, gastric juice, urine, milk, marrow, and also in muscular flesh. At times it is in a free state, but is usually united with alkalies. However much it may be concentrated, it does not crystallize, but remains under the form of syrup or extract. When cold it is tasteless, but when heated has a sharp acid taste. According to Dr. Prout, this acid, like urea, results from the decomposition of the gelatinous parts of the system; accord- ing to Berzelius, however, it is a general product of the spontaneous decomposition of animal matters within the body. Liebig3 formerly denied, that any lactic acid is formed in the stomach in health; and affirmed, that the property possessed by many substances, such as starch, and the varieties of sugar, by contact with animal matters in a state of decomposition, of passing into lactic acid, had induced physiologists too hastily to assume the fact of the production of lactic acid during healthy digestion:—yet he now admits its presence. 7. Sugar of milk.—This substance, which is so called because it has a saccharine taste, and exists chiefly, if not solely, in milk, differs from ordinary sugar in not fermenting. It is obtained by evaporating whey, formed during the making of cheese, to the consistence of honey; al- lowing the mass to cool; dissolving ; clarifying and crystallizing. It commonly crystallizes in regular parallelopipedons, terminated by pyra- mids with four faces. It is white; semitransparent; hard, and of a slightly saccharine taste. 8. Sugar of diabetes.—In diabetes mellitus, the urine, which is often passed in enormous quantity, contains, at the expense of the economy, a large amount of peculiar saccharine matter, which, when properly purified, appears identical in properties and composition with vegetable 1 Liebig's Animal Chemistry, p. 316. a Proceedings of the American Philosophical Society at the Centennial Celebration in Phila May, 1843, and Transactions of the A. P. Society, vol. ix. pt. 2, Philad., 1845 3 Op. cit., p. 107. ORGANIC ELEMENTS. 55 sugar, and approaches nearer to the sugar of grapes—glucose—than to that of the cane. It is obtained in an irregularly crystalline mass, by evaporating diabetic urine to the consistence of syrup, and keeping it in a warm place for several days. It is purified by washing in cold, or—at the most—gently heated alcohol, till the liquor comes off colour- less ; and then dissolving it in hot alcohol. By repeated crystallization it is thus rendered pure.1 In the notes of two cases of diabetes mel- litus now before the author, it appears, that sixteen ounces of the urine of one patient, of the specific gravity of 1*034, afforded a straw-co- loured extract, which, when cold and consolidated, weighed one ounce and five drachms. The same quantity of the urine of the other patient, specific gravity 1*040, yielded one ounce and seven drachms. Neither extract appeared to contain urea when nitric acid was added; but when a portion was dissolved in water, and subjected to a temperature of 212°, traces of ammonia were manifested on the vapour being presented to the fumes of chlorohydric acid. From this a conclusion was drawn, that urea was present, as it is the only known animal matter decom- posed by the heat of boiling water. In a little more than a month, the subject of the latter case passed about four hundred and eighty pints of urine, or about seventy-five pounds troy of diabetic sugar! 9. Bilin or Picromel.—M. Thenard2 discovered this principle in the bile of the ox, sheep, dog, cat, and several birds; Chevalier, in that of man. To obtain it, the acetate of lead of commerce must be added to bile until there is no longer any precipitate. By this means, the yellow matter of the bile and the whole of the fatty matter are thrown down, united with the oxide of lead ; the phosphoric acid of the phosphate of soda, and the sulphuric acid of the sulphate of soda, are likewise precipi- tated. The picromel may then be thrown down from the filtered liquor by the subacetate of lead. The precipitate, which is a combination of picromel with oxide of lead, must now be washed and dissolved in acetic acid. Through this solution, sulphuretted hydrogen is passed to sepa- rate the lead; the solution is then filtered, and the acetic acid driven off by evaporation. Pure picromel is devoid of colour, and has the same appearance and consistence as thick turpentine. Its.taste is at first acrid and bitter, but afterwards sweet. Its smell is nauseous, and specific gravity greater than that of water. When digested with resin of bile, a portion of the latter is dissolved, and a solution obtained, which has a bitter and a sweet taste, and yields a precipitate with the subacetate of lead and the stronger acids. This is the compound that causes the peculiar taste of the bile. 10. Cholesterin.—This is a constituent principle of the blood, bile, medullary neurine, and vernix caseosa. It is often precipitated from bile in a crystalline state; and forms of itself concretions which have an evidently laminated texture. It has been very frequently met with in morbid secretions and tissues; in the fluid of dropsies; in that of cysts and hydatids; and in medullary fungus and other tumours. At 1 Prout, Medico-Chirurg. Transact., viii. 538. a Memoir. d'Arcueil, i. 23, and Traite de Chimie, torn. hi. 56 MATERIAL COMPOSITION OF MAN. times, it is dissolved ; at others, swims upon the fluid in brilliant plates, or forms solid masses. It is obtained from biliary calculi by boiling in water, and dissolving them afterwards in boiling alcohol. On cooling, crystals of cholesterin separate. These inorganic and organic elements—with others of less moment discovered by modern chemists—variously combined and modified by the vital force, constitute the different parts of the animal fabric. Chemistry, in its present improved condition, enables us to separate them, and to investigate their properties; but all the information we derive from this source relates to bodies, that have been influenced by the vital force, but are no longer so; and in the constant muta- tions that occur in the system whilst life exists, and under its control- ling agency, the same textures might exhibit very different chemical characteristics, could our researches be directed to them under those circumstances. Whenever, therefore, the physiologist has to apply chemical elucidations to operations of the living machine, he must re- collect, that all his analogies are drawn from dead matter, which dif- fers so widely from the living as to suggest the necessity of a wise and discriminating caution. The components of the animal body are invariably found under two forms—solids and fluids. Both are met with in every animal, the for- mer being derived from the latter; for, from the blood every part of the body is separated; yet they are mutually dependent, for every liquid is contained in a solid. The blood itself circulates in solid vessels. Both, too, possess an analogous composition ; are in constant motion, and incessantly converted from one into the other. Every animal consists of a union of the two ; and this union is indispensable to life. Yet certain vague notions with regard to their relative pre- ponderance in the economy, and to their agency in the production of disease, have led to discordant doctrines of pathology,—the solidists believing, that the cause of most affections is resident in the solids; the humorists, that we are to look for it in the fluids. In this, as in similar cases, the mean will lead to the most satisfactory result. The causes of disease ought not to be- sought in the one or the other exclu- sively. c. Of the Solid Parts of the Human Body. A solid is a body whose particles adhere to each other, so that they do not separate by their own weight; but require the agency of some extraneous force to effect the disjunction. Anatomists reduce all the solids of the human body to twelve varieties ;—bone, cartilage, muscle, ligament, vessel, nerve, ganglion, follicle, gland, membrane, areolar membrane, and viscus. 1. Bone is the hardest of the solids. It forms the skeleton * the levers for the various muscles to act upon; and serves for the protec- tion of important organs. 2. Cartilage is of a white colour, formed of very elastic tissue • covering the articular extremities of bone to facilitate their movements • sometimes added to bones to prolong them, as in the case of the ribs • SOLID PARTS. 57 at others, placed within the articulations to act as elastic cushions; and, in the foetus, forming a substitute for bone. Hence, cartilages are di- vided into articular or incrusting, cartilages of prolongation, interarti- cular cartilages, and cartilages of ossification. 3. Muscles constitute the flesh of animals. They consist of fasci- culi of red and contractile fibres, extending generally from one bone to another; and are the agents of all movements. 4. Ligaments are tough; difficult to tear; and, under the form of cords or membranes, serve to connect different parts with each other, particularly bones and muscles; hence their division, by some anato- mists, into ligaments of bones—as the ligaments of the joints; and ligaments of muscles,—as the tendons and aponeuroses. 5. Vessels are solids, having the form of canals, in which the fluids circulate. They are called—according to the fluid they convey—san- guineous (arterial and venous), chyliferous, lymphatic, &c. 6. Nerves are cords, consisting of numerous tubular fasciculi. These are connected with the brain, spinal marrow, or great sympathetic. They are the organs by which impressions are conveyed to the nervous centres, and by which each part is endowed with vitality. There are three great divisions of the nerves,—the cerebrospinal, true spinal, and organic. 7. Ganglions are solid knots in the course of a nerve which seem to be formed of an inextricable interlacing of nervous filaments. The term is likewise applied, by many modern anatomists, to similar inter- lacings of the ramifications of lymphatic vessels. Ganglions may, consequently, either be nervous or vascular; and the latter, again, may be divided into chyliferous or lymphatic, according to the kind of ves- sel on which they appear. Chaussier, a distinguished anatomist and physiologist, has given the name glandiform ganglions to certain organs whose nature and functions are unknown, but which appear to be con- cerned in lymphosis,—as the thymus gland, the thyroid gland, &c. 8. Follicles or crypts are secretory organs, shaped—when simple—like membranous ampullae or vesicles, formed by an inversion of the outer membranes of the body—the skin and mucous surfaces—and secreting a fluid intended to lubricate them. They are often divided into the simple or isolated; the conglomerate; and the compound, according to their size, or the manner in which they are grouped and united to- gether. 9. Glands are secretory organs not differing essentially from the last. Their organization is more complex; and the fluid, after secretion, is poured out by means of one or more excretory ducts. 10. Membrane.—This is one of the most extensive and important of the substances formed by the areolar tissue. It is spread out in the shape of a web; and, in man, serves to line cavities and reservoirs; and to form, support, and envelope organs. Bichat divides membranes into two kinds, simple and compound, ac- cording as they are formed of one or more layers. Simple membranes are of three kinds, serous, mucous, and fibrous. 1st. Serous membranes constitute all the sacs or shut cavities of the body,—those of the chest and abdomen, for example. 58 MATERIAL COMPOSITION OF MAN. Idly. Mucous membranes line all the outlets of the body,—the air- passages, alimentary canal, urinary and genital organs, &c. Sdly. Fibrous membranes form tendon, aponeurosis, ligament, &c. Compound membranes are formed by the union of the simple, and are divided into fibro-serous, as the pericardium; scro-mucous, as the gall-bladder, at its lower part; and fibro-mucous, as the ureter. 11. Areolar, cellular or laminated tissue—to be described presently —is a sort of spongy or areolar structure, which forms the framework of the solids; fills up the spaces between them, and serves at once as a bond of union and separation. 12. A viscus is the most complex solid of the body; not only as re- gards intimate organization, but use. This name is given to organs con- tained in the splanchnic cavities,—brain, thorax, and abdomen,—and hence the viscera are termed cerebral, thoracic, and abdominal. Every animal solid is either amorphous or fibrous; that is, it is either without apparent arrangement, like jelly; or is disposed in minute threads, called fibres. The disposition of these threads, in different structures, is various. Sometimes, they retain the form of threads; at others, they have that of laminae, lamellae, or plates. Accordingly, when we examine any animal solid, where the organization is percep- tible, it is found to be either amorphous, or fibrous and laminated. This circumstance led the ancients to endeavour to discover an ele- mentary fibre or filament, from which the various organs might be formed. Haller1 embraced the idea, and endeavoured to unravel every texture to this ultimate element,—which, he conceived, is to the physiologist what the line is to the geometer; and, as all figures can be constructed from the line, so every tissue and organ of the body may be built up from the filament. Haller, however, admitted that this elementary fibre is not capable of demonstration, and that it is visible only to the "mind's eye,"—" invisibilis ea fibra, quam sold mentis acie adtingi- mus." It must be regarded, indeed, as a pure abstraction; for, as different animal substances in the mass have different proportions of carbon, hydrogen, oxygen, and nitrogen, it is fair to conclude that the elementary fibre must equally differ in the different substances. The ancients believed that the first product of the elementary fibre was areolar tissue; and that this tissue forms every organ of the body,—the difference in the appearance of the organs arising from the different degrees of condensation of its laminae. Anatomists, however, have been unable to reduce all animal solids to areolar tissue only. In the upper classes of animals, three primary fibres or tissues or anatomical elements are usually admitted,—the areolar, cellular or laminated; the muscular; and the nervous, pulpy or medullary. 1. The areolar, cellular, mucous, filamentous or laminated fibre or tissue is the most simple and abundant of animal solids. It exists in every organized being; and is an element of every solid. In the ena- mel of the teeth only it has not been detected. It is formed of an assemblage of thin laminae, of delicate, whitish, extensible filaments * Elementa Physiologiae, vol. i. lib. i. sect. i. p. 7, Lausan., 1757. PRIMARY AND COMPOUND TISSUES. 59 interlacing and leaving between each other areolas or cells. These filaments—although possessed, like every other living tissue, of con- tractility or the power of feeling an appropriate irritant and of moving responsive to such irritant—do not move perceptibly under the influence of mechanical or chemical stimuli. They are mainky composed of concrete gelatin.—The great bulk of animal solids consists of areolar tissue, arranged as membrane. 2. Muscular fibre or tissue is a substance of peculiar nature; ar- ranged in fibres of extreme delicacy. The fibres are linear, soft, gray- ish or reddish, and manifestly possessed of contractility or irritability; that is, they move very perceptibly under the influence of mechanical or chemical stimuli. They are composed, essentially, of fibrin. Their histology will be described hereafter. Muscular fibres, which are arranged in the form of membranous expansions or muscular coats, differ from proper muscles chiefly in the mechanical disposition of the fibres. The physical and chemical characters of both are identical. The fibres, instead of being collected into fasciculi, are in layers, and, instead of being parallel, interlace. This tissue does not exist in the zoophyte. 3. Nervous, pulpy, or medullary fibre or tissue, which will be referred to hereafter, is much less distributed than the preceding. It is of a pulpy consistence; is composed essentially of albumen united to a phosphuretted fatty matter; and is the organ for receiving and trans- mitting impressions to and from the nervous centres. Of it, brain, cerebellum, medulla spinalis, nerves and their ganglia are composed. Professor Chaussier1 added another primary fibre or tissue,—the albugineous. It is white; satiny; resisting; of a gelatinous nature; and constitutes tendons and tendinous structures. Chaussier is, per- haps, the only anatomist that admits this tissue. Others properly re- gard it as a condensed variety of the areolar. These various fibres or tissues, by uniting differently, constitute the first order of solids; and these, again, by union, give rise to compound solids, from which the different organs are formed. A bone, for ex- ample, is a compound of various tissues; osseous in its body; medullary in its interior; and cartilaginous at its extremities. Bichat2 was the first anatomist who possessed clear views regarding the constituent tissues of the animal frame; and whatever merit may accrue to after anatomists and physiologists, he is entitled to the credit of having pointed out the path, and facilitated the labours of the ana- tomical analyst. The term texture can only apply to solids ; but inasmuch as there are in suspension in certain fluids, as the blood, chyle and lymph, solid corpuscles of determinate form and organic properties, and which are not mere products or secretions of a particular organ, or confined to a particular part, such corpuscles have been looked upon as organized constituents of the body, and therefore considered along with the solid tissues ; and, accordingly, the textures and other organized constituents have been enumerated as follows :3 1 Table Synoptique des Solides Organiques. a Anatomie Gen., Paris, 1801, torn. i. 8 Quain and Sharpey, Human Anatomy, Amer. edit., by Dr. Leidy, i. 39, Philad., 1849. 60 MATERIAL COMPOSITION OF MAN. The blood, chyle and lymph. Bone or osseous tissue. Epidermic tissue, including epi- Muscular tissue. thelium, cuticle, nails, and Nervous tissue. hairs. Bloodvessels. Pigment. Absorbent vessels and glands. Adipose tissue. Serous and synovial membranes. Cellular (areolar) tissue. Mucous membranes. Fibrous tissue. Skin. Elastic tissue. Secreting glands. Cartilage and its varieties. Under the idea, now entertained, that all organized tissues are essen- tially composed of cells having plastic or formative powers, with an intercellular substance or blastema, the tissues have been thus arranged by Schwann,1 the great author of the cell doctrine. 1. Isolated, independent cells. To this class the cells in fluids pre- eminently belong:—lymph globules; blood corpuscles. 2. Independent cells united into continuous tissues; such as the horny tissues and the crystalline lens. 3. Cells in which only the cell walls have coalesced,—cartilage, bone, and the substantia propria (ivory) of the teeth. 4. Fibre cells,—cellular (areolar), fibrous and elastic tissue. 5. Cells in which both the cell walls and cell cavities have coalesced, —muscle, nerve and capillary vessels. Dr. Allen Thomson2 has proposed the following tabular view, which —he remarks—may be adopted in preference to the foregoing as com- bining similar theoretical considerations, with a more immediate refer- ence to the actual form of the prevailing structural elements in the different tissues. He properly adds, however, that this classification is open—as he might have said every arrangement must be—to several objections ; inasmuch as it brings together, under the same head, some parts endowed with different functions; and separates some textures whose functions are closely related; and it does not point out suf- ficiently the usual degree of complexity of the several textures. Some part of it, moreover, is founded on theoretical considerations not yet fully established; and the distinctions on which it rests are based on a structural analysis of various extent in the different textures. On the whole, however, it is a sufficient exponent of the existing state of belief on the subject. I. Organized textures in which the cellular form of the constituent elements is apparent; not unfrequently also presenting granules of molecular deposition. 1. Rounded simple cells, floating loose in fluid, Blood, Lymph, Chyle and Milk corpuscles, cfc. 2. Simple cells massed together, either preserving their cellular form and without other parts intervening, or altered in form and mixed with ' Microscopical Researches into the Accordance in the Structure and Growth of Animals and Plants. Sydenham Society's edit., by Henry Smith, p. 66, London, 1847. a Outlines of Physiology for the Use of Students, pt. i. p. 68, Edinb., 1848.' FLUIDS. 61 other solid elements :—Pigment, Fat, Cuticle, Horny textures, Epithe- lium, Crystalline lens, Cartilage. 3. Simple cells, or their contents, altered in form :—Ciliated texture, Spermatozoa. 4. Compound cells, separate or mixed with other textures :—Ovum, Ganglionic corpuscles. II. Textures exhibiting a simply fibrous structure. 1. Filamentous (areolar) texture; formerly Cellular texture. 2. Fibrous textures:—Tendon, Ligament, Fibrous membranes, Fi- brous plates. 3. Elastic fibrous texture. III. Textures exhibiting a tubular structure. 1. Containing moving fluids:—Bloodvessels and Absorbent vessels. 2. Containing muscular substance:—Striated and non-striated mus- cular fibre. 3. Containing nervous matter :—Primitive nerve tubes. IV. Textures exhibiting a membranous structure. 1. Principally filamentous :—Serous and Synovial membranes. 2. Filamentous and vascular:—Mucous membranes; True skin. 3. Membrane and cells:—Glands. 4. Membrane and Bloodvessels, &c.:—Lungs. In combining to form the different structures, the solids are arranged in various ways. Of these, the chief are in filaments or elementary fibres, tissues, organs, apparatuses, and systems. A filament is the elementary solid. A fibre consists of a number of filaments united together. Occasionally, this is called a tissue:—the term tissue usually, however, means a particular arrangement of fibres. An organ is a compound of several tissues. An apparatus is an assemblage of organs, concurring to the same end:—the digestive apparatus consists of the organs of mastication, insalivation, and deglutition, the stomach, duo- denum, pancreas, liver, &c. These may be, and are, of very dissimilar character, both as regards their structure and functions; but, if they concur in the same object, they form an apparatus. A system, on the other hand, is an assemblage of organs, all of which possess the same or an analogous structure. Thus, all the muscles of the body have a common structure and function; and form, in the aggregate, the muscular system. All the vessels of the body, and all the nerves, for like reasons, constitute, respectively, the vascular, and nervous sys- tems. d. Of the Fluids of the Human Body. The positive quantity or proportion of the fluids in the human body does not admit of appreciation, as it must vary at different periods, and under different circumstances. The younger the animal, the greater is its preponderance. When we first see the embryo, it appears to be almost wholly fluid. As it becomes gradually developed, the proportion of solid parts increases, until the adult age; after which it becomes less and less in the progress of life. During the whole of existence, too, the quantity of fluids in the body fluctuates. At times, there is plethora 62 MATERIAL COMPOSITION OF MAN. or unusual fulness of blood-vessels; at others, the blood is less in quantity. Experiments have been made for the purpose of ascertaining the relative proportion of fluids to solids. M. Richerand says, that they are in the ratio of six to one; M. Chaussier, of nine to one. The latter pro- fessor put a dead body, weighing one hundred and twenty pounds, into a heated oven, and dried it. After desiccation, it was found to be reduced to twelve pounds. It is probable, however, that some of the more solid portions were driven off by the heat employed; and hence, that the estimated proportion of fluids was too high. On this account, M. Be'rard1 thinks, that instead of estimating the proportion of liquids * at nine-tenths, it would be better to take the mean result of experi- ments by M. Chevreul, who performed the desiccation in vacuo and with a very moderate heat. This would give the proportion of water in the human body about 6*667 parts in the 10*000. In the Egyptian mummies, which are completely deprived of fluid, the solids are extremely light, not weighing more than seven pounds; but as we are ignorant of the original weight of the body, we cannot arrive at any approximation. The dead bodies found in the arid sands of Arabia, as well as the dried preparations of the anatomical theatre, afford additional instances of reduction by desiccation. To a less extent, we have the same thing exhibited in the excessive diminution in weight that occurs in disease, and occasionally in those who are apparently in health. Not many years ago, an Anatomie vivante was exhibited in London to the gaze of the curious and scientific, whose weight was not more than eighty pounds. Yet the ordinary functions were carried on, apparently unmodified. In the year 1830, a still more wonderful phenomenon was shown. A man, named Calvin Edson, forty-two years old, five feet two inches high, weighed but sixty pounds. His weight had formerly been one hundred and thirty-five pounds. For sixteen years previously, he had been gradually losing flesh, without any ap- parent disease, having enjoyed perfect health and appetite, and eating, drinking, and sleeping as well as any one. He was properly called the "living skeleton." It was stated in the public journals2 that Dr. Edson, a brother of Calvin, was to all appearance entirely destitute of flesh. He was, in 1847, forty-two years old; of ordinary height—five feet six inches, and yet weighed only forty-nine pounds. He retained all his faculties apparently in full vigour. We have it also, on the authority of Captain Riley,3 that after protracted sufferings in Africa, he was reduced from two hundred and forty pounds to below ninety [?]. The fluids are variously contained; sometimes in vessels—as the blood and lymph; at others, in cavities—as the fluids secreted by the pleura, peritoneum, arachnoid coat of the brain, &c: others are in minute areolae—as the fluid of the areolar membrane; whilst others again, are intimately combined with the solids. They differ likewise in density,—some existing in the state of halitus or vapour; others 1 Cours de Physiologie, p. 200, Paris, 1848. 3 Philadelphia Public Ledger, Feb. 2, 1847. 3 Narrative of the Loss of the American Brig Commerce, &c, p. 302. New York 1817 PHYSICAL PROPERTIES OF TISSUES. 63 being very thin and aqueous—as the fluid of the serous membranes ; and others of more consistence—as the secretion of the mucous mem- branes, animal oils, &c. The physical and chemical properties of the fluids will engage atten- tion when they fall individually under consideration ; and we shall find that one of them at least—the blood—exhibits certain phenomena analogous to those of the living solid. The fluids have been differently classed, according to the particular views that have, from time to time, prevailed in the schools. The an- cients referred them all to four,—blood, bile, phlegm or pituita, and atrabilis; each of which was conceived to abound in one of the four ages, seasons, climates, or temperaments. Blood predominated in youth, in the spring, in cold mountainous regions, and in the sanguine or inflammatory temperament. Pituita or phlegm had the mastery in old age, in winter, in low and moist countries, and in the lymphatic temperament. Bile predominated in mature age, in summer, in hot climates, and in the bilious temperament; and atrabilis was the cha- racteristic of middle age, of autumn, of equatorial climes, and of the melancholic temperament. This was their grand humoral system, which has vanished before a better observation of facts, and more im- proved methods of physical and metaphysical investigation. The atrabilis was a creature of the imagination; the pituitous condition is unintelligible to us; and the doctrine of the influence of the humours on the ages, temperaments, &c, irrational. Subsequently, the humours were classed according to their physical and chemical properties : they were divided, for instance, into liquids, vapours, and gases; into acid, alkaline, and neutral; into thick and thin; into aqueous, mucilaginous, gelatinous, and oily; into saline, oily, saponaceous, mucous, albuminous, and fibrinous, &c. In more modern times, endeavours have been made to arrange them according to their uses in the economy into—1, recrementitial fluids, or those intended to be again absorbed; 2, excrementitial, those that have to be expelled from the body; and 3, those which participate in both purposes, and are hence termed excremento-recrementitial. Blumenbach1 divided them into crude humours, blood, and secreted humours, a division which has been partly adopted by M. Adelon ;2 and Chaussier, whose anatomical arrangements and nomenclature have rendered him justly celebrated, reckoned five classes:—1, those produced by the act of digestion,— chyme and chyle; 2, the circulating fluids,—lymph and blood; 3, the perspired fluids ; 4, the follicular; and 5, the glandular. This arrange- ment has been adopted by M. Magendie,3 and, with slight modification, is perhaps as satisfactory as any that has been proposed. All these will have to engage attention under Secretion. e. Physical Properties of the Tissues. The tissues of the body possess the physical properties of matter in 1 Institutiones Physiological, Sect, ii., § 4. Gotting., 1798. 3 Physiologie de l'Homme, 2de edit., i. 124. Paris, 1829. 3 Precis Elementaire de Physiol., 2de edit., i. 20. Paris, 1825. 64 MATERIAL COMPOSITION OF MAN. general. They are found to vary in consistence,—some being hard, and others soft; as well as in colour, transparency, &c. They have, also, physical properties, analogous, indeed, to what are met with in certain inorganic substances, but generally superior in degree. These are flexibility, extensibility, and elasticity, which are variously com- bined and modified in the different forms of animal matter, but exist to a greater or less extent in every tissue. Elasticity is only exerted under particular circumstances: when the part, for example, is put upon the stretch or compressed, the force of elasticity restores it to its primitive state, as soon as the distending or compressing cause is with- drawn. The tissues, in which elasticity is inherent, are so disposed through the body, as to be kept in a state of distension by the mechani- cal circumstances of situation; but, as soon as these circumstances are modified, elasticity comes into play, and produces shrinking of the sub- stance. It is easy to see, that these circumstances, owing to the con- stant alteration in the relative situation of parts, must be ever varying. Elasticity is, therefore, constantly called into operation, and in many cases acts upon the tissues as a new power. The cartilages of the ribs, joints, &c, are in this manner valuable agents in particular functions. We have other examples of the mode in which elasticity exhibits itself, when the contents of hollow parts are withdrawn, and whenever muscles are divided transversely. The gaping wound, produced by a cut across a shoulder of mutton, is familiar to all. Previous to the division, the force of elasticity is kept neutralized by the mechanical circumstances of situation,—or by the continuity of the parts; but as soon as this continuity is disturbed, in other words, as soon as the me- chanical circumstances are altered, the force of elasticity is exerted, and produces recession of the edges. This property has been described under various names, tone or tonicity, contractilite de tissu, contractilite par defaut a"extension, &c. The other properties, flexibility and extensibility, vary greatly ac- cording to the structure of parts. The tendons, which are composed of areolar tissue, exhibit very little extensibility; and this for wise purposes. They are the conductors of force developed by muscle, and were they to yield, it would be at the expense of the muscular efforts; but they possess great flexibility. The articular ligaments are very flexible, and somewhat more extensible. On the other hand, the fibrous or ligamentous structures, which are employed to support weights, or are antagonists to muscular action,—as the ligamentum nuchse, which passes from the spine to the head of the quadruped,—are very extensible and elastic. Another physical property, possessed by animal substances, is a kind of contractility, accompanied with sudden corrugation and curlin<*. This effect, which Bichat terms racornissement, is produced by heat, and by chemical agents, especially the strong mineral acids. The property is exhibited by leather when thrown into the fire. An effect, in some measure resembling this, is caused by the evapo- ration of the water that is united to animal substances. This consti- tutes what has been called the hygrometric property of animal mem- PHYSICAL PROPERTIES OF TISSUES. 65 branes.1 It is characteristic of dry, membranous structures; all of which are found to contract, more or less, by the evaporation of moist- ure, and to expand again by its re-absorption; hence the employment of such substances as hygrometers. According to M. Chevreul,2 many of the tissues are indebted for their physical properties to the water they contain, or with which they are imbibed. When deprived of this fluid, they become unfit for the purposes for which they are destined in life, and resume them as soon as they have recovered it. A most important property possessed by the tissues of organized bodies is imbibition; a property to which attention has been chiefly di- rected of late years. If a liquid be put in contact with any organ or tissue, in process of time the liquid will be found to have passed into the areolae of the organ or tissue, as it would enter the cells of a sponge. The length of time occupied in this imbibition will depend upon the nature of the liquid and the kind of tissue. Some parts of the bodji, as the serous membranes and small vessels, act as true sponges, ab- sorbing with great promptitude; others resist imbibition for a considera- ble time,—as the epidermis. Liquids penetrate equally from within to without: the process is then called transudation. Some singular facts have been observed regarding the imbibition of fluids and gases. On filling membranous expansions, as the intestine of a chicken, with milk or some dense fluid, and immersing it in water, M. Dutrochet3 observed, that the milk left the intestine, and the water entered it; hence he concluded, that whenever an organized cavity, containing a fluid, is immersed in another fluid, less dense than that which is in the cavity, there is a tendency in the cavity to expel the denser and absorb the rarer fluid. This M. Dutrochet termed endos- mose, or "inward impulsion;" and he conceived it to be a new power, a "physico-organic or vital action." Subsequent experiments showed, that a reverse operation could take place. If the internal fluid was rarer than the external, the transmission occurred in the opposite di- rection. To this reverse process, he gave the name exosmose, or "out- ward impulsion." At times, the term endosmose is applied to the mutual action of two liquids when separated by a membrane;4 at others, to the passage of the liquid, that permeates the membrane in greatest quantity.5 Soon after the appearance of M. Dutrochet's essay, the experiments were repeated, with some modifications, by Dr. Faust,6 and by Dr. 1 Roget, art. Physiology, in Supplement to Encyclopaedia Britannica; and Outlines of Phy- siology, with an Appendix on Phrenology. First American edition, with notes by the author of this work, p. 73, Philad., 1839. a Magendie, Precis Elementaire de Physiologie, 2de edit., 1825, i. 13. 3 Mem. pour servir a I'Histoire Anatoin. et Physiol, des Animaux et des Vegetaux, Paris, 1837; art. Endosmosis, in Cyclopaedia of Anatomy and Physiology, part x. p. 98, June, 1837. See, also, Vierordt, art. Transudation und Endosmose, in Wagner's Handworterbuch der Physiologie, s. 631, Braunschweig, 1848. * Matteucci, Lectures on the Physical Phenomena of Living Beings; translated byPereira, p. 45, Amer. edit., Philad., 1848. s Poiseuille, Comptes Rendus, xix. 944. Paris, 1844. e Amer. Journal of the Med. Sciences, vii. 23, Philad., 1830. VOL. I.—5 6Q MATERIAL COMPOSITION OF MAN. Togno,1 of Philadelphia; and with like results. The fact of this imbi- bition and transudation was singular and impressive; and, with so enthusiastic an individual as M. Dutrochet, could not fail to give birth to numerous and novel conceptions. The energy of the action of both endosmose and exosmose is in proportion, he asserted, to the difference between the specific gravities of the two fluids; and, independently of their gravity, their chemical nature affects their power of transmission. These effects—he at once decided—must be owing t;o electricity. The cavities, in which the changes take place, he conceived to be like Ley- den jars having their two surfaces charged with opposite electricities,— the ultimate effect or direction of the current being determined by the excess of the one over the other. In an interesting and valuable communication by Dr. J. K. Mitchell,2 of Philadelphia, "on the penetrativeness of fluids," many of the vision- ary speculations of M. Dutrochet are sensibly animadverted upon. It is there shown, that he had asserted, in the teeth of some of his most striking facts, that the current was from a less dense to a more dense fluid; and that it was from positive to neg*ative, dependent not on an inherent power of filtration,—a power always the same when the same membrane is concerned,—but modified at pleasure by supposed electrical agencies. This view was subsequently abandoned by M. Dutrochet, in favour of the following principle. It is well known that porous bodies, as sugar, wood, or sponge, are capable of imbibing liquids, with which they are in contact. In such case the liquid is not merely introduced into the pores of the solid, as it would be into an empty space; but is forcibly absorbed, so that it will rise to a height considerably above its former level. This force is molecular, and is the same that we witness in the phenomena presented by the capillary tube, which affords us the simplest case of the insinuation of a liquid into a porous body. It cannot alone, however, cause the liquid to pass entirely through the body. If a capillary tube, capable of raising water to the height of six inches, be depressed, so that one inch only be above the surface, the water will rise to the top of the tube; but no part of it will escape. Even if the tube be inserted horizontally into the side of the vessel containing water, the water will only pass to the end of the tube. The same thing occurs when a liquid is placed in contact with one side of a porous membrane: it enters the pores; passes to the opposite side, and is there arrested. But if this membrane com- municates with a second vessel containing a different liquid—as a saline solution, capable of mixing with the first, and affected to a different degree by capillary attraction—a new phenomenon will be presented. It will be found, that both liquids enter the pores, and pass through to the opposite side. They will not, however, be carried throuo-h with the same force: that which has the greatest power of capillary ascension, has the greatest affinity for the membrane, or will wet it more readily —in other words, that which will rise the highest in a capillary tube, will pass through in greater quantity, and cause an accumulation of liquid on the opposite side. The action is well shown by the simple * Amer. Journal of the Med. Sciences, iv. 73, Philad 1829 ' Ibid., vii. 23, Philad., 1830. PHYSICAL PROPERTIES OF TISSUES. 67 instrument figured in the margin. It consists of a glass tube, the lower extremity of which, covered by bladder, is funnel-shaped. ThisM. Dutrochet termed an endosmometer. If an aqueous solution of either gum or sugar be poured into it, and the closed extremity be immersed in pure water, the water is found to pass continually into the tube by filtration through the membrane, so that the liquid will rise in the tube, and may even flow out at the upper aper- ture. At the same time, a portion of the mucilaginous or saccharine solution will escape from the tube through the bladder, and become mixed with the water, but the quan- tity will be much less than that of the water which entered. The facts and arguments adduced by Dr. Mitchell clearly exhibit, that imbibition and transudation are de- pendent upon the penetrativeness of the liquid, and the penetrability of the membrane; that if two liquids, of dif- ferent rates of penetrativeness, be placed on opposite sides of an animal membrane, " they will in time present the greater accumulation on the side of the less penetrant liquid, whether more or less dense; but will, finally, tho- roughly, and uniformly mix on both sides; and at length, if any pressure exist on either side, yield to that, and pass to the other side."1 In all such cases, there are both endosmose and exosmose—or double imbibition; in other words, a certain quantity of one fluid passes in, and a certain quantity of the other passes out.2 As a general rule, imbibition takes place from the rarer to the denser medium; from pure water or dilute solutions towards those that are more concentrated. It would appear, again, that the stronger cur- rent is always from the medium which has the strongest affinity for the substance of the septum. It is well known, that in the case of a mix- ture of dilute alcohol covered over by a piece of bladder, the alcohol becomes concentrated, owing to the water—a denser fluid—passing more rapidly through the septum or bladder than the alcohol; but if the same mixture be tied over with elastic gum, the contrary effect will be produced—the alcohol escaping in greater quantity.3 The general conditions of the phenomena of endosmose are:—first, that the two liquids shall have an affinity for the septum or interposed membrane; and, secondly, that they shall have an affinity for, and be miscible with, each other. A portion of the communication of Dr. Mitchell relates to an ana- logous subject, to which, as M. Magendie4 has observed, little or no attention had been paid by physiologists,—the permeability of mem- branes by gases. " The laminae," M. Magendie remarks, " of which membranes are constituted, are so arranged that gases can penetrate * Amer. Journal of the Medical Sciences for November, 1833, p. 100. 11 Magendie, Lecons sur les Phenomenes Physiques de la Vie, torn. i. p. 99, Paris, 1836-38. 3 Henle, Allgem. Anat., or Jourdan's French translat., p. 210, Paris, 1843; and Wagner, Elements of Physiology, by Willis, p. 438, Lond., 1842. * Precis Elementaire de Physiologie, 2de edit., 1S25, i. 13; and Lecons, &c, torn. i. p. 132. Endosmo- meter. 68 MATERIAL COMPOSITION OF MAN. them, as it were, without obstacle. If we take a bladder, and fill it with pure hydrogen, and afterwards leave it in contact with atmospheric air, in a very short time the hydrogen will have lost its purity, and be mixed with the atmospheric air, which has penetrated the bladder. This phenomenon is more rapid in proportion as the membrane is thin- ner and less dense. It presides over one of the most important acts of life—respiration ; and continues after death." Dr. Mitchell is the first individual, who directed his observation to the relative penetrativeness of different gases. This he was enabled to discriminate by the following satisfactory experiment, which we give in his own words: " Having constructed a syphon of glass, with one limb three inches long, and the other ten or twelve inches, the open end of the short leg was enlarged and formed into the shape of a funnel, over which, finally, was firmly tied a piece of thin gum elastic. By inverting this syphon, and pouring into its longer limb some clear mercury, a portion of common air was shut up in the short leg, and was in communication with the membrane. Over this end, in the mercurial trough, was placed the vessel containing the gas to be tried, and its velocity of penetration measured by the time occupied in elevating to a given degree the mercurial column in the other limb. Having thus compared the gases with common air, and subsequently by the same instrument, and in bottles with each other, I was able to arrange the following gases according to their relative facility of transmission, beginning with the most powerful:—ammonia, sulphu- retted hydrogen, cyanogen, carbonic acid, nitrous oxide, arseniuretted hydrogen, olefiant gas, hydrogen, oxygen, carbonic oxide, and nitro- gen." He found that ammonia transmitted in one minute as much in volume as sulphuretted hydrogen did in two minutes and a half; cyanogen, in three minutes and a quarter; carbonic acid, in five minutes and a half; nitrous oxide, in six minutes and a half; arseniuretted hydrogen, in twenty-seven minutes and a half; olefiant gas, in twenty-eight minutes; hydrogen, in thirty-seven minutes and a half; oxygen, in one hour and fifty-three minutes; and carbonic oxide, in two hours and forty minutes. It was found, too, that up to a pressure of sixty-three inches of mercury, equal to more than the weight of two atmospheres, the penetrative action was capable of conveying the gases—the sub- jects of the experiment—into the short leg through the gum elastic membrane. Hence, the degree of force exerted in the penetration is considerable. The experiments were all repeated with animal membranes, such as dried bladder and gold-beater's skin, moistened so as to resemble the natural state. The same results, and in the same order, followed as with the gum elastic. The more fresh the membrane, the more speedy and extensive was the effect; and in living animals the transmission was very rapid. To these experiments there will be frequent occasion to refer in the course of this work.1 1 See, connected with this subject, the ingenious papers by Dr. Robert E. Rogers, and Dr. Draper,—the former in the American Journal of the Medical Sciences, May, 1836 p 13- FUNCTIONS OF MAN. 69 All these different properties of animal solids are independent of the vital properties. They continue for some time after the total extinc- tion of life in all its phenomena, and appear to be connected either with the physical arrangement of the molecules, the chemical compo- sition of the substance in which they reside, or with peculiar properties in the body that is made to act on the tissue. They do not, indeed, seem to be affected, until the progress of decomposition has become sensible. Hence, many of them have been termed collectively, by Haller, vis mortua. 2. FUNCTIONS OF MAN. Having described the intimate structure of the tissues, we pass to the consideration of the functions; the character of each of which is, —that it fulfils a special and distinct office in the economy, for which it has in general an organ or instrument, or evident apparatus of organs. Physiologists have not, however, agreed on the number of distinct offices; and hence the difference, in regard to the number and classi- fication of the functions, that prevails amongst them. The oldest division is into the vital, natural, and animal; the vital functions in- cluding those of such importance as not to admit of interruption,—cir- culation, respiration, and innervation; the natural functions those that effect nutrition, digestion, absorption, and secretion; and the animal, those possessed exclusively by animals,—sensation, locomotion, and voice. This classification, with more or less modification, prevails at the pre- sent day. The character of this work will not admit of a detail of every classi- fication which has been proposed; that of Bichat, however, has occu- pied so large a space in the public eye, that it cannot well be passed over. It is followed by M. Richerand,1 and many modern writers. Bichat includes all the functions under two heads,—functions of nutri- tion, which concern the life of the individual, and functions of reproduc- tion, which concern the life of the species. Nutrition requires, that the being shall establish relations around him to obtain the materials of which he may stand in need; and, in animals, the functions that esta- blish such relations, are under the volition and perception of the being. Hence they are divided into two sets; those that commence or precede nutrition; have external relations; are dependent upon the will, and executed with consciousness; and those that are carried on within the body spontaneously, and without consciousness. Bichat adopted this basis; and, to the first aggregate of functions, he applied the term animal life, because it comprised those that characterize animality; the latter he termed organic life, because the functions comprised under it are common to every organized body. Animal life included sensation, motion, and expression; organic life, digestion, absorption, respiration, circulation, nutrition, secretion, &c. In animal life, Bichat recognized and the latter in the same Journal for August, 1836, p. 276 ; Nov. 1837, p. 122 ; and Aug. 1838, p. 302. ' Nouveaux Elemens de Physiologie, 13eme edit., par M. Berard, aine, edit. Beige, p. 42, Bruxelles, 1837; or Amer. reprint of Copland's edit, of De Lys's translation, New York, 1836. 70 FUNCTIONS OF MAN. two series of actions, antagonistic to each other; the one proceeding from without and terminating in the brain, or passing from circum- ference to centre, and comprising the external senses; the other, com- mencing in the brain, and acting on external bodies, or proceeding from centre to circumference, and including the internal senses, loco- motion, and voice. The brain, in which one series of actions terminates and the other begins, he considered the centre of animal life. In organic life, he likewise recognized two series of actions : the one, pro- ceeding from without to within, and effecting composition; the other passing from within to without, and effecting decomposition. In the former, he included digestion; absorption; respiration, by which the blood is formed; circulation, by which the blood is conveyed to different parts ; and the functions of nutrition, and calorification. In the latter, that absorption by which parts are taken up from the body; the cir- culation, which conducts those parts or materials to the secretory or depuratory organs; and the secretions, which separate them from the economy. In this kind of life, the circulation is common to the two movements of composition and decomposition; and, as the heart is the great organ of the circulation, he considered it the centre of organic life. Lastly, as the lungs are united with animal life in the reception of air, and with organic life as the organs of sanguification, Bichat regarded them as the bond of union between the two lives. Genera- tion constituted the life of the species. The classification, adopted in this work, is essentially that embraced by M. Magendie 'f and, after him, by M. Adelon,2 who has written one of the best systems of human physiology that we possess. The FIRST class, or functions of relation or animal functions, includes those that establish our connexion with the bodies that surround us; the sensations, voluntary motions, and expressions. The second class, or functions of nutrition, comprises digestion, absorption, respiration, circulation, nutrition, calorification, and secretion ; and the third class, the func- tions of reproduction,—generation. I. Functions that relate to the preservation of the indi- vidual. II. Functions that relate to the preservation of the species TABLE OF FUNCTIONS. I. Animal or of Relation. II. Nutritive. ) III. Reproductive. ( 1. Sensation. < 2. Muscular Motion. ( 3. Expression or Language. f 4. Digestion. 5. Absorption. | 6. Respiration. «{ 7. Circulation. 18. Nutrition. 9. Calorification. ^10. Secretion. 11. Generation. In studying each of these functions, we shall first of all describe the organ or apparatus concerned in its production,—but so far only as is necessary in a physiological point of view; and shall next detail what has been called the mechanism of the function, or the mode in which it is effected. In many cases, it will happen, that some external agent 1 Precis, &c, i. 32. ' Physiologie de l'Homme, 2de e\lit., i. 116. Paris 1829. FUNCTIONS OF MAN. 71 is concerned,—as light in vision; sound in audition ; odours in olfaction ; tastes in gustation. The properties of these agents will, in all instances, be detailed in a brief manner. The difficulty of observing actions, that are carried on by the very molecules of which the organs are composed, has given rise to many hypothetical speculations, some of which are sufficiently ingenious; others too fanciful to be indulged for a moment; and, as might be expected, the number of these fantasies generally bears a direct pro- portion to the difficulty and obscurity of the subject. It will not be proper to pass over the most prominent of these, but they will not be dwelt upon; whilst the results of direct observation and experiment will be fully detailed; and where differences exist amongst observers, such differences will be reconciled, where practicable. The functions, executed by different organs of the body, can be de- duced by direct observation; although the minute and molecular action, by which they are accomplished in the very tissue of the organ, may not admit of detection. We see blood proceeding to the liver, and the vessels that convey it ramifying in the texture of that viscus, and becoming so minute as to escape detection even when the eye is aided by a powerful microscope. We find, again, other canals in the organ becoming perceptible, gradually augmenting in size, and ultimately terminating in a larger duct, which opens into the small intestine. If we examine each of these orders of vessels in their most minute appre- ciable ramifications, we discover, in the one, always blood; and, in the other, always a very different fluid,—bile. We are hence led to the conclusion, that in the intimate tissue of the liver, and in some part communicating directly or indirectly with both these orders of vessels, bile is separated from the blood; or that the liver is the organ of the biliary secretion. On the other hand, functions exist, which cannot be so demonstratively referred to a special organ. We have every reason for believing, that the brain is the exclusive organ of the mental and moral manifestations; but, as few opportunities occur for seeing it in action; and as the operation is too molecular to admit of direct observation when we do see it, we are compelled to connect the organ and function by a process of reasoning only; yet, we shall find, that the results at which we arrive in this manner are often by no means the least satisfactory. The forces which preside over the various functions are either gene- ral,—that is, physical or chemical; or special,—that is, organic or vital. Some of the organs afford us examples of purely physical instruments. We have in the eye, an eye-glass of admirable construction; in the organ of voice, an instrument of music; in the ear, one of acoustics: the circulation is carried on through an ingenious hydraulic apparatus ; and station and progression involve various laws of mechanics. In many of the functions, again, we have examples of chemical agency, whilst all in which innervation is concerned are incapable of being explained on any physical or chemical principle; and we are constrained to esteem them vital. 72 NERVOUS SYSTEM. BOOK I. ANIMAL FUNCTIONS OR FUNCTIONS OF RELATION. The functions of relation consist, first, of sensibility, and, secondly, of muscular motion, including expression or language. They are all subject to intermission, constituting sleep; a condition which has, con- sequently, by many physiologists, been investigated under this class; but as the functions of reproduction are influenced by the same condi- - tion, the consideration of sleep will be deferred until the third class of functions has received attention. CHAPTER I. SENSIBILITY. Sensibility is the function by which an animal experiences feeling, or has the perception of an impression. In its general acceptation, it means the property possessed by living parts of receiving impressions, whether the being exercising the property has consciousness of it or not. To the first of these cases—in which there is consciousness— Bichat gave the epithet animal; to the second, organic; the latter being common to animals and vegetables, and presiding over the organic functions of nutrition, absorption, exhalation, secretion, &c.; the former existing only in animals, and presiding over the sensations, internal as well as external. Animal sensibility will be considered here. It would be well, indeed, to restrict the term sensibility to cases involving consciousness. Pursuing the plan already laid down, the study of this interesting and elevated function will be commenced, by pointing out, as far as may be necessary, the apparatus that effects it, the nervous system. 1. NERVOUS SYSTEM. Under the name nervous system, anatomists include all those organs that are composed of nervous or pulpy tissue—neurine. In man, it is constituted of three portions: first, of what has been called the cerebro- spinal axis, a central part having the form of a long cord, expanded at its superior extremity, and contained within the cavities of the cranium and spine; secondly, of cords, called nerves, in number thirty-nine pairs, according to some,—forty-two, according to others,—passing laterally between the cerebro-spinal axis and every part of the body; and lastly of a nervous cord, situate on each side of the spine, from the head to the pelvis, forming ganglia opposite each vertebral foramen, and called the great sympathetic. ENCEPHALON. 7S 1. Encephalon.—Under this term are included the contents of the cranium, namely, the cerebrum or brain proper, the cerebellum or little brain, and the medulla oblongata. These parts collectively have been by some called brain. When we look at a section of the encephalon, Fis- 2- in its natural position, we find many distinct parts, and the appearances of numerous and separate organs. So various, indeed, are the prominences and depressions observable on the dissection of the brain, that it is generally esteemed one of the most difficult subjects of anatomy; yet, owing to the attention paid to it in all ages, it is now one of the structures best understood by the anatomist. This complicated organ presents a striking illus- tration of the truth, that the most accurate ana- tomical knowledge does not necessarily teach the function. The elevated actions, which the ence- phalon has to execute, have, indeed, attracted a large share of the attention of the physiologist,— too often, however, without any satisfactory result; yet it may, we think, be safely asserted, that we have become better instructed regarding the uses of particular parts of the brain, within the last few years, than during the whole of the century preceding. The encephalon being of extremely delicate organization, and its functions easily deranged, it was necessary that it should be securely lodged and protected from injuries. Accordingly, it is placed in a round, bony case ; and by an admira- ble mechanism is defended against damage from surrounding bodies. Amongst these guardian agents or tutamina cerebri must be reckoned:— the hair of the head; the skin; muscles; pericra- nium; bones of the skull; the diploe separating the two tables of which the bones are composed, and the dura mater. It is not an easy matter to assign probable uses for the hair on various parts of the body. On the head, its function seems more readily appropria- blel It deadens the concussion, which the brain would experience from the infliction of heavy blows, and prevents the skin of the scalp from being injured by the attrition of bodies. In mili- tary service, the former of these uses has been taken advantage of; and an arrangement, some- what similar to that which exists naturally on the head, has been adopted with regard to the helmet. The metallic substance, of which the ancient and modern helmets are formed, is readily thrown into Anterior view of the Brain and Spinal Marrow. 1, 1. Hemispheres of the cerebrum. 2. Great middle fissure. 3. Cerebrum. 4. Olfactory nerves. 5. Optic nerves. 6. Corpora albi- cantia. 7. Motor oculi nerves. 8. Pons Varolii. 9. Fourth pair of nerves. 10. Lower portion of medulla oblongata. 11, 11. Medulla spinalis. 12, 12. SpinaJ nerves. 13. Cauda equina. 74 NERVOUS SYSTEM. vibration; and this vibration being communicated to the brain might, after heavy blows, derange its functions more even than a wound in- flicted by a sharp instrument. To obviate this, in some measure, the helmet has been covered with horse-hair ; an arrangement which ex- isted in the helmet worn by the Roman soldier. There can be no doubt, moreover, that being bad conductors of caloric, and forming a kind of felt which intercepts the air, the hairs may tend to preserve the head of a more uniform temperature. They are likewise covered with an oily matter, which prevents them from imbibing moisture, and causes them to dry speedily. Another use ascribed to them by M. Magendie,1 is more hypothetical:—that, being bad conductors of electricity, they may put the head in a state of insulation, so that the brain may be less affected by the electric fluid ! It is unnecessary to explain in what manner the different layers of which the scalp is composed; the cellular membrane beneath; the pan- niculus carnosus or occipito-frontalis muscle; and the pericranium covering the bone, act the parts of tutamina. The most important of these protectors is the bony case itself. In an essay written by a dis- tinguished physiologist,2 we have some beautiful illustrations of the wisdom of God as displayed in the mechanism of man, and of his skull in particular; and although some of his remarks may be liable to the censures that have been passed upon them by Dr. Arnott,3 most of them are admirably adapted to the contemplated object. It is impossible, indeed, for the uninitiated to rise from the perusal of his interesting essay, without being ready to exclaim with the poet, "How wonderful, how complicate is man! how passing wonder He that made him such!" Sir Charles Bell attempts to prove, that the best illustration of the form of the head is the dome; whilst Dr. Arnott considers it to be " the arch of a cask or barrel, egg-shell, or cocoa-nut, &c, in which the tena- city of the material is many times greater than necessary to resist the influence of gravity, and comes in aid, therefore, of the curve to resist forces of other kinds approaching in all directions, as in falls, blows, unequal pressures," &c. The remarks of Dr. Arnott on this subject are just; and it is owing to this form of the cranium, that any blow received upon one part of the skull is rapidly distributed to every other; and that a heavy blow, inflicted on the forehead or vertex, may cause a fracture, not in the parts struck but in the occipital or sphe- noidal bones. The skull does not consist of one bone, but of many. These are joined together by sutures,—so called from the bones seeming as if they were stitched together. Each bone consists likewise of two tables; an external, fibrous, and tough; and an internal, of a harder character and more brittle, hence called tabula vitrea. The two are separated from each other by a cellular or cancellated structure, called diploe. On examining the mode in which the tables form a junction with each other at the sutures, we find additional evidences of design exhibited. 1 Precis Elementaire, edit. cit. i. 177. i Sir Charles Bell, in Animal Mechanics—Library of Useful Knowledge, London 1829. » Elements of Physics, or Natural Philosophy, General and Medical, London 1827__re- printed in this country, Philad., 1841. ENCEPHALON. 75 Fig. 3. The edges of the outer table are serrated, and so arranged as to be accurately dovetailed into each other; the tough fibrous texture of the external plate being well adapted for such a junction. On the other hand, the tabula vitrea, which, on account of its greater hardness, would be liable to fracture and chip off, is merely united with its fellow at the suture, by what is called harmony: the tables are merely placed in contact. The precise object of the sutures is not apparent. In the mode in which ossifi- cation takes place in the bones of the skull, the radii from different ossific points must necessarily meet by the "law of conjugation," in the progress of ossification. This has, by many, been esteemed the cause of the sutures; but the explanation is insufficient. Howso- ever it may be, the kind of junction af- fords a beautiful example of adaptation. During the foetal state, the sutures do not exist. They are fully formed in youth; are distinct in the adult age; but in after periods of life become entirely obliterated, the bone then forming a solid spheroid. It does not seem that after the sutures are established, any displace- ment of the bones can take place; and observation has shown, that they do not possess much, if any, effect in putting a limit to fractures. In all cases of severe blows, the skull appears to resist as if it were constituted of one piece. But the separation of the skull into distinct bones, which have a membranous union, is of striking advantage to the foetus in par- turition. It enables the bones to overlap each other; and, in this way, to occupy a much smaller space than if ossification had united them as in after life. It has, indeed, been imagined by some, that there is this advan- tage in the pressure made on the brain by the investing bones,—that the foetus does not suffer from the violent efforts made to extrude the child; but, during the passage through the pelvis, is in a state of fortu- nate insensibility; and pressure suddenly exerted upon the brain is certainly attended with these effects,—a fact, which has to be borne in mind in the management of apoplexy, fracture of the skull, &c. The uses of the diploe, which separates the two tables of the skull, are not equivocal. Composed of a cancellated structure, it is well adapted to deaden the force of blows; and as it forms, at the same time, a bond of union and of separation, a fracture might be inflicted upon the outer table of the skull, and yet be prevented from extending to the tabula vitrea. Such cases have occurred, but they are rare. It Front view of the Skull. 1. Frontal portion of the frontal bone. 2. Nasal tuberosity. 3. Supra-orbital ridge. 4. Optic foramen. 5. Sphenoidal fissure. 6. Spheno-maxillary fissure. 7. Lachrymal fossa, and commencement of the nasal duct. 8. Opening of the anterior nares, and the vomer. 9. Infra-orbital foramen. 10. Malar bone. 11. Symphysis of the lower jaw. 12. Mental foramen. 13. Ramus of the lower jaw. 14. Parietal bone. 15. Coronal suture. 16. Temporal bone. 17. Squamous suture. 18. Great ala of the sphenoid bone. 19. Commence- ment of the temporal ridge. 20. Zygoma of the temporal bone. 21. Mastoid pro- cess. 76 NERVOUS SYSTEM. Fig. 4. will generally happen, that a blow, intended to cause serious bodily injury, will be sufficient to break through both tables, or neither. Lastly, the dura mater, which has been reckoned as one of the tuta- mina cerebri, lines the skull, and constitutes a kind of internal perios- teum to it. It may also be inservient to useful purposes, by deadening the vibrations, into which the head may be thrown by sudden concus- sions ; as the vibrations of a bell are arrested by lining it with a soft material. It is chiefly, however, to protect the brain against itself, that we have the arrangement which prevails. The cerebrum, as well as the cerebellum, consists of two hemispheres; and its posterior part is situate immediately above the cerebellum. It is obvious, then, that without some protection, the hemisphere of one side would press upon its fellow, when the head is inclined to the opposite side; and that the posterior lobes of the brain would weigh upon the cerebellum in the erect attitude. The hemispheres are separated from each other by the falx cerebri, in the upper margin of which is the superior longitudinal sinus. The falx passes between the hemispheres. The tentorium cerebello superexten- sum—a prolongation of the dura mater—passes horizontally forwards so as to support the posterior lobes of the brain, and prevent them from pressing injuriously on the cerebellum. A process of the dura mater passes also between the hemispheres of the cerebellum. Independently of the protection afforded to the encepha- lon, the dura mater lodges the great sinuses into which the veins discharge their blood. These different sinuses empty themselves into the torcular Herophili or confluence of the sinu- ses; and ultimately proceed to con- Falx Cerebri and Sinuses of upper and back gtitute the lateral sinuses, which paSS through the temporal bone, and form the internal jugular veins. The tutamina are not confined to the contents of the cranium. The part of Skull. 1, 2. 3. Section of the bones of the cranium, showing the attachment of the falx major. 4. Anterior portion of superior longitudinal sinus. 5. Middle portion. 6. Inferior portion; the outer table of the cranium removed. 7. Commence- ment of the inferior longitudinal sinus. 8. Its termination in the straight sinus. 9. Sinus spine appears to be, if possible, Still quartus or rectus. 10. Vena Galeni. 11. One , .. , , j T ,, in of the lateral sinuses. 12. Torcular Herophili. better protected. In the Skull, We 13. Sinus of the falx cerebelli. 14. Internal -fl,.™ V>/->«Tr noor. • 1^ <-l,„ „ :___ jugular vein. 15. Dura mater of the spinal See a tirm, DOny Case , 111 the Spine, marrow. Tentorium cerebeiii. 17, n. a structure admitting considerable motion of the parts, without risk of pressure to the marrow. Accordingly, the spine consists of numerous distinct bones or vertebrae, with fibro-cartilaginous—technically called intervertebral—substances placed between each, so that, although the extent of motion between any two of these bones may be small, when all are concerned, it is considerable. The great use of this interver- Falx cerebri. ENCEPHALON. 77 tebral substance is to prevent the jar, that would necessarily be communicated to the delicate parts within the cavities of the spine and cranium, were the spine composed entirely of one bone. In falls from a height upon the feet or breech, these elastic cushions are forcibly compressed; but they immedi- ately return to their former condition, and deaden the force of the shock. In this they are aided by the curvatures of the spine, which give it the shape of the Italic/, and enable it to resist—in the same manner as a steel spring—any force acting upon it in a longitudinal direction. So well is the medulla spinalis protected by the strong bony processes jutting out in various direc- tions from the spine, that it is extremely rare to meet with lesions of the marrow; and it is comparatively of late years that any ex professo treatises have appeared on the subject. Besides the protection afforded by the bony structure to the delicate medulla, M. Magendie1 has pointed out another, which he was the first to detect. The canal, formed by the dura mater around the spinal cord, is much larger than is necessary to contain that organ; but, during life, the whole of the intermediate space is filled with a serous fluid, which strongly distends the membrane, so that it will frequently spirt out to a distance of several inches, when a puncture is made in the membrane. To this fluid he has given the epithet ce- phalo-spinal; and he conceives, that it may act as one of the tutamina of the marrow— which is, as it were, suspended in the fluid— and exert upon it the pressure necessary for the healthy performance of its functions. Beneath the dura mater is a very delicate membrane, the arachnoid, belonging to the class of serous membranes. It surrounds the encephalon in every part; but is best seen at the base of the brain. Its chief use is to secrete a thin fluid, to 1 Precis, &c, edit, cit.i. 181. For an elaborate descrip- tion of the fluid, see Magendie, Recherches Physiolo- giques, &c, sur le Liquide cephalo-rachidien, Paris, 1842; and Dr. Todd, Cyclop, of Anat. and Physiol., part xxv. p. 639, Lond., 1844. Lateral View of the Spinal Column. 1. Atlas. 2. Dentata. 3. Seventh cervical vertebra. 4. Twelfth dorsal vertebra. 5. Fifth lumbar vertebra. 6. First piece of sacrum. 7. Last piece of sacrum. 8. Coccyx. 9. A spinous process. 10, 10. Interverte- bral foramina. 78 NERVOUS SYSTEM. Longitudinal Section of the Brain on the Mesial Line. 1. Inner surface of the left hemisphere. 2. Divided sur- face of the cerebellum, showing the arboi vitae. 3. Medulla oblongata. 4. Corpus callosum, continuous with 5, the for- nix. 6. One of the crura of the fornix descending to 7, one of the corpora albicantia. 8. Septum lucidum. 9. Velum interpositum, communicating with the pia mater of the convolutions through the fissure of Bichat. 10. Section of the middle commissure in the third ventricle. 11. Section of the anterior commissure. 12. Section of the posterior commissure; the commissure is somewhat above and to the left of the number. The interspace between 10 and 11 is the foramen commune anterius, in which the crus of the fornix vleXUS CllOrOldeS (6) is situate. The interspace between 10 and 12 is the fora- ■*■% .-, m, men commune posterius. 13. Corpora quadrigemina, upon CflOrOluea. LUe QUra which is the pineal gland, 14. 15. Iter a tertio ad quartum ventriculum. 16. Fourth ventricle. 17. Pons Varolii, through which are passing the diverging fibres of the corpora pyramidalia. 18. Crus cerebri of the left side, with the third nerve arising from it. 19. Tuber cinereum, from which projects the infundibulum having the pituitary gland ap- pended to its extremity. 20. One of the optic nerves. 21. Left olfactory nerve. The Convolutions of one Side of the Cerebrum, as seen from above. Anterior lobe of the cerebrum. 3. Middle lobe. 2. Posterior lobe. lubricate the brain. This membrane enters into all the cavities of the organ, and in them fulfils a like func- tion. When the fluid accu- mulates to a great extent, the resulting disease is hy- drocephalus chronicus. Anatomists usually de- scribe a third tunic of the brain—the pia mater. This is generally conceived to consist of the minute termi- nations of the cerebral arte- ries, and those of the cor- responding veins; forming at the surface of the brain a vascular network, which passes into the cavities; and, in the ventricles, forms the and tela and pia mater were so called by the older anatomists, because they were conceived to be the origin of all the other membranes of the body. The cerebrum or brain proper has the form of an oval, larger behind. On its outer surface are various un- dulating eminences, called convolutions, because they have been thought to re- semble the folds of the in- testines. They are separated from each other by depres- sions called anfractuosities. They form the hemispherical ganglion of Mr. Solly. In and and the the brain of man, these convolutions are larger than in animals; the anfractuosities deeper. In different brains, the number, size, arrangement of these vary. They are not the same, indeed, in same individual; those of the right hemisphere being disposed differently from those of the left. The_ hemispheres, it has been seen, are separated above by the falx cerebri: below, they are united by a white medullary commissure cor- pus callosum, mSsolobe or great commissure,—great transverse commis- sure of Mr. Solly. If we examine the brain at its base, we find that each hemisphere is divided into three lobes,—an anterior which rests ENCEPHALON. 79 Fig. 8. on the vault or roof of the orbit,—a middle or temporal, filling the mid- dle and lateral parts of the base of the cranium, and separated from the former by a considerable depression, called fissure of Sylvius,— and a posterior, which rests on the tentorium cerebelli. This part of the cerebrum is divided into two very distinct portions by the medulla oblongata. Anterior to it are the crura cerebri or cerebral peduncles— by most anatomists considered to be a continuation of the anterior fas- ciculi which form the spinal marrow and medulla oblongata, and pro- ceeding to form the hemispheres of the brain. Between the anterior extremities of the peduncles are two hemispherical projections, called eminentiae mammillares, which are possessed by man exclusively; have the shape of a pea; and are formed of white nervous tissue externally, of gray within. Anterior to these again is the infundibulum; and a little farther forwards, the chiasma of the optic nerves or the part at which these nerves come in contact. Laterally, and at the inferior surface of the anterior lobes, is a groove or furrow, running from behind to before, and from without to within, in which the olfactory nerve is lodged. At the extremity of this furrow is a tubercle, which is tri- fling in man, but in certain animals is equal to the rest of the brain in bulk. From this the olfactory nerve has been conceived to arise. It is called the ol- factory tubercle or lobe. When we examine the interior of the brain, we find a number of parts to which the anatomist assigns distinct names. Of these the following chiefly concern the physiologist. It has been already remarked, that the corpus cal- losum forms at once the bond of union and of separation between the two hemispheres. It is distinctly perceived, in the form of a long and broad white band, on separating these parts from each other. Beneath the corpus callo- sum is the septum lucidum or median septum, which passes perpendicularly downwards, and separates from each other the two largest cavities of the brain—the lateral ventricles. It is formed of two laminae, which leave a cavity between them, called the fifth ventricle. The fornix or inferior longi- tudinal commissure of Mr. Solly, whose office is to connect the anterior and pos- terior parts of the same hemisphere, as the transverse commissures do those of the opposite hemisphere, is placed hori- zontally below the last. The band of Superior Part of the Lateral Ventricles, Corpora Striata, Septum Lucidum, Fornix, &c, as given by a Transverse Section of the Cerebrum. 1. Section of the os frontis. 2. Section of the os occipitis. 3. Section of the ossa pa- rietalia. 4, 5. Anterior and posterior extre- mities of the middle fissure of the cerebrum. 6. Anterior extremity of the corpus callo- sum. 7. Its posterior extremity joining the fornix. 8, 8. Point to where the corpus callosum joins the lateral medullary matter of the cerebrum. 9. Its place of junction anteriorly. 10. Posterior point of union. 11. Middle portion of the corpora striata (lateral ventricle). 12. Taenia striata. 13. Septum lucidum. 14. Fifth ventricle. 15. Fornix. 16. Posterior crura. 17. Plexus choroides. 18. Ergot or hippocampus mi- nor. 19. Posterior crura, of the lateral ventricle. 80 NERVOUS SYSTEM. fibres which runs in each hemisphere above the corpus callosum, on the edge of the longitudinal fissure, is the superior longitudinal com- missure of Mr. Solly. Its use is supposed to resemble that ascribed to the inferior longitudinal commissure. The fornix is of a triangular shape; and constitutes the upper paries of another cavity—the third ven- tricle. Beneath the fornix, and behind, are the pineal gland and its peduncles, forming the pineal commissure of Mr. Solly, re- specting which so much has been said, by Descartes,1 and others, as the seat of the soul. Within it is a small cavity; and, after six or seven years of age, it al- ways contains some concretions. Again, anterior to the pineal gland, andimmediatelybelowthe fornix, is another cavity—the thirdventricle. Its bottom is very near the base of the brain, and is formed by the nervous layer which unites the peduncles of the brain with the eminentise mammillares. At the sides, it has the thalami nervorum opti- corum. In the lateral ventricles, situ- ate on each side of the corpus callosum, some parts exist which demand attention. In the upper or anterior half, commonly called anterior cornu, and in the ante- rior part of this, two pyriform eminences are seen, of a brown- ish-gray colour, which, owing to their being formed of an assem- blage of alternate layers of white and gray substance, are called corpora striata, the anterior ce- rebral ganglions of Mr. Solly. Behind these, are two whitish medullary bodies called thalami ner- vorum opticorum—posterior cerebral ganglions—which are situate be- fore the corpora quadrigemina, and envelope the anterior extremities of the crura cerebri. Three main sets of fibres may be distinguished in the medullary sub- stance, of which the great mass of the cerebrum is composed. First, the ascending fibres, which proceed from the sensory tract of the me- dulla spinalis, and diverge from the thalami optici to the periphery of Section of the Cerebrum, displaying the surfaces of the Corpora Striata, and Optic Thalami, the cavity of the Third Ventricle, and the upper surface of the Cerebellum. a, t. Corpora quadrigemina,—a testis, e nates. 6. Soft commissure, c. Corpus callosum. /. Anterior pillars of fornix, g. Anterior cornu of lateral ventri- cle, k, k. Corpora striata. ',*. Optic thalami. ♦An- terior tubercle of the left thalamus, z to 5. Third ventricle. In front of z, anterior commissure. 6. Soft commissure, s. Posterior commissure, p. Pineal gland with its peduncles, n, n. Processus a cerebello ad testes, m, m. Hemispheres of the cerebellum, h Superior vermiform process, i. Notch behind the cerebellum. 1 Tractatus de Homine, p. 5, MEDULLA OBLONGATA. 81 the brain; secondly, the de- scending fibres, which con- verge from the periphery to- wards the corpora striata, and then pass downwards to the motor tract of the me- dulla spinalis; and, thirdly, the commissural fibres, which establish a connexion be- tween the various parts of the periphery, and of the substance of the brain. The bulk of the human brain, and of that of the higher animals, is greatly dependent upon the large proportion borne by these last fibres to the rest.1 The cerebellum occupies An under View of the Cerebellum, seen from behind. The medulla oblongata, m, having been cut off a short way below the pons. (Reil.) c. Pons Varolii, d. Middle crus of cerebellum, e, e. Crura cerebri, i. Notch on posterior border, k. Commencement of horizontal fissure. I. Flocculus, or subpeduncular lobe. m. Medulla oblon- gata cut through, q. to 5. The inferior vermiform process, the lower OCCipital IOSSSe, Or lying in the vallecula, p. Pyramid, r. Uvula, n, n. ,-, i ■. n .1 „ „„ 'j.„ „e t-\.~ Amygdala?, s. Nodule, or laminated tubercle, x. Poste- the WhOle 01 the Cavity Ot the rior velum, partly seen. w. Right and left hemispheres of cerebellum. 3 to 7. Nerves. 3, 3. Motores oculorum. 5. Trigeminal. 6. Abducent nerve. 7. Facial and audi- tory nerves. cranium beneath the tento- rium cerebelli. Its size and weight, like those of the brain, differ according to the in- dividual, and the age of the subject under examination. We do not observe convolutions in it. It appears rather to consist of laminae in superposition, sepa- rated from each other by fur- rows. We shall see, hereafter, that the number of cerebral convolutions has been esteemed, in some respects, to accord with the intellect of the individual; and Malacarne asserts, that he has observed a similar corre- spondence, as regards the num- ber of lamin33 Composing the Ce- Posterior Superior View of the Pons Varolii, rebelkm; that he found Only Cerebellum, and Medulla Oblongata and M. Spi- three hundred and twenty-four 1) x Crura cerebri. 2. Pons Varolii or tuber an- ?« -rlio novoKolliiTn r>f an in u. Snpe. the Cerebellum, tWO large White rior portion of the hemispheres of the cerebellum. , ', «■>... 12. Lobulus amygdaloides. 13. Corpus olivare. 14. COrdS paSS tO the pons Varolii, Corpus pyramidale. 15. Medulla spinalis. VOL. I.—6 Carpenter, Human Physiology, p. 215. Lond., 1842. 82 MEDULLA OBLONGATA. having the same disposition as the crura cerebri. They are the crura cerebelli. Owing to the peculiar arrangement of the white and gray cerebral substances, when one of the hemispheres of the cerebellum is divided vertically, an arborescent appearance is presented,—the trunks of the arborization being white, the surrounding substance gray. This ap- pearance is called arbor vitae. The part where all these arborizations meet, near the centre of the cerebellum, is called corpus denticulatum vel rhombdidale. Gall was of opinion, that this body has great agency in the production of the cerebellum. Lastly, the cerebellum covers the posterior part of the medulla oblongata, and forms with it a cavity, called fourth ventricle. The medulla oblongata is so called, because it is the continuation of Fig. 12. Analytical Diagram of the Encephalon—in a Vertical Section. (After Mayo.) s. Spinal cord. r. Restiform bodies passing to c, the cerebellum, d. Corous denratum r.f n.« „«,.« helium, o Olivary body. /. Columns continuous with the olivary bodfeT and central na t of the medulla oblongata, and ascending to the tubercula quadrigemina and optic thalami.p Anterior mr* mids. v. Pons Varolii, n, b. Tubercula quadrigemina. g. Geniculate body of'theTonHn IhJi P™f,« t. Processus cerebelli ad testes, a. Anterior lobe*of the brain. q. Posterio/lobe of the brahi MEDULLA OBLONGATA. 83 and On the medulla spinalis in the cavity of the cranium. It is likewise termed mesocephale, from its being continuous with the spinal marrow in one direction, and sending towards the brain strong prolongations—crura cerebri; and to the cerebellum similar prolongations—crura cerebelli; so that it appears to be the bond of union between these various parts. In its lower portion, it seems to be merely a continuation of the me- dulla spinalis, except that it is more expanded superiorly where it joins the pons Varolii. This portion of the medulla oblongata is called, by some, tail of the medulla oblongata; by others, the rachidian bulb; and, by others again, it is regarded as the medulla oblongata. Its lower surface rests on the basilary gutter of the occipital bone exhibits a groove which divides the spinal cord into two portions. each side of this furrow are two oblong eminences, the innermost of which is called corpus pyramidale, the outermost, corpus olivare, which arise from the anterior column of the medulla spinalis, or are a continuation and subdivision of this column. These oval bodies are surrounded by a superficial groove, which, in some instances, is partially interrupted by some arciform fibres, which cross it at its lower part. At the lower third of the medulla oblongata, fibres of the anterior pyramids decussate, and form an anatomical demarcation between the medulla oblon- gata and the spinal cord. The decussation takes place by from three to five bundles of fibres from each pyramidal body. This decussation, as will be seen, hereafter, is interesting in regard to the cross effect induced by certain diseases of the brain. On the posterior surface of the medulla oblongata, the posterior fasciculi separate to form the fourth ven- tricle : at the sides of this ventricle are the corpora restiformia, or inferior peduncles of the cerebellum, —so called because they seem to aid in the forma- tion of that part of the encephalon; and on the in- ner side of each corpus restiforme is the small body—the posterior pyramid. Again, in addition to the corpora pyramidalia and olivaria—which de- rive their origin from, or are continuous with, the anterior fasciculi of the spinal cord, and are destined, according to some, to form the brain—and the cor- pora restiformia, which are continuations of the posterior fasciculi, and are destined to form the cere- bellum, there exists, according to some anatomists, other fasciculi in the rachidian bulb. All these are interesting points of anatomy, but are not of so much importance physiologically; notwithstanding even the views promulgated by Sir Charles Bell.1 He considers that a column exists between the corpora olivaria and corpora restiformia, Anterior View of the Medulla Oblongata, showing the decus- sation of the Pyra- mids, and of the up- per part of the Spinal Uord. (After Mayo.) p. Anterior pyramids. r. Restiform bodies, o. Olivary bodies, d. De- cussating fibres, al. An- tero-lateral column of the spinal cord. c. An- terior fissure of the cord, the floor of which forms the anterior commis- sure. 1 The Nervous System of the Human Body: from Transactions of the Royal Society from 1821 to 1829, London, 1830. Reprinted in. this country, Washington, 1833. 84 SPINAL MARROW. which extends below through the whole spine, but above does not proceed farther than the point where the rachidian bulb joins the tuber annulare ; and that this column gives origin to a particular order of nerves—the respiratory. The corpora olivaria, and the posterior corpora pyramidalia, are regarded by Mr. Solly1 as ganglia;—the former of the function of respiration,—the latter of the sense of hearing. The anterior and upper half of the medulla ob- longata bears the names pons Varolii, tuber annu- lare, and nodus cerebri; and to this are attached, superiorly, the corpora or tubercula quadrigemina. In the very centre of the pons, the crura cerebri bury themselves; and by many, they are considered to decussate; by others, to be prolongations of the anterior column of the spinal marrow. Sir C. Bell thinks, that the pons Varolii stands in the same re- lation to the lateral portions of the cerebellum, that the corpus callosum does to the cerebrum ;—that it is the great commissure of the cerebellum, uniting its lateral parts, and associating the two organs. The medulla oblongata consists chiefly of the cen- tres of the nerves of respiration and deglutition, which, as elsewhere shown, are strictly reflex in their action. a 2. The spinal marrow extends, in the vertebral -p canal from the foramen magnum of the occipital F TUST bone above to the first or second lumbar vertebra, ^p^ where it terminates in the cauda equina. It is chiefly composed of medullary matter, but not entire- Transverse Sections of i WT'j.\.' ,i ■ •,■ i . • j the Spinal Cord. vso- Within, the cmeritious substance is ranged . immediately below irregularly, but has a crucial form when a section is made. The marginal illustrations exhibit sections of the spinal cord of man at different points; and the proportion of gray and white matter at each. From the calamus scriptorius in the fourth ventricle, and the rim a formed by the corpora pyramidalia be- fore, two fissures extend downwards, which divide the spinal marrow into lateral portions. The two lateral portions are divided into an anterior and a posterior, so that the cord has four distinct portionsv By some, indeed, it is conceived to consist of three columns—an anterior, posterior, and a middle or lateral. The vertebral canal is lined by a strong ligamentous sheath, running down its whole length. The dura mater likewise envelopes the medulla at the occipital foramen, being firmly united to the ligaments; but far- ther down it constitutes a separate tube. The tunica arachnoidea from E the decussation of the pyramids, b. At middle of cervical bulb. C.Mid- way between cervical and lumbar bulbs. B. Lumbar bulb. E. An inch lower. f. Very near the lower end. a. Anterior surface, p. Pos- terior surface. The points of emergence of the anterior and poste- rior roots of the nerves are also seen. 1 The Human Brain, its Configuration, Structure, Development, and Physiology &c, p. 147, London, 1836. See, on this subject, Dr. John Reid, on the Anatomy of the Medulla Oblongata, in Edinb. Med. and Surg. Journ., Jan., 1841, p. 12. NERVES. 85 the brain adheres loosely to the cord, having the cephalo-spinal fluid within it; and the pia mater closely embraces it. 3. Nerves.—The nerves are cords of the same nervous substance as that which composes the encephalon and spinal marrow; extending from these parts, and distribu- ted to the various organs of the body, many of them interlacing in their course, and forming plexuses: others having knots or ganglions, and almost all vanishing in the parts to which they are distributed. The generality of English anatomists reckon thir- ty-nine pairs of nerves; the French, with more propriety, forty-two. Of these, nine, accord- ing to the English— twelve, according to the , French—draw their ori- gin from, or are con- nected with, the ence- phalon; and are hence called encephalic nerves; and thirty from the me- dulla spinalis; and hence termed spinal. The encephalic nerves emerge from the cra- nium by means of fora- mina at its base. They are — proceeding from before to behind — the first pair or olfactory, distributed to the organ of smell; the second pair nerve or optic, the -expansion of which forms the retina ',. the third pair, motores oculi or common oculo-muscular, which send filaments to most of the muscles of the eye ; the fourth pair, trochleares, pathetici or internal oculo-muscular, dis- tributed to the greater oblique muscle of the eye; the fifth pair, tri- facial, trigemini, or symmetrical nerve of the head, (Bell,) which send their branches to the eye, nose, and tongue; the sixth pair, abduc&ntes or external oculo-muscular, which are distributed to the abductor or rectus externus oculi; the facial nerve, portio dura of the seventh pair, Shows the under Surface or Base of the Encephalon freed from its Membranes. a, anterior, b, middle, and c, posterior lobe of cerebrum.—a. The fore part of the great longitudinal fissure, b. Notch be- tween hemispheres of the cerebellum, c. Optic commissure. d. Left peduncle of cerebrum, e. Posterior perforated space. e to i. Interpeduncular space. /,/'. Convolution of Sylvian fissure, h. Termination of gyrus fornicatus behind the Sylvian fissure, i. Infundibulum. I. Right middle crus or peduncle of cerebellum, m, m. Hemispheres of cerebellum, n. Corpora albicantia. o. Pons Varolii, continuous at each side with middle crura of cerebellum, p. Anterior perforated space, q'. Horizon- tal fissure of cerebellum, r. Tuber cinereum. s, s'. Sylvian fissure, t. Left peduncle or crus of cerebrum, u, u. Optic tracts, v. Medulla oblongata, a:. Marginal convolution of the longitudinal fissure.^1 to 9 indicate the several pairs of cerebral nerves, numbered according to the usual notation, viz., 1. Olfac- tory nerve. 2. Optic. 3. Motor nerve of eye. 4. Pathetic. 5. Trifacial. 6. Abducent nerve of eye. 7. Auditory, and 7'. Fa- cial. 8. Glosso-pharyngeal, S'. Vagus, and8". Spinal accessory 86 NERVES. nervus communicans faciei or respiratory nerve of the face, distributed to the muscles of the face; the acoustic nerve, auditory nerve or portio mollis of the seventh pair, which passes to the organ of hearing; the eighth pair, pneumogastric, par vagum or middle sympathetic, which is dispersed particularly on the larynx, lungs, heart, and stomach; the glosso-pharyngeal, often considered as part of the last, and whose name indicates its distribution to the tongue and pharynx; the great hypo- glossal, ninth pair or lingual nerve distributed to the tongue; and the spinal accessory of Willis, which arises from the spinal cord in the cer- vical region; ascends into the cranium, and issues by one of the fora- mina to be distributed to the muscles of the neck. All these proceed, perhaps, from the medulla oblongata;—the brain and cerebellum not furnishing one. The spinal nerves are thirty in number on each side. They make their exit by the intervertebral foramina, and are divided into eight cervical, twelve dorsal, five lumbar, and five or six sacral. The encephalic nerves are irregular in their formation, and, with the exception of the fifth pair, originate from one root. Each of the spinal nerves arises from two fasciculi, the one anterior, and the other poste- rior : these roots are separated from each other by the ligamentum denticulare; but they unite beyond this ligament, and near the inter- vertebral foramen present one of those knots, known under the name of ganglions or ganglia, in the formation of which the posterior root is alone concerned. When the nerves have made their exit from the cranium and spine, they proceed to the organs to which Fig. 16. they have to be distributed; ramifying more and more, until they are ultimately lost sight of, even when vision is aided by a powerful microscope. It is not positively decided, whether the nervous fibres have any distinct terminations either in the nervous centres, or in the organs to which they are distributed. In the gray matter of the brain of the vertebrata, they would appear to form a kind of plexus of loops ; and the ulti- mate fibres do not seem to anastomose. The following has been described as the mode in which the nervous fibres are generally distributed to the peripheral organs. The trunks subdivide into small fasciculi, each of which consists of from two to six fibres, and these form plexuses, whose arrangement bears a general resemblance to that of the ele- ments of the tissue in which they are placed. The primitive fibres then se- parate; and each, after passing over several elementary parts of the contain- Terminal nerves, on the sac of the second molar tooth of the lower jaw, in the sheep; showing the arrangement in loops. (After Valentin.) NERVES. 87 ing tissue, or after forming a single narrow loop, as in the sensory papillae, returns to the same or to an adjoining plexus, and pursues its way to the nervous centre from which it set out. According to this view, there is no more a termination of nerves, than there is of blood- vessels. Both form circles. More recent observations seem, however, to have demonstrated, that in different situations the loop-like appear- ance is fallacious; and that the ultimate fibres divide into fibrils, the terminations of which are lost in the tissues. Investigations, again, by Henle and Kolliker1 show, that some of the peripheral nervous fibrils term- Fi 17 Fig 18< mate in small bodies, seated espe- cially in the nerves of the fingers and toes, which, from their having been discovered, in 1830, by Pacini of Padua, have been called Pa- cinian corpuscles; but of whose uses little can be said. They have not been observed on any motor nerves, so that they would not seem to have anything to do with motion. They exist in many nerves of the sympathetic class, and are not pre- sent on many sensitive nerves; so that, it has been properly inferred, they are probably not connected with acuteness of sensation. Of the encephalic nerves, the olfactory, auditory, and acoustic the Pacinian corpuscles J ' c r\ •i.'v b. Unusual form, from the mesentery of the cat; ---nerveS OI Special Sensibility--- showing two included in a common envelope:— t i , ,-i • i , • , • _ a, b are the two nerve-tubes belonging to them. clearly pass on to their destination, ' without communicating with any other nerve. The spinal nerves, at their exit from the intervertebral foramina, divide into two branches, an anterior and a posterior, one being sent to each aspect of the body. The anterior branches of the four superior cervical pairs form the cer- vical plexus, from which all the nerves of the neck arise; the last four cervical pairs and the first dorsal form the brachial plexus, whence proceed the nerves of the upper extremities; whilst the branches of the five lumbar nerves, and the five sacral form the lumbar and sciatic plexuses; the former of which gives rise to the nerves distributed to the parts within the pelvis; the second to those of the lower limbs. The anterior branches, moreover, at a little distance from the exit of the nerve from the vertebral canal, communicate with an important and unique portion of the nervous system, the great sympathetic. Each nerve consists of numerous fasciculi surrounded by areolar 1 Ueber die Pacinischen Korperchen an den Nerven des Menschen und der Saugethiere, Zurich, 1844; reviewed in Brit, and For. Med. Rev., January, 1845, p. 78; and Todd and Bowman, Physiological Anat. and Physiology of Man, i. 395, London, 1845, or Amer. edit.; and W. Bowman, Cyclopaedia of Anat. and Physiol., by Dr. Todd, pt. xxvii. p. 876, Lond., Mar., 1846. Pacinian Corpuscles. a. Nerve from the finger, natural size; showing SIR CHARLES BELL'S DIVISION OF NERVES. membrane; and, according to Reil,1 of an external envelope, called neurilemma, which, in the Fig. 19. opinion of most anatomists, is nothing more than an areolar envelope, similar to that which surrounds the vessels and mus- cular fibres. Until of late years, the RepresentsaNerveconsistingofmanysmallerCords nerves were Universally divided, or Funiculi wrapped up in a common cellular according to their Origin, into Sheath- encephalic and spinal; but, thtreTsteTXrsBiVllnefie)funiculusdrawnoutfr°m more recently, anatomical di- visions have been proposed, based upon the uses they appear to fulfil in the economy. For one of the most beautiful of this kind we are mainly indebted to Sir Charles Bell. It has been already seen, that the encephalic nerves are con- nected with the encephalon by one root, whilst the spinal nerves arise from two ; the one connected with the anterior tract of the spinal marrow, the other with the posterior. If these different roots be ex- Fig. 20. A portion of the Spinal Marrow, show- ing the Origin of some of the Spinal Nerves. 1. Anterior or motor root of a spinal nerve. 2. Posterior or sensory root. 3. Ganglion connected with the latter. Plans in outline, showing the Front a, and the Sides b, of the Spinal Cord, with the Fissures upon it; also sections of the Gray and White Matter, and the Roots of the Spinal Nerves. a, a. Anterior. p,p. Posterior fissure, b. Posterior, and c. Anterior horn of gray mat- ter, e. Gray commissure, a, e, c. Anterior white column, c, e, b. Lateral columns. a, e, b. Antero-lateral column, b, e, p. Pos- terior columns, r. Anterior, and s. Poste- ' rior roots of a spinal nerve. perimented on, we meet with results varying considerably. If we divide the anterior root, the part to which the nerve is distributed is deprived of motion; if the posterior root be cut, the part is deprived of sensi- bility. We conclude, therefore, that each of the spinal nerves consists 1 De Structura Nervorum, Hal. 1796. SYSTKM OF UKSriliATOKY NKltVKS- . /;«^Aa*U SYMMETUH'Al, XKIIVKS. J'nac SIR CHARLES BELL'S DIVISION OF NERVES. 89 of filaments destined for both motion and sensibility; that the ence- phalic nerves, which have but one root, are destined for one of these exclusively, and that they are either nerves of motion, or of sensation, according as their roots arise from the anterior or the posterior tract of the medulla. It has already been remarked, that the medulla oblongata, according to some anatomists, is composed of three fasciculi or columns on each side ;—an anterior, a middle, and a posterior; and it has been affirmed by Sir Charles Bell, that whilst the anterior column gives origin to nerves of motion ; and the posterior to nerves of sensibility; the middle gives rise to a third order, having the function of presiding over the respiratory movements ; and which Sir Charles, accordingly, calls respi- ratory nerves. To this third order belong,—the accessory nerve of Willis or superior respiratory; the vagus; the glosso-pharyngeal; the facial, called by him the respiratory nerve of the face; the phrenic; and another having the same origin—the external respiratory. Sir Charles's views, if admitted, lead, consequently, to the belief, that there are at least three sets of nerves,—one destined for sensation; another for motion; and a third for a particular kind of motion—the respira- tory; and that every nerve of motion communicates to the muscles, to which it is distributed, the power of aiding, or taking part in, motions of one kind or another ; so that a muscle may be paralyzed, as regards certain movements, by the section of one nerve, and yet be capable of others of a different kind, by means of the nerves that are uninjured. The accompanying plate exhibits the system of respiratory nerves, as given by Mr. Shaw,1 son-in-law of Sir Charles Bell, who was prema- turely snatched from existence, after having made numerous useful contributions to medical and surgical science. A, the cerebrum, B, the cerebellum, C C 8. Branches of the glosso-pharyngeal. C, the spinal marrow, D, the tongue, E, the 9. Lingualis, sending branches to the tongue, larynx, F, the lungs, G, the heart, H, the sto- and to the muscles on the fore part of the mach, I, the diaphragm. larynx. 111. Parvagum, arising by a single set of 10. Origins of the superior external respira- roots and passing to the larynx, lungs, heart, torn or spinal accessory. and stomach. fl. Branches of the last nerve proceeding 2. Superior laryngeal branches of the par to the muscles of the shoulder. vagum. 12 12 12. Internal respiratory or phrenic 3. Recurrent or inferior laryngeal branches passing to the diaphragm. of the par vagum. The origins of this nerve are seen to be 4. Pulmonic plexus of the par vagum. much higher than they are generally de- 5. Cardiac plexus of the par vagum. scribed. 6. Gastric plexus of the par vagum. 13. Inferior external respiratory, to the mus- 7. Respiratory nerve or portio dura passing cles on the side of the chest. to the muscles of the face, arising by a series of single roots. Yet this division is by no means universally admitted; and even by some who are of opinion, that the sensitive and motor filaments arise from distinct tracts of the spinal cord, it is denied that this is the case with those that originate from the upper part of the cord; there being in the medulla oblongata a blending of the sensitive and motor tracts which cannot easily be explained. Pathological cases, too, occasionally 1 Manual of Anatomy, &c, 3d edit., Lond., 1822. Reprinted in this country. 90 NERVOUS SYSTEM. occur, which throw great difficulty on this matter. Two of the kind have been related by Mr. Stanley and Dr. Budd,1 in which there was disease confined to the posterior column; yet sensation remained un- impaired, whilst the power of motion in the lower extremities was lost. Much evidently remains to be accomplished, before the precise arrangement of the columns of the spinal cord, and of the relations of the nerves connected with them, can be esteemed established. Sir Charles Bell,2 indeed, subsequently renounced his first opinion, that the posterior roots of the spinal nerves proceed from the posterior column, and described them as arising from the middle or lateral column; affirming, at the same time, that it is not impossible that the posterior column may be connected with the sensitive roots of the spinal nerves, although he has not hitherto succeeded in tracing it. Messrs. Grainger and Swan maintain, that both sets are connected with the lateral columns only; the anterior and posterior lateral fissures definitely limiting the two roots. Perhaps, as suggested by Dr. Carpenter,3 both these state- ments may be too exclusive. The anterior roots would seem to have a connexion with both the anterior and lateral columns; and the posterior cannot be said to be restricted to the lateral column, some of their fibres entering the posterior division of the cord. Most physiologists are now of opinion, both from experiment and reflection, that there is no special column destined for respiration, and that there appears to be nothing so peculiar in the action of the respi- ratory muscles, that they should require a distinct set of nerves.4 Sir C. Bell proposed a further arrangement of the nerves, more natural and philosophical than the unmeaning numeration according to the system of Willis, and better adapted to facilitate the com- prehension of this intricate portion of anatomy. According to this, all the nerves of the body may be referred to two great classes—the original, primitive or symmetrical,—and the irregular or superadded. It has been already remarked, that a division of the spinal cord has been presumed to correspond to the cerebrum ; and another to the cere- bellum. Now, every regular nerve has two roots, one from the anterior of these columns, and another from the posterior. Such are the fifth pair; the sub-occipital; the seven cervical; the twelve dorsal; the five lumbar; and the six sacral,—that is, thirty-two perfect, regular, or double nerves,—including, to state more briefly, all the spinal nerves, and one encephalic—the fifth pair. The fifth pair is found to arise from the encephalon by two roots, and to have a ganglion upon the posterior root. It is, accordingly, classed with the spinal nerves; and, like them, according to Sir Charles Bell, conveys both motion and sen- sibility to the parts to which it is distributed. These regular nerves are common to all animals, from the zoophyte to man. They run out laterally; or in a direction perpendicular to the longitudinal division of the body; and never take a course parallel to it. The other class is called irregular or superadded. The different 1 Medico-Chirurgical Transactions, vol. xxiii., Lond., 1840. 3 Nervous System, &c, 3d edit., p. 234. London, 1836. 3 Principles of Human Physiology, 2d Amer. edit., p. 125. Philad., 1845 * Dr. Reid, op. cit., Jan., 1838, p. 175. GREAT SYMPATHETIC. 91 nervous cords, proceeding from it, are distinguished by a simple fasci- culus or single root. All these are simple in their origins; irregular in their distribution; and deficient in that symmetry which characterizes those of the first class. They are superadded to the original class; and correspond to the number and complication of the superadded organs. Of these, there are the third, fourth, and sixth, distributed to the eye; the seventh, to the face; the ninth, to the tongue; the glosso- pharyngeal, to the pharynx; the vagus, to the larynx, heart, lungs, and stomach; the phrenic, to the diaphragm; the spinal accessory, to the muscles of the shoulders; and the external respiratory, to the out- side of the chest. The reason of the seeming confusion in this latter class is to be looked for in the complication of the superadded apparatus of respiration, and in the variety of offices it has to perform in the higher classes of animals. The accompanying plate exhibits, in one view, the nerves destined to move the muscles in all the varieties of respiration, speech, and facial expression. In the plate of regular or symmetrical nerves, A is the cerebrum, B, the cerebellum, Fig. 22. C C, the crura cerebri, D D, the crura cere- belli, E E E, the spinal marrow. 1 1. Branches of the fifth pair, arising from the union of the crura cerebri and crura cerebelli, and having a ganglion at the root. 2 2. Branches of the sub-occipital nerves, which have double origins and a ganglion. 3 3. Branches of the four inferior cervical nerves, and of the first dorsal, forming the axillary plexus. The origins of these nerves are similar to those of the fifth and of the sub-occipital. 4 4 4 4. Branches of the dorsal nerves, which also arise in the same manner. 5 5. The lumbar nerves. 6 6. The sacral nerves. So much for the anatomy of two great portions of the nervous system. There remains to be considered a third, and by no means the least interesting or important. 4. Great Sympathetic.—This nerve, called also trisplanchnic, splanchnic, ganglionic, great intercostal, vegetative, and or- ganic, is constituted of a series of ganglions, joined to each other by a nervOUS trunk, and extending Rdotsofa Dorsal Spinal Nerve, and its union with down the side of the spine, from the base of the cranium to the Sympathetic. c, c. Anterior fissure of the spinal cord. a. Anterior root. p. Posterior root, with its ganglion, a'. Ante- OS COCCVgis Or lowest bone. It rior branch p'. Posterior branch, s. Sympathetic. •/.° . , e. Its double junction with the anterior branch of the Communicates With each Ol the spinal nerve by a white and a gray filament. spinal nerves, and with several 92 NERVOUS SYSTEM. Fig. 23. of the encephalic; and from the ganglions, formed by such com- munication, sends off nerves, which accompany the arteries, and are distributed particularly to the organs of involuntary functions. At its upper part, it is situate in the carotid canal, where it appears under the form of a ganglionic plexus ; two fila- ments of which proceed to join the sixth pair of encephalic nerves, and another to meet the Vidian twig of the fifth pair. By means of the fifth pair, it communicates also with the oph- thalmic ganglion, which Bichat considered to belong to it. On issuing from the carotid canal, the nerve passes downwards, along the side of the spine, to the sacrum ; presenting a series of ganglions;—three in the neck, —the superior, middle, and in- ferior cervical; twelve in the back,—the thoracic; five in the loins,—the lumbar; and three or four in the sacrum,—the sa- cral. When it reaches the coccyx, it terminates by a small ganglion, called coccygeal; or by uniting with the great sympa- thetic of the opposite side. The ganglions are of an irre- gular, but generally roundish, shape. They consist of nervous filaments, surrounded by a red- dish-gray, pulpy, albuminous, or Great Sympathetic Nerve. 1. Plexus on the carotid artery in the carotid foramen. 2. Fixth nerve (motor externus). 3. First branch of the fifth, or ophthalmic nerve. 4. A branch on the septum narium going to the incisive fora- men. 5. Recurrent branch or Vidian nerve dividing into the carotid and petrosal branches. 6 Poste- rior palatine branches. 7. Lingual nerve joined by the choTda tympani. 8. Portio dura of the seventh pair. 9. Superior cervical ganglion. 10. Middle cervical ganglion. 11. Inferior cervical ganglion. 12. Roots of the great splanchnic nerve arising from the dorsal ganglia. 13. Lesser splanchnic nerve. 14. Renal plexus. 15. Solar plexus. 16. Mesenteric plexus. 17. Lumbar ganglia. 18. Sacral gan- glia. 19. Vesical plexus. 20. Rectal plexus. 21. Lumbar plexus (cerebro-spinal). 22. Rectum. 23. Bladder. 24. Pubis. 25. Crest of the ilium. 26. Kidney. 27. Aorta. 28. Diaphrogm. 29. Heart. 30. Larynx. 31. Submaxillary gland. 32. Incisor teeth- 33. Nasal septum. 34. Globe of the eye. 35, 36. Cavity of the cranium. gelatinous substance, which differs from the gray matter of the brain. Sir E. Home1 considers their structure to be intermediate between that 1 Lect. on Comp. Anat., v. 194, Lond., 1828. GREAT SYMPATHETIC. 93 of brain and nerves; the brain being composed of small globules sus- pended in a transparent elastic jelly; the nerves made up of single rows of globules, and the ganglions, consisting of a congeries of nervous fibres compacted together.1 Volkmann and Bidder, and Reichert,2 consider the sympathetic nerve-fibres to be distinct in size and structure from the cerebro-spinal; but Valentin maintains there is no difference. Authors are by no means agreed with regard to the uses of these gan- glions. Willis,3 Haller,4 and others, considered them to be small brains for the secretion of the nervous fluid or animal spirits; an opinion, which has been embraced by Richerand,5 and Cuvier ;6 the latter of whom remarks, that the ganglia are larger and more numerous when the brain is deficient in size. Lancisi,7 and Vicq d'Azyr, regarded them as a kind of heart for the propulsion of these spirits, or as reser- voirs for keeping them in deposit. Scarpa8 treats them as synonymous with plexuses; but plexuses with the filaments in close approximation; and plexuses he regards as ganglions, the filaments of which are more separated. He consequently believes, with many physiologists, that their office is to commingle and unite various nervous filaments with each other. Dr. Wilson Philip9 thinks, that they are secondary sources of nervous influence ; that they receive supplies of it from all parts of the brain and spinal marrow, and transmit the united influence to the organs to which the nerves are distributed; whilst some conceive, that at least one office is to communicate irritability to the tissues.10 John- stone,11 Reil,12 Bichat,13 and others, are of opinion that their use is to render the organs, which derive their nerves from them, independent of the will. These views are sufficiently discordant; and well indicate the intrinsic obscurity of the subject. That of Dr. Philip is the most probable. Containing the vesicular or gray matter, which seems to be everywhere concerned in the production of nerve-power, the ganglia may be re- garded as agents of nervous reinforcement; although we may remain uncertain as to the mode in which their office is executed.14 It is affirmed 1 See, on the Histology of the Organic or Sympathetic Nervous Fibres, Mr. Paget, Brit, and For. Med. Rev., July, 1842, p. 279. 2 Muller's Archiv., 1844, cited by Mr. Paget, in Brit, and For. Med. Rev., April, 1845, p. 572. 3 Cerebri Anatome, cui accessit Nervorum Descriptio, &c, Lond., 1664, cap. xxvi. « De Vera Nervi Intercostalis Origine, Gotting., 1793; Collect. Dissert. Anat., ii. 939; and Oper. Minor, i. 503. 6 See Appendix to Eng. edit., by Dr. Copland. 6 Lecons d'Anatomie Compar. Introd., p. 26. t Dissert, de Structura Usuque Gangliorum, ad J. B. Morgagnium, in Morgagni Adver. Anat., v. 101, Lugd. Bat., 1741. * De Nervis Comment., cap. ii. 320. 9 Philosoph. Transact, for 1829; and Inquiry into the Nature of Sleep and Death, Lond., 1834, p. 14. '0 Fletcher, Rudiments of Physiology, P. ii. a. p. 68, Edinb., 1836. " Philosophical Transactions, vols. 54, 57, and 60; Essays on the Use of the Ganglions of the Nerves, Shrewsbury, 1771; and Medical Essays and Observations relating to the Nervous System, Evesham, 1795. " Archiv. fur die Physiol., s. 226, vii., Halle, 1807. '3 Anatomie Generale, torn. i. 200, and ii. 405. u See the excellent article by Wagner, entitled Sympathischer Nerv, Ganglienstructur und Nervetiendigungen, in his Handworterbuch der Physiologie, 17te Lieferung, s. 360, Braun- schweig, 1847; another by Budge on the Sympathetic, with special relation to the Hearts action, Ibid., s. 406; and on the Sympathetic Ganglia of the Heart by Wagner, Ibid., s. 450. 94 NERVOUS SYSTEM. by M. Robin, in a communication made by him to the Academie des Sciences, of Paris, in June, 1847, that the ganglia of the great sympa- thetic and of the cerebro-spinal nerves enclose the same kind of gan- glionary globules, and of elementary tubes, but in different proportions; and hence he does not regard them as separate nervous systems. Although connected with the brain by the branches of the fifth and sixth pairs of encephalic nerves, and with the spinal cord by the spinal nerves, the sympathetic does not appear to be directly influenced by either; as the functions of the parts to which its ramifications are dis- tributed continue for some time after both brain and spinal marrow have been separated; nay, as in the case of the heart and intestines, after they have been removed from the body. Yet many discussions have been indulged regarding the origin of this important part of the nervous system; some assigning it to the brain, others to the spinal marrow, whilst others again esteem it a distinct nerve, communicating with the brain and spinal cord, but not originating from either; receiving, according to M. Broussais,1 by the cerebral nerves, the excitant influence, and applying it to movements that are independent of the centre of perception. In like manner, he affirms, when irritation predominates in the viscera, it is conveyed by the ganglionic to the cerebral nerves, which transmit it to the brain. Reil and Bichat, esteeming* the sym- pathetic to be the great nervous centre of involuntary functions, have termed it the organic nervous system, in contradistinction to the animal nervous system, which presides over the animal functions; whilst Lob- stein,2 who has published an ex professo work on the subject, assigns three functions to it. 1. To preside over nutrition, secretion, the action of the heart, and the circulation of the blood; 2. To maintain a com- munication between different organs of the body; and 3. To be the connecting medium between the brain and abdominal viscera. Remak,3 who believes that the animal economy possesses two sensoriums,—the one in the cerebro-spinal axis, the other in the ganglionic system,— considers, that as in the cerebro-spinal system of nerves two orders of phenomena occur,—the perception of sensation, and the reaction or reflection of volition ; so, in the organic nervous system, two analogous actions take place,—organic perception, or, as it has been called, Hal- lerian irritability, and reaction or organic reflection, as shown by J. Muller.4 From the result of his own researches, Dr. Carpenter5 inferred, that the sympathetic system does not exist in the lowest classes of animals in a distinct form;—that the nervous system of the invertebrata, taken as a whole, bears no analogy to it, and that as the divisions of this become more specialized, some appearance of a separate sympathetic • A Treatise on Physiology applied to Pathology, translated by Drs. John Bell and R La Roche, p. 257, Philad., 1832. a De Nervi Sympath. Human., &c, translated by Dr. Pancoast, Philadelphia, 1831. 3 Ammon's Monatschrift, June, 1840; and Edinb. Med. and Surg. Journal, Jan. 1841 p. 249. 4 Elements of Physiology, by Baly, i. 736, Lond.', 1838. 6 Dissertation on the Physiological Inferences to be deduced from the Structure of the Nervous System in the Invertebrated Classes of Animals, Edinb., 1839; reprinted in Dungli- son's Med. Library, Philad., 1839: also, his Principles of Human Physioloev n 111 Inn- ,l«n 1849 e>}' *" > GREAT SYMPATHETIC. 95 presents itself, but it is never so distinct as in the vertebrata; hence he deduces, and with probability, that as the sympathetic system is not developed in proportion to the predominant activity of the functions of organic life, but in proportion to the developement of the higher division of the nervous system, its office is not to preside over the former, but to bring them in relation with the latter; so that the actions of the organs of vegetative life are not dependent upon it, but influenced by it in accordance with the operations of the system of animal life. Again, the great sympathetic has been esteemed to be the visceral nerve par excellence, or the one that supplies the different viscera with their nervous influence,—a part of its office as the nervous system of involuntary functions. On examining the course of the great sympa- thetic, we find many filaments proceeding from the cervical and thoracic ganglions, interlacing and forming the cardiac plexus, from which the nerves of the heart and great vessels arise. The same thoracic gan- glions furnish a branch to each intercostal artery. A nerve of the great sympathetic—called the great splanchnic or visceral—proceeding from some of the thoracic ganglions, passes through the pillars of the diaphragm into the abdomen, and terminates in the large plexus or ganglion, called the semilunar; and this by uniting with its fellow of the opposite side, constitutes the still more extensive interlacing,—the solar plexus. From 4feis, numerous filaments proceed, which—by ac- companying the coronaria ventriculi, hepatic, splenic, spermatic, renal, superior and inferior mesenteric, and hypogastric arteries—are distri- buted to the parts supplied with blood by these arteries,—the stomach, liver, spleen, testes, kidneys, intestines, &c. Weber,1 however, who examined the great sympathetic in different animals, affirms, that the splanchnic may not be the sole visceral nerve, but that the eighth pair may share in the function. He states, that the great sympathetic is less developed, the lower the animal is in the scale; whilst the eighth pair is more and more developed as we descend, and at length is the only visceral nerve in some of the mollusca. Sir A. Cooper's2 experi- ments satisfied him, that this nerve is essential to the digestive process; but of this we shall have to speak hereafter. In the prosecution of those experiments, he found, that when the great sympathetic was tied on a dog, but little effect was produced: the animal's heart appeared to beat more quickly and feebly than usual; but of this circumstance he could not be positive, on account of the natural quickness of its action. The animal was kept seven days, at which time one nerve was ulcerated through, and the other nearly so, at the situation of the ligatures. Another animal on which the sympathetic had been tied nearly a month before, was still living when he wrote. When the pneumogastric or eighth pair, the phrenic, and the great sympathetic were all tied on each side, "the animal lived little more than a quarter of an hour, and died of dyspnoea."3 These experiments would appear to show, either that the great sym- pathetic is not so indispensable to the economy as has been imagined; 1 Anatom. Comparat. Nerv. Sympath., Lips., 1817. 3 Guy's Hospital Reports, vol. i. p. 457, London, 1836. 3 Ibid., p. 471. 96 NERVOUS SYSTEM. or that it is, in every part, a generator of nervous influence, so that if its connexion with the brain or any other viscus be destroyed, the divided portions may still possess the power of generating nervous agency. But if we admit this as regards the system of the great sym- pathetic, we shall find, that it is difficult to extend it to detached por- tions of the nervous system of animal life- It must be confessed, that our knowledge of the uses of this great division of the nervous system is far from being precise; for whilst some physiologists believe it to be concerned in every involuntary and organic action; Dr. Proctor1 thinks, that the nearest approach to a positive determination of its use that we can arrive at with our present limited knowledge is, that "it is for the purpose of regulating the tonic contraction of the arterial system, and for nothing else." One distin- guished observer, M. Magendie,2 inquires whether we have sufficient reason for the belief, that it is a nerve at all! and a writer3 of distinc- tion, Dr. J. C. B. Williams, admits, that nothing is definitely known as to the properties communicated by ganglionic nerves; and he adds, "Before the influence of the ganglionic system can be employed as an element in pathology, its existence must be proved, and its properties defined in physiology: this has not been done." According to the experiments of M. Flourens,4 the semilunar is the only ganglion that exhibits any great sensibilityljjfiand hence it has been considered as a sort of intervention to connect the viscera with the encephalon. M. Lepelletier5 thinks we are justified in dividing the nerves into five classes:—the first, comprising the nerves of special sensibility,—the olfactory, optic, lingual branch of the fifth pair, and auditory:—the second, the nerves of general sensibility, the fifth pair; and the spinal nerves, through their posterior root:—the third, comprising the volun- tary motors; the spinal nerves, by their anterior roots, the motores oculorum or common oculo-muscular, the external oculo-muscular, and the hypoglossal:—the fourth, instinctive motors, involuntary, respira- tory nerves of Sir Charles Bell, the pathetic, facial, glosso-pharyngeal, pneumogastric, and spinal accessory; and the fifth, nerves of vital association and nutrition—the filaments and plexuses of the ganglionic system. Dr. Fletcher6 adopts a different arrangement. He divides them into ganglionic and cerebro-spinal; the latter being subdivided into the respiratory, motiferous, sensiferous, and regular; the last in- cluding those Avhich communicate both the faculty of sensibility and the stimulus of volition. ' Medico-Chirurg. Rev., Jan., 1845, p. 182. 2 Precis de Physiologie, 2de edit., i. 171. Paris, 1825. 3 Principles of Medicine, 3d Amer. edit., by Dr. Clymer, p. 200, note, Philad., 1848. 4 Recherches Experimentales sur les Proprietes et les Fonctions du Systeme Nerveux &c, 2d edit., p. 229, Paris, 1842. 5 Traite de Physiologie Medicale et Philosophique, iii. 250, Paris, 1832. 6 Rudiments of Physiology, P. ii.a. p. 71, Edinb., 1836. NERVOUS SYSTEM. GANGLIONIC. CEREBBO-SPINAL. Those immediately con- nected respectively with Respiratory. Motiferous. Sensiferous. Regular. The Ophthalmic, The Pathetic, The Motor Ocu- The Olfactory, The Sub-occi- The Cavernous, The Facial, li) The Optic, pital, The Otic, The Glosso- A part of the The Ophthalmic The seven Cer- The Sphenopalatine, pharyngeal, lower Maxil- branch of the vical, The Sub-maxillary, The Pneumo- lary branch of Trigeminus, The twelve Dor- The three Cervical, gastric, the Trigemi- The Upper Max- sal, The Cardiac, The Accessory, nus, illary branch The five Lum- The twelve Dorsal, The Phrenic, The Abductor, of the Trige- bar, The five Sacral. The Cceliac, and The Hypoglos- minus, The five Lumbar, The External sal. A part of the The five Sacral, and Respiratory. lower Maxil- The Coccygeal lary branch of Ganglions. the Trigemi-nus, The Auditory. 5. True Spinal, Excito-Motory or Reflex Nervous System.—Dr. Marshall Hall1 has proposed another division of the nervous system, which is calculated to explain many of the anomalous circumstances we so frequently witness. He proposes to divide all the nerves into 1. The cerebral or sentient and voluntary. 2. The true spinal or excito-motory. 3. The ganglionic or nutrient and secretory. If the sentient and voluntary functions be destroyed by a blow on the head, the sphincter muscles still contract when irritated, because the irritation is conveyed to the spine, and the reflex action takes place to the muscle so as to throw it into contraction. But if the spinal marrow be now destroyed, the sphincters remain entirely motionless; because the centre of the system is destroyed. Dr. Hall thinks, that a peculiar set of nerves constitute, with the true spinal marrow as their axis, the second subdivision of the nervous system; and as those of the first subdivision are distinguished into sentient and voluntary, these may be distinguished into excitor and motory. The first, or excitor nerves, pursue their course principally from internal surfaces, charac- terized by peculiar excitabilities, to the vesicular centre of the medulla oblongata and medulla spinalis; the second or motor nerves pursue a reflex course from the medulla to the muscles, having peculiar actions concerned principally in ingestion and egestion. The motions con- nected with the first or cerebral subdivision are sometimes—indeed frequently—spontaneous; those connected with the true spinal are, he believes, always excited. Dr. Hall thinks that there is good rea- son for viewing the fifth, and posterior spinal nerves as constituting an external ganglionic system for the nutrition of the external organs; and he proposes to divide the ganglionic subdivision of the nervous sys- tem into 1, the internal ganglionic, which includes that usually deno- minated the sympathetic, and probably filaments of thepneumogastric; and 2, the external ganglionic, embracing the fifth and posterior spinal nerves. To the cerebral system he assigns all diseases of sensation, perception, judgment, and volition,—therefore all painful, mental, and comatose, and some paralytic diseases. To the true spinal or excito- ' Lectures on the Nervous System, London, 1836, and American edit,Philad., 1S36. Also, his Lectures on the Theory and Practice of Medicine, in the London Lancet for Feb. 3, and Feb. 7, 1838. VOL. I.—7 98 NERVOUS SYSTEM. motory system belong all spasmodic and certain paralytic diseases. He adds, that these two parts of the nervous system influence each other both in health and disease, as they both influence the ganglionic system.1 The views of Dr. Hall on the excito-motory function have been em- braced by Miiller,2 Grainger,3 Carpenter,4 and indeed, with more or less modification,- by almost all physiologists.5 Dr. Carpenter inferred from his inquiries, that the actions most universally performed by a nervous system are those connected with the introduction of food into the di- gestive cavity, and that we have reason to regard this class of actions as every where independent of volition, and perhaps also of sensation, —the propulsion of food along the oesophagus, in man, being of this character;—that for the performance of any action of this nature, a nervous circle is requisite, consisting of an afferent nerve, on the peri- pheral extremities of which an impression is made,—a ganglionic cen- tre, where the white fibres of which that nerve consists terminate in gray matter, and those of the efferent nerve originate in like manner; and an efferent trunk conducting to the contractile structure the motor impulse, which originates in some change between the gray and white matter ;—that in the lowest animals such actions constitute nearly the entire function of the nervous system,—the amount of those involving sensation and volition being very small; but as we ascend the scale, the evidence of the participation of true sensation in the actions neces- sary for acquiring food, as shown by the developement of special sen- sory organs, is much greater; but that the movements immediately concerned with the introduction of food into the stomach remain under the control of a separate system of nerves and ganglia, to the action of which the influence of the cephalic ganglia—the special if not the only seat of sensibility and volition—is not essential; that, in like manner, the active movements of respiration are controlled by a sepa- rate system of nerves and ganglia, and are not dependent upon that of sensation and volition, although capable of being influenced by it;— that whilst the actions of these systems are, in the lower tribes, almost entirely of a simply reflex character, we find them, as we ascend, gra- dually becoming subordinate to the will; and that this is effected by the mixture of fibres proceeding directly from the cephalic ganglia with those arising from their own centres ;—that the locomotive organs, in like manner, have their own centres of reflex action, which are inde- pendent of the influence of volition, perhaps also of sensation;—that the influence of the will is conveyed to them by separate nervous fibres, proceeding from the cephalic ganglia, and that similar fibres probably convey to the cephalic ganglia the impressions destined to produce sen- 1 Principles of the Theory and Practice of Medicine, by Marshall Hall, M. D., F. R. S., p. 243, London, 1837, and American edit, by Drs. Bigelow and Holmes, Bost., 1839'. a Handbuch der Physiologie, s. 333, and s. 688, Coblenz, 1835, 1837, or the English trans- lation by Dr. Baly, i. 707, London, 1838. 3 On the Structure and Functions of the Spinal Cord, London, 1837, 4 Op. cit. 5 Todd and Bowman, the Physiological Anatomy and Physiology of Man, p. 312. London, 1845. NERVOUS SYSTEM. 99 sations;—that the stomato-gastric, respiratory, and locomotive centres are all united in the spinal cord of the vertebrata, where they form one continuous ganglionic mass, and that the nerves connected with all these likewise receive fibres derived immediately from the cephalic ganglia;— and lastly, that whenever peculiar consentaneousness of action is re- quired between different organs, their ganglionic centres are united more or less closely; and that the trunks themselves are generally con- nected by bands of communication. On the whole, in the present state of our knowledge, we are justified, perhaps, in adopting the systematic summary of the functions of the nervous system, and the general purposes to which it is inservient, as given by the writer last cited.1 1. The nervous system receives im- pressions, which, being conveyed by its afferent fibres to the sensorium, are there communicated to the conscious mind; and are inservient, in some manner, to the acts of that mind. As the result of these acts, a motor impulse is transmitted along efferent nerves to particular mus- cles, which excites them to contraction. Of these acts the encephalon, and nerves communicating with it, are the organs. 2. Certain parts of the nervous system receive impressions, which are propagated along afferent fibres that terminate in ganglionic centres distinct from the Bensorium. In these, a reflex motor impulse is thus excited, which is transmitted along efferent trunks proceeding from those centres, and excites muscular contraction without any necessary intervention of sen- sation or volition. The organs of this function are the gray matter of the spinal cord, which is not continuous with the fibrous structure of the brain, and the trunks connected with it. It is the true spinal or excito-motory system of Dr. Hall. 3. There is yet a division of the nervous system, which appears to have for its object to combine and harmonize the muscular movements immediately connected with the maintenance of organic life. It may likewise influence, and connect with each other the functions of nutrition, secretion, &c. ; although these—like the muscular movements immediately connected with the maintenance of organic life—are doubtless essentially independent of it; and—as has been shown—can be carried on where it does not exist. The organ of these acts is the great sympathetic. Of late—as will be seen hereafter—Dr. Carpenter2 has contended with much force for the existence of a series of sensory ganglia, separate and distinct from those that compose the cerebrum and cerebellum—"ganglia of the nerves of sensation, common and special, which are superposed, as it were, on the medulla oblongata," and which, together, constitute the real sen- sorium. It has been urged by Dr. Laycock,3 in a paper read before the Bri- tish Association at York, in accordance with views published by him four years previously, that the brain, although the organ of conscious- ness, is subject also to the laws of reflex action; and that in this re- spect it does not differ from other ganglia of the nervous system. He 1 Human Physiology, p. 79, London, 1842. a Principles of Human Physiology, 4th Amer. edit., p. 320, Philad., 1850. 3 British and Foreign Medical Review, Jan., 1845, p. 298. 100 NERVOUS SYSTEM. regards the cerebral nerves, and especially the optic, auditory, and olfactory, as afferent excitor nerves, along which impressions pass to the central axis; thence to be communicated to the motor nerves, and thus give rise to combined muscular acts, or to irregular spasmodic movements. Hydrophobia is adduced by him as a good illustration of these cerebral reflex movements. The acknowledged excito-motory phenomena in the disease may be induced.—First. Through the nerves of touch, as by the contact of water with the surface of the head, hands, chest, lips, and pharynx. Secondly. By a current of air im- pinging on the face or chest. Thirdly. By a bright surface, as a mir- ror. Fourthly. By the sight of water; and Fifthly. By the idea of water, as when it is suggested to the patient to drink. The author has been in the habit of offering as an example of the same kind, vomiting induced by the sight of a disgusting object. Here the impression is first made upon the brain through an organ of sense, and the reflex motor phenomena concerned in vomiting are in- stantaneously excited;—facts, which at least prove, that although the gray matter of the spinal marrow may continue to execute its func- tions, when those of the cerebro-spinal nervous system are suspended, —as during sleep or an attack of epilepsy, it is capable of being excited to action by impressions made through the latter, in the same manner as by impressions made on the afferent spinal nerves themselves. From all that has been said, it will be un- derstood, that each nerve as it issues from the spinal canal must be composed of various fasciculi:—one, sensory or of sensation, con- nected with the posterior medullary tract, and continuous with the medullary matter of the brain ; another, connected with the ante- rior medullary tract, and conveying the in- fluence of volition from the brain along the spinal cord and nerves to the muscles; a third, consisting of excitor fibres, terminating in the gray or ganglionic matter of the cord, and conveying impressions to it; and a fourth, consisting of motor fibres, arising from the gray matter of the cord, and con- veying the nervous influence reflected to the muscles. It would appear that a part of each root Structure of the Spinal Cord, ac- enters the gray matter of the cord ; whilst a cording to Stilling. part is continuous with the white or medullary a. posterior fibres continuous matter; and Dr. Stilling1 affirms—as the re- with the anterior of the same side, ' . » fa »o «-uc *v through the nucleus of the cord, suit ot his researches—that of the fibres of b. Posterior fibres continuous with ,i ^^„j.„_" „ «^^i„ „„___v i • ^t. the anterior of the opposite side, tne posterior roots some form loops in the gray matter, and become continuous with those of the anterior roots of the same side; whilst others cross the 1 Untersuchungeu uber die Textur des Ruckenmarl.s, von Dr. B. Stilling und Dr. J. Wal- 1: ch, s. 51. Leipz , 1&42. NERVOUS TISSUE. 101 gray matter, and become continuous with those of the anterior roots of the opposite side. It has been shown, too, by Mr. New- port,1 that there are other fibres, which pass from the posterior into the anterior rOOtS Of Other nerves, above Transverse Section of the Medulla. (After Stilling.) and DelOW, DOttl On tile Tlle transverse gray fibres are the continuation of the roots Same and the OPPOSite °* tne nerves; tne longitudinal white and gray fibres are in- . . "*■ dicated by points. side. Much, doubtless, still remains to be accomplished, before we can consider views in regard to the nervous system established. Like many important questions of physiology, they may be regarded as in a tran- sition state; but the zeal and activity of physiological inquirers are daily throwing light upon many points; and of these there are none surrounded with more obscurity than those that appertain to the nerv- ous system. All the parts described as constituting the nervous system—brain, cerebellum, medulla spinalis, and nerves—are formed of the primary nervous fibre, the nature of which has been already described. The neurine or substance of which they are constituted is soft and pulpy; but the consistence varies in different portions, and, in the whole, at different ages. In the foetus it is almost fluid ; in youth of greater firmness; and in the adult still more so. This softness of structure in the encephalon of the foetus is by no means inutile. It admits of the pres- sure, which takes place, to a greater or less extent in all cases of par- turition, whilst the head is passing through the pelvis, without the child sustaining any injury. On examining, however, the consistence of dif- ferent brains, it is necessary to inquire into the period that has elapsed since the death of the individual, as the brain loses its firmness by being kept; and ultimately becomes semifluid. It is likewise rendered fluid by disease, constituting ramollissement du cerveau or mollescence of the brain, to which the attention of pathologists has been directed of late years, but without much important advantage to science. When the encephalon is fresh, it has a faint, spermatic, and some- what tenacious smell. This, according to M. Chaussier, has persisted for years in brains that have been dried. Neurine has been subjected to analysis by M. Vauquelin,2 and found to contain, water, 80*00; white fatty matter, 4*53; red fatty matter, called cerebrin, 0*70; osmazome, 1*12; albumen, 7*00; phosphorus, 1*50; sulphur, acid phosphates of potassa, lime, and magnesia, 5*15. M. Couerbe's analysis of that of the brain3 gives, 1. A pulverulent yellow fat, stearconote; 2. An elastic yellow fat, cerancephalote; 3. A reddish-yellow oil, eleancephol; 4. A white fatty matter, cerebrote, ' Philosophical Transactions, 1843, and Dr. Carpenter, 2d Amer. edit., p. 125, Philad., 1845. a Annales de Chim., lxxxi. 37; and Annals of Philosophy, i. 332. 8 Annales de Chimie et de Physique, lvi. 160. 102 NERVOUS SYSTEM. the white fatty matter of Vauquelin, the myelocone of Kiihn; 5. Cere- bral cholesterin—cholesterote; and the salts found by Vauquelin,— lactic acid, sulphur, and phosphorus, which form a part of the fats above-mentioned.1 In the spinal cord, there is more fatty matter, and less osmazome, albumen, and water. In the nerves, albumen predomi- nates, and fatty matters are less in quantity. Researches by M. Las- saigne show, that water constitutes T75ths of the nerves; and T8oths of the brain ; whilst the proportion of albumen in the former is f^ths; in the latter, y^o^8* He found the neurine of different parts of the brain to be composed as follows : The whole Brain. White portion. Gray portion Water, 77-0 73-0 850 Albumen, 96 9-9 7-5 White fatty matter, 7-2 13-9 10 Red fatty matter, 3*1 0-9 3-7 Osmazome, lactic acid, and salts, 20 10 1-4 Earthy phosphate, 1*1 1*3 1-2 100-0 100-0 1000' M. Raspail3 has pointed out two other differences. First, when a nerve is left upon a plate of glass in dry air, it becomes dry, without putrefying, whilst cerebral neurine putrefies in twenty-four hours ; and secondly, the dried nerve has all the physical characters of the corneous substances,—nails, hair, and other analogous bodies; and in their chemical relations, these bodies do not differ sufficiently to repel the analogy. Neither the chemical analysis of neurine, nor inquiry into its minute structure by the aid of the microscope, has, however, thrown light upon the wonderful functions executed by this elevated part of the organism. It would seem, that neurine is, in composition, intermediate between fat and the compounds of protein: it contains nitrogen, which is not present in fats, but in smaller proportion than in protein; and, on the other hand, it is much richer in carbon than protein or its compounds. Phosphorus, tQO, is an essential ingredient. According to recent re- searches by M. Frdmy, there is in cerebral neurine a peculiar acid, ana- logous to the fatty acids, which he calls cerebric acid, and which contains nitrogen and phosphorus : this is mixed with an albuminous substance; with an oily acid—oleo-phosphoric; with cholesterin ; and with small quantities of olein and margarin, and oleic and margaric acids.4 To the naked eye, neurine appears under two forms;—the one gray and of a softer consistence; the other white, and more compact. The former is called the vesicular, gray, cortical, cineritious, or pulpy sub- stance ; the latter, the tubular, white, medullary, or fibrous, called "tubular" in consequence of its consisting of tubes of great minuteness, which are filled with a kind of granular pith that can be squeezed from them,—a view adopted by most histologists. Dr. James Stark has,5 1 For John's Analysis of the white and gray cerebral matter, see Journal de Chimie Medi- cale, Aout, 1835. See, also, Simon's Medical Chemistry, p. 81, Lond., 1845. a Journal de Chim. Medic; and Pharmaceutisches Central Blatt, Nov. 19 1836 s. 765. 3 Chimie Organique, p. 217, Paris, 1833. 4 Journ. des Connais. Med.-Chir., Jan., 1841; also Turner and Liebi^'s Chemistry 7th edit., p. 1195, Lond., 1842. 6 Proceedings of the Royal Society, No. 56, Lond., 1843. NERVOUS TISSUE. 103 however, affirmed, as the result of his examination, that the matter which fills the tubes is of an oily nature, differing, in no essential respect, from butter or soft fat, and remaining of a fluid consistence during the life of the animal, or whilst it re- F'g- 26- tains its natural tem- a 2 3 perature; but becoming ""' lll,n11" * '1'J granular or solid when the animal dies. The diameter of these cylin- drical tubuli has been estimated to vary from about the T^oth to the ith of a line. The 1 , 24Tjl Tubular Nerve-fibres. a. Tubular nerve-fibres, showing the sinuous outline and double contours. B. Diagram to show the parts of a tubular fibre, viz.: 1, 1. Mem- branous tube. 2,2. White substance ox medullary sheath. 3. Axis nerves are wholly com- posed of it. The tubular nervous matter, wherever it is found, seems to consist of fibres, which have a definite arrangement. Two kinds of primitive fibre, according to the researches of Messrs. Todd and Bowman,1 are present in the nervous system, which they dis- tinguish as the tubular Gbrp nr VPVVP tiibp and ot primitive band. Jiure Ul ne/ VK LWUV, dliu c Figure (imaginary) intended to represent the appearances oc- the QelatinOUS fibre ___ casionally seen in the tubular fibres. 1, 1. Membrane of the tube , ,. • £ • i. l It, seen a* Parts where the white substance has separated from it. 2. the former infinitely tile A partwhere the white substance is interrupted. 3. Axis project- „,-______„,__„„„ „^ j ii„ ing beyond the broken end of the tube. 4. Part of the contents of more numerous, and the thl tube escaped. latter found chiefly in the sympathetic system- T.he tubular fibres vary in diameter from TgTo „th even to TTJ£o^th of an inch; but their average width is from j^^th to 3 Jjj^th of an inch. The gelatinous fibre is devoid of the whiteness that characterizes the tubular fibre; and the gray colour of certain nerves, it has been thought, is dependent chiefly upon the presence of a large proportion of gelatinous fibres. Hence they have been sometimes termed gray fibres. These are in general smaller than the tubular fibres,—their dia- i . .-, , ,r j (a and b magnified 340 diameters, after meter ranging between the g^o™ an(1 Hannover; c and d after Remak.) the 4 o'uijth of an inch. 1 Dr. Todd, Art. Nervous Centres, in Cyclop, of Anat. and Phys., Pt. xxvi., p. 707; and The Physiological Anatomy and Physiology of Man, p. 208, London, 1845. Fig. 27. JE5L ~**%e&ttm?r-- f"S£&e> ■: Gelatinous Nerve-fibres. 104 NERVOUS SYSTEM. Fig. 28. Ganglion Corpuscles. After Valentin. In one a second nucleus is visible. The nucleus of several contains one or two nucleoli. Fig. 29. Histologists are generally of opinion, that the central portion of each nerve-fibre differs from the peripheral: the former has-been termed by Rosenthal and Purkinje the axis-cylinder; the latter is the medullary or white substance of Schwann, and to it the white colour of the cere- bro-spinal nerves is chiefly due. The researches of histologists have shown that vesicles or cells containing nuclei and nucleoli, and called also nerve corpuscles and globules and gan- glion corpuscles and globules, are the essen- tial elements of gray or vesicular matter. These are found in the nervous centres, mingled with nerve-fibres, and imbedded in a dimly shaded or granular substance. They give to the ganglia and to certain parts of the brain and spinal cord the pecu- liar grayish or reddish-gray appearance by which they are characterized. They are large nucleated cells, filled with a finely granular material; some of which is often dark, like pigment;—the nucleus, which is vesicular, containing a nu- cleolus. The marginal figure (Fig. 28) represents some that have a regular outline. Others, as in Fig. 29, arecau- date or stellate, and have tu- bular processes issuing from them, filled with the same kind of granular matter as is contained in the corpuscle. The gray substance is not always at the exterior, nor the medullary in the interior. In the medulla spinalis, their situation is the reverse of what it is in the brain. In the invertebrata, the gray matter forms the nuclei of the ganglia, which are the centres of the nervous sys- tem; and the true spinal Stellate or Caudate Nerve Corpuscles. After Hannover. System, which Occupies the interior of the spinal cord, has been regarded as a chain of similar ganglia. It is the organ, as already shown, of the excito-motory nervous function. Ruysch consider- ed, that the gray portion owes its colour to the blood-vessels that enter a, a. From the deepter part of the gray matter of the con- volutions of the cerebellum. The larger processes are di- rected towards the surface of the organ, b. Another from the cerebellum, c, d. Others from the post-horn of gray matter of the dorsal region of the cord. These contain pig- ment, which surrounds the nucleus in c. In all the speci- mens the processes are more or less broken. Magnified 200 diameters. CIRCULATION IN THE ENCEPHALON. 105 it j1 and, in this opinion, Haller, Adelon,2 and others,3 concur; but this is not probable, and it has not been by any means demonstrated.4 The medullary portion has the appearance of being fibrous ; and it has been so regarded by Leeuenhoek,5 Vieussens, Steno, and by Gall and Spur- zheim.6 Malpighi7 believed the gray cortical substance to be an assem- blage of small follicles, intended to secrete the nervous fluid; and the white medullary substance to be composed of the excretory vessels of these follicles; and an analogous view is entertained by most physiolo- gists of the present day,—the gray matter at least being regarded as the generator of the nervous influence; the white matter as chiefly concerned in its conduction. Gall and Spurzheim conjecture, that the use of the gray matter is to be the source or nourisher of the white fibres. The facts, on which they support their view, are, that the nerves appear to be enlarged when they pass through a mass of gray matter, and that masses of this substance are deposited in all parts of the spinal cord where it sends out nerves; but, Tiedemann8 has remarked, that in the foetus the medullary is developed before the cortical portion, and he conceives the use of the latter to be—to convey arterial blood, which may be needed by the medullary portion for the due execution of its functions. After all, however, it must be admitted with Dr. Allen Thomson,9 that the general conclusion deducible from all the facts would seem to be, that whilst the gray fibres predominate in the organic or sympathetic nerves, and the tubular fibres in the cerebro-spinal nerves, these two elements are mixed, in various proportions, in the great divi- sions of the nervous system; and that, therefore, these divisions, al- though, in a great measure, structurally different, are not altogether distinct from, or independent of, each other. "But"—he properly adds—" in regard to the whole subject of the structure and nature of the different varieties of the nervous texture, it is unquestionable that much still remains to be ascertained by laborious investigation." Sir Charles Bell10 affirms, that he has found, at different times, all the internal parts of the brain diseased, without loss of sense; but he has never seen disease general on the surface of the hemispheres without derangement or oppression of mind during the patient's life; and hence he concludes, that the vesicular matter of the brain is the seat of the intellect, and the tubular of the subservient parts.11 A similar use has been ascribed to the vesicular portion, from pathological observations, by MM. Foville and Pinel Grandchamp.12 This view would afford con- siderable support to the opinions of Gall, Spurzheim, and others, who consider the organs of the cerebral faculties to be constituted of ex- 1 Oper. Amstel., 1727. a Physiologie de l'Homme, 2de edit., i. 208, Paris, 1829. 3 Carpenter, Human Physiology, p. 81, Lond., 1842. 4 Todd, Cyclop, of Anat. and Physiol., Pt. xxv. p. 647, Lond., 1844. 6 Philos. Transact., 1677, p. 899. 6 Recherches sur le Systeme Nerveux e*h general, et sur celui du Cerveau en particulier, avec figures, Paris, 1809. 7 Oper. Malpighii, and Mangeti Bibl. Anat., i. 321. 8 Anatomie und Bildungsgeschichte des Gehirns, mit Tafeln, Niirnberg, 1816. 9 Outlines of Physiology, Pt. i. p. 155, Edinb., 1848. 10 Anatomy and Physiology, 5th American edit., by J. D. Godman,p. 29, New York, 1827. 11 See two interesting pathological cases, confirming this view of the function of the gray matter, by Dr. Cowan, in Provincial Medical and Surgical Journal, April 16, 1845. a Sur le Systeme Nerveux, Paris, 1820. 106 NERVOUS SYSTEM. Fig. 30. pansions of the columns of the spinal marrow and medulla oblongata, and to terminate by radiating fibres on the periphery of the brain; as well as to those of M. Desmoulins,1 and others who regard the convolu- tions as the seat of the mind. We have, however, cases on record, that signally conflict with this view of the subject; in which the cortical substance has been destroyed, and yet the moral and intellectual mani- festations have been little, if at all, injured. Many years ago, the author dissected the brain of an individual of rank in the British army of India, in the anterior lobes of which neither medullary nor cortical portion could be distinguished,—both one and the other appearing to be broken down into a semi-purulent, amorphous substance; yet the intellectual faculties had been nearly unimpaired; although the morbid process must have been of some duration. The encephalon affords us many striking instances of the different effects produced by sudden, and by gradual interference with its functions. Whilst a depressed portion of bone or an extravasation of blood may suddenly give rise to the abo- lition of the intellectual and moral faculties, gradual com- pression by a tumour may scarcely interfere with any of its manifestations. The circulation of blood in the encephalon requires notice. The arteries are four in num- ber,—two internal carotids, and two vertebrals: to these may be added the spinal or middle artery of the dura mater, arteria meningeea me- dia. The carotid arteries enter the head through the carotid canals, which open on each side of the sella tur- cica, or of the chiasma of the optic nerves. The vertebral arteries enter the head through the foramen magnum of the occipital bone; unite on the medulla oblongata to form the basilary artery, which passes forward along the middle of the pons varolii; and, at the anterior part of the pons, gives off lateral branches, which Circle of Willis. 1. Vertebral arteries. 2. Two anterior spinal branches uniting to form a single vessel. 3. One of the posterior spinal arteries. 4. Posterior meningeal. 5. Inferior cere- bellar. 6. Basilar artery giving off its transverse branches toeitherside. 7. Superior cerebellar artery. 8. Posterior cerebral. 9. Posterior communicating branch of the in- ternal carotid. 10. Internal carotid, showing the curva- tures it makes within the skull. 11. Ophthalmic artery divided across. 12. Middle cerebral artery. 13. Anterior cerebral arteries connected by, 14. Anterior communicat- ing artery. ' Anatomie des Systemes Nerveux des Animaux a Vertebres, p. 599, Paris 1825. CEPHALO-SPINAL FLUID. 107 inosculate with corresponding branches of the carotids, and form a kind of circle at the base of the brain, which has been called circulus arte- riosus of Willis. The passage of the blood-vessels is extremely tortu- ous, so that the blood does not enter the brain with great impetus; and they become capillary before they penetrate the organ,—an arrange- ment of importance, when we regard the large amount of blood sent to it. This has been estimated as high as one-eighth of the whole fluid transmitted from the heart. The amount does not admit of accurate appreciation, but it is considerable. It of course varies according to circumstances. In hypertrophy of the heart, the quantity is sometimes increased; as well as in ordinary cases of what are called determinations of blood to the head. Here, too large an amount is sent by the arterial vessels; but an equal accumulation may occur, if the return of the blood from the head by the veins be-in any manner impeded,—as when we stoop, or compress the veins of the neck by a tight cravat, or by keeping the head turned for a length of time. Congestion or accumu- lation of blood may therefore arise from very different causes. Sir Astley Cooper1 found by experiment, that the vertebral arteries are more important vessels as regards the encephalon and its functions in certain animals, as the rabbit, than the carotids. The nervous power is lessened by tying them; and, in his experiments, the animals did not, in any case, survive the operation more than a fortnight. In the dog, he tied the carotids with little effect, but the ligature of the verte- brals had a great influence. The effect of the operation was to render the breathing immediately difficult and laborious ; owing, in Sir Astley's opinion, to the supply of blood to the phrenic nerves, and the whole tractus respiratorius of Sir Charles Bell, being cut off. The animal became dull, and indisposed to make use of exertion; or to take food. Compression of the carotids and the vertebrals at the same moment, in the rabbit, destroyed the nervous functions immediately. This was effected by the application of the thumbs to both sides of the neck, the trachea remaining free from pressure. Respiration ceased entirely, with the exception of a few convulsive gasps. The same fact was evinced in a clearer and more satisfactory manner by the application of ligatures to the four vessels, all of which were tightened at the same instant. Stoppage of respiration and death immediately ensued. The cerebral, like other arteries, are accompanied by branches of the great sympathetic. The researches of Purkinje,2 Volkmann,3 and Rainey,4 have shown the existence of a large number of nerves in con- nection with the encephalic and spinal arachnoid. They do not seem to communicate with the roots of the spinal nerves, but belong exclusively to the sympathetic.5 The encephalic veins are disposed as already de- scribed, terminating in sinuses formed by the dura mater, and conveying 1 Guy's Hospital Reports, i. 472, London, 1836. 2 Muller's Archiv. fur Anatomie, p. 281, Berlin, 1845. 3 Art. Nervenphysiologie, Wagner's Handworterbuch der Physiologie, lOte Lieferung, s. 494, Braunschweig, 1845. 4 Medico-Chirurgical Transactions for the year 1845. 6 D. Brinton, Art. Serous and Synovial Membranes, in Cyclop, of Anat. and Physiol., Pt xxxiv. p. 525, Lond., Jan. 1849. 108 NERVOUS SYSTEM. Fig. 31. their blood to the heart by means of the lateral sinuses and internal jugulars; but of the peculiarities of the circulation in the encephalon, mention will be made in the appropriate place. No lymphatic vessels have been detected in the encephalon; yet, that absorbents exist there is proved by the dissection of apoplectic and paralytic indi- viduals. In these cases, when blood has been effused, the red particles are gradually taken up, with a portion of the fibrinous part of the blood, leaving a cavity called an apoplectic cell, which is at the same time the evidence of previous extravasation and subsequent absorption. The whole of the nervous system is well supplied with bloodvessels. In the vesi- cular neurine of the nervous centres, the capillaries surround the ganglion cells or globules; and in the tubular they pass between the nerve-tubes, being connected at intervals by transverse branches. When the skull of the new-born infant, which, at the fontanelles, consists of mem- brane only—or the head of any one who has received an injury, that exposes the brain—is examined, two distinct move- ments are perceptible. One, which is gene- rally obscure, is synchronous with the pulsation of the heart and arteries; the other, much more apparent, is connected with respiration, the organ seeming to sink at the time of in- spiration, and to rise during expiration. This phenomenon is not confined to the cerebrum, but exists likewise in the cerebellum and spinal marrow. The motion of the encephalon, synchronous with that of the heart, admits of easy explanation. It is owing to the pulsation of the circle of arteries at the base of the brain elevating the organ at each systole of the heart. The other movement is not so readily intelligible. It has been attributed to the resistance, experienced by the blood in its passage through the lungs during expi- ration, owing to which an accumulation of blood takes place in the right side of the heart; this extends to the veins and to the cerebral sinuses and an augmentation of bulk is thus occasioned. We shall see hereafter, that one of the forces conceived to propel the blood along the vessels is atmospheric pressure. According to that view, the sinking down of the brain during inspiration is explicable: the blood is rapidly drawn to the heart; the quantity in the veins is consequently diminished* and sinking of the brain succeeds. " ' Sinuses of the Base of the Skull. 1. Ophthalmic veins. 2. Cavernous sinus of one side. 3. Circular sinus: the figure occupies the position of the pituitary gland in the sella turcica. 4. Inferior petrosal sinus. 5. Transverse or anterior occipital sinus. 6. Supe- rior petrosal sinus. 7. Internal jugular vein. 8. Foramen magnum. 9. Occi- pital sinuses. 10. Torcular Herophili. 11, 11. Lateral sinuses. Fig. 32. Capillary Net-work of Nervous Centres. CEPHALO-SPINAL FLUID. 109 On dissection, we find that the encephalon fills the cavity of the cra- nium; during life, therefore, it must be pressed upon, more or less, by the blood in the vessels, and by the serous fluid exhaled by the pia mater into the subarachnoid tissue. Thence it penetrates into the ventricles, —according to M. Magendie, at the lower end of the fourth ventricle, at the calamus scriptorius. The quantity varies according to the age and size of the patient, and usually bears an inverse proportion to the size of the encephalon. It is seldom, however, less than two ounces, and often amounts to five. M. Magendie is of opinion, that the fluid is secreted by the pia mater, and states, that it may be seen transuding from it in the living animal. The results of chemical analysis appear to show, that it differs from mere serum. It is obviously, however, almost impracticable—if not wholly so—to separate the consideration of this fluid from that met with in the cavity of the arachnoid. The spinal marrow does not, as we have seen, fill the vertebral canal; the cephalo-spinal fluid exerts upon it the necessary pressure; added to which, the pia mater seems to press more upon this organ than upon the rest of the cerebro-spinal system. A certain degree of pressure appears, indeed, necessary for the due performance of its functions; and if this be either suddenly and considerably augmented, or dimi- nished, derangement of function is the result. M. Magendie,1 however, asserts, that he has known animals, from which the fluid had been re- moved, "survive without any sensible derangement of the nervous func- tions. It is this fluid, which is drawn off by the surgeon when he punctures in a case of spina bifida. When the brain is examined in the living body, it exhibits properties, which, some years ago, it would have been esteemed the height of hardi- hood and ignorance to ascribe to it. The opinion has universally pre- vailed, that all nerves are exquisitely sensible. Many opportunities will occur for showing, that this sentiment is not founded on fact; even the encephalon itself,—the organ in which perception takes place,—is insensible, in the common acceptation of the term; that is, we may prick, lacerate, cut, and even cauterize it, yet no painful impression will be produced. Experiment leaves no doubt regarding the truth of this, and we find the fact frequently confirmed by pathological cases. Portions of brain may be discharged from a wound in the skull, and yet no pain be evinced. In his "Anatomy and Physiology," Sir C. Bell2 remarks, that he cannot resist stating, that on the morning on which he was writing, he had had his finger deep in the anterior lobes of the brain; when the patient, being at the time acutely sensible, and capable of expressing himself, complained only of the integument. A pistol-ball had passed through the head, and Sir Charles, having ascer- tained, that it had penetrated the dura mater by forcing his finger into the wound, trephined on the opposite side of the head, and extracted it. By the experiments, instituted by MM. Magendie,3 Flourens and i Precis Elementaire, seconde £dit., i. 192; and Recherches Physiologiques et Cliniques sur le Liquide Cephalo rachidien ou Cerebrospinal, Paris, 1842. ' Fifth Amer. edit, by J. D. Godman, ii. 6, 1827. 3 Precis Elementaire, i. 325. 110 SENSATIONS. others, it has been shown, that an animal may live days, and even weeks, after the hemispheres have been removed; nay, that in certain animals, as reptiles, no change is produced in their habitudes by such abstraction. They move about as if unhurt. Injuries of the surface of the cere- bellum exhibit, that it also is not sensible; but deeper wounds, and especially such as interest the peduncles, have singular results,—to be explained hereafter. The spinal cord is not exactly circumstanced in this manner. Its sensibility is exquisite on the posterior surface; much less on the anterior, and almost null at the centre. Considerable sen- sibility is also found within, and at the sides of, the fourth ventricle; but this diminishes as we proceed towards the anterior part of the medulla oblongata, and is very feeble in the tubercula quadrigemina of the mammalia. It has been shown, that the spinal nerves, by means of their poste- rior roots, convey general sensibility to the parts to which they are dis- tributed. But there are other nerves, which, like the brain, are them- selves entirely devoid of general sensibility. This has given occasion to a distinction of nerves into those of general and of special sensi- bility. Of nerves, which must be considered insensible or devoid of general sensibility, we may instance the optic, olfactory, and auditory. Each of these has, however, a special sensibility; and although it may exhibit no pain when irritated, it is capable of being impressed by appropriate stimuli—by light, in the case of the optic nerve; by odours, in that of the olfactory; and by sound, in that of the auditory. Yet we shall find, that every nerve of special sensibility seems to re- quire the influence of a nerve of general sensibility; the fifth pair. Many nerves appear devoid of sensibility, as the third, fourth, and sixth pairs; the portio dura of the seventh; the ninth pair of encephalic nerves; and, as has been shown, all the anterior roots of the spinal nerves. The parts of the encephalon, concerned in muscular motion, will fall under consideration hereafter. 2. PHYSIOLOGY OF SENSIBILITY. Sensibility we have defined to be—the function by which an animal experiences feeling, or has the perception of an impression. It in- cludes two great se^s of phenomena; the sensations, properly so called, and the intellectual and moral manifestations. These we shall investi- gate in succession. a. Sensations. A sensation is the perception of an impression made on a living tissue;—or, in the language of Gall, it is the perception of an irrita- tion. By the sensations we receive a knowledge of what is passing within or without the body'; and, in this way, our notions or ideas of them are obtained. When these ideas are reflected upon, and compared with each other, we exert thought and judgment; and they can be re- called with more or less vividness and accuracy by the exercise of memory. ACCOMPLISHED IN THE ENCEPHALON. Ill The sensations are numerous, but they may all be comprised in two divisions,—the external and the internal. Vision and audition afford us examples of the former, in which the impression made upon the organ is external to the part impressed. Hunger and thirst are in- stances of the latter, the cause being internal; necessary ; and depend- ing upon influences seated in the economy itself. Let us endeavour to discover in what they resemble each other. In the first place, every sensation, whatever may be its nature,—ex- ternal, or internal,—requires the intervention of the encephalon. The distant organ—as the eye or ear—may receive the impression, but it is not until this impression has been communicated to the encephalon, that sensation is effected. The proofs of this are easy and satisfactory. If we cut the nerve proceeding to any sensible part, put a ligature around it, or compress it in any manner;—it matters not that the object, which ordinarily excites a sensible impression, is applied to the part,—no sensation is experienced. Again, if the brain, the organ of perception, be prevented in any way from acting, it matters not that the part impressed, and the nerve communicating with it, are in a con- dition necessary for the due performance of the function, sensation is not effected. We see this in numerous instances. In pressure on the brain, occasioned by fracture of the skull; or in apoplexy, a disease generally dependent upon pressure, we find all sensation, all mental manifestation, lost; and they are not regained until the compressing cause has been removed. The same thing occurs if the brain be stu- pefied by opium; and, to a less degree, in sleep, or when the brain is engaged in intellectual meditations. Who has not found, that in a state of reverie or brown study, he has succeeded in threading his way through a crowded street, carefully avoiding every obstacle, yet so little impressed by the objects around as not to retain the slightest recollec- tion of them ! On the other hand, how vivid are the sensations when attention is directed to them ! Again, we have numerous cases in which the brain itself engenders the sensation, as in dreams, and in insanity. In the former, we see, hear, speak, use every one of our senses appa- rently ; yet there has been no impression from without. Although we may behold in our dreams the figure of a friend long since dead, there can obviously be no impression made on the retina from without.1 The whole history of spectral illusions, morbid hallucinations, and maniacal phantasies, is to be accounted for in this manner. Whether, in such cases, the brain reacts upon the nerves of sense, and produces an impression upon them from within, similar to what they experience from without during the production of a sensation, will form a subject for future inquiry. Pathology also affords several instances where the brain engenders the sensation, most of which are" precursory signs of cerebral derangement. The appearance of spots flying before the eyes, of spangles, depravations of vision, hearing, &c, and a sense of numbness in the extremities, are referable to this cause; as well as the singular fact well known to the operative surgeon, that pain is often 1 Adelon, Art. Encephale (Physiologie), in Diet, de Med., vii. 514, Paris, 1823, and Phy- siol, de l'Homme, torn. i. p. 239, 2de edit., Paris, 1829. 112 SENSATIONS. felt in part of a limb, months after the limb has been removed from the body. These facts prove, that every sensation, although referred to some organ, must be perfected in the brain. The impression^ is made upon the nerve of the part, but the appreciation takes place in the common sensorium. There are few organs which could be regarded insensible, were we aware of the precise circumstances under which their sensibility is elicited. The old doctrine—as old' indeed as Hippocrates1—was, that the tendons and other membranous parts are among the most sensible of the body. This opinion was implicitly credited by Boer- haave, and his follower Van Swieten ;2 and in many cases had a decided influence on surgical practice more especially. As the bladder consists principally of membrane, it was agreed for ages by lithoto- mists, that it would be improper to cut or divide it; and, therefore, to extract the stone dilating instruments were used, which caused the most painful lacerations of the parts. Haller3 considered tendons, liga- ments, periosteum, bones, meninges of the brain, different serous mem- branes, arteries and veins, entirely insensible; yet we know, that they are exquisitely sensible when attacked with inflammation. One of the most painful affections to which man is liable is the variety of whitlow that implicates the periosteum; and in all affections of the bone which inflame or press forcibly upon that membrane, there is excessive sensi- bility. It would appear, that the possession of vessels or vascularity is a necessary condition of the sensibility of any tissue. Many parts, too, are affected by special irritants; and, after they have appeared insensible to a multitude of agents, show great sensi- bility when a particular irritant is applied. Bichat endeavoured to elicit the sensibility of ligaments in a thousand ways, and without suc- cess ; but when he subjected them to distension or twisting, they im- mediately gave evidence of it. It is obvious, that before we determine that a part is insensible, it must have been submitted to every kind of irritation. M. Adelon affirms, that there is no part but what may become painful by disease. From this assertion the cuticle might be excepted. If we are right, indeed, in our view of its origin and uses, as described hereafter, sensibility would be of no advantage to it; but the contrary. In the present state, then, of our knowledge, we are justified in assert- ing, that bones, cartilages, and membranes are not sensible to ordi- nary external irritants, when in a state of health,—or in other words, that#we are not aware of the irritants, which are adapted to elicit their sensibility. That sensibility is due to the nerves distributed to a part is so gene- rally admitted as not to require comment. Dr. Todd4 has affirmed, that the anatomical condition necessary for the developement of the greater or less sensibility in an organ or tissue is the distribution in it of a greater or less number of sensitive nerves; and that the anato- mist can determine the degree to which this property is enjoyed by any - Foesii (Eeonom. Hippocr. " Nfwpov." a Aphorism. 164, and 165, and Comment 3 Oper. Minor., torn. i. * Art. Sensation, Cyclopedia of Anat. and Physiology, pt. xxxiv. p. 511 Jan. 1849 / ACCOMPLISHED IN THE ENCEPHALON. 113 tissue or organ by the amount of nervous supply, which his research discloses. It may well be doubted, however, whether such sensibility be by any means in proportion to the number of nerves received by a part. Nay, some parts are acutely sensible in disease into which nerves cannot be traced. To explain these cases, Reil1 supposed that each nerve is surrounded at its termination by a nervous atmosphere, by which its action is extended beyond the part in which it is seated. This opinion is a mere creation of the imagination. We have no evi- dence of any such atmosphere; and it is more philosophical to presume, that the reason we do not discover nerves may be owing to the imper- fection of our vision. We may conclude, that the action of impression occurs in the nerves of the part to which the sensation is referred. As to the mode in which this impression affects them we are ignorant. Microscopic ex- amination of the nerves connected with sensory organs would seem to show, that they come into relation with a substance very analogous to the gray mat- Pig- 33- ter of the encephalon, although its elements are somewhat differently arranged. The nervous fibres, too, appear to terminate in close approximation with a vascular plexus; and a granular structure is present, which— as in the cortical portion of the brain— seems to be intermediate. This point has been regarded as the origin of the afferent fibres ; and as the Seat of changes made by Distribution of Capillaries at the external impressions.2 surface of the skin of the finger. The facts mentioned show, that the ac- tion of perception takes place in the encephalon ; and that the nerve is merely the conductor of the impression between the part impressed and that organ. If a ligature be put round a nerve, sensation is lost below the ligature; but it is uninjured above it. If two ligatures be applied, sensibility is lost in the portion included between the liga- tures ; but it is restored if the upper ligature be removed. The spinal marrow is sensible along the whole of its posterior column, but it also acts only as a conductor of the impression. M. Flourens destroyed the spinal cord from beloAV, by slicing it away; and found, that sensibility was gradually extinguished in the parts corresponding to the destroyed medulla, but that the parts above evidently continued to feel. Per- ception, therefore, occurs in the encephalon; and not in the whole, but in some of its parts. Many physiologists—Haller, Lorry, Rolando, and Flourens3—sliced away the brain, and found that the sensations continued until the knife reached the level of the corpora quadrigemina; and, again, it has been found, that if the spinal cord be sliced away from below upwards, the sensations persist until we reach the medulla oblongata. * Exercitat. Anatom. Fascic, i. p. 28, and Archiv. fur die Physiologie, B. iii. 3 Carpenter, Human Physiology, p. 85, Lond., 1842. 3 Rolando, Saggio sopra la vera Struttura del Cervello, Sassari, 1809; and Flourens, Re- cherches Experimentales sur les Proprietes et les Fonctions du Systeme Nerveux, &c, 2de edit., Paris, 1842. VOL. I.—8 114 SENSATIONS. It is, then, between these parts, that we must place the cerebral organs of the senses, and it is with this part of the cephalo-spinal axis, that the nerves of the senses are actually found to communicate. Mr. Lawrence1 saw a child with no more encephalon than a bulb, which was a continuation of the medulla spinalis, for about an inch above the foramen magnum, and with which all the nerves from the fifth to the ninth pair were connected. The child's breathing and temperature were natural; it discharged urine and faeces; took food, and at first moved very briskly. It lived four days. If we divide the posterior roots of the spinal nerves and the fifth pair, general sensibility is lost; but if we divide the nerves of the senses, we destroy only their functions. We can thus understand why, after decapitation, sensibility may remain for a time in the head. It is instantly destroyed in the trunk, owing to the removal of all com- munication with the encephalon; but the fifth pair is entire, as well as the nerves of the organs of the senses. Death must of course follow almost instantaneously from loss of blood; but there is doubtless an appreciable interval during which the head may continue to feel; or, in other words, during which the external senses may act.2 M. Julia Fontanelle3 has indeed concluded, from a review of all the obser- vations made on this matter, that, contrary to the common opinion, death by the guillotine is one of the most painful; that the pains of decollation are horrible, and endure even until there is an entire ex- tinction of animal heat ! It need scarcely be said, that all these infer- ences are imaginative, and perhaps equally fabulous with the oft-told story of Charlotte Corday scowling at the executioner after her head was removed from her body by the guillotine; and this conclusion is strongly confirmed by the results of experiments on a robber—who was beheaded with the sword—by Drs. Bischoff, Heerman, and Jolly, who inferred that consciousness must have ceased instantaneously.4 But if such be the case with man, it most assuredly is not so with the inferior animals. Ample evidence will be afforded hereafter to show, that both sensation and volition may persist in the rattlesnake and alligator long after the head has been removed from the body. Singular facts in regard to the latter animal have been recorded by Dr. Leconte,5 and more recently, by Dr. Dowler,6 of New Orleans. It has been remarked, that the cerebral hemispheres may be sliced away without abolishing the senses. The experiments of Rolando and Flourens, which have been repeated by M. Magendie, show, however, that the sight is an exception;—that it is lost by their removal. If the right hemisphere be sliced away, the sight of the left eye is lost; and conversely;—one of the facts that prove the decussation of the optic 1 Medico Chirurg. Transact., v. 166. * Berard, Rapports du Physique et du Moral, p. 93, Paris, 1823. 3 Phoebus, Art. Enthauptung, in Encyclopad. Worterb. der Medicin. Wissenchaft. xi. 204, Berlin, 1835. 4 A condensed account of Dr. BischofFs Remarks, from Muller's Archiv., by S. L. L. Big- ger, is in the Dublin Journal of Medical Science, Sept., 1839, p. 1. 5 New York Journal of Medicine, for Nov., 1845, p. 335, and Sir Charles Lyell Travels in North America, Amer. edit., i. 237. New York, 1849. 6 Contributions to Physiology, New Orleans, 1849, from New Orleans Journal of Medi- cine. SENSORY GANGLIA. 115 Fig. 34. nerves. The experiments of these gentlemen show, that vision, more than the other senses, requires a connexion with the organ of the intel- lectual faculties—the cerebral hemispheres; and this, as M. Magendie has ingeniously remarked, because vision rarely consists in a single im- pression made by light, but is connected with an intellectual process, by which we judge of the distance, size, shape, &c, of bodies. It has been well suggested and maintained by Dr. Carpenter,1 that whilst the cerebral ganglia are the organs of the higher intellectual and moral acts; there is a series of ganglia, con- nected with the reception of impressions from without, which are seated near the base of the brain, and are hence termed by him sensory ganglia. As we descend in the ani- mal scale, these ganglia become more marked; whilst the cerebral hemispheres become less and less; until ultimately the animal appears to have its encephalic organs limited almost wholly to those that are concerned in the reception of impressions from without, and the originating of motor impulsions from within. These ganglia are seated at the base of the brain: from the origin of the auditory nerves to those of the olfactory. c< Brain of Squirrel, laid open. The hemispheres, b, drawn to either side to show the subjacent parts, c. The optic lobes. D. Cerebel- lum, thai. Thalamus opticus, c s. Corpus striatum. Fig. 35. Fig. 36. Pike. Brain of Turtle. a. Olfactive ganglia, b. Cerebral hemi- spheres, c. Optic ganglia, d. Cerebellum. Brains of Fishes. Olfactive lobes,or ganglia, b. Cerebral hemi- spheres, c. Optic lobes, d. Cerebellum. Dr. Carpenter is disposed to regard the optic thalami as ganglia for the reception of tactile impressions, and the corpora striata as ganglia con- 1 Principles of Human Physiology, 4th Amer. edit., p. 370, Philad., 1850. 116 SENSATIONS. nected with motion. He esteems them to be, moreover, the centre of consensual or instinctive movements, or of automatic movements involv- ing sensation;—a topic which will receive attention elsewhere. Having arrived at a knowledge that in man and the upper class of animals, perception is effected in a part of the encephalon, our acquaint- ance with this mysterious process ends. We know not, and we probably never shall know, the action of the brain in accomplishing it. It is cer- tainly not allied to any physical phenomenon; and if we are ever justi- fied in referring functions to the class of organic and vital, it may be those, that belong to the elevated phenomena, which have to be con- sidered under the head of animal functions. We know them only by their results: yet we are little better acquainted with many topics of physical inquiry;—with the nature of the electric fluid for example. The organs, then, that form the media of communication between the parts impressed and the brain, are the nerves and spinal marrow. M. Broussais,1 indeed, affirmed, that every stimulation capable of causing perception in the brain, runs through the whole of the nervous system of relation; and is repeated in the mucous membranes, whence it is again returned to the centre of perception, which judges of it according to the view of the viscus to which the mucous membrane belongs; and adapts its action as it perceives pleasure or pain. We are totally unacquainted with the material character of the fluid, which passes with the rapidity of lightning along nervous cords; and it is as impossible to describe its mode of transmission, as it is to depict that of the electric fluid along a conducting wire. As in the last case, we are aware of such transmission only by the result. Still, hypotheses, as on every obscure matter of inquiry, have not been wanting.2 Of these, three are chiefly deserving of notice. The first, of greatest anti- quity, is, that the brain secretes a subtile fluid, which circulates through the nerves, called animal spirits, and which is the medium of commu- nication between the different parts of the nervous system; the second regards the nerves as cords, and the transmission as effected by means of the vibrations or oscillations of these cords; whilst the third ascribes it to the operation of electricity. 1. The hypothesis of animal spirits has prevailed most extensively. It was the doctrine of Hippocrates, Galen, the Arabians, and of most of the physicians of the last centuries. Des Cartes3 adopted it energe- tically ; and was the cause of its more extensive diffusion. The great grounds assigned for the belief were;—first, that as the brain receives so much more blood than is necessary for its own nutrition, it must be an organ of secretion; secondly, that the nerves seem to be a conti- nuation of the tubular matter of the brain; and it has already been remarked, that Malpighi considered the cortical neurine to be follicular, and the medullary to consist of secretory tubes. It was not unnatural, therefore, to regard the nerves as vessels for the transmission of these spirits. As, however, the animal spirits had never been met with in a 1 Traite de Physiologie, &c, Paris, 1822: or translation by Drs. Bell and La Rnr-he 3d Amer. edit., p 63, Philad., 1832. ' * Fletcher's Rudiments of Physiology. P. ii. b. p. 08, Edinb., 1836. 3 Tractatus de Homine, p. 17, Lugd. Bat., 1664. HYPOTHESIS OF VIBRATIONS. 117 tangible shape, ingenuity was largely invoked in surmises regarding their nature; and, generally, opinions settled down into the belief that they were of an ethereal character. For the various views that have been held upon the subject, the reader is referred to Haller,1 who was himself an ardent believer in their existence, and has wasted much time and space in an unprofitable inquiry into their nature. The truth is, that we have not sufficient evidence, direct or indirect, of the existence of any nervous fluid of the kind described. Allusion has been already made to the views, in regard to the tubular structure of the white neu- rine, admitted by most observers: Berres,2 affirms that the forms, which the nervous substance assumes under the magnifying glass, can only be compared to those of canals and vesicles; but whether they be hollow he does not attempt to decide. M. Raspail3 has concluded, that the opinion of their being hollow, and containing a fluid, is unsupported by facts; for although he admits, that M. Bogros succeeded in injecting the nerves with mercury, he thinks that the passage of the metal along them was owing to its having forced its way by gravity. Modern histologists accord with great unanimity as to the tubular structure of the medullary neurine; but we have no reason for considering the brain the organ of any ponderable secretion. Yet the term "animal spirits," although their existence is not now believed, is retained in popular language. We speak of a man who has a great flow of animal spirits, but without regarding the hypothesis whence the expression originated. The term nervous fluid is still used by physiologists. By this, how- ever, they simply mean the medium of communication or of convey- ance, by which the nervous influence is carried with the rapidity of lightning from one part of the system to another; but without com- mitting themselves as to its character ;—so that, after all, the idea of animal spirits is in part retained, although the term, as applied to the nervous fluid is generally exploded. Dr. Good4 directly admits them under the more modern title; Mr. J. W. Earle5 firmly believes in the existence of a circulation in the nervous system,—and it is not easy to conceive, that the brain does not possess the function of elaborating some fluid,—galvanoid or other,—which is the great agent in the nerv- ous function. 2. The hypothesis of vibrations is ancient, but has been by no means as generally admitted as the last. Among the moderns, it has received the support of Condillac,6 Hartley,7 Blumenbach,8 and others; some supposing, that the nervous matter itself is thrown into vibrations; others, that an invisible and subtile ether is diffused through it, which acts the sole or chief part. As the latter is conceived, by many, to be the mode in which electricity is transmitted along conducting wires, 1 Elementa Physiologiae, x. 8. a Oesterreich. Med. Jahrbuch., B. ix., cited in Brit, and Foreign Med. Review, January, 1838, p. 219. 3 Chimie Organique, p. 218. Paris, 1833. 4 Study of Medicine, with Notes by S. Cooper, Doane's Amer. edit., vol. ii., in Proem to Class iv. Neurotica, New York, 1835. 6 New Exposition of the Functions of the Nerves, by James William Earle, Part. I. Lon- don, 1833. 6 (Euvres, Paris, 1822. t Observations on Man, &c, chap. i. sect. 1. London, 1791. 8 Institutiones Physiologicae, § 226. 118 SENSATIONS. it is not liable to the same objections as the former. Simple inspec- tion, however, of a nerve at once exhibits, that it is incapable of being thrown into vibrations. It is soft; never tense; always pressed upon in its course; and, as it consists of filaments destined for very differ- ent functions,—sensation, voluntary and involuntary motion, &c—we cannot conceive how one of these filaments can be thrown into vibra- tion without the effect being extended laterally to others ; and great confusion being thus induced. The view of Dr. James Stark1 in regard to the structure of the tubes of the nerves, has led him to adopt a modification of the theory of vibrations. Believing, that the matter which fills the tubes is of an oily nature,—and as oily substances are known to be non-conductors of electricity; and farther, as the nerves have been shown by the experiments of Bischoff to be amongst the worst possible conductors of electricity,—he contends, that the nervous energy can be neither electricity nor galvanism, nor any property re- lated to them; and he conceives, that the phenomena are best explained on the hypothesis of undulations or vibrations propagated along the course of the tubes by the oily globules they contain. 3. The last hypothesis is of later date,—subsequent to the disco- veries in animal electricity. The rapidity with which sensation and volition are communicated along the nerves, could not fail to suggest a resemblance to the mode in which the electric and galvanic fluids fly along conducting wires. Yet the great support of the opinion was in the experiments of Dr. Wilson Philip2 and others, from which it ap- peared, that if the nerve proceeding to a part be destroyed,—and the secretion, which ordinarily takes place in the part be thus arrested,— the secretion may be restored by causing the galvanic fluid to pass from one divided extremity of the nerve to the other. The experi- ments, connected with secretion, will be noticed more at length here- after. It will likewise be shown, that in the effect of galvanism upon the muscles, there is a like analogy ;—that the muscles may be made to contract for a length of time after the death of the animal, and even when a limb is removed from the body, on the application of the galvanic stimulus; whilst comparative anatomy exhibits to us great development of nervous structure in electrical animals, which astonish us by the intensity of the electric shocks they are capable of commu- nicating. Physiologists of the present day generally, we think, accord with the electrical hypothesis. The late Dr. Young,3 so celebrated for his knowledge in numerous departments of science, adopted it prior to the interesting experiments of Dr. Philip; and Mr. Abernethy,4 whilst he is strongly opposing the doctrines of materialism, goes so far as to consider some subtile fluid not merely as the agent of nervous transmission, but as forming the essence of life itself. By putting a ligature, however, around a nervous trunk, its functions, as a con- ductor of nervous influence, are paralyzed, whilst it is still capable 1 Proceedings of the Royal Society, No. 56, Lond., 1843. 2 Philosoph. Trans, for 1815, and Lond. Med. Gazette for March 18, and March 25, 1837. 3 Med. Literature, p. 93. Lond., 1813. * Physiological Lectures, exhibiting a view of Mr. Hunter's Physiology, &c. Lond., 1817. EXTERNAL SENSATIONS. 119 of conveying electricity; and, moreover, when wires are inserted into an exposed nerve, and their opposite extremities are attached to the galvanometer, no movement of the needle has been observed by Person, Miiller, Matteucci, and by Todd and Bowman.1 Dr. Bostock,2 too, has remarked, that before the electrical hypothesis can be con- sidered proved, two points must be demonstrated; first, that every function of the nervous system may be performed by the substitution of electricity for the action of nerves; and secondly, that all nerves admit of this substitution.' This is true, as concerns the belief in the identity of the nervous and electrical fluids; but we have, even now, evidence sufficient to show their similarity; and that we are justified in considering the nervous fluid to be electroid or galvanoid in its na- ture, emanating from the brain by some action unknown to us, and transmitted to the different parts of the system to supply the expendi- ture, which must be constantly taking place. Reil,3 Senac,4 Prochaska, Scarpa,5 and others are of opinion, that the nervous agency is generated throughout the nervous system ; and that every part derives sensation and motion from its own nerves. We have satisfactorily shown, however, that a communication with the ner- vous centres is absolutely necessary in all cases, and that we can imme- diately cut off sensation in the portion of a nerve included between two ligatures, and as instantly restore it by removing the upper ligature, and renewing the communication with the brain. a. External Sensations. The external sensations are those perceptions Avhich are occasioned by the impressions of bodies external to the part impressed. They are not confined to impressions made by objects external to us. The hand applied to any part of the body; any two of its parts brought into con- tact; the presence of its own secretions or excretions may equally excite them. M. Adelon,6 has divided them into two orders—first, the senses, properly so called, by the aid of which the mind acquires its notion of external bodies, and of their different qualities; and secondly, those sen- sations which are still caused by the contact of some body; and yet afford no information to the mind. It is by the external senses, that we become acquainted with the bodies that surround us. They are the instruments by which the brain receives its knowledge of the universe; but they are only instruments, and cannot be considered as the sole regulators of the intellectual sphere of the individual. This we shall see is dependent upon another and still higher nervous organ,—the brain. The external senses are generally considered to be five in number; for, although others have been proposed, they may perhaps be reduced to some modification of these five,—tact or touch, taste, smell, hearing, 1 The Physiological Anatomy and Physiology of Man, p. 242. Lond., 1845., 2 An Elementary System of Physiology, 3d edit., p. 148. Lond., 1836. 3 De Strnctura Nervorum, Hal., 1796. * Traite de la Structure du Cosur, &c., liv. iv. chap. 8. Paris, 1749. * Tabulas Neurologic^. Ticin., 1794, § 22. « Physiologie de 1' Homme, torn. i. p. 259, 2de edit. Paris, 1829. 120 EXTERNAL SENSATIONS. and vision. All these have some properties in common. They are situate at the surface of the body, so as to be capable of being acted upon with due facility by external bodies. They all consist of two parts: —the one, physical, which modifies the action of the body, that causes the impression; the other nervous or vital, which receives the impres- sion, and conveys it to the brain. In the eye and the ear, we have better exemplifications of this distinction than in the other senses. The physical portion of the eye is a true optical instrument, which modifies the light, before it impinges upon the retina. A similar modification is produced by the physical portion of the ear on the sonorous vibra- tions, before they reach the auditory nerve; whilst in the other senses, the physical portion forms a part of the common integument in which the nervous portion is seated, and cannot be easily distinguished. Some of them, again, as the skin, tongue, and nose, are symmetrical, that is, composed of two separate and similar halves, united at a median line. Others, as the eye and ear, are in pairs; and this, partly perhaps, to enable the distances of external objects to be appreciated. We shall find, at least, that there are certain cases, in which both the organs are necessary for accurate appreciation. Two of the senses—vision and audition—have, respectively, a nerve of special sensibility; and, until of late years, the smell has been believed to be similarly situate. In the present state of our knowledge, we cannot decide upon the precise nerve of taste, although it will be seen that a plausible opinion may be indulged on the subject. The general sense of touch or feeling is certainly seated in the nerves of general sensibility connected with the posterior roots of the spinal nerves and the fifth encephalic pair; and according to some,1 in the glosso-pharyngeal and pneumogastric nerves. The other senses seem intimately connected with one nerve of general sensibility,—the fifth pair. This is especially the case with those senses that possess nerves of special sensibility; for, if the fifth pair be cut, the function is abolished or impaired, although the nerve of special sensibility may remain entire. Being instruments by which the mind becomes acquainted with ex- ternal bodies, it is manifestly of importance, that the senses should be influenced by volition. Most of them are so. The touch has the plia- ble upper extremity, admirably adapted for the purpose. The tongue is movable in almost every direction. The eye can be turned by its own immediate muscles towards objects in almost all positions. The ear and the nose possess the least individual motion; but the last four, being seated in the head, are capable of being assisted by the muscles adapted for its movements. All the senses may be exercised passively and actively. By direct- ing the attention, we can render the impression more vivid; and hence the difference between simply seeing or passive vision, and looking attentively; between hearing and listening ; smelling and snuffing; touching and feeling closely. It is to the active exercise of the senses, that we are indebted for many of the pleasures and comforts of social existence. Yet, to preserve the senses in the vigour and delicacy, 1 Longet, Traite de Physiologie, ii. 176, note. Paris, 1850. SENSE OF TOUCH. 121 which they are capable of acquiring by attention, the impressions must not be too constantly or too strongly made. The occasional use of the sense of smell, under the guidance of volition, may be the test on which the chemist, perfumer, or wine-merchant, may rely in the discrimi- nation of the numerous odorous characteristics of bodies; but, if the olfactory nerves be constantly, or too frequently, stimulated by excit- ants, of this or any other kind, dependence can no longer be placed upon them as a means of discrimination. The maxim that " habit blunts feeling," is true only in such cases as the last. Education can, indeed, render it extremely acute.' Volition, on the other hand, en- ables us to deaden the force of sensations. By corrugating the eye- brows and approximating the eyelids, we can diminish the quantity of light when it is too powerful. We can breathe through the mouth, when a disagreeable odour is exhaled around us; or can completely shut off its passage by the nostrils, with the aid of the upper extremity. Over the hearing we have less command as regards its individual ac- tion : the upper extremity is here always called into service, when we desire to diminish the intensity of any sonorous impression. Lastly. It is a common observation, that the loss of one sense occa- sions greater vividness in others. This is only true as regards tbe senses that administer chiefly to the intellect,—those of touch, audition, and vision, for example. Those of smell and taste may be destroyed ; and yet the more intellectual senses may be uninfluenced. In the singular condition of artificial somnambulism or hypnotism, the author has seen the various senses rendered astonishingly acute. The cause of the superiority of the remaining intellectual senses, when one has been lost, is not owing to any superior organization in those senses; but is another example of the influence of education. The remaining senses are exerted attentively to compensate for the privation; and they become surprisingly delicate. We proceed to the consideration of the separate senses, beginning with that of tact or touch, because it is most generally distributed, and may be regarded as that from which the others are derived. They are all, indeed, modifications of the sense of touch. In the taste, the sapid body; in the smell, the odorous particle; in the hearing, the sonorous vibration; and in the sight, the particle of light, must impinge upon or touch the nervous part of the organ, before sensation can, in any of the cases, be effected. SENSE OF TACT OR TOUCH—PALPATION. The sense of tact or touch is the general feeling or sensibility, pos- sessed by the skin especially, which instructs us regarding the tempe- rature and general qualities of bodies. By some, touch is restricted to the sense of resistance alone; and hence they have conceived it necessary to raise into a distinct sense one of the attributes of tact or touch. The sense of heat, for example, has been separated from tact; but although the appreciation of external bodies by tact or touch differs 1 Berard, Rapport du Physique et du Moral, p. 245; Paris, 1823. 122 SENSE OF TOUCH. —as will be seen—in some respects from our appreciation of their temperature, its consideration properly belongs to the sense we are considering, in the acceptation here given to it, and adopted by all the French physiologists. According to them, tact is spread generally in the organs, and especially in the cutaneous and mucous surfaces. It exists in all animals; whilst touch is exercised only by parts evidently destined for that purpose, and is not present in every animal. It is nothing more than tact joined to muscular contraction and directed by volition. So that, in the exercise of tact, we may be esteemed pas- sive; in that of touch, active. The organs concerned in touch, execute other functions besides; and in this respect touch differs from the other senses. Its chief organ, however, is the skin ; and hence it is necessary to inquire into its struc- ture, so far as is requisite for our purpose. 1. ANATOMY OF THE SKIN, HAIR, NAILS, ETC. The upper classes of animals agree in possessing an outer envelope or skin, through which the insensible perspiration passes; a slight de- gree of absorption takes place; the parts beneath are protected; and the sense of touch is accomplished. In man, the skin is generally considered to consist of four parts,—the cuticle, rete mucosum, corpus papillare, and corium ; but when reduced to its simplest expression, the whole of the integument, with the mucous membrane, which is an ex- tension of it, may be regarded as a continuous membrane, more or less involuted, more or less modified by the elementary tissues which com- pose it or are in connexion with it, and within which all the rest of the animal is contained. It consists of two elements—a basement tissue or membrane, composed of simple membrane, uninterrupted, homo- geneous, and transparent; covered by an epithelium or pavement of nucleated particles.1 1. The epidermis or cuticle is the outermost layer. It is a dry, membranous structure, devoid of vessels and nerves ; yet it is described by some recent investigators as a tissue of a somewhat complex organiza- tion, connected with the functions of exhalation and absorption; but its vitality is regarded to be on a par with that of vegetables. The absence of nerves proper to it renders it insensible; it is coloured; and exhales and absorbs in the manner'of vegetables. It is, so far as we know, entirely insensible; resists putrefaction for a long time, and may be easily obtained in a separate state from the other layers by maceration in water. ^ It is the thin pellicle raised by a blister. The cuticle is probably a secretion or exudation from the true skin, which concretes on the surface; becomes dried, and affords an efficient protection to the corpus papillare beneath. It is composed, according to some, of concrete albumen ; according to others, of mucus; and is pierced by oblique pores for the passage of hairs, and for the orifices of exhalant and absorbent vessels. MM. Breschet and Roussel de Vauzeme2 affirm, that there is a special "blennogenous or mucific apparatus" for 1 Todd and Bowman, The Physiological Anatomy and Physiology of Man, p. 404 London 1845. a Nouvelles Recherches sur la Structure de la Peau, par M. Breschet, Paris 1835. ORGANS OF TOUCH. 123 the secretion of this mucous matter, composed of a glandular paren- chyma or organ of secretion situate in the substance of the derma, and Fig. 38. Fig. 39. of excretory ducts, which issue from the organ, and deposit the mucous matter between the papillae; but such an apparatus is not usually admitted. It is probable, that the cuticle is placed at the surface of the body, not simply to protect the corpus papillare ; but to prevent the constant imbibition and transudation that might take place did no such envelope exist. It exfoliates, in the form of scales, from the head ; and in large pieces, from every part of the body, after certain cutaneous diseases. M. Flourens,1 who has closely and accurately investigated the ana- tomy of the cutaneous envelope, considers that the skin of the coloured races has an apparatus, which is wanting in the white variety of the species. This apparatus he names pigmental,—appareil pigmental. It is composed of a layer (lame) or membrane which bears the pig- ment, and of the pigment itself. Above it are two cuticles. In the white variety the pigmental apparatus is wanting, and consequently the skin is more simple than that of the coloured races. The skin of the white variety approaches that of the coloured in some remarkable points. First.—The superficial layer or lame of the derma is every- where of a peculiar appearance, which is different from that of the 1 Anatomie Generate de la Peau et des Membranes Muqueuses, p. 34, Paris, 1843. 124 SENSE OF TOUCH. Vertical Section of the Cuticle from the Scrotum of a Negro. Fig. 41. rest of the derma. Secondly.—Around the nipple of the white woman, the superficial layer of the derma presents the same granular appear- ance as the pigmental membrane of the coloured races. And thirdly. —The pigmental layer around the nipple of the white woman is placed, as in the coloured races, under the two cuticles. Modern histologists consider the Fig. 40. epidermis to be composed of a series of flattened, scale-like cells, epider- mic cells, which, when first formed, are of a spheroidal shape; but gra- dually dry up. These form various layers. According to M. Raspail,1 it consists of a collection of vesicles de- prived of their contents, closely ap- a. Deep cells, loaded with pigment. 6. Cells nl*pfl fftCPthpr Ar'ipd and thrown off at.a higher level, paler and more flattened, pneu HOgeUier, Urieu, dllU UllOWii oil c. Cells at the surface, scaly and colourless as Jn the form of brannV SCaleS. He in the white races.—Magnified 300 diameters. . . . ^ . „ , regards it as the outer layer or the corium. The epidermoid tissues have the simplest structure of any solids. Analysis has shown, that the che- mical constitution of the membranous epidermis of the sole of the foot is the same as that of the compact horny matter of which nails, hair, and wool are composed. 2. The corpus or rete mucosum, rete Malpighii, mucous web, is gene- rally regarded as constituting the next layer. It was considered by Malpighi to be mucus, secreted by the papillae, and spread on the surface of the corpus papillare, to preserve it in the state of suppleness necessary for the performance of its functions. Section of the Skin. In this rete mucosum, the colouring i. cuticle, showing the oblique lamin* of matter of the dark races seems to ex- which it is composed and the imbricated dis- ist. It is black in the African, or position of the ridges upon its surface. 2. , . , -p, . . ' Rete mucosum. 3. Two of the quadrilateral rather in the .hithiopian; and copper- papillary masses seen in the palm of the hand i j • .r i .. n r^ i. • i or sole of the foot; they are composed of Coloured in the mulatto.3 (xaultier minute conical papillae. 4. Deeper layer of rnnsidprs it Tft hp pnrrmnoorl r>f frmr the cutis, the corium. 5. Adipose vesicles; conslaerS IT, 10 De COmpOSed Ot lOUr showing their appearance beneath the micro- layers*, but this notion is not admit- scope. 6. Perspiratory gland with its spiral "j , . . duct, as seen in the paim of the hand or sole ted by anatomists, and scarcely con- ghL^t,esuPchr^ifffi cerns the present inquiry. M. Bre- of the foot with a strai: ?caj£-- 8; Tw° hairs frbm the scaip enclosed schet affirms, that there "is a special m their follicles; their relative depth in the . ' *"wv, iu a ojjci/io.1. skin preserved. 9. A pair of sebaceous glands " chrOmatogeUOUS OX Colorific anpa- opening by short ducts into the follicle of the . >> o •> ,, •' , ±Z hair. ratus, lor producing the colouring * Chimie Organique, p. 245, Paris, 1833. 3 Sir E. Home, Lect. on Comp. Anar., v. 278. 3 Recherches Anatomiques sur le Systeme Cutane de 1'Homme, Paris, 1811. ORGANS OF TOUCH. 125 matter, composed of a glandular or secreting parenchyma, situate a little below the papillae, and presenting special excretory ducts, which pour out the colouring matter on the surface of the derma. Modern observers deny, that there is any such distinct layer. Some regard it as the deepest or most recently formed part of the cuticle. M. Flourens1 considers, that the term corpus mucosum ought to be re- placed by that of pigmental apparatus,—appareil pigmental; and that the term rete or corpus reticulare in the signification of a special network situate between the derma and the two cuticles, ought to be banished from anatomy. The nature of the pigment will be referred to hereafter, under Secretion. The rete mucosum is considered to be the last formed portion of the cuticle. 3. The corpus papillare, or what M. Breschet calls the " neu- rothelie or mammillary nervous apparatus," is seated next below the rete mucosum. It consists of a collection of small papillae, formed by the extremities of nerves and vessels, which, after having passed through the corium beneath, are grouped in small pencils or villi on a spongy, erectile tissue. These pencils are disposed in pairs, and, when not in action, are relaxed, but become erect when employed in the sense of Fis- 42- touch. They are very readily seen, when the cutis vera is exposed by the action of a blister; and are always evident at the palmar surface of the hand, and especially at the tips of the fingers, where they have a concentric arrange- ment. These villi are sometimes called papillae. They are, in reality, prolongations of the skin ; . Papilla? of the palm, the Cu- .*' .ttitttii <>i tide being detached.—Mainl- and consequently—as M. flourens-* has re- fled35diameters. marked — "the pretended corpus papillare, taken as a body, apart and distinct from the derma, is but an idle name." 4. The corium, cutis vera, derma, true skin, is the innermost layer of the skin. It consists of a collection of dense fibres, intersecting each other in various directions; and leaving between them holes for the passage of vessels and nerves. It forms a firm stratum, giving the whole skin the necessary solidity for accomplishing its various ends ; and consists chiefly of gelatin ;—hence it is used in the manu- facture of glue. Gelatin, when united with tannic acid, forms a sub- stance which is insoluble in water; and it is to this combination that leather owes the properties it possesses. The hide is first macerated in lime-water to remove the cuticle and hairs, and leave the corium or gelatin. This is then placed in an infusion of oak bark, which con- tains tannic acid. The tannic acid and the skin unite ; and leather is the product. These four strata constitute the skin, as it is commonly called; yet all are comprised in the thickness of two or three lines. The cutis vera is united to the structures below by areolar tissue; and this, with ' Op. cit., p. 38. 2 Op. cit., p. 38. 126 SENSE OF TOUCH. the layers external to it, forms the common integument. In certain parts of the body, and in animals more particularly, the cutis vera is adherent to muscular fibres, inserted more or less obliquely. These form the muscular web, mantle or panniculus carnosus. The layer is well seen in the hedge-hog and porcupine, in which it rolls up the body, and erects the spines; and in birds, raises the feathers. In man, it can hardly be said to exist. Some muscles, however, execute a similar func- tion. By the occipito-frontalis, many persons can move the hairy scalp; and by the dartos the skin of the scrotum can be corrugated. These two parts, therefore, act as panniculi carnosi. In the skin are situate numerous sebaceous follicles or crypts, which separate an oily fluid from the blood, and pour it over the surface to lubricate and defend it from the action of moisture. They are most abundant, where there are folds of the skin, or hairs, or where the sur- face is exposed to friction. We can generally see them on the pavilion of the ear, and their situation is often indicated by small dark spots on the surface, which, when pressed between the fingers, may be forced out along with the sebaceous secretion, in the form of small worms. By the vulgar, indeed, these are considered to be worms. The follicular secretions will engage attention hereafter. Fig. 43. Sections of Hair. a. Transverse section of a hair of the head, showing the exterior cortex, the me- dulla or pith with its scattered pigment, and a central space filled with pigment. b. A similar section of a hair, at a point where no aggregation of pigment in the axis exists, e. Longitudinal section, with- out a central cavity, showing the imbrica- tion of the cortex, and the arrangement of the pigment in the fibrous part. d. Sur- face, showing the sinuous transverse lines formed by the edges of the cortical scales. d'. A portion of tne margin, showing their imbrication. — Magnified 150 diameters. (Todd and Bowman.) The consideration of the hair belongs naturally to that of the skin. The roots are in the form of bulbs; taking their origin in small follicles or open sacs, hair follicles, formed by the inversion of the cutis, and lined by a reflexion of the epidermis. Around each bulb there are two capsules, the innermost of which is vascular and a continuation of the corium. The hair itself consists of a horny, ex- ternal covering, and a central part, called medulla or pith. When we take hold of a hair by the base, with the thumb and forefinger, and draw it through them from the root towards the point, it feels smooth to the touch; but if we draw it through from the point to the root, we feel the surface rough; and it offers considerable resistance. It is, therefore, concluded, that the hair is bristled, imbricated or consists of eminences pointing towards its outer extremity, and it is upon this structure, that the operation of felting is dependent—the hairs being mechanically entangled and retained in that state by the inequalities of their surface. Certain observers have, however, failed in detect- ing this striated appearance by the aid HAIR. 127 of the microscope; and Dr. Bostock1 affirms, that he had an opportunity of viewing the human hair, and the hair of various kinds of animals, in the excellent microscope of Mr. Bauer, but without being able to observe Magnified view of the Root of the Hair. Thin Layer from the Scalp. (Kohlrausch.) a. Stem or shaft of hair cut across, b. Inner, and e. o, a. Sebaceous glands, b. Hair, with Outer layer of the epidermic lining of the hair follicle, its follicle, c. (Gurlt.) called also the root-sheath, d. Dermic or external coat of the hair follicle, shown in part. e. Imbricated scales about to form a cortical layer on the surface of the hair. it. Bichat,2 however, and more recently, Dr. Goring,3 and most histolo- gists, have assigned this as their structure; and the author has had repeated opportunities for confirming it with his own admirable micro- scope, made by Smith, of London. Modern observers believe, that, as in other structures, growth takes place from cells, which are a modification of those of the epidermis. The primary cells become elongated, and generate within themselves fasciculi of fibres or secondary cells, which interlace to form the hair cylinder. The walls of these fibre-cells are at first soft and permeable; and the lower part of the hair, which is composed of them, seems to admit the passage of fluid without much difficulty. At a short distance from the base, the horny character of the hair, caused by the deposit of horny matter in the interior of the fibres, becomes apparent. "There is then, at the base, a continual formation of soft fibrous tissue, by which the length of the cylinder is increased; whilst at a short distance above it, there is a continual consolidation of this (as it progressively arrives at that point) by the deposit of a peculiar secretion in its substance."4 i Physiology, p. 52, 3d edit., Lond., 1836. 3 Anat. General., torn, iv., § 2. 3 Journal of Science, New Series, vol. i. 433. « Carpenter, Human Physiology, § 637. Lond., 1842. 128 SENSE OF TOUCH. The colour of the hair is different in different races and individuals. By some, this is considered to depend upon the fluids contained in the pith. M. Vauquelin1 analyzed the hair attentively, and found it to con- sist chiefly of an animal matter, united to a portion of oil, which appeared to contribute to its flexibility and cohesion. Besides this, there is another substance, of an oily nature, from which he considers the colour of the hair is derived. The animal matter, according to that chemist, is a species of mucus; but other chemists believe it to be chiefly albumen. Vauquelin found, that the colouring matter is destroyed by acids; and he suggests, that when it has suddenly changed colour and become gray, in consequence of any mental agitation, this may be owing to the pro- duction of an acid in the system, which acts upon the colouring matter. The explanation is hypothetical, and is considered, arid characterized as such by Dr. Bostock; but it must be admitted, that the same objec- tion applies to the view he has substituted for it. He conceives it "more probable that the effect depends upon a sudden stagnation in the vessels, which secrete the colouring matter; while the absorbents continue to act, and remove that which already exists." There is, how- ever, no more real evidence of "stagnation of vessels" than there is of the formation of an acid. Our knowledge is limited to the fact, that a sudden and decided change in the whole pileous system may occur after great or prolonged mental agitation. " My hair is gray, but not with years, Nor grew it white in a single night, As men's have grown from sudden fears." Byron's " Prisoner of Chillon." "Danger, long travail, want and wo, Soon change the form that best we know : For deadly fear can time outgo, And blanch at once the hair. Hard toil can roughen form and face, And want can quench the eye's bright grace, Nor does old age a wrinkle trace More deeply than despair." Scott's " MarmwnA"1 It is stated by M. De Lamartine,3 that such a change occurred in a single night to the queen of Louis the 16th—the unfortunate Marie Antoinette—when the royal party was arrested at Varennes, in 1791. But a similar, though more gradual change, is produced by age. We find some persons entirely gray at a very early period of life; and, in old age, the change happens universally. It is not then difficult to suppose, that some alteration in the nutrition of the hair may super- vene, resembling that which occurs in the progress of life. Dr. Bostock doubts the fact of such sudden conversions; but the instances are too numerous for us to consider them entirely fabulous. Still, it is difficult to comprehend how parts, which, like the extremities of the hair, are 1 Annales de Chimie, torn, lviii. p. 41, Paris, 1806. a For many such cases see M. E. Wilson, a Practical Treatise on Healthy Skin p 95 London, 1845. ' ' *' 3 "La reine ne dormit pas. Toutes ses passions, de femme, de mere, de reine la colere la terreur, la desespoir, se livrerent un tel assaut dans son ame, que ses cheveux' blonds la vieille, furent blancs le lendemain."—Histoire des Girondins, i. 116. Paris 1847. HAIR. 129 foreign to nutrition, can change so rapidly. M. Lepelletier1 ascribes it to two very different causes. First, to defective secretion of the colouring fluid, without any privation of nutrition. In this case, the hairs may live and retain their hold, as we observe in young individuals: —and secondly, to the canals, which convey the fluid into the hair, being obliterated, as in old age. The same cause, acting on the nutritious vessels of the bulb, produces, successively, privation of colour, death, and loss of those epidermoid productions. According to other physiologists, the seat of colour is in the horny covering of the hair; and, in the largest hairs or spines of the porcu- pine, this seems to be the case, the pith being white, and the horny covering coloured. There is often an intimate relationship observed between the colour of the hair and that of the rete mucosum. A fair complexion is accompanied with light hair; a swarthy with dark;— and we see the connexion still more signally displayed in those animals that are spotted—the colour of the hair being variegated like that of the skin. Hairs differ materially according to the part of the body on which they grow. In some parts they are short, as in the armpits; whilst on the head it is not easy to say what would be the precise limit to the growth, were they left entirely to nature. In the Malay, it is by no means uncommon to see them touch the ground. The hair has various names assigned to it, according to the part on which it appears,—beard, whiskers, mustachios, eyebrows, eyelashes, &c. In many animals it is long and straight; in others crisped, when it is called wool. If stiff, it is termed a bristle; if inflexible, a spine. It is entirely insensible, and, excepting in the bulbous portion, is not liable to disease. Dr. Bostock affirms, that under certain circumstances hairs are subject to a species of inflammation, when vessels may be detected, at least in some of them, and they become acutely sensitive. Their sensibility under any known circumstances may be doubted. They appear to be anorganic, except at the root; and, like the cuticle, resist putrefaction for a length of time. The parts that do not receive vessels are nourished by transudation from those that do. Bichat and Gaultier were of the opinion of Dr. Bostock;—misled, apparently, by erroneous reports concerning plica polonica; but Baron Larrey2 has satisfactorily shown that plica is confined to the bulbs : the hairs them- selves continue devoid of sensibility. It is difficult to assign a plausible use for the hair. That of the head has already engaged attention; but the hair, which appears on certain parts at the age of puberty and not till then, and that on the chin and upper lip of the male sex only, set our ingenuity at defiance. In this respect, the hair is not unique. Many physiologists regard certain parts, which exist in one animal, apparently without function, but which answer useful purposes in another, to be vestiges indicating the harmony that reigns through nature's works. The generally useless nipple and mamma of one sex might be looked upon in this light; but 1 Traite de Physiologie Medicale et Philosophique, torn. iii. p. 42, Paris, 1832. a Memoires de Chirurgie Militaire, t. iii. 108, Paris, 1812. VOL. I.—9 130 SENSE OF TOUCH. the tufts of hair on various parts cannot, in any way, be assimilated to the hairy coating that envelopes the bodies of animals ; and is, in them, manifestly intended as a protection against cold. There is another class of bodies connected with the skin, and ana- logous in nature to the last described,—the Fig. 46. nails. These serve a useful purpose in touch, and consequently require notice here. In the system of De Blainville, they constitute a subdivision of the hairs, which he dis- tinguishes into simple and compound,— simple, when each bulb is separated, and has a distinct hair;—compound, when seve- ral pileous bulbs are agglomerated, so that the different hairs, as they are formed, are cemented together to constitute a solid body of greater or less size,—nail, scale, horn, „ . , , „,. t, , r &c. In man, the nail alone exists ; the chief Section of the Skin on the end of . > . . , the Finger. and obvious use ot which is to support the The cuticle and nail, n, detached pulp of the finger, whilst it is exercising from the cutis and matrix, m. touch. Animals are provided with horns, beaks, hoofs, nails, spurs, scales, &c. All these, like the hair, grow from roots; and are considered to be analogous in their physical and vital properties. Meckel, and De Blainville, Bonn, Walther, Lavagna, and others, are of opinion, that the teeth are of the same class; and that they belong, originally, to the skin of the mouth. The nails, near their origin, are seen, under the microscope, to con- sist of primary cells, almost identical with those of the epidermis; these gradually dry into scales; and the growth of the nail appears to be effected by the constant generation of cells at its root and under sur- face; and as successive layers are pushed forward, each cell becomes larger, flatter, and drier, and more firmly fixed than those around it.1 The chemical composition of the epidermis and the nails is similar to that of the hair: yet according to Mulder,2 there are material differ- ences in their properties;—the latter, being almost insoluble in strong acetic acid, in which the other two are readily soluble: hence—he infers— the composition of hair and of horn and whalebone must differ materi- ally; and, that, accordingly, Scherer's conclusion, that they are all identical is incorrect. The following are the results of the analysis of each of these bodies. Epidermis. Horn. Whalebone. Hair. c. 50.28 51.03 51.86 50.65 H. 6.76 6.80 6.87 6.36 N. 17.21 16.24 15.70 17.14 0. 25.01 22.51 21.97 20.85 s. 0.74 3.42 3.60 5.00 For physiological purposes, the above description is sufficient. A few 1 Henle, edit, cit., i. 289, Paris, 1843. 3 The Chemistry of Vegetable and Animal Physiology, translated by Fromberg, p. 527. Edinb. and London, 1849. MUCOUS MEMBRANES. 131 words will be necessary regarding the mucous membranes, which resem- ble the skin so much in their properties, as to be, with propriety, termed dermoid. If we trace the skin into the various outlets, we find, that a continuous, soft, velvety membrane—epithelium—exists through their whole extent; and, if the channel has two outlets, as in the alimentary canal, this membrane, at each outlet, commingles with the skin; and appears to differ but slightly,from it. So much, indeed, do they seem to form part of the same organ, that physiologists have described the absorption, that takes place from the intestinal mucous membrane, as external. They cannot, however, in the higher order of animals, be considered completely identical; nor is the same membrane alike in its whole extent. They have all been referred to two great surfaces;—the gastro-pulmonary—comprising the membranes of the outer surface of the eye, ductus ad nasum, nose, mouth, and respiratory and digestive passages; and the genito-urinary—which line the whole of the genital and urinary apparatuses. In addition to these, a membrane of similar character lines the meatus auditorius externus, and the excretory ducts of the mammae. The analogy between the skin and mucous membranes is farther shown by the fact, that if we invert the polypus, the mucous membrane gradually assumes the characters of skin; and the same circumstance is observed in habitual descents of the rectum and uterus. In the mucous membranes—especially at their extremities, which appear to be alone concerned in the sense of touch—the same super- position of strata is generally considered to exist as in the skin—viz., epidermis or epithelium, rete mucosum, corpus papillare, and cutis vera. They have, likewise, similar follicles, called mucous; but nothing Separated Epithelium Cells from Pavement-Epithelium of the Mucous mucous membrane of mouth. Membrane of the smaller bronchial tubes. 6. With nuclei, c. And nucleoli. a. Nuclei with double nucleoli. analogous to the hairs; unless we regard the teeth to be so, in corre- spondence with the views of Meckel, De Blainville, and others. The attention of anatomists has been closely directed to the ultimate structure of the mucous system. In the mucous tissues two structures have been separately described, especially by Mr. Bowman,1 who has thrown much light on the subject. These are the basement membrane— as he terms it—and the epithelium. The former is a simple, homoge- neous expansion, transparent, colourless, and of extreme tenuity, situate ' Cyclopaedia of Anat. and Physiology, pt.xxiii. p. 486, April, 1842. Fig. 47. 132 SENSE OF TOUCH. on its parenchymal surface, and giving it shape and strength. This serves as a foundation on which the epithelium rests. It may frequently be demonstrated with very little trouble in the tubuli of the glands, especially of the kidney, which are but very slightly adherent, by their external surface, to the surrounding tissue. M. Flourens1 considers that every mucous membrane is composed of three laminae or layers,—the derma, epidermis, and corpus mucosum situate between the derma and epidermis. The corpus mucosum of mucous membranes is continuous at all the outlets of the body, and is identical with the second epidermis; differing, therefore, from the corpus mucosum of the skin, a term which—as elsewhere remarked—he thinks ought to be abolished. Histological examination exhibits the epithelium to consist of cells, which are termed epithelial, and have various shapes. The two chief are tesselated or pavement epithelium, and cylinder or conical epithe- lium. Epithelium is not, however, confined to mucous membranes, but, of late years, has been found to exist elsewhere; it is always in contact with fluids, and of a soft, pliant cha- Pig- 48. racter. Tesselated epithelium covers the serous and synovial membranes, the lining membrane of the blood-vessels, and the mucous membranes, except where cylinder epithelium exists. It is spread over the mouth, pharynx and oesophagus, conjunctiva, vagina, and entrance of the female urethra. The cells composing it are usually po- lygonal; and are well seen in the marginal figure. Cylinder epithelium is found in the intestinal canal, beyond the cardiac orifice, in the larger ducts of the salivary glands, in the ductus com- munis choledochus, prostate, Cowper's glands, vesiculae seminales, vas deferens, tubuli uriniferi, and urethra of the male; and lines the urinary passages of the female from the orifice of the urethra to the beginning of the tubuli uriniferi of the kidneys. In all these situations, it is continuous with tesselated Tesselated Epithelium. Extremity of one of the tu- buli uriniferi, from the kidney of an adult; showing its tes- selated epithelium. — Magni- fied 250 diameters. (Wagner.) Fig. 49. Scales of Tesselated Epithelium. (After Henle.) a. Section of epithelium of conjunctiva with some scales loosened. The more deeply seated scales from the human conjunctiva. B. Scales from surface of cheek. epithelium, which lines the more delicate ducts of the various glands. The cells have the form of long cylinders or truncated cones, arranged side by side, the apices attached to the mucous membrane or to flat • Op. cit., p. 80. PHYSIOLOGY OF TOUCH. 133 Fig. 50. Diagram of the Structure of an Involuted Mucous Membrane, showing the continuation of its elements in the follicles and villi. f, F. Two follicles, b. Basement membrane, c. Submucous tissue, e. Epithelium, v. Vascular layer, n. Nerve, v. Villus, covered with epithelium, v'. Villus, whose epithelium has been shed. epithelial cells lying upon it; the base being free. Each cell, nearly midway between the base and apex, encloses a flat nucleus with nucleoli. Fig. 51. Cylinders of Intestinal Epithelium. (After Henle.) a. From the cardiac region of the human stomach, b. From jejunum, c. Cylinders seen when looking on their free extremities. D. Ditto, as seen in a transverse section of a villus. Epithelium is sometimes furnished with cilia, or is said to be ciliated. The nature and uses of these cilia, as well as the different varieties of mucous membrane, will be described hereafter. 2. PHYSIOLOGY OF TACT AND TOUCH. In describing the physiology of the sense of touch, it will be conve- nient to revert to the distinction already made between the sense when passively and actively exerted ; or between tact, and touch. The mode, 587736370240 134 SENSE OF TOUCH. however, in which the impression is made is in each case alike, and equally simple. It is merely necessary, that the substance, which causes it, should be brought in contact with what may be termed the physical part of the organ—the cuticle; the ^nervous part is seated in the corpus papillare, for if the nerves proceeding to this layer of the skin be cut, the sense is destroyed. In the exercise of _ touch, each of the layers seems to have its appropriate office: the corium, the inner- most layer, the base on which the others rest, offers the necessary re- sistance, when bodies are applied to the surface; the rete mucosum is unconcerned in the function : the erectile tissue, on which the papillae are grouped, probably aids them in their appreciation of bodies; and the epidermis modifies the tactile impression which might become too intense, or be painful, did this anorganic envelope not exist. The de- gree of perfection of the sense is greatly influenced by the state of the cuticle. Where thin—as upon the lips, glans penis, clitoris, &c— the sense is very acute; where thick and hard, it is obtuse; and where removed—as by blistering—the contact of bodies gives pain, but does not occasion the appropriate impression of touch. Professors Weber1 and Valentin2 have shown that the tactile power of the skin is not proportionate to its sensibility. The mammae, for ex- ample, are easily tickled, and susceptible of great pain when irritated; yet they are moderately endowed with the sense of touch. The differ- ent parts of the skin, too, vary in their tactile power. The left hand, in most persons, is more sensible to temperature than the right, proba- bly owing to the epidermis being thinner from less use. Weber made various experiments for the purpose of determining the relative sensi- bility of different portions of the skin, by touching the surface with the legs of a pair of compasses, the points of which were inserted into pieces of cork. The person's eyes being closed at the time, the legs were brought together so as to be separated by different distances. The following are some of the results of his experiments. Lines. Lines Point of middle finger 1 3 Mucous membrane of gums 9 Point of tongue ... i Lower part of forehead - 10 Palmar surface of third finger i Lower part of occiput 12 Red surface of lips 2 Back of hand 14 Palmar surface of middle finger - 2 Neck, under lower jaw - 15 Dorsal surface of third finger 3 Vertex 15 Tip of the nose ... 3 Skin over patella 16 Dorsum and edge of tongue 4 Skin over sacrum 18 Part of Jips covered by skin Palm of hand 4 18 18 5 Dorsum of foot - Skin of cheek 5 Skin over sternum 20 Extremity of great toe 5 Skin beneath occiput 24 Hard palate 6 Skin over spine, in back 30 Dorsal surface of fore finger 7 Middle of the arm 30 Dorsum of hand - 8 -------------thigh 30 Weber found, that the distance between the legs of the compasses 22ste 1 See art. Tastsinn und das Gemeingefuhl, in Wagner's Handworterbuch der Physiolcne, ste Lieferung. s. 539. Braunschweig, 1849. His earlier experiments are detailed and confirmed by Dr. Allen Thomson, in Edinb. Med. and Surg. Journal, for July 1833. a Lehrbuch der Physiologie des Menschen, ii. 565. Braunschweig, 1844- and Grundriss der Physiologie, s. 331. Braunschweig, 1846. APPRECIATION OF TEMPERATURE. 135 seemed to be greater, although it was really less, when they were placed upon more sensitive parts. It has been supposed, that some of the recorded instances of great resistance to heat have been caused by unusual thickness, and com- pactness of cuticle, together with a certain degree of insensibility of the skin. The latter may be an important element in the explanation ; but some of the feats, executed by persons of the character alluded to, could hardly have been influenced by the former, as the resistance seemed almost equally great in the delicately organized mucous mem- branes. A Madame Girandelli,—who was exhibited in Great Britain many years ago,—was in the habit of drawing a box with a dozen lighted candles along her arm, putting her naked foot upon melted lead, and of dropping melted sealing-wax upon her tongue, and im- pressing it with a seal, without appearing to experience uneasiness; and several years ago (1832), a man of the name of Chabert excited in this country the surprise which followed his exhibitions in London a year or two previously, and gave him the appellation of the " Fire King." In addition to the experiments performed by Madame Giran- delli, Chabert swallowed forty grains of phosphorus ; washed his fingers in melted lead ; and drank boiling Florence oil with perfect impunity. For the phosphorus he professed to take an antidote, and doubtless did so. It is probable, also, that agents were used by him to deaden the painful impressions ordinarily produced by hot bodies applied to the surface. A solution of borax or alum spread upon the skin is said to exert a powerful effect of the kind; but, in addition to the use of such agents, there must be a degree of insensibility of the corpus papillare; otherwise it is difficult to understand why those hot substances did not painfully inflame the surface. We see, daily, striking differences in individuals in the degree of sensibility of the mucous membrane of the mouth and gullet, and are frequently surprised at the facility with which certain persons swallow fluids of a temperature that would excite the most painful sensations in others. In this, habit has unquestionably much to do. In the mucous membranes, tact is effected in the same way as in the Bkin. The layers, of which it is constituted, participate in like man- ner; but the sense is more exercised at the extremities of the mem- brane than internally. The food, received into the mouth, is felt there; but after it has passed into the gullet it excites hardly any tac- tile impression; and it is not until it has reached the lower part of the membrane, in the shape of excrement, that its presence is again indi- cated by this sense. Pathologically, we have some striking instances of this difference in different parts of the mucous membrane. If an irritation exists within the intestinal canal, the only indication we may have of it is itching of the nose, or at one extremity of the membrane. In like manner, a cal- culus in the bladder is indicated by itching of the glans penis; and a similar exemplification is offered during the passage of a gall-stone through the ductus communis choledochus. On its first entrance, the pain experienced is of the most violent character; this, after a time subsides,—as soon, indeed, as the calculus has got fairly into the canal. 136 SENSE OF TOUCH. One of the great purposes of the sense of tact is to enable us to judge of the temperature of bodies. This office it executes alone. No other sense participates in it. It requires no previous exercise; is felt equally by the infant and the adult, and requires only the proper de- velopment of its organs. The relative temperature of bodies is accu- rately designated by the instrument called the thermometer; but very inaccurately by our own sensations; and the reason of this inaccuracy is sufficiently intelligible. In both cases, the effect is produced by the disengagement of a subtile fluid, called caloric or the matter of heat, which pervades all bodies, and is contained in them to a greater or less extent. This caloric is constantly passing and repassing between bodies, either by radiation or by conduction, until there is an equilibrium of caloric and all have the same temperature as indicated by the ther- mometer. Hence, objects in the same apartment will exhibit, cseteris paribus, a like temperature by this test. From this law, however, the animal body must be excepted. The power which it possesses of gene- rating its own heat, and of counteracting the external influences of temperature, preserves it constantly at the same point. Although, however, all objects may exhibit the same temperature, in the same apartment, when the thermometer is applied to them; the sensations communicated by them may be very different. Hence the difficulty, which the uninstructed have in believing, that they are actually of identical temperature;—that a hearth-stone, for instance, is of the same degree of heat as the carpet in the same chamber. The cause of the different sensations experienced in the two cases is, that the hearth- stone is a much better conductor of the matter of heat than the carpet. The consequence is, that caloric is more rapidly abstracted by it from the part of the body which comes in contact with it, and the stone appears to be the colder of the two. For the same reason, when these two substances are raised in temperature above that of the human body, the hearth-stone will appear the hotter of the two ; because, it conducts caloric and communicates it more rapidly to the body than the carpet. When the temperature of the surrounding air is higher than 98°, we receive caloric from the atmosphere, and experience the sensation of heat. The human body is capable of being penetrated by the caloric of substances exterior to it, precisely like those substances themselves; but, within certain limits, it possesses the faculty of consuming the heat, and retaining the same temperature. When the temperature of the atmosphere is only as high as our own—an elevation which it not un- frequently attains in many parts of the United States—we still expe- rience the sensation of unusual warmth ; yet no caloric is communicated to us. The cause of this feeling is, that we are accustomed to live in a medium of a less elevated temperature, and consequently to give off caloric habitually to the atmosphere. Lastly, in an atmosphere of a temperature much lower than that of the body, heat is incessantly abstracted from us; and, if rapidly, we have the sensation of cold. From registers, kept by the illustrious founder of the University of Virginia, Mr. Jefferson, at his residence at Monticello,1 lat. 37° 58', long. 78° 40', it appears that the mean 1 Virginia Literary Museum, p. 36, Charlottesville, 1830. APPRECIATION OF TEMPERATURE. 137 temperature of that part of Virginia, is about 55|° or 56°; and that the thermometer varies from 5J° in the coldest month, to 94° in the warmest. Now, the temperature of the human body being 98°, it fol- lows, that heat must be incessantly parting from us, and that we ought, therefore, to experience constantly a sensation of cold; and this we should unquestionably do, were we not protected by clothing, and aided by artificial temperature during the colder seasons. Yet, accustomed as the body is to give off caloric, there is a temperature, in which, clothed as we are, we do not feel cold, although we may be disengaging heat to some extent. This temperature may perhaps be fixed somewhere between 70° and 80° in the climate of the middle portions of the United States. So much, however, are our sensations in this respect dependent upon the temperature which has previously existed, that the comfortable point varies at different seasons. If the thermometer, for instance, has ranged as high as 98°, and has maintained this elevation for a few days, a depression of 15° or 20° will be accompanied by feelings of discom- fort; whilst a sudden elevation from 30° to 75° may occasion an op- pressive feeling of heat. In northern Siberia, M. von Wrangel1 found, that only a few degrees of frost was currently denominated "warm weather;" and that after having been accustomed to the winter tempe- rature of that climate, it seemed to him, that 10° of cold, 22° below the freezing point of Fahrenheit, was a mild temperature. During the voyages, made by Captain Parry and others to discover a northwest passage, it was found, that after having lived for some days in a tempe- rature of 15° or 20° below 0, it felt comfortable when the thermometer rose to zero. These are the great sources of the deceptive nature of our sensations as to warmth and cold which enable us to judge merely of the com- parative conditions of the present and the past; and hence it is, that a deep cellar appears warm in winter and cold in summer. At a certain distance below the surface, the temperature of the earth indicates the medium heat of the climate; yet, although this may be stationary, our sensations on descending to it in winter and summer would be by no means the same. If two men were to meet on the middle of the South American Andes,—the one having descended, and the other ascended, —their sensations would be very different. The one, who had descended, coming from a colder to a warmer atmosphere, would experience warmth; whilst the other, who had ascended, would feel correspondently cool. An experiment, often performed in the chemical lecture-room, exhibits the same physiological fact. If, after having held one hand in iced, and the other in warm water, we plunge both into water of a medium heat, it will seem warm to the one hand, and cold to the other. But our sensations are not guided solely by bodies surrounding us. They are often greatly dependent, especially in disease, on the state of the animal economy itself. If the power, which the system possesses of forming heat, be morbidly depressed—or if, in consequence of old age, or of previous sickness, calorification does not go on regularly and energetically, a temperature of the air, which to the vigorous is agree- 1 Reise des kaiserlich Russischen Flotten Lieutenants F. v. Wrangel, langs der Nordkuste von Siberien, u. s. w. Berlin, 1839, translated in Harper's Family Library. 138 SENSE OF TOUCH. able, may produce an unpleasant impression of cold. Under opposite circumstances, a feeling of heat exists. In regard to the mode in which the temperature of bodies is appre- ciated, there are peculiarities, which would favour the idea of the sense of heat being distinct from that of tact or touch. Professor Weber, for example, found that the left hand is more sensitive than the right, although the sense of touch is more acute in the latter ; and that if the two hands, at the time of like temperature, be plunged into separate basins of water, the one in which the left hand is, will appear to be the warmer, even although its temperature may be somewhat lower than that of the other. It would seem, too, from Weber's experiments, that in regard to sensations of heat and cold, a weaker impression made upon a large surface appears more powerful than a stronger made upon a small surface; and, accordingly, to judge of nice shades of difference in the temperature of a fluid, the whole hand will enable a variation to be detected, that would be inappreciable to the finger. A difference of one-third of a degree it is affirmed, may be easily detected, when the same hand is placed successively in two vessels of water, or any other fluid.1 These and other phenomena of an analogous kind have led to the suggestion, that every nerve of sensation is composed of several nerves, each of which may have its special function; and that the nerves of touch comprise some which appreciate temperature, others, which perceive the resistance of bodies, and others which effect touch properly so called. In proof of this a recent writer urges that either of these faculties may be lost, without the other being so. Thus, when the arm has been "asleep," and sensibility is returning to it, the hand first perceives temperature, then the resistance of bodies, and it is not until some time afterwards that the faculty of touch, pro- perly so called, is exercised. In the lower extremities the contrary takes place; the sense of touch first returns; then a sensation of pricking is experienced, followed by the perception of temperature, and the power of appreciating resistance returns last. It may be added, that many cases are recorded, in which the sense of temperature has been lost, whilst the ordinary sense of tact remained; and, as remarked by Dr. Carpenter,2 it is an additional evidence in favour of the distinct- ness of nervous fibres to convey the impressions of temperature, that these are frequently affected,—a person being sensible of heat or of chilliness in some part of the body,—without any real alteration of its temperature, whilst there is no corresponding affection of the tactile sensations. By tact we are likewise capable of forming a judgment of many of the qualities of bodies,—such as their size, consistence, weight, distance, and motion. This faculty, however, is not possessed exclusively by the sense in question. We can judge of the size of bodies by the sio-ht; of distance, to a certain extent, by the ear, &c. To appreciate these cha- racters, it is necessary, that the sense should be used actively; that we should call into exercise the admirable instrument with which we are 1 E. H. Weber, Art. Tastsinn und das Gemeingefuhl in Wagner's Handworterbuch der Physiologie, 22ste Lieferung, s. 549. Braunschweig, 1849. a Principles of Physiology, 2d Amer. edit., p. 229. Philad., 1845. THE HAND THE GREAT ORGAN. 139 provided for that purpose; and in many of them we are greatly in- structed by the muscular sense. In treating of the external senses generally, it was remarked, that we are capable of judging, by their aid, of impressions made on us by portions of our own body. By the sense of touch we can derive infor- mation regarding its temperature, shape, consistence, &c. An opinion has, indeed, been advanced, that this sense is best adapted for proving our own existence, as every time that two portions of the body come in contact, two impressions are conveyed to the brain, whilst if we touch an extraneous body, there is but one. The tact of mucous membranes is extremely delicate. The great sensibility of the lips, tongue, tunica conjunctiva, Schneiderian mem- brane, lining membrane of the trachea and urethra, is familiar to all. Excessive pain is produced in them by the contact of extraneous bodies; yet, in many cases, they signally exemplify the effect of habit in blunt- ing sensation. The first introduction of a bougie into the urethra generally produces intense irritation; but after a few repetitions the sensation may become scarcely disagreeable. To appreciate accurately the shape and size of objects, it is neces- sary, that they should be embraced by a part of the body, which can examine their surfaces, and be applied to them in every direction. In man, the organ well fitted for this purpose is the hand. This is situate at the free extremity of a long and flexible member, which admits of its being moved in every direction, and renders it not only well adapted for the organ of touch, but for that of prehension. Man alone pos- sesses a true hand; for although other animals have organs of prehen- sion very similar to his, they are much less complete. Aristotle and Galen termed it the instrument of instruments, and its construction was considered worthy of forming the subject of one of the " Bridge- water Treatises" " On the Power, Wisdom, and Goodness of God, as manifested in the Creation,"—a task assigned to Sir Charles Bell. The chief superiority of the hand consists in the size and strength of the thumb, which stands out from the fingers, and can be brought in opposition to them, so as to enable us to grasp bodies, and to execute various mechanical processes under the guidance of the intellect. So important was the thumb esteemed by Albinus,1 that he called it a lesser hand to assist the larger—"manus parva majori adjutrix." In addition to the advantages referred to, the hand is furnished with a highly sensible integument. The papillae are largely developed, especially at the ex- Fi8- 52- tremities of the fingers, where they are ranged in concentric circles, and rest upon a spongy tissue, by many considered to be erectile, and serving as a cushion, and are well supplied with capillary vessels. (See Figs. 33 and 52.) At the posterior extremity of the fingers, are the nails, which support the pulps of the fingers behind; and render the contact with _ ° i i j- . -,. , mi • i Capillary Net-work at margin external bodies more immediate. This happy iips. 6 ' De Sceleto, p. 465. 140 SENSE OF TOUCH. organization of the soft parts of the hand alone concerns the sense of touch directly. The other advantages, which it possesses, relate to the power of applying it under the guidance of volition. Of the mode in which touch is effected it is not necessary to treat. Being nothing more than tact, exerted by an appropriate instrument, the physiology of the two must be identical. Metaphysicians have differed widely regarding the services that ought to be attributed to the touch. Some have greatly exaggerated them, considering it the sense par excellence, the first of the senses. It is an ancient notion to ascribe the superiority of man over animals and his pre-eminence in the universe—his intelligence, in short—to the hand. Anaxagoras asserted, and Helvetius1 revived the idea, "that man is the wisest of animals because he possesses hands." The notion has been embraced, and expanded by Condillac,2 Buffon,3 and many modern phy- siologists and metaphysicians. Buffon assigned so much importance to the touch, that he believed the cause why one person has more intel- lect than another is his having made a more prompt and repeated use of his hands from early infancy. Hence, he recommended, that infants should use them freely from the moment of birth. Other metaphysi- cians have considered the hand the source of mechanical capabilities; but the same answer applies to all these views. It can only be re- garded as an instrument by which information of particular kinds is conveyed to the brain; and by which other functions are executed, under the direction of the will. The idiot often has the sense more delicate than the man of genius or than the best mechanician, whilst the most ingenious artists have by no means the most delicate touch. We have, indeed, some striking cases to show, that the hand is not en- titled to this extravagant commendation. Not many years ago, a Miss Biffin was exhibited in London, who was totally devoid of upper and lower extremities; yet she was unusually intelligent and ingenious. It was surprising to observe the facility with which she hem-stitched; turning the needle with the greatest rapidity in her mouth, and insert- ing it by means of the teeth. She painted miniatures faithfully, and beautifully;—holding the pencil between her head and neck. All her motions were, in fact, confined to the tongue and lips, and to the muscles of the neck. M. Magendie4 alludes to a similar case. He says, that there was, in Paris, at the time he wrote, a young artist, who had no signs of arm, forearm, or hand, and whose feet had one toe less than usual, —the second; yet his intelligence was in no respect inferior to that of boys of his age; and he even gave indications of distinguished ability. He sketched and painted with his feet. Not many years ago, a Miss Honeywell, born without arms, travelled about this country. She had acquired so much dexterity in the use of the scissors, as to be able, by holding them in her mouth, to cut likenesses, watch-papers, flowers, &c. She also wrote, drew, and executed all kinds of needlework with the utmost ease and despatch. How fatal are such authentic examples to the views of Helvetius and others! 1 De 1'Homme, &c, torn. i. * Traite des Sensations, P. i. 3 Histoire Naturelle, torn. vi. 4 Precis Elementaire, 2de edit., i. 154 Paris 1825. THE GEOMETRICAL SENSE. 141 But, it has been said, that touch is the least subject to error of all the senses: it is the regulating—the geometrical sense. In part only is this accurate. It certainly possesses the advantage of allowing the organ of sense to be brought into immediate contact with the body that excites the impression; whilst, in the case of olfaction, the organ receives the impression of an emanation from the body; and, in vision and audition, only the vibration of an intervening medium. Yet some of the errors into which touch falls are as grievous as those that happen to the other senses. How inaccurate is its appreciation of the temperature of bodies! We have attempted to show, that it affords merely relative knowledge,—the same substance appearing hot or cold to us, according to the temperature of the substance previously touched. Nay, infalli- bility so little exists, that we have the same sensation communicated by a body that rapidly abstracts caloric from us, as by one that rapidly supplies it. By touching frozen mercury, which requires a temperature of —40° of Fahrenheit to be congealed, we experience the sensation of a burn. Again, if we cross the fingers and touch a rounded body—a marble, for instance—with two of the pulps at the same time; instead of experiencing the sensation of one body, we feel as if there were two,— an illusion produced by the lateral portions of fingers being brought in apposition, which are naturally in a different situation, and at a distance from each other; and, as these two parts habitually receive distinct impressions when separated, they continue to do so when ap- plied to opposite sides of the rounded body. It has been asserted, that the touch is the great corrector of the errors into which the other senses fall. But let us inquire, whether, in this respect, it possesses any decided superiority over them. For this purpose, the distinction of the sensory functions into immediate and mediate has been adopted. Each sense has its immediate function, which it possesses exclusively; and for which, no other can be substituted. The touch instructs us regarding resistance; the taste appreciates savours; the smell, odours; audition, sound; and vision, colours. These are the immediate functions of the senses, each of which can be accomplished by its own organs, but by no other. As concerns the immediate func- tions of the senses, therefore, the touch can afford no correction. Its predominance, as regards the mediate functions of the senses, is like- wise exaggerated. The mediate functions are those that furnish im- pressions to the mind; and by aid of which it acquires its notions of bodies. The essential difference between these two sets of functions is, that the mediate can be effected by several senses at once, and may be regarded as belonging to the cerebrum. Vision, olfaction, and audition participate in enabling us to judge of distances, as well as touch; the sight instructs us regarding shape, &c. It has been affirmed by meta- physicians, that touch is necessary to several of the senses to give them their full power, and that we could form no notion of the size, shape, and distance of bodies, unless instructed by this sense. The remarks already made have proved the inaccuracy of this opinion. The farther examination of it will be resumed under Vision. The senses are, in truth, of mutual assistance. If the touch falls into error, as in the 142 SENSE OF TOUCH. case of inaccurate appreciation of temperature, the sight, aided by appropriate instruments, dispels it. If the crossed fingers convey to the brain the sensation of two rounded bodies, when one only exists, the sight apprises us of the error; and if the sight and touch united impress us with a belief in the identity of two liquids, the smell or the taste will often detect the erroneous inference. But, it has been said by some, touch is the only sense that gives us any notion of the existence of bodies. M. Destutt-Tracy1 has satis- factorily opposed this, by showing that such notion is a work of the mind, in acquiring which the touch does not assist more immediately than any other sense. "The tactile sensations," he observes, "have not of themselves any prerogative essential to their nature, which dis- tinguishes them from others. If a body affects the nerves beneath the skin of my hand, or if it produces certain vibrations in those distributed on the membranes of my palate, nose, eye, or ear, it is a pure impres- sion which I receive ; a simple affection which I experience ; and there seems to be no reason for believing that one is more instinctive than another; that one is more adapted than another for enabling me to judge that it proceeds from a body exterior to me. Why should the simple sensation of a puncture, burn, titillation, or pressure, give me more knowledge of the cause, than that of a colour, sound, or internal pain? There is no reason for believing it." There are, indeed, nu- merous classes of bodies, regarding whose existence the touch affords us no information, but which are detected by the other senses. On the whole, then, we must conclude, that the senses mutually aid each other in the execution of certain of their functions ; that each has its province, which cannot be invaded by others; and that too much preponderance has been ascribed to the touch by metaphysicians and physiologists. Ministering, however, as it does, so largely to the mind, it has been properly ranked with vision and audition as an intellectual sense.2 By education, the sense of touch is capable of acquiring extraordinary acuteness. To this circumstance must be ascribed the surprising feats we occasionally meet with in the blind. For all their reading and writing they are, indeed, indebted to this sense. Sauhderson—who lost his eyesight in the second year of his life, and was Professor of Mathe- matics at Cambridge, England—could discern false from genuine medals; and had a most extensive acquaintance with numismatics.3 As an instance of the correct notions, which may be conveyed to the mind of the forms and surfaces of a great variety of objects, and of the sufficiency of these notions for accurate comparison, Dr. Carpenter4 mentions the case of a blind friend, who has acquired a very complete knowledge of conchology, both recent and fossil; and who is not only able to recognize every one of the numerous specimens in his own cabi- net, but to mention the nearest alliances of a shell previously unknown 1 Elemens dldeologie, lere Partie p. 114, 2de edit. Paris, 1804. a Gall, Sur les Fonctions du Cerveau, i. 99, Paris, 1825. 3 Abercrombie's Inquiries concerning the Intellectual Powers; Amer edit n 55 New York, 1832. '' ^ ' 4 Principles of Human Physiology, 4th American edit., § 525, Philad., 1850. IN ANIMALS. 143 to him, when he has thoroughly examined it by the touch. Baczko, referred to by Rudolphi,1 who describes his own case, could discriminate between samples of woollen cloth of equal quality but of different colours. The black appeared to him among the roughest and hardest: to this succeeded dark blue and dark brown, which he could not, how- ever, distinguish from each other. The colours of cotton and silk stuffs he was unable to discriminate ; and he properly enough doubts the case of a Count Lynar, blind, who, it was said, was capable of judging of the colour of a horse by the feel. The only means the blind can possess of discriminating colours must be through the physical differences of surface, which render it capable of reflecting one ray or combination of rays, whilst it absorbs the rest; and if these differences were insuf- ficient to enable Baczko to detect the differences between cotton and silk fabrics, it is not probable, that the sleek surface of the horse would admit of such discrimination. In animals the organ of touch varies. The monkey's resembles that of man. In other quadrupeds, it is seated in the lips, snout, or pro- boscis. In molluscous animals, the tentacula; and in insects, the antennae or feelers, are organs of touch, possessing, in some, very great sensi- bility. Bats appear to have this to an unusual degree. Spallanzani observed them, even after their eyes had been destroyed and the ears and nostrils closed, flying through intricate passages, without striking the walls, and dexterously avoiding cords and lines placed in the way. The membrane of the wings is, in the opinion of Cuvier and many others,2 the organ that receives an impression produced by a change in the resistance of the air. M. Jurine concludes, that neither hearing nor smell is the channel through which they obtain perception of the presence and situation of surrounding bodies. He ascribes this extraordinary faculty to the great sensibility of the skin of the upper jaw, mouth, and external ear, which are furnished with large nerves; whilst Sir Anthony Carlisle attributes it to the extreme delicacy of hearing possessed by the animal ;3 a view which is confirmed by ex- periments instituted by the author's friend, Professor J. K. Mitchell, of Philadelphia. Certain experiments by Mr. Broughton,4 sanction the idea that this may be, in part, dependent upon their whiskers. These, which are found on the upper lip of feline and other animals, are plentifully supplied with nerves, which seem to proceed from the second branch of the fifth pair, and are lost in the substance of the hairs. In an experiment, made by Mr. Broughton on a kitten, he found that whilst the whiskers were entire, it was capable of threading its way, blindfold, from a labyrinth in which it was designedly placed; but it was totally unable to do so when the whiskers were cut off. It struck its head repeatedly against the sides ; ran against all the corners; and tumbled over steps placed in the way, instead of avoiding them, as it did prior to the removal of the whiskers. From facts like these Mr. Broughton drew the conclusion, that cer- * Grundriss der Physiologie, 2er Band, s. 85, Berlin, 1823. 2 Carpenter, Human Physiology, p. 253, Lond., 1842. 3 See Roget's Animal and Vegetable Physiology, ii. 399, Amer. edit., Philad., 1836. * London Medical and Physical Journal, for 1823. 144 SENSE OF TOUCH. tain animals are supplied with whiskers for the purpose of enabling them to steer clear of opposing bodies in the dark. SENSE OE TASTE OR GUSTATION. The sense of taste teaches us the quality of bodies called sapidity. It is more nearly allied to touch in its mechanism than any other of the senses, as it requires the immediate contact of the body with the organ of taste, and the organ is, at the same time, capable of receiving tactile impressions distinct from those of taste. Of this we have a striking example, if we touch various portions of the tongue with the point of a needle. We find two distinct perceptions occasioned. _ In some parts the sensation of a pointed body without savour; and in others, a me- tallic taste is experienced. Pathological cases, too, exhibit, that the sense of taste may be lost, whilst general sensibility remains,—and con- versely. The organ of gustation is not, therefore, restricted to that sense, but participates in touch.' Yet so distinct are those functions, that touch can, in no wise, supply the place of its fellow sense, in de- tecting the sapidity of bodies. This last is the immediate instruction afforded by gustation. 1. ANATOMY OF THE ORGANS OF TASTE. The chief organ of taste is the tongue, or rather the mucous mem- brane covering the upper surface, and sides of that organ. The lips, inner surface of the cheeks, palate, and fauces, participate in the func- tion, especially when particular savours are concerned. M.'Magendie1 includes the oesophagus and stomach; but we know not on what grounds: his subsequent remarks, indeed, controvert the idea. The lingual branch of the fifth pair is, according to him, incontestably the nerve ' of taste; and, as this nerve is distributed to the mouth, we can under- stand, why gustation should be effected there; but not how it can be accomplished in the oesophagus and stomach. The tongue consists almost entirely of muscles, which give it great mobility, and enable it to fulfil the various functions assigned to it; for it is not only an organ of taste, but of mastication, deglutition, and articulation. The muscles being under the influence of volition, enable the sense to be executed passively or actively. As regards gustation, the mucous membrane is the portion immedi- ately concerned. This is formed, like the mucous membranes in gene- ral, of the different layers already described. The corpus papillare requires farther notice. If the surface of the tongue be examined, it will be found to consist of myriads of fine papillae or villi, that give the organ a velvety appearance. These papillae are, doubtless, like those of the skin, formed of the final ramifications of nerves, and of the ra- dicles of exhalant and absorbent vessels, united by means of a spongy erectile tissue. Great confusion exists among anatomists in their de- scriptions of the papillae of the tongue. Those certainly concerned in the sense of taste may, however, be included in two divisions:—1st, the conical or pyramidal,—the finest sort by some called filiform; and 2dly, * Precis de Physiol., i. 139. ORGANS OF TASTE. 145 as well as of the Palatine Arch. 1, 1. Posterior lateral half arches, with the palato- pharyngei muscles and tonsils. 2. Epiglottic carti- lage, seen from before. 3, 3. Ligament and mucous the fungiform. The former are Fig. 53. broader at the base than at the top; and are seen over the whole surface of the tongue, from the tip to the root. The latter, which are larger at the top than the base, and resemble the mushroom, — whence their name, — are spread about, here and there, on the surface of the organ. These must be distinguished from a third set, the papillae capitatae or circumvallatse, which are situate near the base of the tongue in two V shaped lines at the base of the organ. They are circu- lar elevations from g-gth to T*2th of an inch wide, each with a cen- tral depression, and surrounded Front View of the Upper Surface of the Tongue, by a circular fissure, at the out side of which, again, is a slight ly elevated ring; the central ele vifirrn anrl rbo v'no- Vioinrr fnvmcrl membrane, extending from the root of the tongue to vation ana tne ring oeing ioimea the base of the epiglottic cartilage. 4. one of the Of Close Set Simple Papillae. The Pou?hes on.the s,ide of the posterior fraenum, in which pi rr # food sometimes lodges. 5. Foramen caecum. 6. Pa- epithellUm Of the tongue IS Of the pillae conica;, seu maximae. 7. The white point at the , i , j • , vi .i r end of the line, and all like it, are the papillae fungi- teSSelated Variety, flke that Ot formes. 8. Side of the tongue, and ruga; transversa; the epidermis. Over the fun- ?o4ubeimis- 9" PapiHse fillformes- 10- Point of the giform papillae, it forms a thin- ner layer than elsewhere; so that they stand out more prominently than the rest. That which covers the conical papillae, according to Messrs. Todd and Bowman,1 has a singu- lar arrangement; being extreme- Fig. 54. ly dense and thick, and project- ing from their sides and tops in the form of long, stiff, hair- like processes; many of which bear a strong resemblance in structure to hairs; and some ac- tually contain hair tubes. All the nerves that pass to the parts whose office it is to ap- preciate savours, must be con- sidered to belong to the gusta- tory apparatus. These are the View of a Papilla of the smallest class, magnified • c • -n i i_ 25 diameters. interior maxillary; several bran- i nf +Vi fll • + '^'le "00PS °f blood-vessels are here shown, each CneS 01 tne Superior, UlamentS loop containing usually only one vessel. from the spheno-palatine and naso-palatine ganglions ; the lingual branch of the fifth pair, com- ' The Physiological Anat. and Physiology of Man, i. 439, Lond., 1848, or Amer. edit., p. 382. VOL. I.—10 146 SENSE OF TASTE. Fig. 55. Vertical Section of one of the Gustatory Papillae of the largest class, showing its conical form, its sides, and the fissure between the different Papilla?. The length of some of the divided blood-vessels, a tranvserse section of others, and the vessels which rise up from the surface like loops or meshes, are also shown. Fig. 56. The Hypoglossal; Lingual branch of fifth pair; Glosso-Pha- ryngeal and deep-seated Nerves of the Neck. 1. The hypoglossal nerve. 2. Branches communicating with the fnstatory nerve. 3. A branch to the origin of the hvoid muscles . The descendens noni nerve. 5. The loop formed wi'th the branch from the cervical nerves. 6. Muscular branches to the depressor muscles of the larynx. 7. A filament from the second cervical nerve, and 8r a filament from the third cervical, uniting to form the communicating branch with the loop from the descendens noni 9. The auricular nerve.- 10. The inferior dental nerve. 11. Its mylo-hyoidean branch. 12. The gustatory nerve. 13. Thechorda- tympani passing to the gustatory nerve. 14. The chorda-tympani leaving the gustatory nerve to join the sub-maxilkiry ganglion 15. The sub-maxillary ganglion. 16. Filaments of communication with the lingual nerve. 17. The glosso-pharyngeal nerve. 18. The pneumogastric or par vagum nerve. 19. The three upper cer- vical nerves. 20. The four inferior cervical nerves. 21. The first dorsal nerve. 22, 23. The brachial plexus. 24, 25. The phrenic nerve. 26. The carotid artery. 27. The internal jugular vein. monly called the gus- tatory nerve; the whole of the ninth pair or hypoglossal; and the glosso-pharyngeal. To which of these must be assigned the function of gustation, we shall inquire presently. Like the skin and mucous membranes in general, that of the tongue and mouth con- tains, in its substance, numerous mucous fol- licles, which secrete a fluid that lubricates the organ, and keeps it in a condition adapted for the accomplishment of its functions. Some of these are placed very conspicuously in the mucous membrane of the tongue. They are the papillae capitatse of some anatomists—er- roneously named, as they are not formed like papillae, and exe- cute a very different office. They are mu- cous follicles, and ought to be so called. The fluids, exhaled from the mucous mem- brane of the mouth, and the secretion of the different salivary glands, likewise aid in gustation; but they are more concerned in mas- tication and insaliva- tion, and will require notice under another head. 147 Papilla? of the Tongue. a. Vertical section near the middle of the dorsal surface of the tongue: a, a. Fungiform papillae. b. Filiform papilla?, with their hair-like processes, c. Similar ones deprived of their epithelium.— Magnified 2 diameters. B. Filiform compound papilla? : a. Artery, v. Vein. c. Capillary loops of the secondary papilla?. 6. Line of basement membrane, d. Secondary papilla?, deprived of e, e, the epithelium. /. Hair-like processes of epithelium capping the simple papilla?.—Magnified 25 diameters, g. Separated nucleated particles of epithelium, magnified 300 diameters. 1, 2. Hairs found on the surface of the tongue. 3, 4, 5. Ends of hair-like epithelial processes, show- ing varieties in the imbricated arrangement of the particles, but in all a coalescence of the particles towards the point. 5. Incloses a soft hair.—Magnified 160 diameters. 2. SAVOURS. Before proceeding to explain the physiology of gustation, it may be ne- cessary to inquire briefly into the nature of bodies as connected with their sapidity; or, in other words, into savours, which are the cause of sapidity. The ancients were of opinion, that the cause of sapidity is a peculiar principle, which, according to its combination with the constituents of bodies, gives rise to various savours. This notion has been long aban- doned ; and chiefly, because we observe no general or common charac- ters amongst sapid bodies, which ought to be were they pervaded by the same principle; and because bodies may be deprived of their sapidity by subjecting them to appropriate processes. Many of our culinary processes have been instituted for this purpose: the infusion of tea is indebted for all its attractions to the power we possess of separating, by boiling water, the savoury from the insipid portions of the plant. A sapid principle must, therefore, be esteemed an integrant molecule of a body; not the same in all cases, but as heterogeneous in its nature as the impressions made upon the organ of taste. 148 SENSE OF TASTE. When the notion was once entertained, that a sapid principle is an integrant molecule, sapidity was attempted to be explained by its shape. It was said, for instance, that if the savour be sweet, the molecule must be round; if sharp, angular; and so forth. Sugar was said to possess a spherical,—acids, a pointed, or angular molecule. ^ We know, however, that substances which resemble each other in the primitive shape of their crystal, impress the organ of taste differently; and that solution, which must destroy most—if not all—the influence from shape, induces no change in the savour. Others have referred sapidity to a kind of chemical action between the molecules, and the nervous fluid. This view has been suggested by the fact, that, as a general principle, sapid, like chemical bodies, act only when in a state of solution; that the same savours usually belong to bodies possessed of similar chemical properties, as is exemplified by the sulphates and nitrates; and that, in the action of acids on the tongue and mouth, we witness a state of whiteness and constriction, indicative of a first degree of combination. All these circumstances, however, admit of another explanation. There are unquestionably many sub- stances, which do combine chemically,—not with a nervous fluid, of whose existence we know nothing,—but with the mucus of the mouth; and the sapidity resulting from such combination is appreciated by the nerves of taste; but there are many bodies, which are eminently sapid, and yet afford us instances of very feeble powers of chemical com- bination ; nay, in numerous cases, we have not the least evidence that such powers exist. Vegetable infusions or solutions are strong ex- amples of the kind,—of which syrup may be taken as the most fami- liar. The effect of solution is easily intelligible; the particles of the sapid body are in this way separated, and come successively into contact with the gustatory organ ; but there is some reason to believe, that solution is not always requisite to give sapidity. Metals have generally a peculiar taste, which has been denominated metallic; and this, even if the surface be carefully rubbed, so as to free it from oxide, which is more or less soluble. Birds, too, whose organs of taste are as dry as the corn they select from a mass of equally arid substances, are probably able to appreciate savours. The taste produced by touch- ing the wires of a galvanic pile with the tongue has been offered as another instance of sapidity exhibited by dry bodies. This is, more probably, the effect of the chemical action on the fluids covering the mucous membrane of the tongue, which always follows such contact. Such chemical change must, however, be confined to these fluids; and, when once produced, the nerve of taste is impressed by the savour de- veloped in the same manner as it is in cases of morbid alterations of the secretion of the mucous membrane. In both cases, a body pos- sessing considerable and peculiar sapidity may fail to impress the nerves altogether, or may do so inaccurately. The notion of any che- mical combination with the nervous fluid must of course be discarded, as there is not the slightest evidence in favour of the hypothesis; yet the epithet chemical was once applied to this sense on the strength of it; in opposition to the senses of touch, vision, and audition, which were called mechanical, and supposed to be produced by vibrations of the nerves of those senses. CLASSIFICATION OF SAVOURS. U9 The savours, met with in the three kingdoms of nature, are innu- merable. Each body has its own, by which it is distinguished: few instances occur in which any two can be said to be identical. This is the great source of difficulty, when we attempt to throw them into classes, as has been done by physiologists. Of these classifications, the one by Linnaeus1 is best known: it will elucidate the unsatisfactory character of the whole. He divides sapid bodies into sicca, aquosa, viscosa, salsa, acida, styptica, dulcia, pinguia, amara, acria, and nau- seosa. He gives also examples of mixed savours, acido-acria, acido- amara, amaro-acria, amaro-acerba, amaro-dulcia, dulci-styptica, dulci- acida, dulci-acria, and acri-viscida; and remarks, that the majority are antitheses to each other, two and two,—as dulcia and acria ; pin- guia and styptica; viscosa and salsa; and aquosa and sicca. Boer- haave2 again divides them into* primary and compound; the former including the sour, sweet, bitter, saline, acrid, alkaline, vinous, spiritu- ous, aromatic, and acerb;—the latter resulting from the union of cer- tain primary savours. There is no accordance amongst physiologists as to those that should be esteemed primary, and those secondary and compound ; although the division appears to be admissible. The acerb, for example—which is considered primary by Boerhaave—is by others, with more propriety, classed among secondary or compound, and be- lieved to consist of a combination of the acrid and acid. We under- stand, however, sufficiently well the character of the acid, acrid, bitter, acerb, sweet, &c.; but when, in common language, we have to depict other savours, we are frequently compelled to take some well-known substance as a standard of comparison. According to M. Adelon,3 the only distinction we can make amongst them is,—into the agreeable and disagreeable. Yet of the unsatisfac- tory nature of this classification he himself adduces numerous proofs. It can only, of course, be applicable to one animal species, often even to an individual only; and often again only to such individual when in a given condition. Some animals feed upon substances, that are not only disagreeable but noxious to others. The most poisonous plants have an insect which devours them greedily and with impunity: the southern planter is well aware, that this is the case with his to- bacco, unless the operation of worming be performed in due season. The old adage, that " one man's meat is another man's poison," is metaphorically accurate. Each individual has, by organization or asso- ciation, dislikes to particular articles of food, or shades of difference in his appreciation of tastes, which may be esteemed peculiar; and, in certain cases, these peculiarities are signal and surprising. Of the strange differences, in this respect, that occur in the same individual under different circumstances, we have a forcible instance in the pregnant female, who often ardently desires substances, that were previously perhaps repugnant to her, or, at all events, not relished. The sense, too, in certain diseases—especially of a sexual character, or such as are connected with the state of the sexual functions—becomes strangely depraved, so that substances, which can in no way be ranked 1 Amoenit. Academ., ii. 335. a Pra?lect. Academ., torn. iv. 3 Physiologie de l'Homme, seconde edit, i. 301, Paris, 1829. 150 PHYSIOLOGY OF TASTE. as eatables are greedily sought after. A young lady was under the care of the author, whose bonne bouche was slate pencils. In other cases, we find chalk, brickdust, ashes, dirt, &c, preferred. Habit, too, has considerable effect in our decisions regarding the agreeable. The Roman liquamen or garum, the most celebrated sauce of antiquity, was prepared from half putrid intestines of fish; and one of the varieties of the Onoi Xi\ amDer> and yet they had scented for 14,600 days a stratum of air at least a foot in thickness. But how much larger must these molecules be than those of light— provided we regard it as consisting of molecules—seeing that glass is capable of arresting the former, but suffers the other to penetrate it in every direction. Nor need we be so much surprised at the excessive diffusibility of odorous particles, when we call to mind the facts on record in regard to the transmission through the air of fine particles of sand. Gene- rally, according to Mr. Darwin,5 the atmosphere of the Cape Verd Islands is hazy; and this is caused by the falling of impalpably fine dust, which was found to have slightly injured the astronomical instru- ments. The morning before they anchored at Porto Praya, he collected a little packet of this brown-coloured fine dust, which appeared to have 1 Voyages and Travels in India. London, 1809. a Embassy to the courts of Muscat and Siam, &c, p. 154. Philad., 1838. » Medical Examiner, March, 1846, p. 159. * Elementa Physiolog., torn. v. lib. xiv. sect. 2, p. 157. Lausann., 17C9. 6 Journal of Researches into the Natural History and Geology of the countries visited during the voyage of H. M. S. Beagle round the world, &c. Amer. edit, i. 5. New York, 1846. 164 SENSE OF SMELL. been filtered from the wind by the gauze of the vane at the mast-head. Sir Charles Lyell also gave him four packets of dust which fell on a vessel a few hundred miles northward of these islands. Professor Ehrenberg found, that this dust consisted, in great part, of infusoria with silicious shields, and of the silicious tissue of plants. In five little packets which Mr. Darwin sent him, he ascertained no less than sixty-seven different organic forms! The infusoria, with the exception of two ma- rine species, were all inhabitants of fresh water. Mr. Darwin has found no less than fifteen different accounts of dust having fallen on vessels when far out in the Atlantic. From the direc- tion of the wind whenever it has fallen, and from its having always been observed during those months when the harmattan is known to raise clouds of dust high in the atmosphere, it is pretty certain that it must proceed from Africa. It is, however—as Mr. Darwin remarks— a singular fact, that, although Professor Ehrenberg is acquainted with many species of infusoria peculiar to Africa, he found none of these in the dust sent him; but, on the other hand, discovered in it two species which he knew as living only in South America. " The dust," says Mr. Darwin—" falls in such quantity as to dirty everything on board, and to hurt people's eyes; vessels even have run on shore owing to the obscurity of the atmosphere. It has often fallen on ships when seve- ral hundred, and even more than a thousand miles from the coast of Africa, and at points sixteen hundred miles distant in a north and south direction. In some dust, which was collected on a vessel three hundred miles from the land, I was much surprised to find particles of stone above the thousandth of an inch square, mixed with finer matter. After this fact, one need not be surprised at the diffusion of the far lighter and smaller sporules of cryptogamic plants." The air is not the only vehicle for odours. It has been seen, that they adhere to solid bodies ; and that, in many cases, they can be separated by aqueous or spirituous distillation. The art of the per- fumer consists in fixing and preserving them in the most agreeable and convenient vehicles. Yet, it was at one time strenuously denied, that they could be conducted through water; and, as a natural consequence of this, that fishes could smell. M. Dumeril, for example, maintained, that odours, being essentially of a volatile or gaseous nature, cannot exist in fluids;—and, moreover, that fishes have no proper olfactory organ;—that the part which is commonly considered in them to be such is the organ of taste. This opinion is entertained by few. We have seen that odours can be retained in fluids, and not many natural- ists of the present day will be hardy enough to deny that fishes have an organ or sense of smell. At all events, few anglers, who have used the oil of rhodium, or other attractive bait, will be disposed to give up the results of their experience without stronger grounds than any that have been assigned by the advocates of that view of the subject. Be- sides, air is contained in considerable quantity in water, so that odor- ous substances might reach the olfactory organs through it. When it was determined, that odours consist in special molecules given off from bodies, it was attempted to explain their action on the pituitary membrane in the same manner as that of savours on the ODOURS. 165 membrane of the tongue. It was conceived that the shape of the mole- cules of a pungent odour is pointed, that of an agreeable one, round. Others, again, were of opinion, that olfaction is owing to some chemi- cal union between the odorous molecule and the nervous fluid, or be- tween it and the nasal mucus. None, however, have attempted to specify the precise chemical composition that renders a body odorous. The sensations do not present the most favourable occasions for exhi- biting chemical agency ; and, in this particular sense, it is probably no farther concerned than in the sense of touch; and not so much as in that of taste. It is sufficient for the odorous particle—animal, vege- table, or mineral—to come in contact with the olfactory nerves, in order that the odour shall be appreciated; and we may, in vain, look for chemical action in many of those animal and vegetable perfumes,#- as musk, amber, camphor, vanilla, &c.—which astonish us by their intensity and diffusibility. The same remarks, that were made on the classification of savours, are applicable to that of odours. They are not less numerous and varied; and each substance, as a general rule, has its own, by which it is distinguished. Numerous attempts have been made to group them; but all have been unsatisfactory. The classification proposed by Lin- naeus,1 was—into Odores aromatici, those of the flowers of the pink, bay leaves, &c.; 0. fragrantes, those of the lily, jessamine, &c.; 0. ambrosiaci, those of amber, musk, &c.; 0. alliacei, those of garlic, assafoetida, &c.; 0. hircini, (like that of the goat,) those of the Orchis hircina, Chenopodium vulvaria, kc.; 0. tetri, repulsive or virous,— those of the greater part of the family solanese; and lastly, 0. nau- seosi, those of the flowers of the veratrum, &c. A simple glance at this division will exhibit its glaring imperfections. No two persons could agree to which of any two of the cognate classes a particular odour should be referred. None of the other classifications, that have been proposed, are more satisfactory. M. Fourcroy divided them into extractive or mucous, fugaceous oily, volatile oily, aromatic and acid, and hydrosulphureous;—and Lorry into camphorated, narcotic, ethe- real, volatile acid, and alkaline. The distinction into animal, vegetable, and mineral, is not more commendable. Musk is the product of an animal of the ruminant family; but the odour is not confined to that animal. It is contained in the civet; in the flesh of the crocodile; and in the musk-rat. Haller asserts, that his own perspiration smelt of it. It is met with, likewise, in the vegetable kingdom;—in Erodium mos- chatum, in the seeds of Abelmoschus, the flowers of Rosa moschata, and Adoxa moschatellina, and in some of the varieties of the melon and pear; and, what is perhaps more surprising, in mineral sub- Btances ;—as in certain preparations of gold; and in some earths of which tea-pots are made in China and Japan. The odour of garlic, again, is found not only in that vegetable, but in assafoetida, in arsenic, when thrown upon hot coals; and in Bufo pluvialis, a species of toad. In by far the majority of cases, we can only designate an odour by 1 Aincenitat. Academic. Erlang., 1787, 1790. 166 SENSE OF SMELL. comparing it with that of some well-known substance; hence the epi- thets musky, alliaceous, spermatic, &c. M. Adelon asserts, that the sole classification which can be adopted, is into the agreeable and dis- agreeable. But even the miserably imperfect division proposed by Haller1 is better than this: he made three classes—Odores suaveo- lentes, 0. medii, and 0. fostores. The truth is, that all the objections made to the division of savours into agreeable and disagreeable, are equally applicable to odours. Assafoetida, we have seen, was employed by the ancients as a condiment; and, although with us it has the name devil's dung, it is by many of the Asiatics, called food of the gods. We find, too, certain animals that are almost enchanted by particular odours. The cat, for example, if catmint—Nepeta cataria,—or the r&t of valerian— Valeriana officinalis—be placed in its way. Again, odours, generally thought agreeable, are to some persons intolerable. To many, as to Professor Miiller,2 mignonette has but an herb-like odour. The smell of the callicanthus is to most individuals pleasant; but exceedingly disagreeable to some; and, according to Arnold,3 whilst the flower of Iris Persica was pronounced to possess an agreeable odour by forty-one out of fifty-four persons, four considered it to have little scent; by eight it was declared to be devoid of odour, and by one to be disagreeable. These differences, like those in the appreciation of savours by animals, must be referred to minute and inappreciable differences of organization. Odours have been considered to be possessed of medicinal and even of poisonous properties. Some individuals, whose peculiarity of con- stitution renders them very liable to the action of ipecacuanha or jalap, experience the emetic effects of the former, or the cathartic qualities of the latter, by merely smelling them for a short time; and the majority of individuals, by pounding jalap or rhubarb find themselves sooner or later more or less affected. By smelling strong alcohol for a considerable time, intoxication may be induced, as not unfrequently happens to the spirit-taster, who is young in his vocation. It has also been asserted, that the constant application of this sense to the discrimination of teas in the English East India Company's ware- houses has laid the foundation for numerous head affections; but the report originated in prejudice, or in accidental coincidences, and has not been found to be accurate. In all cases in which we see medicinal or poisonous effects actually produced by substances inhaled through the nostrils, we cannot attempt to explain them by the simple impression made by the odorous parti- cles on the olfactory nerves. They must be accounted for by minute particles of the medicinal or poisonous substance being diffused in the atmosphere, and coming in contact with the mucous membrane, through which they are absorbed, and in this manner enter the circulation. Odours have, likewise, been considered to possess nutritive proper- ties; and this, chiefly, perhaps, from the effect known to be produced 1 Elementa Physiolog., torn. v. lib. xiv. p. 162, Lausann., 1769. 2 Elements of Physiology, by Baly, p. 1317. Lond., 1839. 3 Physiology, ii. 561, cited by Dr. Carpenter, art. Smell, in Cyclopaedia of Anatomy and Physiology, pt. xxxvi. p. 703. London, June, 1849. PHYSIOLOGY OF OLFACTION. 167 by savoury smells upon the appetite. It is not probable, that absorp- tion can occur to a sufficient extent to account for the apparent satia- tion. The fact can only be explained by the effect upon the nervous system, which influences the appetite materially, as we see in the effect of various mental emotions. The first impact of a nauseous odour, or even the view of a disgusting object, frequently converts the keenest appetite into loathing. Yet, anciently, it was believed, that life might be sustained for a time, by simply smelling nutritious substances. Democritus is said to have lived three days on the vapour of hot bread; and Bacon refers to a man who supported an abstinence of several days by inhaling the odour of a mixture of aromatic and alli- aceous herbs. Two hundred years ago these notions were entertained to a great extent; and they suggested the viaticum for travellers pro- ceeding.to the moon, according to the plan proposed by Dr. John Wil- kins, Bishop of Chester.1 "If we must needs feed upon something," he remarks, "why may not smells nourish us?" Plutarch and Pliny, and divers other ancients, tell us of a nation in India that lived only upon pleasing odours; and it is the common opinion of physicians that these do strangely both strengthen and repair the spirits." Fuller,2 a learned cotemporary of the bishop, affords an amusing instance of litigation, arising from this supposed nourishing character of odours. A poor man being very hungry, stayed so long in a cook's shop who was dish- ing up the meat, that his stomach was satisfied with the smell thereof. The choleric cook demanded of him pay for his breakfast; the poor man denied having had any; and the controversy was referred to the deci- sion of the next man that should pass by, who chanced to be the most notorious idiot in the whole city: he, on the relation of the matter, determined that the poor man's money should be put betwixt two empty dishes, and that the cook should be recompensed with the jingling of the money, as the man had been satisfied by the smell of the cook's meat. It need scarcely be said, that if the vapour from alimentary sub- stances be capable, in any manner, of serving the purposes of nutrition, it can only be by passing into the blood-vessels of the lungs. 3. PHYSIOLOGY OF OLFACTION. In order that the sense of smell may be duly exercised, it is neces- sary that the emanation from an odorous body shall not only impinge upon the pituitary membrane, but that it shall do so with some degree of force. It must, in other words, be drawn in with the inspired air. Perrault3 and Lower4 found, that by making an opening into the tra- chea of animals, and preventing the inspired air from passing through the nasal fossae, smell was not effected; and that dogs, which were the subjects of the experiment, readily ate food they had previously re- 1 The Discovery of a New World, or a Discourse tending to prove, that 'tis possible there may be another Habitable World in the Moon, with a Discourse concerning the possibility of a passage thither. Lond., 1638. 4 Holy State, London, 1640. 3 Ess. de Phys., iii. 29. * Needham, de Format. Foetus, p. 165; and Haller, edit, cit, v. 173. 168 SENSE OF SMELL. fused. These experiments were repeated by Professor Chaussier, and with like results.1 They explain why we use effort to draw in air loaded with an odour that is agreeable to us; and, on the contrary, arrest the respiration, or make it pass entirely through the mouth when odours are disagreeable. Still they are occasionally so diffusible and expansible, that they reach, notwithstanding, the olfactory mem- brane; and we are compelled to shut them off by calling in the aid of the upper extremity. The air being the ordinary medium for the con- veyance of odorous molecules, we can understand why the organ of smell should form a part of the air passages. The use of the nose is to direct the air, charged with odours, to- wards the upper part of the nasal fossae. Its situation is well adapted for the reception of emanations from bodies beneath it, and its appro- priate muscles allow the nostrils to be more or less expanded or con- tracted. These uses assigned to the nose are demonstrated by the fact, that they, whose noses are deformed—especially the flat-nosed— or whose nostrils are directed forwards, instead of downwards, have commonly the sense feebly developed. The loss of the nose, too, either by accident or disease, has been found to destroy the sense com- pletely; and by no means the least advantage of the rhinoplastic ope- ration is the enjoyment afforded by the improvement of this sense. M. Be'clard affirms, that an artificial nose, formed of paper or other appropriate materials, is sufficient to restore it, so long as the substi- tute is attached.2 It is proper to remark, however, that in a case which fell under the author's observation, although the nose had been lost by syphilis, the smell persisted; and two cases of a similar kind occurred to M. P. H. Berard.3 The mode in which olfaction is effected appears to be as follows:— The inspired air, loaded with odorous particles, traverses the nasal fossae; and, in its passage, comes in contact with the pituitary mem- brane, through the medium of the nasal mucus. The use of this mucus seems to be, not only to keep the organ properly lubricated, but to arrest the particles as they pass,—not by any chemical attraction, but in a mechanical manner. The olfactory nerves being distributed on the membrane, receive the impression of the molecules, and, in this manner, sensation is accomplished. The use of the different spongy or turbinated bones would seem to be to enlarge the olfactory surface. According to some, however, they form channels to direct the air towards the openings of the sinuses. The sinuses, themselves, afford subjects for physiological discussion. By many they are considered to add to the extent of olfactory surface: by others, to furnish the nasal mucus. No hesitation would be felt in pronouncing both the spongy bones and sinuses to be useful in olfaction, were it not that the olfactory nerves or first pair have not been traced on the pituitary membrane covering the middle and inferior spongy bones, or on that lining the different sinuses;—that the sinuses are 1 Adelon, op. cit, i. 335. 2 Magendie, Precis Elementaire, 2de edit, i. 136, Paris, 1825. 3 Art. Olfaction, Diet de Medecine, 2de edit, xxii. 9, Paris, 1S40. PHYSIOLOGY OF OLFACTION. 169 wanting in the infant, which, notwithstanding, appreciates odours;— that they exist only in the mammalia;—and that experiments would seem to show, that the upper part of the olfactory organ is more parti- cularly destined for the function, and that the sinuses, which, as well as the membrane covering the middle and lower spongy bones, are supplied by filaments from the fifth pair of nerves, are not sensible to odours. Messrs. Todd and Bowman1—from the fact, that on the septum narium and turbinated bones bounding the direct passage from the nostrils to the throat, the lining membrane is rendered thick and spongy by the presence of ample and capacious submucous plexuses of both arteries and veins, of which the latter are by far the larger and more tortuous— surmise, and Dr. Carpenter2 thinks, with much probability, that the chief use of these may be to impart warmth to the air, before it enters the pro- per olfactive portion of the cavity; as well as to afford a copious supply of moisture, which may be exhaled by the abundant glandulae seated in the membrane. "The remarkable complexity of the lower turbinated bones in animals with active scent, without any ascertained distribution of the olfactory nerves upon them, has"—they remark—"given countenance to the supposition, that the fifth pair may possess some olfactory endowment, and seems not to have been explained by those who rejected that idea. If considered as accessory to the perfection of the sense in the way above alluded to, this striking arrangement will be found consistent with the view, which thus limits the power of smell to the first pair of nerves." That the upper part of the nasal fossae is the great seat of smell is proved by the facts referred to regarding the uses of the nose. Dessault mentions the case of a young female, who had a fistula in the frontal sinuses, and who could not perceive an odorous substance, when pre- sented at the orifice of the fistula, because there was no communication with the proper portion of the nasal fossae, although she was capable of breathing through the opening. M. Deschamps, the younger, relates the case of a man, who had a fistula of the frontal sinus, through which ether might be injected without its odour being appreciated, provided all communication had been previously cut off between the sinus and the upper part of the nasal fossae; but if this precaution had not been taken, the sense was more vivid, when the odours passed through the fistulous opening, than when they reached the organ by the ordinary channel. Again;—M. Richerand3 found that highly odoriferous injec- tions, thrown through a fistulous opening in the maxillary sinus or antrum of Highmore, produced no olfactory sensation whatever. All these facts would seem to lead to the belief, that the upper part of the nasal fossae, on which the first pair or olfactory nerves are distribu- ted, is the chief seat of olfaction, and that the inferior portions of these fossae, as well as the different sinuses communicating with them, are not primarily concerned in the function: but, doubtless, offer secondary advantages of no little importance. This conclusion, would, however, seem to admit, what is not by any means universally admitted, that the 1 Physiological Anatomy and Physiology of Man, ii. 3. 2 Art. Smell, Cyclop, of Anat. and Physiol., Pt. xxxvi. p. 694, Lond., June, 1 849. 3 Elemens de Physiologie, edit 13eme par Berard, p. 202, Bruxelles, 1837. 170 SENSE OF SMELL. olfactory is the sole or chief nerve of smell. Especially difficult is it to embrace this view, and not to believe that the spongy bones and sinuses, on which the fifth pair are distributed, are agents in perfecting the sense, when we find them so largely developed in animals that possess unusual delicacy of smell, as the dog and elephant. It has already been remarked, that the ancients believed the olfactory nerves to be canals for conveying away the pituita or phlegm from the brain. Diemerbroeck, also, maintained this view.1 At the early part of the last century, however, the olfactory was supposed to be the proper nerve of smell, and the opinion prevailed, with few dissentient voices, until within the last few years. Inspection of the origin and distribution of the nerve seems to indicate it as admirably adapted for special sensibility con- nected with smell. It is largely developed in animals in proportion to their acuteness of the sense, and is distributed on the very part of the pituitary membrane to which it is necessary to direct air, loaded with odorous emanations, in order that they may be appreciated. M. Ma- gendie2 has, however, endeavoured to show by experiment, that the sense of smell is in no wise, or little, dependent upon the olfactory nerve, but upon branches of the fifth pair. Prior to the institution of his experi- ments, he had observed with astonishment, that after he had removed the cerebral hemispheres, with the olfactory nerves of animals, they still preserved this sense. He had noticed, too, that it continued in lunatics, who had fallen into a state of stupor, and in whom the sub- stance of the brain appeared, on dissection, greatly disorganized. These facts induced him to expose the olfactory nerves on living animals, and to experiment upon them; and he found, in the first place, that the nerves were insensible to puncture, pressure, and the contact of the most odorous substances. He afterwards satisfied himself, that after their division the pituitary membrane not only preserved its general sensibi- lity, appreciated the contact of bodies, but also, strong odours, those of ammonia, acetic acid, oil of lavender, Dippel's oil, &c. On the other hand, having divided the fifth pair of nerves within the cranium, and left the olfactory nerves entire, he remarked, that the pituitary mem- brane had lost its general sensibility; was no longer sensible to contact of any kind; and had lost the power of appreciating odours. From these experiments, he considered himself justified in inferring, that the olfactory nerve does not preside over the general sensibility of the nose; that it has, at the most, a special sensibility as concerns odours; and that if the olfactory be the nerve of smell, it requires the influence of the fifth pair, in order that it may act. Lastly; he asks, may not the general and special sensibility be comprised in the same nerve in the sense of smell, as they are in that of taste;—in the fifth pair? These experiments are interesting; but they by no means establish, that the fifth pair is the olfactory nerve. The numerous facts, already mentioned, attract us irresistibly to the first pair or olfactory, as they have been exclusively called. It has been already remarked, that the fifth is concerned in all the facial senses; that it conveys to them general 1 Anatome Corporis Humani, lib. iii. cap. 8, Ultraject, 1672. 2 Precis Elementaire, 2de edit, i. 132. IMMEDIATE FUNCTION OF SMELL. 171 sensibility or feeling; and that some of them are unquestionably sup- plied with nerves of special sensibility;—the eye with the optic; and the ear with the auditory; but that neither the one nor the other can exert its special function, without the integrity of the fifth. The olfac- tory nerve is probably in this category,—is the nerve of special sensi- bility. It is true, that in the experiments of M. Magendie the animal appeared to be affected by odorous substances, after the division of the first pair; but a soured of fallacy existed here, in discriminating accu- rately between the general and special sensibility. Some of the sub- stances employed were better adapted for eliciting the former than the latter;—ammonia and acetic acid, for example. The immediate function of the sense of smell is to appreciate odours. In this it cannot be supplied by any other sense. The function is in- stinctive; requires no education; and is exerted as soon as the parts have attained the necessary degree of development. In many respects the sens'e is intimately connected with that of taste; and the impres- sions made upon each are frequently confounded. In the nutritive function, the smell serves as a kind of advanced guard or sentinel to the taste; and warns us of the disagreeable or agreeable nature of the aliment; but if a substance repugnant to the smell be agreeable to the taste, the smell soon loses its aversion, or at least becomes less disa- greeably impressed. The smell is not, however, in man so useful as a sentinel to the taste, as it is to animals: there are many bodies,—those containing prussic acid for example,—which are extremely pleasing by the odours they exhale, and yet are noxious to man. In the animal kingdom, this sense is greatly depended upon, and is rarely a fallacious guide. It enables animals to make the proper selection of the noxious from the innocent;—the alimentary from that which is devoid of nutri- ment ;—the agreeable from the disagreeable ; and the power appears to be instinctive or dependent upon inappreciable varieties of structure in the organs concerned in olfaction. As an intellectual sense, smell is not entitled to a higher rank than taste. Its mediate functions are very limited. It enables the chemist, mineralogist, and perfumer, to discriminate bodies from each other. We can, likewise, by it form a slight—but only a slight—idea regard- ing the distance and direction of bodies, owing to the greater intensity of odours near an odorous body, than at a distance from it. Under ordinary circumstances, the information of this kind derived by olfac- tion is inconsiderable; but in the blind; and in the savage, who is accustomed to exercise all his external senses more than the civilized, its sphere of utility and accuracy is largely augmented. Of this we shall have to speak presently. We find it, too, surprisingly developed in certain animals; in which it is considered, by the eloquent Buffon, as an eye that sees objects not only where they are, but where they have been,—as an organ of gustation, by which the animal tastes not only what it can touch and seize, but even what is remote, and cannot be attained; and he esteems it a universal organ of sensation, by which animals are most readily and most frequently impressed; by which they act and determine, and recognise whatever is in accordance with, or in 172 SENSE OF SMELL. opposition to, their nature. The hound amongst quadrupeds affords us a familiar example of the extreme delicacy of this sense. For hours after the passage of game, it is capable of detecting its traces,; and the bloodhound can be trained to indicate the human footsteps with unerr- ing certainty. Until of late years, it was almost universally believed, that many of the birds of prey possess an astonishingly acute sense of smell. Hum- boldt1 relates, that in Peru, Quito, and in the province of Popayan, when they are desirous of taking the gigantic condor— Vultur gryphus of Linnaeus—they kill a cow, or horse, and in a short time, the odour of the dead animal attracts those birds in numbers, and in places where they were scarcely known to exist. It is asserted, too, that vultures went from Asia to the field of battle at Pharsalia, a distance of several hundred miles, attracted thither by the smell of the killed!2 Pliny,3 however, exceeds almost all his contemporaries in his assertions on this matter. He affirms, that the vulture and the raven have the sense of smell so delicate, that they can foretell the death of a man three days beforehand, and in order not to lose their prey they arrive upon the spot the night before his dissolution! The turkey-buzzard of the United States is a bird of this class, and it is surprising to see how soon they collect from immense distances after an animal has died in the forests. The observations and experiments of the ornithologist Audubon4 would seem, however, to show that this bird possesses the sense of smell in a less degree than the carnivorous quadruped. He stuffed the skin of a deer with hay, and after the whole had become perfectly dry and hard, placed it in an open field on its back, and in the attitude of a dead animal. In the course of a few minutes a vul- ture was observed flying towards it, which alighted near, and began to attack it; tearing open the seams, and pulling out the hay; but finding that it could obtain nothing congenial to its taste, it took flight. It was found, too, that when animals in an advanced state of putridity were lightly covered over so as to prevent vultures from seeing them, they remained undisturbed and undiscovered, although the birds re- peatedly flew over them. In some other experiments it was found, that birds of prey were attracted by well-executed representations of dead animals painted on canvass and exposed in the fields,—and in others, that young vultures, enclosed in a cage, exhibited no tokens of their perceiving food, when it could not be seen by them, however near them it was brought. These results—which were obtained, also, by Dr. Bachman in the presence of a number of scientific gentlemen of Charleston, South Carolina—are strange, inasmuch as the olfactory apparatus of the turkey-buzzard, when examined by the comparative anatomist, exhibits great development, and admirable adaptation for acuteness of smell. They are confirmed, however, by more recent expe- riments on the condor by Mr. Charles Darwin,5 a distinguished natu- 1 Rec. de Zoolog. et d'Anat. Comp., 2de livr., p. 73. Paris, 1807. 1 Haller, edit, cit, torn. v. lib. xiv. p. 158. 3 Hist. Nat, lib. x. cap. 6, p. 230, Lugd. 1587. * Ornithological Biography, p. 33, Boston, 1835; Loudon's Mag. of Nat. Hist, vii. 167. s Journal of Researches into the Natural History and Geography of the countries visited during the voyage of H. M. S. Beagle round the World. Amer. edit, New York, 1846. IMPROVED BY EDUCATION. 173 ralist. He tied several condors by ropes in a long row at the bottom of a wall; and having folded up a piece of meat in white paper, he walked backwards and forwards carrying it in his hand at the distance of about three yards from them; but no notice whatever was taken of it. He then threw it on the ground within one yard of an old male bird, which looked at it for a moment with attention, but regarded it no more. With a stick he pushed it closer and closer, until at last the bird touched it with its beak: the paper was then instantly torn off with fury, and at the same moment every condor in the long row began struggling, and flapping its wings. "Under the same circumstances, it would have been quite impossible to have deceived a dog." As the organ of smell, in all animals that respire air, is situate at the entrance of the organs of respiration, it is probable that its seat, in insects, is in the mouth of the air tubes. This sense appears to guide them to the proper kinds of food, and to the execution of most of the few offices they perform during their transient existence. Occasionally, however, they are deceived by the resemblance between odours of sub- stances very different in other qualities. Certain plants, for example, emit a cadaverous odour similar to putrid flesh, by which the flesh-fly is attracted, and led to deposit its ova in places that can furnish no food to its future progeny. As regards the extent of the organ of smell, man is undoubtedly worse situate than most animals; and all things being, in other respects, equal, it may be fair to presume, that those, in which the olfactory membrane is most extensive, possess the sense of smell most acutely. It is curious, however, that certain animals, which have the sense of smell in the highest degree, feed on the most fetid substances. The dog, for instance, riots in putridity; and the birds of prey, to which reference has been made, but whose acuteness of smell, we have seen, has been contested, have similar enjoyment. The turkey-buzzard is so fetid and loathsome, that his captors are glad to loosen him from bond- age; and it is affirmed, that if his ordinary foetor be insufficient to produce his release, he affords an irresistible incentive, by ejecting the putrid contents of his stomach upon them I1 One inference may, perhaps, be drawn from this penchant of animals with exquisite olfactories for putrid substances;—that the taste of the epicure for game, kept until it has attained the requisite fumet, is not so unnatural as might at first sight appear. Like the senses already described, that of smell is to a certain extent under the influence of volition:—in other words, it can be exerted actively, and passively. Its active exercise—as when we smell any substance to enjoy its sweets, or test its odorous qualities—generally requires prehension, the proper direction of the head towards the object, and more or less contraction of certain muscles of the alae nasi. Doubt- less, here again, the papillae are capable of being erected under atten- tion, as in the senses of taste and touch. On the other hand, we can throw obstacles in the way of the reception of disagreeable odours; and, if necessary, prevent their ingress altogether, by compressing the nostrils with the upper extremity. * Wilson's American Ornithology, by Geo. Ord, Philad., 1803-1814. 174 SENSE OF HEARING. Lastly:—like the other senses, smell is capable of great improvement by education. The perfumer arrives, by habit, at an accurate discri- mination of the nicest shades of odours; and the chemist and the apothecary employ it to aid them in distinguishing bodies from each other; and in pointing out the changes that take place in them, under the influence of heat, light, moisture, &c. In this way, it becomes a useful chemical test. The effect of education is likewise shown, by the difference between a dog kept regularly accustomed to the chase, and one that has not been trained. For the same reason, in man, the sense is more exquisite in the savage than in the civilized state. In the latter, he can have recourse to a variety of means for discriminating the proper- ties of bodies; and hence has less occasion for acuteness of smell than in the former; whilst, again, in the latter state, numbers destroy the sense to procure pleasure. The use of snuff is one of the most common of these destructive influences. Of the acuteness of the sense of smell in the savage we have an example on the authority of Humboldt: he affirms, that the Peruvian Indians in the middle of the night can distinguish the different races by their smell,—whether they are European, American, Indian, or negro. To the same cause must be ascribed the delicacy of olfaction generally observed in the blind. The boy Mitchell,1 who was born blind and deaf, and whose case will have to be referred to hereafter, was able to distinguish the entrance of a stranger into the room by smell alone. A gentleman, blind from birth, from some unaccountable impression of dread or antipathy, could never endure the presence of a cat in the apartment. One day, in company, he suddenly leaped up ; got upon an elevated seat; and exclaimed, that a cat was in the room, begging them to remove it. It was in vain that the company, after careful inspection, assured him he was under an illusion. He persisted in his assertion and state of agitation; when, on opening the door of a small closet, it was found that a cat had been accidentally shut up in it. SENSE OF HEARING OR AUDITION. Audition makes known to us the peculiar vibrations of sonorous bodies, that constitute sounds. It differs from the senses which have already been described, in the fact, that contact is not required between the organ of sense and the sonorous body; or between it and any emanation from the body. It is, however, a variety of touch, but pro- duced by a medium acted upon by the vibratory body. 1. ANATOMY OF THE ORGAN OF HEARING. The auditory apparatus is a subject of intricate study to the young anatomist; and unfortunately when he has become acquainted with the numerous minute portions to which distinct and difficult appellations have been appropriated, he has, as in many other cases, attained a tedious detail of names, without having added to his stock of physio- 1 Wardrop's History of James Mitchell, Lond., 1813; and Dugald Stewart's Elements of the Philosophy of the Human Mind, iii. 401, 3d edit, Lond., 1808. ORGAN OF HEARING. 175 View of the Left Ear in its Natural State. 1, 2. Origin and termination of the helix. 3. Anthelix. 4. Antitragus. 5. Tragus. 6 Lobus of the external ear. 7. Points to the scapha, and is on the front and top of the pinna. 8. Concha. 9. Meatus auditorius externus. Fig. 64. logical information. Happily, it is not necessary for our purpose to go so minutely into the description of the organ of hear- ing. According to the plan hitherto pur- sued, allusion will be made to those portions only that concern the physiological in- quirer. In the ear, as well as in the eye, we have the distinction between the physical and nervous portions of the organ more clearly exhibited than in the skin, mouth, or nose. The nervous portion is situate deeply within the organ; and the parts between it and the exterior act physically—on so- norous vibrations, in the case of the ear; and on light, in that of the eye. The organs of the senses hitherto con- sidered are symmetrical. Those of audi- tion are two in number, distinct but har- monious, and situate at the sides of the head, in a part of the temporal bone, ge- nerally called, from its hardness, pars pe- trosa, and by the French and German anatomists regarded as a distinct bone, under similar appella- tions—Le Rocher, and F els en be in, ("rock- bone.") This bone is seated at the base of the skull, so that the internal parts of the auditory organ are deeply and securely lodged. For facility of de- scription, the ear may be divided into three portions:—1. Exter- nal ear or that exte- rior to the membrana tympani; 2. Middle ear—the space con- tained between the membrana tympani and internal ear; and 3. The internal ear in which the auditory nerve is distributed. 1. External Ear. This portion of the auditory apparatus is corn- General View of the External, Middle, and Internal Ear, as seen in a Prepared Section. (From Scarpa.) a. The auditory canal, b. The tympanum or middle ear. c. Eus- tachian tube, leading to the pharynx, d. Cochlea; and e. Semicir- cular canals and vestibule, seen on their exterior, as brought into view by dissecting away the surrounding petrous bone. The styloid process projects below; and the inner surface of the carotid canal is seen above the Eustachian tube. 176 SENSE OF HEARING. monly looked upon as an acoustic instrument, for collecting the so- norous rays or vibrations, and directing them, in a concentrated state, to the parts within. It is composed of the pavilion, and meatus audi- torius externus. The pavilion varies in size and position in different individuals. It is the fibro-cartilaginous, thin, expanded portion, which is an append- age, as it were, to the head. It is irregular on its anterior surface; presenting several eminences and depressions. The eminences are five in number; and have been called, by anatomists, helix, anthelix, tragus, antitragus, and lobe. The helix forms the rim of the pavilion: the tragus is the small nipple-like projection on the facial side of the meatus auditorius; the antitragus is the projection opposite to this,— forming the lower portion of the anthelix; and the lobule is the fatty, pendulous portion, to which ear-rings are attached. The depressions are three in number—the groove of the helix or cavitas innominata; the fossa navicularis or scapha; and the concha. The name of the first sufficiently indicates its situation; the second is nearer the meatus auditorius; and the third is the expanded portion, which joins the com- mencement of the meatus, and is bounded by the anthelix, tragus, and antitragus. The pavilion is supple and elastic ; and, beneath the skin are numerous sebaceous follicles, which are distinctly perceptible, and give the skin its polish, and probably a portion of its suppleness. On the different eminences, some muscular fibres are perceptible, which it is not necessary, for our purpose, to distinguish; for in man at least they are but vestiges—as the French term them—to indicate the uni- form plan that appears to have prevailed in the formation of verte- brated animals: if they have any office it must be unimportant. Nu- merous vascular and nervous ramifications are distributed on the pavilion. It is at- tached to the head by different ligaments, called—from their situation or attachments —zygomato-auricular or anterior-auricu- lar :—temporo-auricular or superior-au- ricular, and mastoido-auricular or posteri- or-auricular ; all of which terminate on the convex part of the concha. Three muscles, in animals at least, are attached to the ear to move the pavilion. These occupy the same position as the ligaments described; and have similar names. In man, they, again, are mere vestiges; but in many animals—as the horse—they are largely developed, and capable of moving Anterior View of the External Ear, the pavilion in various directions; and as well as of the Meatus Audito- j.i_ „ i. ■■ <■ rius, Labyrinth, &c. there are persons, who possess a degree of 1. The opening into the ear at the voluntary power over it. bottom of the concha. 2 Meatus au- The meatus auditorius externus extends ditonus externus or cartilaginous ca- „ . . ^ih n»o calciiuo nai. 3. Membrana tympani stretched from the inner extremitv of the concha to upon its ring. 4. Malleus. 5. Stapes. ,i V. x • -r , w" ,"" . 6. Labyrinth. the membrana tympani. In the adult, it ORGAN OF HEARING. 177 is about an inch long; narrower in its middle than extremities; longer inferiorly than superiorly, owing to the obliquity of the membrana tympani; and slightly curved upwards about its middle. The outer orifice is furnished with down or hairs—vibrissse—like the orifices of certain other canals. The meatus is osseous, for the space of half an inch, and penetrates the temporal bone. More externally, it is formed of fibro-cartilage,—a prolongation of that of the concha. It is lined by an extension of the skin, which becomes gradually thinner as it proceeds inwards, and is ultimately reflected over the outer surface of the mem- brana tympani. Beneath this skin, numerous sebaceous glands or folli- cles are situate, which secrete the bitter humour, called cerumen. This humour occasionally becomes inspissated; obstructs the canal; prevents sonorous vibrations from reaching the membrana tympani, and is thus the cause of deafness. Softening it, by means of warm water or oil, or soap and water dropped into the meatus, and removing it by means of the syringe, restores the hearing. The portion of the auditory apparatus arbitrarily termed the exter- ternal ear, is a complete cul-de-sac, formed by a prolongation of the common integument. There is no opening communicating with the next portion—the middle ear ;—the membrana tympani, with its der- moid envelopes, forming at once the medium of union and separation Fig-66- between the two. A knowledge of a b this fact would somewhat diminish the alarm in cases where insects or other extraneous bodies get into the meatus. The pain is excruciating, owing to the great general sensibi- lity of this portion of the auditory apparatus; but the chief dread en- tertained is, that the irritating sub- 1^ta™f^^lSn(Bf5d2fter r- h n poVp two layers of the lamina spiralis to be dis- Vjel mdll JJdmefe, umagon, and £ C n n e CK.B. tributed upon the membrane which invests It is the most intricate part of the organ the lamina. 7. Membranous portion of the „, . ,. r -, • o lamma spiralis, t. Loops formed by fiia- of bearing, and does not admit of easy ments of cochlear nerve. 9,9. Scala tym- j____:„x.*„„ Tt :. • i i i : pani of second turn of cochlea. io. io. description, it is a conoidal canal, spi- Scala vestibuli of second turn; the septum raUy convoluted, makino- tWO tumS UOOn between the two is the lamina spiralis. 11. . ■* . ' »*"^"0 un v im uo u^« Scala tympani of remaining half turn. 12. itself, and resting On a bonV nudeUS Or Remaining half turn of scala vestibuli; the .-i-i ' n j ?• t mi i i> i dome placed over this half turn is the cu- pillar, Called modiolus. The base 01 the pola. 13. Lamina of bone which forms •...s.lsvno *- ' of seven colours;— ..--■;;.>'' red, orange, yellow, ..••';.'.-•''' green, blue, indigo, .,.•-;'.'.••-'' and violet. Each of v,fy-"' these colours admits White of no farther decom- Prismatic Spectrum. position when again passed through the prism; and the whole lengthened image of the sun is called the pris- matic or solar spectrum. In this dispersion of the coloured rays, it will be observed that the red ray is the least turned from its course; and is hence said to be the least refrangible; whilst the violet is most so. Such is the spectrum, as depicted by Newton: since his time, it has, by some, been reduced to three colours,—red, yellow, and blue; as certain of the colours can be composed from others,—the green, for example, from the blue and yellow. Wollaston made it to consist of four; red, green, blue, and violet; Sir J. Herschel of four; red, yellow, blue, and violet: and, more recently, Sir David Brewster has restricted it to three; red, yellow, and blue. The causes which have led to these various divisions, it is not our province to explain. Each of the rays, of which the spectrum is composed, appears to have a different calorific and chemical action; but this also is a subject, that nowise concerns the function under consideration. The decomposition of light into its constituent rays enables us to explain the cause of the colour of different substances. When white light impinges upon a body, the body either absorbs all the rays that compose it; reflects all; or absorbs some, and reflects others. If it reflects the whole of the light to the eye, it is of a white colour; if it absorbs all, or reflects none, it is black; if it reflects only the red ray, and absorbs all the rest, it is red; and so of the other colours. The cause, why one body reflects one ray, or set of rays, and absorbs others, is unknown. It is conceived to be owing to the nature and particular arrangement of its molecules; which is probable. But we are still as much in the dark as ever. It is accounting for the ignotum per ignotius. Two other points require a brief notice, being intimately concerned in vision;—the aberration of sphericity, and aberration of refrangibility. It has been remarked, that rays of light—after passing through a con- vex lens, or medium whose surfaces are convex—converge, and are brought to a focus behind it. The whole of the rays do not, however, LIGHT. 213 D' meet in this focus. Those that are nearest the axis, R" F of the lens, Fig. 82, are refract- ed to a focus more Fis- 82- remote from the lens, _ _ / w, than those that fall T>/M. -.. B on the lens at a dis- /llfiy '"*'••.. tance from the axis. ~ /UHl-------l!^-___l__ -■■""'■ The rays R', R", and R."----------jgBjj|----~3^5SfH F R"', are brought to a k.'"-------------rlBBf/—---~~~^*' '""'-■' focus at F, whilst the rays R L, and W", xl» L' converge at the \L7 point I, much nearer Aberration of Sphericity. the lens. In like manner, rays which fall upon the lens intermediate between the rays R and R', will have their foci intermediate between I and F. This diver- sity of focal distances is called spherical aberration or aberration of sphericity: the distance I F is the longitudinal spherical aberration; and B A the lateral spherical aberration, of the lens. This aberration is the source of confusion in common lenses; and as it is dependent upon the shape of the lens, it has been obviated by forming these instru- ments of such degrees of curvature, that the rays, falling upon the centre or margins of the lens, may be refracted to the same focus. This is effectually accomplished by lenses, whose sections are ellipses or hyperbolas. In a common lens, the inconvenience is obviated by employing lenses of a small number of degrees, or by interposing an opaque body—called, by the opticians, a diaphragm—anterior to the lens, so that the rays of light can only impinge upon the central part, and consequently be refracted to the same focus. This diaphragm is present in all telescopes, and occupies the situation of the curves D and D', so as only to admit the rays R', R", and R'", to fall upon the lens. Such an apparatus, we shall find, exists in the human eye. Lastly,—it has been already observed, that the different rays, con- stituting the solar spectrum, are unequally refrangible,—the red being the least, the violet the most so; hence the cause of their dispersion in the spectrum. It follows from this fact, that, whenever light expe- riences refraction, there must be more or less dispersion of its consti- tuent rays; and the object, seen by the refracted ray, will appear coloured. This must, of course, occur more particularly near the margins of the lens, where the surfaces become less and less parallel until they meet. The inconvenience resulting from this dispersion is called the aberration of refrangibility or chromatic aberration, and it has been attempted to be obviated by glasses, which have been termed, in consequence, achromatic. These are made by combining transparent bodies of different dispersive powers, in such sort, that they may com- pensate each other; and thus the object be seen in its proper colours, notwithstanding the refraction. Dr. Blair found, for example, that by enclosing chloride of antimony, B E, between two convex lenses of crown glass, A D and C F, the parallel rays R R, and R were refracted to a single focus at P without the slightest trace of secondary colour. 2425 214 SENSE OF SIGHT. ABC DEF Aberration of Refrangibility. Fig- 83. Newton was of opinion, that the light, in travers- ing a refracting medium, always experiences a dis- persion of its rays, pro- portional to its refraction. > He therefore believed, that it would be impos- sible to fabricate an achromatic glass. This is one of the rare cases in which that illustrious philosopher erred. Since his time—and chiefly by the labours of Mr. Dollond—instruments have been formed on the prin- ciples above mentioned, so as to greatly diminish the inconveniences sustained from the use of common lenses; although they may still not be perfectly achromatic. The inconvenience is farther obviated by the diaphragm in telescopes, already referred to. As the dispersion is most experienced near the margin of the lens, it shuts off the rays, which would otherwise fall upon that portion, and diminishes the extent of aberration. The human eye is achromatic. It is obviously essential that it should be so; and this result is owing to a combination of causes. It is formed of media of different dispersive powers. Its lens is con- stituted of layers of different densities, and it is provided with a dia- phragm of singularly valuable construction. Such are the prominent points of the beautiful science of optics, that chiefly concern the physiologist as an introduction to vision. Others will have to be adverted to, as we consider the eye in action. 2. ANATOMY OF THE ORGAN OF VISION. The human eye is almost spherical, except for the prominence at its anterior and transparent part—the cornea. It has been compared to a telescope, and with much propriety; as many of the parts of that instrument have been added to exe- Fis- 84. cu^e special offices, which are admi- rably performedby the eye—the most perfect of all optical instruments. Every telescope consists, in part, of a tube, which always comprises pieces, capable of readily entering into each other. Within this cylinder are glasses or lenses, placed in suc- cession from one extremity to the other. These are intended to re- Front View of the Left Eye-moderately fract tne rays of "g^? and to bring them to determinate foci. Within i. Superciiia. 2. cilia of each eyelid 3. the telescope is a kind of partition Interior palpebra. 4. Internal canthus. 5. Ex- „ r i i • j ternal canthus. 6. Caruncula lachrymalis. 7. 01 paper Or metal, having a round Plica semilunaris. 8. Eyeball. 9. Pupil. * * • •■ - - 1 J. 7--------O — hole in its centre, and usually placed ORGAN OF VISION. 215 Fig. 85. near a convex glass, for the purpose of diminishing the surface of the lens accessible to the rays of light, and thus of obviating spherical aberration. The interior of the tube and of the diaphragm is coloured black, to absorb the oblique rays, which are not inservient to vision; and thus to prevent them from causing confusion. This arrangement is nearly a counterpart of that which exists in the eye. The tube of the instrument is represented by three membranes in superposition,— the sclerotic, choroid, and retina; the last receiving the impression of light. Within, are four refracting bodies, situate one behind the other ; and intended to bring the rays of light to determinate foci,—the cornea, aqueous humour, crystalline lens, and vitreous humour. Lastly, in the interior of the eye, near the anterior surface of the crystalline, is a diaphragm—the iris, having an aperture in its centre—the pupil. These different parts demand a more detailed notice. 1. Coats of the Eye.—Before describing the coats of the eye it may be remarked, that the eyeball is invested with a membranous tunic, which separates it from the other structures of the orbit; and forms a smooth, hollow surface by which its motions are facilitated. This investment has been variously called, cellular capsule of the eye, ocular capsule, tunica vaginalis oculi, and submuscular fascia. The sclerotic is the outermost proper coat. It is that which gives shape to the organ, and which constitutes the white of the eye. It is of a dense, resisting, fibrous nature, belonging to what M. Chaussier calls albugineous tissue. Behind, it is penetrated by the optic nerve ; and before, the cornea is dovetailed into it. It has, by some anatomists, been considered a prolongation of the dura mater, accompany- ing the optic nerve ; whilst the choroid has been regarded as an extension of the pia mater; and the retina of the pulp of the nerve. The sclerotic is the place of insertion for the various muscles that move the eyeball, and is manifestly intended for the protection of the internal parts of the organ. Immediately within the scle- rotica, and feebly united with it by vessels, nerves, and areolar tissue,1 is the Choroid COat:---a 1-. Curved lines'.marking the arrangement of vense » . . . . vorticosoe. 2,2. Ciliary nerves. 3. A long ciliary ar- SOlt, thin, Vascular, and nerVOUS tery and nerve. 4. Ciliary ligament. 5. Iris. 6. Pupil. 1 In the situation of this areolar tissue, Arnold describes a serous membrane, Spinnwebenhaut Arachnoidea oculi, Lamina fusca sclerotica!—Arnold liber das Auge, Tab. iii., Fig. 2, and Weber's Hildebrandt's Handbuch der Anatomie, iv. 68, Braunschweig, 1832. Side View of the same Eye, as in Fig. 84, showing that the Cilia of the Upper Lid are con- cave upwards, and those of the Lower Lid concave down- wards. The general Convexity of the Eyeball is seen. Fig. 86. Choroid Coat of the Eye. 216 SENSE OF SIGHT. #f&i membrane. It completely lines the sclerotic; and has, consequently, the same shape and extent. Behind, it is perforated by the optic nerve; before, it has the iris united with it; and within, it is lined by the retina, which does not, however, adhere to it,—the black pignient sepa- rating them from each other. It is chiefly composed of the ciliary vessels and nerves, and consists of two distinct laminae, to the innermost of which Ruysch—the son—gave the name membrana Ruyschiana. In fishes these laminae are very perceptible, being separated from each other by a substance, which M. Cuvier considers to be glandular. The choroid is impregnated and lined by a dark-coloured mucous pigment, stratum pigmenti, pigmentum nigrum. In some cases, as in the albino, FiCT 87 this substance, which is exhaled from the choroid, is light-coloured, ap- proximating to white. Leopold Gmelin1 conceives that it approaches the nature of indigo; Dr. Young,2 regards it as a mucous substance, united to a quantity of carbonaceous matter, upon which its colour de- pends ; and Berzelius,3 from his chemical investigations, considers it to consist chiefly of carbon and iron; Pigmentum Nigrum. but Professor Jacob thinks it obvi- a. choroid epithelium, with the cells filled ously an animal principle sui generis, with pigment, except at a, where the nuclei are . *j .■,• i_j visible. The irregularity of the pigment-ceiis its elements being oxygen, nydrogen, i8Be%men^cins°/roPrrfThent8ubstance of the carbon, and nitrogen. Dr. Apjohn choroid. A detached nucleus is seen .—Magnified found 100 parts, in a drV State, leave, 320 diameters. ..r ' J ' 7 when incinerated, 4*4o ot a calx consisting of chloride of calcium, carbonate of lime, phosphate of lime, and peroxide of iron. Mr. Thomas Wharton Jones has examined the layer of black pigment on the inner surface of the choroid microscopi- cally. He states that it possesses organization, and constitutes a real membrane—pigmental mem- brane—consisting of very minute flat bodies of an hexagonal form, joined together at their edges.4 It is generally considered to con- sist of pigment cells, which form a kind of pavement, and are some- what of a polyhedral shape; lying in a very regular manner, with some intercellular substance between them. On the outer side of the bottom of the cavity of the eye, there is 1 Dissert. Sistens Indagationem Chemicam Pigmenti Nigri Oculorum Taurorum, Gotting., 1812. z Medical Literature, p. 521, Lond., 1813. 3 Medico-Chirurg. Trans., iii. 225. * Art. Eye, by Dr. Jacob, in Cyclop, of Anat. and Physiol., Part x. p. 181, for June, 1837. Retina. 1. Terminating anteriorly in a scalloped border. 2. Foramen of Sommering. 3. Zonula ciliaris. 4. Crystalline lens. ORGAN OF VISION. 217 a small shining space, destitute of pigment, through which the colours of the membrana Ruyschiana appear. This is termed tapetum. It is met with only in quadrupeds. The retina is the last coat, if we except a highly delicate serous membrane — discovered by Dr. Jacob,1 of Dublin, and called after him Tunica Ja- cobi,—which is interposed be- tween the retina and the cho- roid coat.2 It appears to be composed of cylindrical, trans- parent, and highly refractive bodies, which are arranged perpendicularly to the surface of the retina,—their outer ex- tremities imbedded, to a great- er or less depth, in a layer of the pigmentum nigrum. The only plausible suggestion, which, according to Messrs. Kirkes and Paget3, has been offered, concerning the use of these bodies, is that of Briicke, who thinks it not unlikely, that they may serve to con- duct back to the sensitive portion of the retina those rays of light which have tra- versed that membrane, and have not been entirely ab- sorbed by the pigmentum ni- grum. Mr. George H. Field- ing, of Hull,4 has affirmed, that immediately behind the retina, and in connexion with it, there is a peculiar membrane, separable into distinct layers from the choroid, and supplied with bloodvessels, which he proposes to name membrana versicolor. He presumes, that it receives the vibrations of light, and communicates them to the retina: the eyes, used for experiment, were those of the ox and sheep. The retina lines the choroid, and is a soft, thin, pulpy, and grayish membrane, formed chiefly, if not wholly, by the final expansion of the optic nerve. M. Ribes,5 indeed, esteems it a distinct membrane, on which the optic nerve is distributed;—a structure more consistent ' Philosoph. Transact, for 1819; Medico-Chirurg. Transactions, xii., Lond., 1823, and Art. Eye, in Cyclop, of Anat. and Phys., p. 186. 2 Philosophical Transactions for 1829, p. 300. 3 Manual of Physiology, American edition, p. 405, Philadelphia, 1849. 4 Second Report of the British Association for the Advancement of Science; or Amer. Journal of the Med. Sciences, Nov., 1833, p. 220. 5 Memoir, de la Societe Medicale d'Emulation, vii. 86. Fig. 89. 1. The nervous structure, viz., the nerve-fibres (6) be- tween nerve-cells (a, c). 2. Jacob's membrane. 3. Inner surface of choroid, d. One of the small pointed bodies of Jacob's membrane. Fig. B. The Outer Surface of Jacob's Membrane. (From Hannover.) Opposite e, the twin cones are obscurely seen, not being in focus, while, at the lower part of the figure, near/, the same bodies are clearly discernible. Towards the right side of the figure, where the objects are disturbed, the twin cones project like papillae, at g, the small rods being in a great measure lost at this place. And these (small bodies) are seen to become horizontal towards the extre- mity of the object, h, where some are in disorder. 218 SENSE OF SIGHT. Fig. 90. with analogy. On its inner surface it ia in contact with the membrane of the vitre- ous humour; but they are not adherent. Anteriorly, it terminates near the ante- rior extremity of the choroid, forming a kind of ring, from which an extremely delicate lamina is given off. This is re- flected upon the ciliary processes; dips into the intervals separating them, and, accord- ing to some anatomists, passes forward as far as the crystalline. Modern ob- servers—Messrs. B. C. R. Langenbeck, Treviranus, Gottsche, Volkmann, E. H. Weber, Michaelis, and others, have ex- amined minutely into the anatomy of the retina, and have shown that it consists of several layers:—Langenbeck says three; Michaelis, four. The outer layer of the true retina is con- sidered to be formed by the optic nerve, which, at its entrance into the eye, divides into numerous small fasciculi of ultimate fibrils, that spread themselves out, and inosculate with each other by an inter- Fig. 91. Part of the Retina of a Frog seen from the outer surface. Magnified 300 times. (Treviranus.) Vertical Section of the Human Retina and Hyaloid Membrane. h. Hyaloid membrane. h\ Nuclei on its inner surface, c. Layer of transparent cells, connecting the hyaloid and retina, c'. Separate cell enlarged by imbibition of water, n. Gray nervous layer, with its capillaries. 1. Its fibrous lamina. 2. Its vesicular lamina. 1'. Shred of fibrous lamina de- tached. 2'. Vesicle and nucleus detached, g. Granular layer. 3. Light lamina frequently seen, g'. Detached nucleated particle of the granular layer, m. Jacob's membrane. m>. Appearance of its par- ticles, when detached, m". Its outer surface.—Magnified 320 diameters. change of fibrils, so as to form a net-like plexus. From this plexus, the fibres of which lie in the plane of the surface of the vitreous humour, a very large number of fibrils arises in a direction perpendicular to the surface, so as to be all directed towards the centre of the eye. These pass through a delicate layer of areolar tissue, containing a minute plexus of bloodvessels, and from this every fibril receives a sheath, w-hich envelopes its extremity, and thus forms a minute papilla. The surface of the retina, in contact with the vitreous humour, is wholly composed of these papillae, which are closely set together. Dr. ORGAN OF VISION. 219 Papillae of the Retina of the Frog, seen from the side turned to- wards the vitreous humour. The four higher rows are seen sideways.—Mag- nified 300 times. (Trevi- ranus.) Fig. 93. Carpenter1 thinks there can be little doubt that Fig. 92. they are identical with the globules of the retina of Weber. The diameter of these globules in man, according to Weber, is from the g^th to ss^th of an inch. About a sixth of an inch on the outside of the optic nerve, and in the direction of the axis of the eye, or of a line drawn perpendicularly through the centre of the cornea, is a yellow spot, about a line in extent, having a depression in its centre. This spot and depression are the limbus luteus or ma- cula lutea, and foramen centrale of Sommering.2 The yellow spot does not exist in the foetus;3 and the folds, described by Sommering as surrounding the yellow spot, would appear to be a post mortem appearance. In the examination of two convicts, three hours after execution, the fora- men was not seen satisfactorily.4 The retina receives many blood-vessels, which proceed from the central artery of the retina, or of Zinn. This vessel—it is important to observe — enters the eye through the centre of the optic nerve, the porus opticus, and, before passing directly through the vitreous humour, sends off late- ral branches to the retina. 2. Diaphanous parts of the Eye.—The parts that act as refracting bodies, are either transparent membranes, or fluids con- tained in capsules, which give them a fixed shape. These parts are the cornea, aqueous humour, crystalline, and vitreous humour. The cornea is the convex transparent part of the eye, advancing in front of the rest of the organ, as a watch-glass does before the case; and appearing like the segment of a smaller sphere superadded to a larger. It was, for a long time, con- sidered to be a prolongation of the scle- rotic ; but they are manifestly distinct membranes, being separable by macera tion. Plan oft he Structures in the Fore Part of the Eye, seen in section. 1. Conjunctiva. 2. Sclerotica. 3. Cornea. 4. Choroid. 5. Annulus albi- Thp nncifprior ,7 mi thick), a. Aqueous humour: anterioT Called anterior Chamber Of the eye. lhe chamber and (a) posterior chamber, b cornea is generally considered to be com- crystalline ien.. c vitreous humour. 1 Human Physiology, p. 262, Lond., 1842. 2 Sommering, in Comment. Societ. Gotting., torn. xiii. 1795-98; A. ab Ammon, de Genesi et Usu Maculae Lutea?, &c, Vinar., 1830. s Rudolphi, Grundriss der Physiologie, B. ii. Abtheil, 1, s. 176, Berlin, 1823. * W. E. Horner, Special and General Anatomy, 5th edit., p. 426, Philad., 1839, and J. Pancoast, in Wistar's Anatomy, 8th edit., Philad., 1842. 220 SENSE OF SIGHT. Fig. 94. Posterior Segment of Transverse Sec- tion of the Globe of the Eye seen from within. 1. Divided edge of three tunics. The membrane covering the whole internal surface is the retina. 2. Entrance of optic nerve with arteria centralis retinae piercing its centre. 3, 3. Ramifications of arteria centralis. 4. Foramen of Sommering, in centre of axis of eye ; the shade from sides of the section ob- scures the limbus luteus which sur- rounds it. 5. A fold of the retina, 'which generally obscures the foramen of Som- mering after the eye has been opened. posed of several thin laminae in superposi- tion, which have been compared to horn ; and hence the name of the membrane: but Mr. T. Wharton Jones1 denies this, and describes it as consisting merely of inter- weaving bundles of fibres. Like corneous tissue in general, it possesses neither blood- vessels nor nerves. In animals, the dens- ity and convexity of the cornea vary with the media in which they live, and with the condition of the other refractive parts of the eye. In old age, the membrane is harder, tougher, and less transparent than in youth ; and it frequently becomes completely opaque in its circumference, presenting the appearance called arcus senilis,—in German, Grei senbogen. Nerves have been traced into the sub- stance of the cornea. They are ramifica- tions of the ciliary.2 The aqueous humour is a slightly viscid fluid, which occupies the whole of the space between the posterior surface of the cornea Fig. 95. Vertical Section of the Sclerotic and Cornea, showing the continuity of their tissue between the dotted lines. a. Cornea. 6. Sclerotic. In the cornea, the tubular spaces are seen cut through, and in the sclero- tic, the irregular areolae. Cell-nuclei, as at c, are seen scattered throughout, rendered more plain by acetic acid.—Magnified 320 diameters. and the anterior surface of the crystalline. This space is divided by the iris into two chambers—an anterior and a posterior—the latter being the small interval between the hinder surface of the iris, and the anterior surface of the crystalline. Sir David Brewster3 erro- neously asserts that the posterior chamber contains the crystalline and 1 Introduction to W. Mackenzie's Practical Treatise on Diseases of the Eye, Lond., 1840. 2 Lond. Med. Gaz., Oct., 1845, cited from Muller's Archiv. 3 A Treatise on Optics, edit, cit., p. 241. ORGAN OF VISION. 221 vitreous humours ; and Dr. Arnott,1 that the anterior and posterior chambers of the eye are the compart- ments before and behind the crystalline. Anato- mists are not agreed, whe- ther the aqueous humour have a proper membrane, which secretes it; or whe- ther it be not an exhalation from the vessels of the iris and ciliary processes. M. Ribes derives it from the vitreous humour. Howso- Fig. 96. Longitudinal Section of the Globe of the Eye. ^. Sclerotic, thicker behind than in front. 2. Cornea, re- ever Secreted, it IS Very ceived within anterior margin of sclerotic, and connected with vnv^.'^l^ v.~„.„».„ *■ A I, it by means of a bevelled edge. 3. Choroid, connected ante- rapidiy regenerated Wnen riorly with (4) ciliary ligament, and (5) ciliary processes. 6. pvinnnfprl • It will follow, from what has v ^ been said, that if the primary *§ M colour, or that to which the eye |^= has been first directed, be added Black %^ \ mkz~~\ s white. to the accidental colour, the result fp| must be the same impression as *0 1| that produced by the union of all \ ^B| - \aIJf the rays of the spectrum—of white ^-^^IPP^^ light. The accidental colour, in 'o5.'par other words, is what the primitive Accidental Colours. colour requires to make it white light. The primitive and accidental colours are, therefore, comple- ments of each other; and hence accidental colours have been called complementary colours. They have likewise been termed harmonic, because the primitive and its accidental colour harmonize with each other in painting. It has been supposed, that the formation of these ocular spectra has frequently given rise to a belief in supernatural appearances,—the retina, in certain diseased states of the nervous sys- tem, being more than usually disposed to retain the impressions, so that the spectrum remains visible for a long time after the cause has been removed. Such appears to be the view of Drs. Ferriar,1 Hib- bert,2 and Alderson,3—the chief writers in modern times, on appari- tions. This subject may be the theme of future discussion. It will be sufficient, at present, to remark, that the great seat and origin of 1 An Essay towards a Theory of Apparitions, Lond., 1813. 2 Sketches of the Philosophy of Apparitions, Edinb., 1825. s An Essay on Apparitions, &c, Lond., 1823. 262 SENSE OF SIGHT. spectral illusions is the brain, and that the retina is no farther con- cerned than it is in dreaming or in the hallucinations of insanity. The retina is able to receive visual impressions over its whole sur- face, but not with equal distinctness or accuracy. When we regard an extensive prospect, that part of it alone is seen sharply, which falls upon the central part, or in the direction of the axis of the eye: we always, therefore, in our examination of minute objects, endeavour to cause the rays from them to impress this part of the retina;—the dis- tinctness of the impression diminishing directly as the distance from the central foramen increases. This central point, called the point of distinct vision, is readily discriminated on looking at a printed page. It will be found, that although the whole page is represented on the retina, the letter to which the axis of the eye is directed is alone sharply and distinctly seen ; and, accordingly, the axis of the eye is directed in succession to each letter as we read. Ir^ making some experiments on indistinctness of vision at a distance from the axis of the eye, Sir David Brewster1 observed a singular peculiarity of oblique vision, namely,— that when we shut one eye and direct the other to any fixed point, such as the head of a pin, and hence see all other objects within the sphere of vision indistinctly, if one of these objects be a strip of white paper, or a pin lying upon a green cloth, after a short time, the strip of paper or the pin will altogether disappear, as if it were entirely removed, the impression of the green cloth upon the surrounding parts of the eye extending itself over the part of the retina, which the image of the pin occupied. In a short time, the vanished image will re-ap- pear, and again vanish. WThen the object seen obliquely is luminous, as a candle, it never vanishes entirely, unless its light is much weak- ened by being placed at a great distance; but it swells and contracts, and is encircled with a nebulous halo,—the luminous impressions ex- tending themselves to adjacent parts of the retina not directly influ- enced by the light itself. From these, and other experiments of a similar character, Sir David infers, that oblique or indirect vision is inferior to direct vision, not only in distinctness, but from its inability to preserve a sustained vision of objects. Yet it is a singular fact, that indirect has a superiority over direct vision in the case of minute objects, such as small stars, which cannot, indeed, be seen by the latter. A mode frequently adopted by astronomers for obtaining a view of a star of the last degree of faintness is to direct the eye to another part of the field, and in this way, a faint star, in the neighbourhood of a large one, often becomes very conspicuous, so as to bear a certain illumination, and yet it en- tirely disappears, as if suddenly blotted out, when the eye is turned full upon it; and, in this way, it can be made to appear and disappear as often as the observer pleases. Sir J. F. W. Herschel, and Sir James South, who describe this method of observation, attempt to account for the phenomenon by supposing, that the lateral portions of the retina, being less fatigued by strong light, and less exhausted by perpetual attention, are probably more sensible to faint impressions • Op. citat, p. 248. DISTINCT VISION. 263 than the central ones; and the suggestion carries with it an air of veri- similitude. Sir David Brewster, however,—from the result developed by his experiments, that, "in the case of indirect vision, a luminous object does not vanish, but is seen indistinctly, and produces an en- larged image on the retina, besides that which is produced by the defect of convorgency in the pencils,"—concludes somewhat mystically, "that a star, seen indirectly, will affect a large portion of the retina from these two causes, and, losing its sharpness, will be more distinct."1 In order that the image of any object may impress the retina, and be perceived by the mind, it must, first of all, occupy a space on the retina sufficiently large for its various parts to be appreciated: in the next place, the image must be distinct or sharp,—in other words, the luminous rays that form it must converge accurately to a focus on the retina: and lastly, the image must be sufficiently illuminated. Each of these conditions varies with the size of the body, and the distance at which it is from the eye; and there are cases, where they are all want- ing, and the object is consequently invisible. An object may be so small, that the eye cannot distinguish it, because the image, formed on the retina, is too minute. To remedy this inconvenience, the object must be brought near to the eye, which increases the divergence of the rays and the size of the image ; but if we approach it .too close to the eye, the rays are not all brought to a focus on the retina, and the image is indistinct. If, therefore, an object be so small, that, at the visual point, to be presently mentioned, the rays proceeding from it do not form an image of sufficient size on the retina, the object is not seen. To obviate this imperfection of the sense, minute bodies may be viewed through a small hole in a piece of paper or card, or with the instrument called a microscope. By looking through the small aperture in the paper or card, the object may be brought much nearer to the eye ; the rays of greatest divergence are prevented by the small- ness of the hole from impinging upon the retina ; and the rest are converged to a focus upon that membrane, so that a sharp and distinct impression is received. The iris is, in this way, useful in effecting dis- tinct vision,—the most divergent rays being, by the contraction of the pupil, prevented from falling upon the crystalline. Any object that does not subtend an angle of the sixtieth of a degree is invisible ; but the visual power differs greatly in individuals. Some eyes are much more capable of minute inspection than others; and greater facility is acquired by practice. Professor Ehrenberg, how- ever, found, that in regard to the extreme limits of vision, there is little difference among persons of ordinarily good sight, whatever may be the focal distance of their eyes. The smallest square magnitude usually visible to the naked eye, either of white particles on a black ground, or of black upon a white ground, is about the 7-J- gth of an inch ; but parti- cles that reflect light powerfully, as gold dust, may be discovered with the naked eye in common daylight, when not exceeding the yy^sth of an inch ; and, when the substance viewed is in lines instead of particles, it may be seen, if held towards the light, when only ^g-^th of an inch in diameter. 1 Op. citat, p. 249. 264 SENSE OF SIGHT. Again, there is a point of approximation to the eye beyond which objects cease to be distinctly seen, in consequence of the rays of light striking so divergently upon the eye, that the focus falls behind the retina. This point, too, varies according to the refractive power of the eye; and is, therefore, different in different individuals. In the myopic or short-sighted, it is much nearer the eye than common; in the presbyopic or long-sighted, more distant. The iris here, again, plays an important part, by its action in shutting off the most diverging rays. There is also a limit beyond which objects are no longer visible. This is owing to the light from them becoming absorbed before it reaches the retina, or so feeble as not to make the necessary impression. The distance, consequently, at which an object may be seen, will depend upon the sensibility of the retina, and partly on the colour of the ob- ject ; a light colour being visible to a greater distance than a darker. A distant object may also be imperceptible owing to the image, traced on the retina, being too minute to be appreciated ; for the size of the image diminishes as the distance of the object increases. The range of distinct vision varies, likewise, with the individual,—and especially with the myopic and presbyopic; and in such case the pupil dilates to admit as much light as possible into the interior of the eye, and to com- pensate in some measure for the defect. Between the ranges of distant and near vision, a thousand different examples occur. In all cases, however, the ocular cone must be brought to a focus on the retina, otherwise there cannot be perfect vision. It has been already observed, in the proem on light, that the distance, at which the ocular cone arrives at a focus behind the lens, is in propor- tion to the length of the objective cone; or, in other words, that the focus of a lens varies with the distance at which a radiant point is situate before it: where the point is near the lens the focus will be more remote behind it; and the contrary. If this occurs in the human eye it must necessarily follow ;—either that it is not necessary for an object to be impressed upon the retina;—or that the eye is capa- ble of accommodating itself to distances;—or if it does not occur, it must be admitted, that, owing to the particular constitution of the eye, the impressions are so made on the retina as not to need such adapta- tion. The whole bent of the foregoing observations on vision would preclude the admission of the first of these postulates. The second has been of almost universal reception, and given rise to many ingenious speculations ; and the third has been seriously urged of late years only. It would occupy too much space to dwell at length upon the various ingenious discussions, and the many interesting and curious experiments, that have resulted from a belief in the power possessed by the eye of accommodating itself to distances. It is a subject, however, which occupies so large a field in the history of physiological opinions, that it cannot be passed over. The chief views, that have been entertained, are :—First. The cornea or lens must recede from, or approach the retina, according to the focal distance, precisely as we adapt our tele- scopes by lengthening or shortening the tube. Secondly. If we suppose the retina to be stationary, the lens must experience a change in its ADAPTATION OF THE EYE TO DISTANCES. 265 refractive powers, by an alteration of its shape or density ; or, TJiirdly. In viewing near objects, those rays only must be admitted, which are nearest the axis of the eye, and are consequently least diverging. 1. The hypothesis, that the adjustment of the eye is dependent upon an alteration of the antero-posterior diameter of the organ, or on the relative position of the humours and retina, has been strongly supported by many able physiologists. Blumenbach1 was of opinion, and his views seem to have been embraced by Dr. Hosack,2 that the four straight muscles of the eye, by compressing the eyeball, cause a protrusion of the cornea, and thus increase the length of the axis. Dr. Monro se- cundus3 believed, that the iris, recti muscles, the two oblique, and the orbicularis palpebrarum participate in the accommodation; and Ham- berger, Briggs,4 and others, that the oblique muscles, being thrown in opposite directions around it, may have the effect of elongating the axis of the eye. Kepler5 thought, that the ciliary processes draw the crystalline forward, and increase its distance from the retina. Des Cartes6 imagined the same contraction and elongation to be effected by muscularity of the crystalline, of which he supposed the ciliary pro- cesses to be the tendons. Porterfield,7 that the corpus ciliare is con- tractile, and capable of producing the same effect. Jacobson,8 that the aqueous humour, by entering the canal of Petit through the apertures in it, distends the canal, and pushes the crystalline forward. Sir Eve- rard Home,9 that the muscular fibres, which he has described as exist- ing between the ciliary processes, move the lens nearer to the retina, and that the lens is brought forward by other means, (which he leaves to conjecture,) when the distance of the object is such as to require it. Dr. Knox,10 that the annulus albus, or the part which unites the choroid and sclerotic coats, is muscular, and the chief agent in this adjustment. Professor Mile,11 of Warsaw, that the contraction of the iris changes the curvature of the cornea; whilst Sir David Brewster12 thinks it "almost certain, that the lens is removed from the retina by the con- traction of the pupil." Without examining these and other views in detail, it may be re- marked, that the nicest and most ingenious examination by the late Dr. Young13 could not detect any change in the length of the axis of the eyeball. To determine this, he fixed his eye, and at the same time forced in upon the ball the ring of a key, so as to cause a very accu- rately defined phantom within the field of perfect vision; then looking 1 Instit. Physiolog., § 276, or Elliotson's translation. 2 Philosoph. Transact, for 1794, p. 146. 3 Three Treatises on the Brain, the Eye, the Ear, p. 137, Edinb., 1797. 4 Nova Visionis Theoria, Lond., 1685. s" Haller, Element. Physiol., xvi. 4, 2. 6 De Homine, p. 45, Lugd. Bat, 1664. 7 A Treatise on the Eye, the Manner and Phenomena of Vision, Edinb., 1759. 8 Magendie, Precis, &c, i. 78. 9 Philosoph. Transact, for 1794, 1795, 1796, and 1797; and Lectures on Comparative Anatomy, iii. 213, Lond., 1823. 10 Edinb. Philos. Transact, x. 56. 11 Magendie, Journal de Physiologie, vi. 166; and Elliotson's Human Physiology, p. 571 Lond., 1840. ' 12 Edinburgh Journal of Science, i. 77; and Treatise on Optics, op. citat, p. 253 13 Philos. Transact for 1795. 266 SENSE OF SIGHT. to bodies at different distances, he expected, if the figure of the eye were modified, that the spot, caused by the pressure, would be altered in shape and dimensions; but no such effect occurred; the power of accommodation was as extensive as ever, and there was no perceptible change either in the size or figure of the oval spot. Again, Sir Everard Home asserts, that all the ingenuity of the distinguished mechanician, Ramsden, was unable to decide, whether, in the adjustment of the eye, there be any alteration produced in the curvature of the cornea. These facts would alone induce a doubt of the existence of this kind of adjust- ment, even if we had not the additional evidence, that many animals are incapable of altering the shape of the eyeball, by the muscles at least. The cetacea, the ray amongst fishes, and the lizard amongst reptiles, have the sclerotica so inflexible as to render any variation in it impossible. With regard to many of the particular views that have been men- tioned, they are mere "cobwebs of the brain," and unworthy of serious argument. In the action of the orbicularis palpebrarum, as suggested by Dr. Monro, there is, however, something so plausible, that many persons have been misled by it. He made a set of experiments to show, that this muscle, by compressing the eyeball, causes the cornea to pro- trude, and thus enables the eye to see near objects more distinctly. When he opened his eyelids wide, and endeavoured to read letters, which were so near the eye as to be indistinct, he failed; but when he kept the head in the same relation to the book, brought the edges of the eyelids within a quarter of an inch of each other, and made an ex- ertion to read, he found he could see the letters distinctly. But Sir Charles Bell1 properly remarks on this experiment, that if the eyelids have any effect upon the eyeball by their approximation, it must be to flatten the cornea; and that the improvement in near vision produced by such approximation, is owing to the most divergent rays being shut off,—as in the experiment of the pinhole through paper. 2. The second hypothesis, which attributes the adaptation to a change of figure in the crystalline itself, has been embraced by all who regard that body to be muscular, and therefore by Leeuwenhoek,2 Des Cartes,3 and Dr. Young.4 These muscular fibres, however, could never be ex- cited by Dr. Young to contraction so as to change the focal power; and their very existence is more than doubtful. The increasing density of the lens towards its centre indicates rather a cellular structure, the cells being filled with transparent matter of various degrees of concentration; and an examination into its intimate physical constitution affords no evidence of muscularity. Professor Forbes,5 of Edinburgh, embraced the view, that the adaptation is owing to a change of figure in the crystalline; but his explanation of its mode of production varies from that given by pre- 1 Anat. and Physiology, Amer. edit, by Dr. Godman, ii. 227, New York, 1827. 2 Boerhaav. Praelect, § 527, torn. iv. p. 92; and Haller, Element. Physiol., lib. xvi. sect. 2. 3 Op. cit. * Op. citat. 5 Proceedings of the Royal Society of Edinb., No. 25, cited in the Amer. Journ. of the Med. Sciences, Oct., 1845, p. 504. ADAPTATION OF THE EYE TO DISTANCES. 267 ceding writers. The lens, he says, is composed of coats more firm and tenacious, as well as more refractive towards the centre, and less so at the sides. These coats are also nearly spherical in the centre, forming a nucleus of considerable resistance. Hence he supposes, that if the lens be compressed in any manner by a uniform hydrostatic pressure, it will yield more readily in a plane at right angles to the axis of vision; and the lens will become more spheroidal, and consequently more re- fractive,—that is, adapted for the vision of objects at small distances. This hydrostatic pressure is believed to be conveyed from the humours of the eye, between which the lens is delicately suspended, and to ori- ginate in the action of the muscles that move the eyeball compressing simultaneously the tough sclerotic coat. It is somewhat singular, that on a subject where so many opportuni- ties have occurred for establishing the fact definitively, such difference of opinion should exist regarding the question, whether an eye from which the crystalline has been removed, as in the operation for cataract, be capable of adjusting itself to near objects. Haller1 and Knox, amongst others, decide the question affirmatively; Porterfield, Young, and Travers,2 negatively. M. Magendie, as we have seen, considers the great use of the crystalline to be,—to increase the brightness and sharp- ness of the image by diminishing its size. Mr. Travers again, regards the adjustment as a change of figure in the lens; not, however, from a contractile power in the part itself, but in consequence of the lamellse, of which it is composed, sliding over each other, when acted upon by external pressure; whilst upon the removal of this pressure, its elastic nature restores it to its former sphericity. The iris is conceived to be the agent in this process; the pupillary part of the organ being, in the opinion of Mr. Travers, a proper sphincter muscle, which, when it con- tracts and relaxes, tends, by the intervention of the ciliary processes, to effect a change in the figure of the lens, which produces a correspond- ing change in its refractive powers. 3. One of the causes to which the faculty of seeing at different dis- tances has been ascribed is the contraction and dilatation of the pupil. It has been already observed, that when we look at near objects, the pupil contracts, so that the most divergent rays do not penetrate the pupil; and vision is distinct. Hence, it has been conceived probable, by De La Hire,3 Haller,4 and others, that the adjustment of the eye to various distances within the limits of distinct vision may be effected by this mechanism, in the same manner as it regulates the quantity of light admitted into the organ. Certain it is, that if we look at a row of minute objects, extending from the visual point outwards, the pupil is seen to dilate gradually as the axis of the eye recedes from the nearest object. An experiment made by the author, on his own eye,5 when a student of medicine, has been quoted by Dr. Fleming6 as confirmatory of this 1 Element. Physiol., lib. xvi. sect. 4. a A Synopsis of the Diseases of the Eye, Lond., 1824. 3 Memoir, de l'Acad. des Sciences de Paris, torn. ix. p. 620. 4 Element. Physiol., torn. v. lib. xvi., 4. * Annals of Philosophy, x. 432. 6 Philosophy of Zoology, i. 187, Edinb., 1822. 268 SENSE OF SIGHT. view. The extract of belladonna has the power, when applied to the eyelids, of dilating the pupil. A newly prepared article was thus ap- plied, and in the space of about twenty minutes the pupil was so much dilated, that the iris was almost invisible. From the time that preter- natural dilatation occurred, objects, presented to this eye with the other closed, were seen as through a cloud. The focus was found to be at twice the distance of that of the sound organ; but, in proportion as the effects of the belladonna passed off, and the pupil approached its natu- ral size, vision became more and more distinct, and the focus nearer and nearer the natural. In the open air, all objects except those near were distinctly seen; but, on entering a room, all was enveloped in mist. There is, indeed, more evidence in favour of the utility of contraction and dilatation of the pupil in distinct vision, within certain limits at least, than of any of the other supposed methods of adjustment; and, accordingly, the majority of opticians of the present day embrace this view of the subject; but without being able to explain satisfactorily the change in the interior of the eye effected by its movements. "It seems difficult," says Sir David Brewster1—one of the latest writers—"to avoid the conclusion, that the power of adjustment depends on the me- chanism, which contracts and dilates the pupil; and as this adjustment is independent of the variation of its aperture, it must be effected by the parts in immediate contact with the base of the iris. By consider- ing the various ways, in which the mechanism at the base of the iris may produce the adjustment, it appears to be almost certain, that the lens is removed from the retina by the contraction of the pupil." The conclusion, drawn by Sir David, does not, however, impress us with the same degree of certainty. Miiller2 thinks it most probable, that the faculty of the eye, which enables it to adjust itself to different distances, depends on an organ, which has a tendency to act by consent with the iris, but yet is in a cer- tain degree independent of it. Reasoning per exclusionem, he thinks it most probable, that the ciliary body has this motor power, and this influence on the position of the lens; but admits, that we have no posi- tive proof of its possessing contractility. More recently, however, as has been shown,3 the existence of a ciliary muscle has been de- monstrated, which, by its contraction, may directly or indirectly advance the lens. M. Pouillet, in his lectures before the Faculte des Sciences of Paris,4 explains the matter with no little confidence by the double effect of the crystalline being composed of different layers, and the mobility of the pupil;—a view, which had been previously maintained in its essential characters by Treviranus.5 As these layers are thinner towards the axis of the crystalline than near its edges, by detaching them successively the curvature of the remainder becomes greater and greater, until the most central portion has the shape of a sphere. Hence, such an apparatus will not have one focus only, but several,— ' Op. citat, p. 252. 3 Elements of Physiology, by Baly, P. v. p. 1150, June, 1S39. 3 Baly and Kirkes, Recent Advances in the Physiology of Motion, the Senses. &c, p. 24, Lond, 184s. 4 Elemens de Physique Experimentale, t. iii. p. 331, Paris, 1832. 5 Beitriige zur Anatom. und Physiol, der Sinnenwerkzeuge, u. s. w., 1828. ADAPTATION OF THE EYE TO DISTANCES. 269 as many, in fact, as there are superposed layers;—the foci being nearer and nearer as we approach the central spherical portion. This arrange- ment, he says, enables us to see at all distances, inasmuch as, "having an infinite number of foci at our disposal, we can use the focus that suits the object we are desirous of viewing." If, for example, it be a near object, the pupil contracts, so as to allow the rays to fall only on the central parts; if more distant, the pupil is dilated to permit the rays to pass through a part that has a more distant focus. It is obvious, however, that in such a case, the ordinary inconve- nience of the aberration of sphericity must result; for when the pupil is dilated, the rays must pass through the more marginal, as well as the central part of the lens. M. Pouillet was aware of this difficulty, but he has not disposed of it philosophically. "It may be said that in opening the pupil widely, the light is not precluded from passing by the centre, and that a kind of curtain would be required to cover the part of the lens, which is unemployed. To this I reply, that there is no necessity to prevent the rays from passing by the axis of the crys- talline; for what is the light, which passes through this small space, compared with that which passes through the great zone of the crystal- line? It may be looked upon as null." It must be admitted, with M. Longet,1 that if the fact of the adapta- tion of the eye to vision at different distances be received as incon- testable, the mechanism of the phenomenon must be regarded as entirely unknown; not one of the explanations offered being able to carry conviction. The whole affair is, indeed, enveloped in perplexity, and it is rendered not less so by the fact mentioned by M. Magendie, that if we take the eye of an albino animal, and direct it towards a luminous object, we find a perfect image depicted on the retina, whatever may be the distance of the object;—the image, of course, being smaller and less luminous when remote, but always distinct. Yet, in this experi- ment, the eye being dead, there can be neither contraction nor dila- tation of the pupil. This result has induced Magendie2—and not too hastily, we think—to draw the conclusion, that although theory may suggest, that there ought to be such adaptation as has been presumed and attempted to be accounted for, observation proves, that such may not be the case; and, consequently, all the speculations on the subject, however ingenious they may be, must fall to the ground. Dr. Fletcher, too, after alluding to the various hypotheses on the subject, adds:— "It appears absurd to attempt to explain a fact which has no real existence, since it has never been proved that the eyeball has any ca- pability of adapting itself to different distances, or that any such adap- tation is required."3 We are, indeed, not justified, perhaps, in admit- ting more than a slight accommodation from the contraction of the pupil in viewing near objects effected in the mode already explained. If the accommodation existed to any material extent, it is difficult to understand, why minor degrees of short or long-sightedness should not ' Traite de Physiologie, ii. 70, Paris, 1S50. 2 Precis Elementaire, i. 72. 3 Rudiments of Physiology, Part iii. p. 48, Edinburgh, 1837. 270 SENSE OF SIGHT. be rectified. Sir Charles Bell1 conceives, "that the mechanism of the eye has not so great a power of adapting the eye to various distances as is generally imagined, and that much of the effect, attributed to mechanical powers, is the consequence of the motion of the pupil and the effect of light and of attention. An object looked upon, if not attended to, conveys no sensation to the mind. If one eye is weaker than the other, the object of the stronger eye alone is attended to, and the other is entirely neglected: if we look through a glass with one eye, the vision with the other is not attended to." " The mind," he adds, "not the eye, harmonizes with the state of sensation, brightening the objects to which we attend. In looking on a picture or panorama, we look to the figures, and neglect the background; or we look to the general landscape, and do not perceive the near objects. It cannot be an adaptation of the eye, but an accommodation, and association of the mind with the state of the impression." The view, which we have expressed upon the subject, is confirmed by the calculations of different investigators. From the refractive powers of the different media of the eye it was calculated by Olbers, that the difference between the focal distances of the images of an object at such distance that the rays are parallel, and of one at the distance of four inches, is only about 0.143 of an inch; so that the change in the distance of the retina from the lens required for vision at all distances, supposing the cornea and lens to maintain the same form, would not be more than about a line. Again:—M. de Simonoff,2 a learned Russian astronomer, asserts, that from a distance of four inches to infinity the changes in the angle of refraction are so small that the apices of luminous cones, in a properly formed eye, must always fall within the substance of the retina; and hence no variation in the shape of the eye, according to the distance of the object, can be necessary. Such facts amply justify the interrogatory of M. Biot;3— whether the aberration of the focus for different distances may not be compensated in the eye by the intimate composition of the refractive bodies, as the aberration of sphericity probably is? Yet, if this be the case, how admirable must be the construction of such an instrument! how far surpassing any effort of human ingenuity! an instrument capa- ble of not only correcting its own aberrations of sphericity, and refran- gibility, but of seeing at all distances.4 It has been before observed, that the visual point varies in different individuals. As an average, it may be assumed at eight inches from the eye. There are many, however, who, either from original confor- mation of the organ, or from the progress of age, wander largely from this average; the two extremes constituting myopy or short-sightedness, and presbyopy or long-sightedness. 1 Anat and Physiology, edit cit, ii. 230. 2 Ma^rendie's Journal de Physiologie, torn. iv. and Precis de Physiol., i. 73. 3 Traite de Physiologie Experimentale, Paris, IS lb. 4 Letters of Euler, by Sir D. Brewster, Amer. edit, i. 163, New York, 1833. See, on this subject, Volkmann, Art. Sehen. in Wagner's Handworterbuch der Physiologie, 14te Lieferung, s. 295, Braunschweig, 1846; and Baly and Kirkes, Recent Advances in the Phy- siology of Motion, the Senses, Generation and Development, p. 20, Lond., 1848. MYOPIC AND PRESBYOPIC EYE. 271 In the myopic or short-sighted the visual point is so close, that objects cannot be seen unless brought near the eye. This defect is owing to too great a refractive power in the transparent parts of the organ; or to Fig. 119. too great a depth of the humours; or it may be caused by unusual convexity of the cornea or crystalline; or from the retina being too distant from the latter. From any one or more of these causes, the rays of light pro- ceeding from distant objects, are Myopic Vision. brought to a focus before they reach the retina, and the objects consequently are not distinctly visible. (Fig. 119.) To see them distinctly, they must be placed close to the eye, in order that the rays may fall more divergently; and the focus be thrown farther back so as to impinge upon the retina. The defect may be palliated by the use of concave glasses, which render the rays, proceeding from the object, more divergent. It is by no means unfre- quent in youth; and the myope has been consoled with the common belief, that, in the progress of life, and in the alterations which take place in the eye from age, he is likely to see well without spectacles, when others of the same age may find them essential. It is probable, however, that this is, in many cases at least, a vulgar error; as we have known different myopic sexagenarians, who have not experienced the slightest improvement. The presbyope, presbytic, or long-sighted labours under an opposite defect. The visual point is much more distant than the average ; and he is unable to see an object unless it is at some distance. This con- Fig. 120. dition is owing to too feeble a re- fractive power in the transparent parts of the eye; to insufficient depth of the eyeball; to too close an approximation between the retina and crystalline; or to too little con- vexity of the Cornea Or crystalline; Presbyopic Vision. so that the rays of light proceeding from a near object are not rendered sufficiently convergent to impinge upon the retina ; but fall behind it. This defect, which is experienced more or less by most people after middle age, is palliated by the use of convex glasses, which render the rays proceeding from an object more convergent, and enable the eye to refract them to a focus farther for- ward, or on the retina. Although the presbyopic eye is unusual in youth, it is sometimes met with. A young friend, at ten or twelve years of age, was compelled to employ spectacles adapted to advanced life; and this was the case with several of the members of a family, to whom the arts have been largely.indebted in this country. One of them, at twenty, was com- pelled to wear spectacles which were almost microscopes. Both the myopic and the presbyopic conditions exist in a thousand 272 SENSE OF SIGHT. degrees; and hence it is impossible to say, a priori, what is the precise lens, that will suit any particular individual. This must be decided by trial. The opticians have their spectacles arbitrarily numbered to suit different periods of life; but each person should select for himself such as will enable him to read without effort at the usual distance. A degree of myopy may be brought on by long-protracted attention to minute and near objects, as we observe occasionally in the watch- maker and engraver; and, again, a person who has been long in the habit of looking out for distant objects, as the sailor, or the watchman at signal stations, is rendered less fitted for minute and near inspec- tion. During the domination of Napoleon, when the conscript laws were so oppressive, the young men frequently induced a myopic state, by the constant use of glasses of considerable concavity;—the defect being esteemed a sufficient ground of exemption from military service. Another subject, which has given rise to much disputation and ex- periment, is, why, as we have two eyes, and the image of an object is impressed upon each of them, wte do not see such object double? Smith1 and Buffon2 consider, that in infancy we do see it so; and that it is not until we have learned by experience,—by the sense of touch for example,—that one object only exists, that we acquire the power of single vision. After the mind has thus become instructed of its error, a habit of rectification is attained, until it is ultimately effected uncon- sciously. The objections to this hypothesis are many and cogent. We are not aware of any instance on record, in which double vision has been observed in those, who, having laboured under cataract from birth, have received their sight by an operation; and we are obviously precluded from knowing the state of vision in the infant, although the simultaneous and parallel motions of the eyes, which are manifestly instinctive, and not dependent upon habit, would induce us to pre- sume, that the images of objects—as soon as the parts have attained the necessary degree of developement—are made to fall upon corre- sponding points of the retina. It may, also, be remarked, in favour of the instinctive nature of this parallel motion of the eyes, that in the blind,—although we may find much irregularity in the motions of the eyeball, owing to no necessity existing for the eyes being directed to any particular point,—the eyeballs move together, unless some de- ranging influence is exerted. The truth is, as we have already ob- served, the encephalon is compelled to receive the impression as it is conveyed to it; and even in cases, in which we are aware of an illu- sion, the perception of the illusion still exists in spite of .all experience. If the finger be pressed on one side of the eyeball, an object, seen in front, will appear double, and the perception of two objects will be made by the brain, although we know from experience that one only exists. This occurs in all the various optical illusions to be presently mentioned. The effect of intoxication has been adduced in favour of this hypo- thesis. It is said that in these cases the usual train of mental asso- ciation is broken in upon, and hence double vision results. The proper 1 Optics, Cambridge, 1738. a Memoir, de 1'Academ. des Sciences, 1743. SINGLE VISION. 273 explanation, however, of this diplopia of the drunkard rests upon other grounds. The effects of inebriating substances on the brain are to interfere with all its functions; and most sensibly, with the voluntary motions, which become irregularly executed. The voluntary muscles of the eye partake of this vacillation, and do not move in harmony, so that the impressions are not made on corresponding points of the retina, and double vision necessarily results. Another hypothesis has been, that although a separate impression is made upon each retina,—in consequence of the union of the optic nerves, the impressions are amalgamated, and arrive at the encephalon, so as to cause but one perception. This was the opinion of Briggs,1 and Ackermann; and at one time it was generally received. Dr. Wollaston2 supposed the consentaneous motion of the eyes to be con- nected with the partial union of the optic nerves. The anatomical and physiological facts relating to the union and decussation of these nerves have already engaged us. By a reference to that subject it will be found, that a true decussation takes place between them, yet that each eye probably has its distinct nerve from origin to termination; and that no suchsemi-decussation, as that contended for by Dr. Wollaston, exis'ts. These facts are unfavourable to the hypothesis of amalgamation of impressions: besides, if we press slightly on the eye, we have a double impression, although the relation of the optic nerves to each other is the same; and, moreover, the same explanation ought to apply to audition, in which we have two distinct impressions, but only a single perception:—yet no one conceives that the auditory nerves decussate. The fusion of the two images into one seems to be a mental operation. Another opinion has been maintained;—that we do not actually receive the perception of two impressions at the same time; and that vision consists in a rapid alternation in the use of the eyes, according as the attention is directed to one or other of them by accidental cir- cumstances. Such was the opinion of M. Dutours.3 A modification of this view was entertained by M. Le Cat,4 who asserts, that, although the right eye is not always the most powerful, it is most frequently employed; and Gall denies, that we use both eyes at the same time, except in the passive exercise of the function. In active vision, he asserts, we always employ one eye only,—sometimes one and sometimes the other; and thus, as we receive but one impression, we necessarily see but one object. In support of this view, he remarks that in many animals the eyes are situate at the sides of the head, so as not to be capable of being directed together to the same object. In them, con- sequently, one eye alone can be used; and he considers this a presump- tion, that such is the case in man. He remarks farther, that in many cases we use one eye by preference, in order that we may see better— as in shooting or in taking the direction of objects in a straight line; and that although, in other cases, both eyes may be open, we still use but one. In proof of this, he says, if we place a small object be- tween the eyes and a lighted body, and look at the latter, the shade 1 Nova Visionis Theoria, Lond., 1685. s Philos. Transact, for 1S24, p. 222. l 3 Memoir, presentees a l'Academie des Sciences, &c, t. iii. & iv. * Op. citat. VOL. I.—18 274 SENSE OF SIGHT. does not fall between the eyes, on the root of the nose, as it ought to do if the body were looked at with both eyes; but on each eye alter- nately, according as the one or the other is directed to it; and, he adds, if, when we squint voluntarily, we see two objects, it is because one eye sees passively, whilst the other is in activity.1 Amongst numerous objections to this view of the subject, a few may be sufficient. Every one must have observed how much more vividly an object is seen with both eyes than with one only. The difference according to Jurin2 is a constant quantity; and, in sound eyes of the ordinary degree of power, amounts to one-thirteenth of the whole effect. But we have experiment to show, that a distinct impression is made upon each eye. If a solar beam be admitted into a dark chamber, and be made to pass through two glasses of tolerable thickness, but of dif- ferent colours, placed close alongside each other, provided the sight be good and the eyes of equal power the light perceived will not be of the colour of either of the glasses, but of an intermediate shade; and if this should not happen, it will be found, that the eyes are of unequal power. When such is the case, the light will be of the colour of the glass placed before the stronger eye. These results were obtained in the Cabinet de Physique of the Faculte de Medecine of Paris, by M. Magendie,3 in the presence of M. Tillaye the younger. The existence of this double impression is proved in another way. If we place any tall, slender object a few feet before us, and examine its relative situation compared with a spot on a wall in the distance, we find, that if the spot be hidden by the stick, when both eyes are open, it will become visible to each eye, when used singly; and be seen on the side of the stick corresponding to the eye employed. But Pro- fessor Wheatstone4 has instituted experiments, which place this matter entirely at rest. He has shown, that in viewing an object having length, breadth, and thickness, the perspective projections upon the two retinae differ according to the distance at which the object is placed before the eyes. If so distant, that to view it the optic axes must be parallel, the two projections are precisely similar; but if so near, that . to view it the optic axes must converge, a different perspective pro- jection is presented to each eye, and these perspectives become more dissimilar as the convergence of the optic axes becomes greater. Not- withstanding this dissimilarity between the two pictures, which is in some cases very great, the object is still seen single, although not exactly resembling either of the two pictures on the retinae. Having thus established, that the mind perceives an object of three dimensions by means of the two dissimilar pictures projected by it on the two retinae, Mr. Wheatstone inquired what would be the visual effect of presenting simultaneously to each eye instead of the object itself its projection on a plane surface as it appears to that eye? For this purpose he imagined an instrument which he calls stereoscope. It 1 Adelon, Physiologie, 2de £dit, i. 457, Paris. 1829. 2 Essay appended to Smith's Optics, Cambridge, 1738; and Haller, Element. Physiol., lib. xvi. 4. 3 Precis, &c, i. 86. Dutours, in Mem. presentees a l'Academ., iii. 514, & iv. 499. * Philosophical Transactions, P. ii., Lond., 1838. SINGLE VISION. 275 consists of two plane mirrors, with their backs inclined to each other at an angle of 90°, near the faces of which two monocular pictures are so disposed, that their reflected images are seen by the two eyes, each looking into one of the mirrors on the same plane. The experiment may, however, be made sufficiently well by the subjoined figures. Fig. 121. Binocular Vision.—Professor Wheatstone's Experiment. Fix the right eye on the right-hand figure, and the left eye on the left-hand figure ; hold between the eyes, in front of the nose, the board of an octavo book. The two figures a a will be seen to approximate, and to run into one, representing the skeleton of a truncated four-sided figure in bold relief, b;—a fact, which shows, that the visual apprecia- tion of solidity or projection arises from the combination in the mind of two different images. These could not exist in a person who has never had more than one eye; and therefore from sight alone he could form no notion of solidity. He would have to combine with sight the evidence afforded by touch. All these facts demonstrate, that two impressions are really made in all cases,—one on each eye;—and yet the brain has perception of but Fig. 122. Fig. 123. .binocular Vision. one. If the law of visible direction, which Sir David Brewster has pointed out (see page 258), be adopted, the cause of single vision with two eyes must be admitted as a necessary consequence. If we are 276 SENSE OF SIGHT. placed at one end of a room, and direct the axes of both eyes to a cir- cular aperture in a window-shutter at the other end, although an image of this aperture may be formed in each eye, yet because the lines of visible direction from similar points of the one image meet the lines of visible direction from similar points of the other, each pair of similar points will appear as one point, and the aperture seen by one eye will exactly coincide with the aperture seen by the other. But if, when an object is seen single with both eyes, we press one eye aside, the image formed by that eye will separate from the other image, and the object will appear double; or, if the axes of both eyes be directed to a point either nearer or more remote than the aperture in the window-shutter, then, in both these cases, the aperture will appear double, because the similar lines of visible direction no longer meet at the aperture.1 In Fig. 122, if we look at the object A, the more dis- tant object, B, will be seen double; and in Fig. 123, if we look at the object B, the nearer object A will be seen double. It is not necessary, however, that the axes of the eyes should be directed accurately on an object, in order that it shall be seen single with both eyes. A whole range of objects may be seen single if their images are thrown on corresponding parts of the retina in both eyes, as in Fig. 124. After all, perhaps the true condition of single vision is, that the two images of an object should be formed on portions of the two retinae that are accustomed to act in concert. In cases of convergent strabis- mus, the patient does not see double; but Binocular Vision. immediately after a successful operation, if the vision of the two eyes be good, he does so; and this continues until the parts of the two retinae have become habituated to act in concert. In the course of the preceding remarks, it was stated, that the eyes are not always of the same power. The difference is sometimes sur- prising. M. Adelon2 mentions the case of a person, one of whose eyes required a convex glass, with a focus of five inches; the other a concave glass, with a focus of four inches. In these cases, it is important to use one unassisted eye only ; as confusion must necessarily arise from directing both to an object. This is the cause why we close one eye in looking through a telescope. The instrument has the effect of ren- dering the focal distance of the two eyes unequal, and of placing them in the same situation as if they were, originally, of different powers. From what has been said it will be understood, that if from any cause, as from a tumour pressing upon one eyeball, from morbid debility of the muscles, or from want of correspondence in the sensi- bility of the two retinae, the eyes be not properly directed to an object, * Optics, p. 44, in Library of Useful Knowledge, Natural Philosophy, vol. i., Lond., 1829, and Treatise on Optics, edit. cit. * Physiologie, edit cit, i. 459. MULTIPLE VISION WITH ONE EYE. 277 double vision will be the consequence. In almost all cases, however, of distortion of the eyeballs, the image falls upon a part of one retina, which is more sensible than the portion of the other on which it falls; the consequence will be, that the mind will acquire the habit of attend- ing to the impression on one eye only; and the other may be so neg- lected, that it will assume a position to interfere as little as possible with the vision of its fellow:—so that, although at first, in squinting, there may be a double impression, vision is ultimately single. Buffon,1 who was of this opinion, affirms, that he examined the eyes of many squinters, and found that they were of unequal power; the weaker, in all cases, having turned away from its direction, and generally towards the nose, in order that fewer rays might reach it, and consequently vision be less interfered with. Yet it is always found, if the sound eye be closed, that the other resumes its proper direction; a fact which disproves the idea of De La Hire2 and others that the cause of strabis- mus or squinting is a difference of sensibility in the corresponding points of the retinae, and that the discordance in the movements of the organs occurs in order that the images may still fall upon points of the retinae that are equally sensible. According to this view, both eyes must of course act. The fact of the diverted eye resuming its proper direction when the sound one is closed is of practical application. Many of the cases of squinting that occur in infancy have been caused by irregular action in the muscles of the eyeball; so that certain of them, from accident or imitation, having been used more frequently than others, the due equilibrium has not been maintained; double vision has resulted; and the affected eye has gradually attained its full obliquity. In these cases, we can, at times, remedy the defect, by placing a bright or con- spicuous object in such a position as to exercise the enfeebled muscles; or, we can compel the whole labour of vision to be effected by one eye, and that the affected one, which, under the stimulus, will be correctly executed, and, by perseverance, the inequality may be obviated. These, indeed, are the only cases in which we can expect to afford relief; for if the defect be in the interior of the eye, in a radical want of correspondence between the retinae, or in inequality of the foci, it is irremediable. It would appear, then, that in confirmed squinting, one eye is mainly, if not solely used, and vision is single,—and that the inclination of one eye inwards may be so great as to deprive it of function, or so slight as to allow the organ to receive rays from the same object as its fellow, and although on different parts of the retina, yet they may become asso- ciated; but, in either case, it would seem, that they, who squint habitu- ally, neglect the impressions on the distorted eye, and see with but one.' It has been remarked, that the eyeball of the imperfect eye is drawn towards the nose, in order that as few rays as possible may penetrate the organ, and the vision of the sound eye be less liable to confusion. Sir Everard Home3 conceives, that it takes this direction in consequence ■ Mem. de I'Academie, 1743, p. 231. * Ibid., torn. ix. 530; Jurin, in Essay appended to Smith's Optics, §§ 178-194. 3 Philos. Transact, 1797, and Lectures on Comparative Anatomy, iii. 238, Lond., 1823. 278 SENSE OF SIGHT. of the adductor muscle being stronger, shorter, and its course more in a straight line than that of any of the other muscles ; and Sir Charles Bell1 ingeniously applies his classification of the muscles of the eye to an explanation of the fact. He asserts, that the recti muscles are in activity whilst attention is paid to the impression on the retina,—but that, when the attention is withdrawn, the recti are relieved, and the eyeball is given up to the influence of the oblique muscles, whose state of equilibrium exists when the eyeball is turned, and the pupil pre- sented, upwards and inwards. Lastly, in persons who are in the habit of making repeated celestial observations, or in those who make much use of the microscope, the attention is so entirely directed to one eye, that the other is neglected, and, in time, wanders about, so as to produce squinting at the pleasure of the individual. In these cases, the eyes become of unequal power; so that one only can be employed where distinct vision is required. Thus far our remarks have been directed to double vision, where both eyes are employed. "We have now to mention a singular fact con- nected with double and multiple vision with one eye only. The author has distinct double vision with each eye ; a lighted lamp, for example, presenting to one, with the other closed, two defined images, the one in advance of the other. If a hair, a needle, or any small object be held before one eye—the other being closed—and within the point of distinct vision, so that the bright light of a lamp or from a window shall fall upon the object in its passage to the eye, or be reflected from it—we appear to see not one object but many. This fact, when it was first observed by the author, appeared to him to have escaped the ob- servation of opticians and physiologists, inasmuch as it had not been noticed in any of the works recently published on optics or physiology. On reference, however, to the excellent " system," of Smith,2 on the for- mer subject, he found in the "Essay upon Distinct and Indistinct Vision" by Dr. Jurin, appended to it, the whole phenomenon explained, and elu- cidated at considerable length. The elaborate character of the expla- nation is probably the cause, why the fact has not been noticed by sub- sequent writers. The best way of trying the experiment is that sug- gested by Dr. Jurin. Take a parallel ruler, and opening it slightly, hold it directly before the eye, so as to look at a window or lamp through the aperture. If the ruler be held at the visual point, the aperture will appear to form one luminous line; but if it be brought nearer to the eye, it will appear double ; or as two luminous lines, with a dark line between them ; and according as the aperture is varied—or the dis- tance from the eye—two, three, four, five or more luminous and dark parallel lines will be perceptible. At first sight, it might seem, that this phenomenon should be referred to the diffraction or inflection, which light experiences in passing by the edges of a small body,—as the hair or needle. Newton had long ago shown, that, when a beam of light shines upon a hair, the hair will cast several distinct shadows upon a screen, and, of course, present several images to the eye. Dr. Rittenhouse3 explains, on the same principle, a ' Anat and Physiol., edit, cit, ii. 235. 2 Optics, edit cit. ' Amer. Philos. Transact, vol. ii. MULTIPLE VISION WITH ONE EYE. 279 curious optical appearance, noticed by Mr. Hopkinson, in which, by the inflection of light, caused by the threads of a silk handkerchief, a mul- tiple image of a distant lamp was presented. The objections, however, to the explanation by inflection are,—that the image always appears sin- gle, if the object be not within the distance of distinct vision ;—and that the same multiple image is presented, when the object is seen by reflection, as when we look at a fine line drawn upon paper; or at a fine needle held in a bright light. In this case, a considerable number of parallel images of the needle may be seen, all equally or nearly equally distinct; and not coloured. Dr. Jurin considers the phenomena to be caused by fits of easy re- fraction and reflection of light. Newton demonstrated, that the rays of light are not, in all parts of their progress, in the same disposition to be transmitted from one transparent medium into another; and that sometimes a ray, which is transmitted through the surface of the second medium, would be reflected back from that surface, if the ray had a little farther to go before it impinged upon it. This change of dispo- sition in the rays,—to be either transmitted by refraction, or to be re- flected by the surface of a transparent medium,—he called their fits of easy refraction, and fits of easy reflection; and he showed, that these fits succeed each other alternately at very small intervals in the pro- gress of the rays. Newton does not attempt to explain the origin of these fits, or the cause that produces them ; but it has been suggested, that a tolerable idea of them may be formed by supposing, that each particle of light, after its emanation from a body, revolves round an axis perpendicular to the direction of its motion, and presents alter- nately to the line of its motion an attractive and a repulsive pole, in virtue of which it will be refracted, if the attractive pole be nearest any refracting surface on which it falls; and reflected, if the repulsive pole be nearest the surface. A less scientific notion of the hypothesis has been suggested; by sup- posing a body with a sharp and a blunt end passing through space, and successively presenting its sharp and blunt ends to the line of its mo- tion. When the sharp end encounters any soft Fig. 125. body it penetrates it; c but when the blunt end ^/^CT^-^ encounters the same body, x^r^^^fcgg^^ T it is reflected or driven ^^^^^^^^^^^^^^^ back. In applying this ^^^^^--f^-^^^^^^^^^^^^^a^ explanation to the pheno- ^^^^ffffZ._____^^^^^t^^^^^^U menon in question, Dr. ' ^^j^r"""—-- ====^^SB^^^^3^5i^^ Jurin presumes, that the ^^^^^^^^^^^^^^^^^^ light, in passing through ^^o^^B^^^^^ the humours of the eye, n^P^^--^^ experiences these fits of t*^^ easy refraction and easy „ ... . ... . ..... „ n ,. m, . ... ,•' Multiple Vision with One Eye. reflection. This will be elucidated by the marginal figure, Fig. 125. Suppose a number of rays of light to proceed from the point A, and to impinge, with dif- 280 SENSE OF SIGHT. ferent degrees of obliquity, on the denser medium, B C ; all the rays that are in fits of easy refraction will pass through the medium to the point D; whilst those that are in fits of easy reflection, will be thrown back into the medium ABC; so that we may presume, that all the rays, which fall upon the parts of the medium B C, correspond- ing to the bases of the dark cones, will be reflected back, whilst those that correspond to the bases of the light cones, will pass to a focus at D. Now, if all the bundles of rays, trans- mitted through the surface B C, be accurately collected into a focus, no other consequence will arise from the other bundles of rays hav- ing been reflected back, than that the focus will be less luminous than it would have been had all the rays been transmitted through it. This explains why, at the distance of distinct vision, we have only a single impression made on the eye. But if we approach the object A, so that the focus is not thrown,—say upon the screen R T, which may be presumed to represent the retina — but behind it; the dark and light spaces will be represented upon the screen, and, of course, in concentric circles. This hap- pens to the eye, when the hair or needle or other object is brought nearer to it than the visual point. We can thus understand, why concentric circles, of the nature mentioned, should be formed upon the retina; but how is it, that the objects seen preserve their linear form ? Suppose a b, Fig. 126, to be a luminous cone, which in a fit of easy refraction has im- pinged upon the retina; and A B, b a, the concentric circles, corre- sponding to the rays that have been reflected. It is Obvious, that every point of the object will be the centre of so many concentric circles on the retina ; and if we imagine the fits of easy reflection and refraction to be the same aroUnd those points, we shall have the dark and lucid lines represented by the tangents to these circles ; and hence we can comprehend why, instead of having one lucid line e f, we have three, separated by dark lines parallel to them; and if the light from the luminous point be strong enough to form more lucid rings than are re- presented in Fig. 126, and the breadth of those rings be not too minute to be perceived, we may have the appearance of five, seven, or more lucid lines, separated by parallel dark lines. The undulatory theory of light offers another explanation of the phenomenon of fits. The waves in the luminous ether along a ray of light, may meet the surface of a transparent body in different conditions of condensation or rarefaction, and their transmission or reflection may be determined by these conditions. G c e E i Multiple Vision with One Eye. We proceed now to consider the advantages, which the mind derives from the possession of this sense, so pre-eminently entitled to the epithet INSENSIBILITY OF THE EYE TO COLOURS. 281 intellectual. Its immediate function is to give us the sensation of light and colour. In this it cannot be supplied by any of the other senses. The action is, therefore, the result of organization; or is a " law of the constitution;" requires no education; but is exercised as soon as the organ has acquired the proper developement. Yet, occasionally, we meet with cases, in which the eye appears to be totally insensible to certain colours, although capable of performing the most delicate functions of vision. Sir David Brewster1 has collected several of these cases from various sources. A shoemaker of the name of Harris, at Allonby, in Cumberland, could only distinguish black and white; and whilst a child, could not discriminate the cherries on a tree from the leaves, except by their shape and size. Two of his brothers were almost equally defective. One of them constantly mistook orange for grass green, and light green for yellow. A Mr. Scott, who describes his own case,2 mistook pink for pale blue, and full red for full green. His father, his maternal uncle, one of his sisters, and her two sons, had the same defect. A Mr. R. Tucker, son of Dr. Tucker, of Ashburton, mistakes orange for green, like one of the Harrises; and cannot dis- tinguish blue from pink, but almost always knows yellow. He mistakes red for brown, orange for green, and indigo and violet for purple. A tailor at Plymouth, whose case is described by Mr. Harvey,3 of Ply- mouth, regarded the solar spectrum as consisting only of yellow and light blue; and he could distinguish, with certainty, only yellow, white and gray. He regarded indigo and Prussian blue as black; and purple as a modification of blue. Green puzzled him exceedingly; the darker kinds appearing to him brown, and the lighter kinds a pale orange. On one occasion, he repaired an article of dress with crimson instead of black silk; and on another occasion patched the elbow of a blue coat with a piece of crimson cloth. A still more striking case is given by Dr. Nicholls4 of a person in the British navy, who purchased a blue uniform coat and waistcoat, with red breeches to match. Sir David Brewster refers to a case that fell under his own observation, where the gentleman saw only the yellow and blue colours of the spectrum. This defect was experienced by Mr. Dugald Stewart,5 who was unable to perceive any difference between the colour of the scarlet fruit of the Siberian crab and that of its leaves. Dr. Dalton,6 the chemist and philosopher,—after whom the defect has been most unjustifiably termed daltonism,—could not distinguish blue from pink by daylight; and in the solar spectrum, the red was scarcely visible; the rest of it appear- ing to consist of two colours, yellow and blue. Mr. Troughton, the optician, was fully capable of appreciating only blue and yellow; and when he named colours, the terms blue and yellow corresponded to the more or less refrangible rays:—all those that belong to the former, exciting the sensation of blueness; and those that belong to the latter that of yellowness. Dr. Hays,7 who has collected the history of nume- 1 Optics, edit, cit; Letters on Natural Magic; and art. Optics, in Library of Useful Know- ledge. * Philos. Trans, for 1778. 3 Edinb. Phil. Transact, x. 253. 4 Medico-Chirurgical Trans., vii. 477, ix. 359. 6 Elements of the Philosophy of the Human Mind, ch. iii. 6 Manchester Memoirs, v. 28. 7 Proceedings of the American Philosophical Society for August 21, 1840. 282 SENSE OF SIGHT. rous cases of achromatopsia,—as this defect has been termed,—and has added the history of one which fell under his own care, was led to infer, from all his researches : 1, that entire inability of distinguishing colours may co-exist with perfect ability to perceive the forms of objects; 2, that the defect may extend to all but one colour, and in such case the colour recognised is always yellow; and, 3, that the defect may extend to all but two colours, and in such case the colours recognised are always yellow and blue;—yet that this is not the fact is sufficiently shown by the examples already given. Dr. Pliny Earle1 has referred to a number of cases, which came within his knowledge, and most of them under his own observation, in which the inability would seem to have been hereditary. Dr. Earle's maternal grandfather and two of his brothers were characterized by it; and among the descendants of the first mentioned, it is met with in seventeen. When thus entailed, it would appear to overleap, at times, one generation or more. It would appear, too, that males are more frequently affected than females. Dr. Earle observed, that the power of accurately distinguishing colours varies at different times in the same person; and that it is not unfre- quently connected with, or accompanied by, a defect in the power of discriminating musical tones. The -opinions of philosophers have varied regarding the cause of this singular defect in eyes otherwise sound, and capable of performing every other function of vision in the most delicate and accurate man- ner. By some, it has been presumed to arise from a deficiency in the visual organ; and by such as consider the ear to be defective in func- tion in those that are incapable of appreciating musical tones, this de- ficiency in the eye is conceived to be of an analogous nature; and the analogy is farther exhibited by the facts, just mentioned, observed by Dr. Earle. "In the sense of vision," says Dr. Brown,2 "there is a species of defect very analogous to the want of musical ear,—a defect which consists in the difficulty, or rather the incapacity, of distinguish- ing some colours from each other—and colours which, to general observers, seem of a very opposite kind. As the want of musical ear implies no general defect of mere quickness of hearing, this visual defect, in like manner, is to be found in persons who are yet capable of distinguishing, with perfect accuracy, the form, and the greater or less brilliancy of the coloured object; and I may remark, too, in con- firmation of the opinion, that the want of musical tone depends on causes not mental but organic, that in this analogous case some at- tempts, not absolutely unsuccessful, have been made to explain the apparent confusion of colours by certain peculiarities of the external organ of sight." Dr. Dalton, who believed the affection to be seated in the physical part of the organ, has endeavoured to explain his own case, by sup- posing, that the vitreous humour is blue, and therefore absorbs a great portion of the red and other least refrangible rays; and Sir David Brewster, in the "Library of Useful Knowledge,"3 appears to think 1 American Journal of the Medical Sciences, April, 1845, p. 346. 2 Lectures on the Philosophy of the Human Mind, vol. i., Boston, 1826. 3 Natural Philosophy, vol. i., Optics, p. 50, Lond., 1829. APPRECIATION OF DISTANCES. 283 that it may depend upon a want of sensibility in the retinae, similar to that observed in the ears of those who are incapable of hearing notes above a certain pitch; but as this view is not contained in his more recent " Treatise on Optics," it is probably no longer considered by him to be satisfactory. The defect in question—difficult as it is to comprehend—has always appeared to the author to be entirely cerebral, and to strikingly re- semble, as Dr. Brown has suggested, the " want of musical ear." As we have already endeavoured to establish, that the latter is dependent upon a defective mental appreciation, the parity of the two cases will, of course, compel us to refer the visual defect, or the want of the "fa- culty of colouring," to the same cause. It has been remarked, that the eye in these cases exercises its function perfectly as regards the form and position of objects, and the degree of illumination of their different portions. The only defect is in the conception of colour. The nerve of sight is probably accurately impressed, and the deficiency is in the part of the brain whither the impression is conveyed, and where perception is effected, which is incapable of accurately appreci- ating those differences between rays, on which their colour rests; and this is the view taken of it by one of the most eminent philosophers of the present day, Sir J. F. W. Herschel.1 The mediate or auxiliary functions of vision are numerous; hence, the elevated rank that has been assigned to it. By it, we are capable of judging, to a certain extent, of the direction, position, magnitude, distance, surface, and motion of bodies. Metaphysicians have differed greatly in their views on this subject; the majority be- lieving, that, without the sense of touch, the eye is incapable of form- ing any accurate judgment on these points; others, that the sense of touch is no farther necessary than as an auxiliary; and that a correct appreciation could be formed by sight alone. The few remarks that may be necessary on this subject will be deferred until the physical and other circumstances which enable us to judge of distance, &c, have been canvassed. The direction or position of objects has already been considered, so far as regards the inverted image formed by them on the retina. The errors that arise on this point are by no means numerous, and seldom give rise to much inconvenience; yet, whenever the luminous cone meets with reflection or refraction before reaching the eye, the retina conveys erroneous information to the sensorium, and we experience an optical illusion. To ascertain the magnitude, distance, and surface of bodies, we are obliged to take into consideration several circumstances connected with the appearance of the object,—such as its apparent size; the intensity of light, shade, and colour; the convergence of the axes of the eyes; the size or position of intervening objects, &c. Porterfield2 enumerates six methods, which are employed in appreciating distance—1. The 1 Encyclopaedia Metropolitana, art. Light ' A Treatise on the Eye, ii. 409, London, 1759. 284 SENSE OF SIGHT. apparent magnitude of objects; 2. The vivacity of their colours; 3. The distinction of their smaller parts; 4. The necessary conformation of the eyes for seeing distinctly at different distances; 5. The direction of their axes; and 6. The interposition of objects. Dr. Brown1 re- duces them to three—1. The difference of the affections of the optic nerve; 2. The different affections of the muscles, employed in varying the refracting power of each eye, according to the distance of objects, and in producing that particular inclination of the axes of the two eyes which directs them both equally on a particular object; and 3. The previous knowledge of the distance of other objects, "which form, with that we are considering, a part of one compound perception." Lastly, Dr. Arnott2 enumerates four modes by which this is effected—1. The space and place, occupied by objects in the field of view, measured by what is termed the visual angle. 2. The intensity of light, shade, and colour. 3. The divergence of the rays of light—and 4. The converg- ence of the axes of the eyes. This enumeration may be adopted with some slight modifications. The circumstances, in our opinion, to be considered, are:— 1. The visual angle, or that formed by two lines, which shave the extremities of an object and cross at Fis-l27- the centre of the crystalline; so that the visual angle, subtended by the object, as A B, Fig. 127, is exactly equal to that subtended by its image a b on the retina. It is obvious, from this figure, that if all objects were equidistant from the eye, and of the same magnitude, they would subtend Visual Angle. the same angle; and if not of the same magnitude, the difference would be accurately indicated-by the difference of the visual angles subtended by them. The two arrows, however, which are of different sizes, sub- tend the same visual angle, and are alike represented on the retina by the image a b. It is clear, then, that the visual angle does not give us a correct idea of the relative magnitudes of bodies, unless we are acquainted with their respective distances from the eye; and, con- versely, we cannot judge accurately of their distances, without being aware of their magnitudes. A man on horseback, when near us, sub- tends a certain visual angle; but, as he recedes from us, the angle be- comes less and less; yet we always judge accurately of his size, because aware of it by experience; but if objects are at a great distance, so as not to admit of their being compared with nearer, by simple vision, we are in a constant state of illusion,—irresistibly believing, that they are much smaller than they really are. This is the case with the heavenly bodies. The head of a pin held close to the eye subtends as large a visual angle as the planet Jupiter, which is one thousand two hundred and eighty-one times bigger than this earth, and is eighty-six thousand miles in diameter. In like manner, a five-cent piece, held at some 1 Lectures on the Philosophy of the Human Mind, vol. i., Boston, 1826. ' Elements of Physics, new Amer. edit, p. 383, Philad., 1841. APPRECIATION OF DISTANCES. 285 distance from the eye, shuts off the sun, although its diameter is eight hundred and eighty-eight thousand miles. The sun and moon, again, by subtending nearly the same visual angle, appear to us of nearly the same size; and the illusion persists in spite of our being aware of the mathematical accuracy, with which it has been determined, that the former is ninety-six millions of miles from us, and the latter only two hundred and forty thousand. The visual angle, again, subtended by an object, differs greatly according to the position of the object. A sphere has the same appearance or bulk, when held at a certain dis- tance from the eye, whatever may be the position in which it is viewed; and, accordingly, the visual angle, subtended by it, is always identical. Not so, however, with an oval. If held, so that the rays from one of its ends shall impress the eye, it will occasion a circular image, and subtend a much smaller angle than if viewed sideways, when the image will be elliptical, or oval. The same thing must occur with every object, whose longitudinal and transverse diameters differ. It is obvious, that if any such object be held in a sloping position towards the eye, it will appear more or less shortened; in the same manner as the slope of a mountain or inclined plane would appear much greater, if placed perpendicularly before the eye. This appearance is what is called foreshortening ; and it may be elucidated by the following figure. Suppose a man to be standing on a level plain, with his eye at c (Fig. 128), looking down on the plain. The portion of the surface a d, which is next to him, will be seen without any foreshortening; but if we sup- pose him to regard succes- sively the portions df,fg, and g b of the plain, the angle, subtended by each portion, will diminish; so that if the angle a c d be 45°, d \. Concave Mirror. Fig. 131. Fig. 130. eye. If the mirror be concave, the object appears magnified, provided the light from the upper part of the object, as A B, Fig. 130, be reflected to an eye at F, and that from the lower part of the object meet the other at this point. To an eye so placed, the object appears magnified and seems to be at C D, or in the prolongation of the rays which fall upon the cornea. If the mirror be convex (Fig. 131), for like reasons, the cross will seem to be smaller. The cornea constitutes a mirror of this class, in which we have an accurate miniature representation of objects. Rays that are refracted in passing through different media, give rise to visual illusions. We have seen, that the ray from an object at F, Fig. 77, in the pool of water, I J, does not proceed into the air in the direction of F C 0, but in that of the line F C A; and if we suppose the eye to be placed at A, the object will not be seen at F, but will appear to be at /; the pool will, consequently, appear shallower than it really is, by the space at which/ is situate above the bottom. We can now understand why rivers appear less deep than .they are, when viewed obliquely; and why the lower end of a pole, immersed in water, should, when seen obliquely, appear to be bent towards the surface. In shooting fish in the water, or in attempting to harpoon them, this source of error has to be cor- rected. Birds, too, that live upon the inhabitants of the water, have to learn, from experience, to obviate the optical illusion; or to descend perpendicularly upon their prey, in which direction, as we have seen, no refraction takes place. Similar remarks apply to fish that leap out of the streams to catch objects in the air. The Chaetodon rostratus, about six or eight inches long, frequents the sea-shores in the East Indies: when it observes a fly sitting on the plants that grow in shallow water it swims to the distance of five or six feet, and then, with sur- prising dexterity, ejects out of its tubular mouth a single drop of water, Convex Mirror. DURATION OF IMPRESSION OF LIGHT. 295 which never fails to strike the fly into the sea, where it soon becomes its prey.1 Hommel—a Dutch governor—put some of these fish into a tub of water, and pinned a fly on a stick within their reach. He daily saw the fish shoot at the fly, and with such dexterity, that they never failed to hit the mark.2 Pallas describes the Siaena jaculatrix as securing flies by a similar contrivance.3 If the light, before reaching the eye, passes through bodies of a len- ticular shape, it undergoes modifications, which have given occasion to the formation of useful instruments devised for modifying the sphere of vision. If the lens be double convex, the body, seen through it, appears larger than it is, from the illusion, so often referred to, that we always refer the object in the direction of the line that impinges upon the retina. The object, consequently, appears to be greatly aug- mented. (See Fig. 83.) For the same reasons an object seems smaller to the eye at A, Fig. 80, when viewed through a double concave lens. Again, if the light, before reaching the cornea, be made to pass through a diaphanous body, which is itself coloured, and consequently allows only the rays of its own colour to traverse it, the object is not seen of its proper colour, but of that of the transparent body. An impression of light continues to affect the retina for some time after the impression has ceased, certainly for the sixth part of a second.4 If, therefore, a live coal be whirled round, six or seven times in a second, it will seem to be a continuous circle of fire. It is owing to this cir- cumstance, that meteors seem to form a line of light—as in the case of the falling star; and that the same impression is conveyed by a sky- rocket in its course through the air. We have an elucidation of the same fact in the instrument or toy—called, by Dr. Paris, thaumatrope— which consists of a circle, cut out of a card, and having two silken strings attached to opposite points of its diameter: by twisting these with the finger and thumb the card may be twirled round with consider- able velocity. If we make on one side a black stripe as in the marginal figure 132, and on the other side one at right angles to it, Fig. 133, and cause the card to revolve rapidly, we shall see a cross. And if on one side Fig. 132. Fig. 133. of the card a chariot is drawn—and on the other a charioteer, and the card be twirled round six or seven times in a second, the charioteer will be seen in the chariot,—the duration of the impressions on the retina being ' Fleming's Philos. of Zoology, i. 195. 2 Philos. Trans., liv. 89. 8 Philos. Trans., lvi. 186; also, Mr. Sharon Turner's Sacred History of the World Amer edit, i. 205, New York, 1832. « D'Arcy, Memoires de l'Academie des Sciences, p. 439, Paris, 1765; and Plateau, Annales de Chimie, &c, vol. lviii. p. 401. 296 ADDITIONAL SENSES. such as to cause the figures, drawn on both sides of the card, to be seen at nearly the same time. The phantasmascope, phenakistiscope and anorthoscope, act upon similar principles.1 It is by accurate attention to various optical illusions, and to the laws of the animal economy on which they are founded, that many of them can be produced in the arts at pleasure. Painting is, in truth, little more than depicting on canvass the various optical errors, which we are habitually incurring. To conclude:—the sense of sight differs materially in the scale of animals: in few is the organization more perfect or the function better executed than in man. Situate at the upper and anterior part of the body, the organ of vision is capable of directing its regards over a large extent of surface: the axes of the two organs can be converged upon objects in various situations, which cannot be done by many animals; and they are very movable under the domination of a muscular appa- ratus of admirable arrangement. Still, the eye is not as delicately organized as in some animals, wThich are capable of seeing objects at a distance that would be totally beyond the reach of the visual powers of man. Like the other senses, sight can be exerted actively and passively; hence the difference between simply seeing, and looking. In the latter, the eye is directed to the object by the proper muscles; and it is not improbable, that the nerve may be aroused to a more accurate and deli- cate reception of impressions, as we have reason for believing is the case in the other senses. Like them, it admits of great improvement by education. The painter, and the worker in colours are capable of nice discrimination, and detect the minutest shades of difference with great facility. In savage life, where the tracks or marks through the almost interminable forests, or over the pathless wilds, are the only guides, the greatest acuteness of vision is necessary; and, accordingly, we find the North American Indian, in this respect, eminently distin- guished. The mariner, too, accustomed to look out for land, or for a hostile sail, detects it in the distant horizon long before it can be per- ceived by the landsman, and appreciates its distance and course with signal accuracy,—education, in this case, not only communicating to his eye facility in being impressed, but improving the intellectual pro- cess, by which the estimation of distances is arrived at. ADDITIONAL SENSES. The five senses constitute so many special nervous systems, each concerned in its appropriate function; and, although conveying ideas of the external world to the brain, and connected with that organ, they are to a certain extent independent of it. The generality of physiologists admit these five only; but some have suggested others, differing, in general, from the five, in having no organ at the surface of the body exclusively concerned in the function. Buffon regarded as a sixth sense the intense sensation experienced during the venereal act; but this can 1 Miiller, Principles of Physics and Meteorology, p. 310, Philad., 1848. ADDITIONAL SENSES. 297 only be esteemed a peculiar variety of tact in the mucous membrane of the genital organs,—differing from ordinary tact in those parts, in requiring in both sexes a special condition of the membrane; and, in the male, one such, that the sperm, when excreted, shall make the neces- sary impression upon it; and, consequently, appertaining to both the external and internal sensations;—the state of the membrane being referable to the latter, and the effect of the contact of the sperm to the former. Some have spoken of a sense of heat and cold:—this has been referred to under the head of tact;—others of a muscular sense, by which we acquire a knowledge of the motions that muscular contractions give rise to, and learn to apportion the effort to the degree of effect to be produced. Animal magnetizers have suggested a sixth sense, to which man owes the capability of being acted upon by them: but this is suppo- sititious, and the facts admit of a more ready and satisfactory explana- tion. A sense of hunger has been described as situate at the upper orifice of the stomach:—a sense of thirst in the oesophagus, and a pneu- matic sense in the lungs; but these are rather internal sensations. The German physiologists have suggested another sense, which they term coensesthesis, Gemeingef iihl, Gemeinsinn, Korpergefiihl, Lebenssinn, Individualitatssinn, and Selbstgefuhl ("common feeling, common sensation, bodily feeling, feeling of life, sense of life, sense of individuality, and self-feeling"). This is not seated in any particular part of the body, but over the whole system; hence termed "common." It is indicated by the lightness and buoyancy, which we occasionally experience, apparently without any adequate cause; as well as by a sense of lassitude and fatigue unconnected with muscular action or disease. To it, likewise, belong the involuntary shuddering, glow, and chilliness, experienced under like circumstances. It is manifestly one of the numerous internal sensations, felt by the frame, and every portion of it, according as they are in a perfect state of health, or labouring under irritation or oppression; but can scarcely be regarded as an additional or sixth sense.1 It has been supposed, that certain animals may possess other senses than the five. Of this we can have no positive evidence. We are devoid of the means of judging of their sensations; and if we meet with an additional organ, which seems adapted for such a purpose, we have nothing but conjecture to guide us. Under the sense of touch it was said, that the bat is found to be capable of avoiding obstacles placed in its way intentionally, when the eyes, nostrils, &c, have been closed up; and that it readily returns to the holes in caverns to which it is habituated. Spallanzani supposed that this was owing to its being possessed of a sixth sense. We have seen, that the circumstance is explicable by unusual delicacy of one of the external senses. Again; the accuracy with which migratory animals return to their accustomed haunts, has given rise to the notion of a sense of locality. Quadrupeds, the ape not excepted, have two bones in the face, in ' Purkinje, art. Coenaesthesis, in Encycl. Worterb. der Medicinisch. Wissenschaft viii. 116, Berlin, 1832; and Muller's Elements of Physiology, by Baly, P. v. p. 1087, London, 1839. See, also, E. H. Weber, art. Tastsinn und das Gemeingefuhl, in Wagner's Handworterbuch der Physiologie, 22ste Lieferung, s. 562, Braunschweig, 1849. 298 ADDITIONAL SENSES. addition to those found in man. These contain the roots of the dentes incisores, when such are present; but they also exist in animals that are destitute of teeth. They are termed ossa intermaxillaria, ossa incisoria, and ossa labialia; and are situate, as their names import, at the anterior part of the jaw, and between the ossa maxillaria or jaw bones. Jacobson1 considers them to be an organ of sense, as they communicate with the exterior, and are largely supplied with vessels and nerves. Accordingly, this has been esteemed a sensitive apparatus, connected with the season of love in animals ; and, by other naturalists, as a sense intermediate between those of taste and smell, and intended to guide the animal in the proper selection of food. It need hardly be said, that this is all imaginary. M. Adelon,2 it was remarked, makes two divisions of the external sensations:—those that convey information to the mind; and those that do not. The former have engaged attention; the latter will not occupy us long. They comprise but two—itching and tickling. Both of these occur in the skin and mucous membranes, and near the com- munication of the latter with the skin; or, in other words, near the termination of the outlets which they line. Itching, however, is not always an external sensation,—that is, not always caused by the contact of a body external to it. It frequently arises from an altered condi- tion of the organic actions of the part in which it is experienced, as in cutaneous affections; in itching at the nose produced by irritation in the intestinal canal; itching of the glans penis in cases of calculi of the urinary bladder, &c.; but commonly the sensation is caused by an extraneous body, and we are irresistibly led to scratch, no matter how it may be caused. When it arises extraneously, it can generally be readily allayed; but, when dependent upon a morbid condition of the texture of the part, it becomes a true disease, and the source of much suffering. If the itching be accompanied with a feeling of motion, or of purring in the part, it is called tingling. This kind of purring often occurs without itching. Tickling or titillation is always caused by the contact of some ex- traneous substance; and is therefore a true external sensation. Although occurring in the skin, and in the commencement or termination of the mucous membranes, all parts are not equally susceptible of it; and some,—as the lining membrane of the genital organs,—are only, or chiefly so, under special circumstances. The sides, palms of the hands, and soles of the feet, are the most sensitive in this respect; not, per- haps, because the nerves are more numerous in those parts, but because, owing to thinness or suppleness of skin, or to other inappreciable cir- cumstances, they are more susceptible of this kind of excitation. We find, too, that individuals differ as much as the parts of the body do in this respect;—some being not ticklish, or incapable of being thrown into the spasm, which the act,—nay, even the threatening of the act, —produces in others. Cases are on record, in which prolonged titilla- tion has caused general convulsions, and even death. Le Cat3 terms 1 Annales du Musee, xviii. 412. 2 Physiologie de l'Homme, 2de edit, i. 481, Paris, 1829. 3 Traite des Sens, Paris, 1767. INTERNAL SENSATIONS. 299 it an hermaphroditic sensation, inasmuch as, whilst it excites laughter, it is insupportable; and, consequently, seems to be intermediate between pleasure and pain. c. Internal Sensations. The external sensations make us acquainted with the universe sur- rounding us ; and convey to the mind a knowledge of every thing that can be, in any manner, inservient to our necessities. Such necessities have, however, to be suggested to the mind, before it reacts through the aid of the organs of prehension or otherwise on external bodies, and this is accomplished by the internal or organic sensations. Without the intervention of an external cause, every organ of the body is capable of transmitting to the encephalon a number of different impressions, many of which impel the organs to acts that are necessary not only for the preservation of the individual and of the species, but also for the perfect developement of the faculties. Such are the sensa- tions of hunger and thirst; the impulse that leads to the union of the sexes; and the feeling we have of the necessity for intermission in the exercise of the muscles, and the intellect. They have been divided into three species by some physiologists;—the first arousing, or giving impulse to, the action of organs, and warning the brain of the different necessities of the system. They have been called wants or instinctive desires.1 Such are hunger, thirst, the desire to evacuate the urine and faeces; that of respiration, the venereal appetite {le genesique, amour physique), accouchement, &c. They belong to those that arise, when it is necessary the organs should act.—The second occur during the action of organs. They are often obscure, but sometimes acute. Amongst these are the impressions accompanying the different excre- tions,—as of the sperm, urine, &c. (although, as we have seen, these partly belong to the external sensations); the impressions that warn us of our partial or general movements, of the progress of digestion, and of intellectual labours. The last succeed to the action of organs, especially when such action has been too long continued; hence the inward feeling of fatigue after too long exertion of the functions of the senses, of the intellectual and moral faculties, and of the organs of muscular motion; the necessity of repose after prolonged muscular exertion; and of sleep, to recruit the nervous system, and to fit it for the exertions it has to make during the waking condition. The mode in which these sensations are effected is analogous to that of the external sensations. There is an impression on the part to which the sensation is referred; an action of perception accomplished by the encephalon; and one of transmission, executed by a nerve passing between the two. The last two actions are probably executed in the same manner as in the external sensations. The first, or the mode in which the impression is effected, and the character of the im- pression itself, are more obscure. In the external sensations, we can refer the impression to a known irritant,—special in some of the senses: ' Adelon, art. Besoins, in Diet de Medecine, i. 367, Paris, 1821; and Physiologie de l'Homme, i. 482. 300 MORBID SENSATIONS. —more general in others. We know, that light impresses the retina; —aerial undulations the acoustic nerve, &c.; but, in the internal sen- sations or sentiments, as some of the French writers term them, the source of the irritation is in some modified action of the part itself, in the very tissue of the organ, and hence the result is said to be organic. In the internal sensation of hunger, for example, the impression is en- gendered in the organ,—how, we know not,—is thence conveyed to the brain, and the sensation is not effected until the latter has acted. The same may be said of all the internal sensations. They differ, in other respects, also, from the external. Whilst the latter may be entirely passive, or rendered active by volition, without either action being the cause of particular pleasure or inconvenience, the former are little influenced by volition. Constituting the wants—the instinctive desires—which impel to acts, that are necessary for the preservation and full developement of the individual and of the species, such in- dependence is of course essential. On many of them, however, habit or accustomed volition has a certain degree of influence; and they can unquestionably be augmented or moderated by licentious indulgence or restraint. The influence of habit is exemplified by the regularity with which the appetite returns at stated intervals; and by the differ- ence between that of the gourmand and of the temperate individual. It is most strikingly evidenced, however, in its influence over the moral wants; which may even spring up from social indulgence, and hence are not instinctive or organic. We are every day compelled to witness the striking difference between the individual who practises restraint upon his wants, and the libertine, who, like the animals sur- rounding him, gives unbridled sway to his natural and acquired appe- tites. All the internal sensations, when satisfied or responded to in mode- ration, communicate a feeling of pleasure; but if resisted, pain re- sults. If hunger be prolonged, there is a general feeling of uneasi- ness, which rapidly abates after food is received into the stomach; but if satiety be produced, uneasiness follows; and this applies to all the appetites or wants. The special internal sensations will engage us, when the functions to which they belong fall under consideration. Like the external sensations, they must, of course, administer to the intellect, to an extent which will be seen hereafter. Their influence and nature were entirely neglected until of comparatively late years, when attention was directed to them chiefly through the labours of MM. Cabanis1 and of Destutt-Tracy ;2 and they now form subjects for interesting speculation, with the metaphysician more especially. The morbid sensations belong more particularly to pathology; a brief notice of them will consequently be all that is necessary here. They are comprised under the term pain. In its enlarged significa- tion, this word, as is well known, means every uneasy or disagreeable sensation or moral affection;—thus including sadness, anger, terror, as well as the painful impressions felt in the extremities or trunks of 1 Rapport du Physique et du Morale de l'Homme, torn, ii., Paris, 1802. * Elemens d'Ideologie, 2de edit, Paris, 1804. MENTAL FACULTIES. 301 the nerves. It is the latter only—or physical pain—that concerns us at present. Like every other sensation, although it may be referred exclusively to the part impressed, pain requires the intervention of the encephalon ; for if the nerves, proceeding from a part to that organ, be cut, tied, compressed, or stupefied by narcotics; or if the action of the brain itself be blunted from any cause, as by the use of opium, ether, or chloroform, or by any compression, accidental or other, the sensation is no longer experienced. We can thus understand why pain is felt less during sleep; and the astonishing cases of resistance to pain, witnessed in the lunatic, and in religious or other enthusiasts who have been subjected to bodily torture. An opposite condition of the nerv- ous system is the cause of the great sensibility to impressions in the nervous and hysterical. It is obvious, that pain may be either an external or internal sensa- tion, according as the cause of irritation is extraneous, or seated in the tissue of organs ; and that it must vary considerably, both as re- gards the precise irritant, and the part affected; hence the difference between the pain caused by a burn, and that by a cutting instrument; and the immense variety of pains to which the human frame is sub- ject, and the attentive study of which is so indispensable to the patho- logist. So much for the sensations. These, we have seen, are innumerable, for each sense is capable of myriads of different impressions. We now pass to the consideration of those functions that enable man—although worse provided with means of defence and offence than the beasts sur- rounding him, and possessing no covering to protect him from the sum- mer's heat or the winter's cold—to provide himself means of defence ; to render the animals around him subservient to his use; to cover his nakedness, and protect himself against atmospheric changes ; to devise mechanical arts; to fathom the laws, that govern the bodies by which he is surrounded, and to establish himself undisputed^ master of the earth. MENTAL FACULTIES. The external senses convey to the brain the different impressions made upon them by surrounding bodies; but, of themselves, they would be unable to instruct the mind regarding the universe. It is necessary, that the brain should act before any perception of them can exist. The mental faculties, in other words, convert the impressions into ideas. The internal sensations, on the other hand, consist, as we have seen, of the numerous wants and appetites necessary for the pre- servation of the individual, and the species. In addition to these, man possesses another series of faculties, which influence his character and disposition, and direct his social existence: these are the affective or emotive faculties or faculties of the heart. The study of these different mental and moral phenomena constitutes what has been called psycho- l°9y->—so termed from an idea, that they are exclusively dependent upon the mind. The notion was, at one time, universal, and hence the appellation metaphysician, applied to such as were considered to pro- ceed in their investigations beyond what was physical, material, or cor- poreal. 302 MENTAL FACULTIES. There is no subject, which has given occasion to so much excitement and controversy, as that of the connexion of the mental faculties with the encephalon. " It has unfortunately happened," says Dr. Bostock,3 " that this subject, which is one of great interest and curiosity, has sel- dom been viewed with that philosophical spirit which should always direct our investigations, and by which alone we can expect to arrive at truth. It is admitted, that certain errors may be so interwoven with our accustomed associations, on topics connected with morals and reli- gion, as to render it doubtful, on some occasions, how far we ought to attempt their removal; but if this concession be made on the one hand, it is incumbent upon us, on the other, not to inflame the prejudices, which may exist on these topics, but to use our endeavours to correct all undue excitement, and thus to bring the mind into that tranquil state, which may enable it to receive truth without fear of injury." In such a spirit ought every discussion on the subject to be conducted ; and in such a spirit will the few remarks that follow be offered. The chief opinions* which have been indulged on the subject are,— 1st. That all the mental phenomena are immaterial, and the exclusive product of the mind. 2dly. That the sentient principle within us re- quires the intervention of an organ, through which it acts; in other words, that mind is a principle superadded to organization ; and 3dly. That where there is no organization there is no perception :—that wher- ever an organized structure, like the brain, exists, perception exists ; that where the organization is imperfect, perception is imperfect; where the organization is sound and vigorous, perception is clear and vigorous; where it is impaired, perception is impaired; and that when organization ceases perception ceases also. This last view is ma- terialism. It supposes, that a certain condition of matter is capable of thinking, reasoning, and understanding. The doctrine,—that our intellectual and moral acts are superadded to organization, and that there is an organ concerned in their mani- festation, is the one embraced by the generality of physiologists, and is most consistent with reason and analogy: it is but justice, how- ever, to admit, that the views of those, who consider that a certain organization produces thought, are not deserving of the anathemas that have been directed against them on the score of irreligion. The charge would rather apply to those who doubt the power of Omnipo- tence to endow matter with such attributes. Were the mental and moral phenomena the exclusive products of the immaterial principle within us, they would hardly form subjects for physiological inquiry. That they are allied to organization is inferred for the following rea- sons. As they constitute so many functions, were they not provided with an organ or organs, they would form so many exceptions;—each of the sensations requiring an organ for its accomplishment. Again, our inward feeling induces us to refer them to a particular part of the frame: whilst thought appears to be effected within the head, the chief expressions of the passions are felt in the region of the heart or stomach. The faculties, moreover, are not the same in every individual. One * Physiology, 3d edit, p. 744, Lond., 1836. ORGAN OF THE MENTAL FACULTIES. 303 man is a poet; another a mathematician ; or one is benevolent, another cruel. If these faculties were the exclusive product of the mind, and of course not to be ascribed to diversity of organization, we should have to admit, that each individual has a different immaterial principle, and of course, that there must be as many kinds as there are individuals. Lastly. The faculties vary in the same individual according to circum- stances. They are not the same in the child as in the adult; in the adult as in one advanced in life; in health as in disease ; in waking as in sleep. During an attack of fever they become temporarily deranged; and are permanently so in all the varieties of insanity.1 These facts are inexplicable under the doctrine, that they are the exclusive product of the mind or immaterial principle. An immaterial or spiritual prin- ciple ought to be immutable ; yet we should have to suppose it capable of alteration; of growing with the growth of the body, and of becom- ing old with it; of being awake or asleep; sound or diseased. All these modifications must be caused by varying organization—of the brain in particular. We may conclude, then, that the intellectual and moral faculties are not the exclusive product of the mind; that they require the interven- tion of an organ; and, that this organ is the encephalon, or a part of it —the cerebrum or brain—is announced by many circumstances. In the first place, they are phenomena of sensibility, and hence we should be disposed to refer them to a nervous organ; and, being the most ele- vated phenomena of the kind, to the highest of the nervous organs. In the second place, inward feeling impels us to refer them thither. We not only feel the process there, during meditation; but the sense of fatigue, which succeeds to hard study, is felt there likewise. The brain, again, must be in a state of integrity, otherwise the faculties are de- ranged; or, for the time, abolished. In fever, it becomes affected directly or indirectly, and the consequence is, perversion of the intellect, in the form of delirium. If the organ be more permanently disordered, as by the pressure of an exostosis or tumour, or by some alteration in its structure or functions—less appreciable in its nature—insanity, in some form, may be the result. In serious accidents to the encephalon, we observe the importance of the cerebrum to the proper exercise of the mental faculties clearly evinced. A man falls from a height, and fractures his skull. The consequence is, depression of a portion of bone, which exerts a degree of compression upon the brain; or extravasation of blood from some of the encephalic vessels attended with similar results. From the moment of the infliction of the injury, the whole of the mental and moral mani- festations are suspended, and do not return until the compressing cause is removed by the operation of the trephine. M. Richerand cites the case of a female, who had a portion of the brain accidentally exposed, and in whom it was found, that pressing on the brain completely suspended consciousness, which was not restored until the pressure was removed. A similar case occurred to Professor Wistar; and another is related by 1 Adelon, art. Encephale, Diet de Medecine, vol. vii.; and Physiologie de l'Homme torn. i. edit. cit. 304 MENTAL FACULTIES. M. Lepelletier.1 A patient of a M. Pierquien had an extensive caries of the os frontis, with perforation of the bone, which exposed the brain covered by its membranes. When she slept soundly, the organ sank down; when she dreamed, or spoke with feeling, turgescence and marked oscillations were perceptible; when the brain was pressed upon, she stopped in the middle of a sentence or a word, and when the pres- sure was removed, she resumed the conversation, without any recollec- tion of the experiment to which she had been subjected. An important difference in the effect is, however, noticed in such cases according to the suddenness or tardiness with which the pressure is made. Whilst a sudden compression suspends the intellectual and moral manifesta- tions for a time; slow pressure, produced by the gradual formation of a tumour, may exist without exhibiting, in any manner, the evidences of its presence. Accordingly, the anatomist is at times surprised to discover such morbid formations in the brains of persons who have never laboured under any mental aberration. A negative argument in favour of this function of the brain has been deduced from the fact, that disease of other portions of the body, even of the principal organs, may exist and pass on to a fatal termination, leaving those faculties almost unimpaired. Such is proverbially the case with phthisis pulmonalis; the subject of which may be flattering himself with hopes never to be realized, and devising schemes of future aggrandizement and pleasure until within a few hours of his dissolution. The intellectual faculties differ in each individual, and vary mate- rially with the sex. The brain is, in all these cases, equally different. Much may depend upon education; but it may, we think, be laid down as an incontrovertible position, that there is an original difference in the cerebral organization of the man of genius and of him who is less gifted; and that, as a general rule, in the former the brain is much more developed than in the latter. Whilst the brain of the man of intellect may measure from nineteen to twenty-two inches in circum- ference, that of the idiot frequently does not exceed thirteen, or is not greater than in the child one year old. It was an ancient observation, that a large development of the anterior and superior parts of the head is a characteristic of genius; and, accordingly, we find, that all the statues of the sages and heroes of antiquity are represented with high and prominent foreheads. In the older poets, we meet with many evidences, that the height of the forehead was regarded as an index of the intellectual or moral character of the individual. Thus Shakspeare: "We shall lose our time, And all be turn'd to barnacles, or to apes, With foreheads villanous low." Caliban, in " Tempest."—Act iv. "Ay, but her forehead's low, and mine's as high." Julia, in the " Two Gentlemen of Verona."—Act iv. The relation between the size of the head and the mental manifesta- tions has, indeed, interwoven itself into our ordinary modes of speech. And again: 1 Physiologie Medicale, &c, iii. 242, Paris, 1832. THE BRAIN THE ORGAN OF THE MENTAL FACULTIES. 305 "Let it not be believed," says a distinguished writer,1 "an affair of accident, that a head of considerable dimensions is found, from time to time, to coincide with a distinguished genius. Although the amour propre may object, the law is general. I have neither met in antiquity, nor in modern times a man of vast genius, whose head ought not to be ranged in the latter class, which I have just established, especially if attention be paid to the great developement of the forehead. Look at the busts and engravings of Homer, Socrates, Plato, Demosthenes, Pliny, Bacon, Sully, Galileo, Montaigne, Corneille, Racine, Bossuet, Newton, Leibnitz, Locke, Pascal, Boerhaave, Haller, Montesquieu, Voltaire, J. J. Rousseau, Franklin, Diderot, Stoll, Kant, Schiller, &c." Yet we are not always accurate in estimating the size of the brain from the developement of the head. Dr. Sewall2 has clearly shown, that skulls of the same dimensions, as measured by the craniometer, differ largely as to the quantity of cerebral substance, which they are capable of containing. With the assistance of Dr. Thomas P. Jones, of Washington, and of Professor Ruggles, of the Columbian College, he instituted various experiments. In the first series, he ascertained the volume of each skull, brain included : in the second series, the volume of the brain alone or the capacity of the cerebral cavity ; and in order to render the difference in capacity more obvious, the volume of each skull, brain included, was reduced to the dimensions of 70 fluidounces. The results of the experiments on five skulls, delineated in the plates of Dr. Sewall's work, were as follows :— Volume of Skull, Brain included. Volume of Brain, Plate II. 70 oz 56-22 oz. III. - do. . • 5172 IV. do. . 46-21 V. - do. . - 34-79 VII. do. - 25-33 In two of these skulls, consequently, of the same external dimen- sions, there was a difference in the volume of brain of 31*89 oz. Dr. Sewall infers from his observations, that no phrenologist, however ex- perienced, can, by any inspection of the living head, ascertain whether a person has a skull of one inch or one-eighth of an inch in thickness; or whether he has 56*22 ounces of brain, or only 25*33 ounces. To the view, that the mental capacity is in a ratio with the size of the brain there must be numerous exceptions; for, independently of bulk, there may obviously be an organization productive of results, in which the largely developed organ may be greatly deficient. Size is only one of the elements of activity of an organ. " Whilst there is an evident connexion," says a recent writer,3 "between a large quantity of cere- bral matter, and a highly developed intellect, the quality of the mind and that of the brain-substance may also be supposed to have a close relation to each other. In great power of action a large muscle is needed, but for vigorous and well-adjusted muscular movement a cer- 1 Gall, Sur les Fonctions du Cerveau, ii. 342, Paris, 1825. 3 An Examination of Phrenology, in Two Lectures, 2d edit, p. 66, Boston, 1839. 3 Todd and Bowman,The Physiological Anatomyand Physiology of Man,p.262, Lond., 1845. VOL. I.—20 306 MENTAL FACULTIES. tain quality of fibre is also necessary to give full scope to the nervous power. It is impossible to determine what the peculiarity in quality is, out some idea of the great influence which it may possess in the exer- cise of the two great vital forces, the muscular and nervous, may be gained from comparing the energy and action of a well-bred horse, with one of those, which, in the language of the turf, shows little or no breeding. The actual amount of muscular or nervous fibre may be the same in both, or it may be less in the horse of good breeding than in the other, yet the former does his work and endures fatigue better." The difference between the moral of the male and the female is sig- nal ; and there is no less in the shape of the encephalon in the two sexes. Observation, not only by anatomists but by sculptors and painters, shows, that the superior and anterior parts of the brain are less deve- loped in the female, whose forehead is, therefore, as a general rule, smaller; whilst the posterior are larger. In the system of Gall, the anterior and superior parts are considered to be connected with -the intel- lectual manifestations, which are more active in man ; whilst the poste- rior are concerned in the softer feelings, which predominate in the cha- racter of the female. The mental and moral faculties vary also, in the same individual, according to age, health, and disease; and in the waking and sleeping state. In all these conditions, we have reason to believe the state of the encephalon is as various. The anatomist notices a manifest difference between its organization in the infant and in the adult or aged. Like the other organs of the body, it is gradually de- veloped until the middle period of life ; after which it decays with the rest of the frame. Our acquaintance with the minute organization of the body does not enable us to say on what changes these differences are dependent. We see them only in their results. By the minutest examination of the special nerves of sense we are incapable of saying, why one should appreciate the contact of sapid bodies, another that of light, &c. During sleep, again, in which the functions of the brain are more or less suspended, the condition of the organ is modified; and mania or delirium probably never occurs without the physicaLcondition of the brain having undergone some change, directly or indirectly. It is true, that, on careful examination of the brains of the insane, it has often happened, that no morbid appearance has presented itself; but the same thing has been observed on inspecting those who have died of apoplexy or paralysis, in which not a doubt is entertained that the cause is seated in the encephalon, and that it consists in a physical alteration of its tissue. These are a few of the cases which make us sensible of the limited nature of our powers of observation. They by no means encourage, in the most sceptical, the belief, that the tissue of the organ is not implicated. The investigations of the morbid anatomist, conse- quently, afford us few data on which to form our opinions on this sub- ject. The effect of intoxicating substances is mainly exerted on the brain. When taken in moderation, all the faculties are excited ; but if pushed too far, the intellectual and moral manifestations become perverted. This can only be through their action on the cerebral organ. We can thus understand, how regimen may cause important modifications THE BRAIN THE ORGAN OF THE MENTAL FACULTIES. 307 in the brain. Climate has probably a similar influence; hence, the dif- ference between the characters of different nations and races. The skull of the Mongol is different from that of the Kelto-Goth or of the Ethio- pian ; and the brain, as well as its functions, exhibits equal diversity.. Again, it has been argued, that the facts noticed in the animal king- dom are in favour of the brain being the organ concerned in the men- tal manifestations ; that, if each animal species has its own psychology, in each the encephalon has a special organization; and that in those which exhibit superior powers, the brain is found large, and more com- plicated. To a great extent this is true. Nothing, indeed, seems more erroneous than the notion, that even sensibility to pain is equal in every variety of the animal creation. As we descend in the scale, the nervous system is found becoming less and less complicated; until ultimately it assumes the simplest original character, which has laid the foundation for one of the divisions of Sir Charles Bell's system; and although it is impossible to change places with the animal, we have the strongest reasons for believing, that the sensibility diminishes as we descend; and that the feeling, expressed by the poet, that the beetle, which we tread upon— " In corporal sufferance finds a pang as great As when a giant dies"— however humane it may be, is physiologically untrue. The phenomena in favour of this view that present themselves to the naturalist are numerous and interesting ; and afford signal evidence of creative wis- dom in endowing the frames of those beings of the animal kingdom, that are most exposed to injury and torture, with a less sensible organi- zation. The frog continues sitting, apparently unconcerned, for hours after it has been eviscerated; the tortoise walks about after having lost its head; and the divisions of the polypus, made by the knife, form so many distinct animals. Redi removed the whole of the brain of a common land tortoise: the eyes closed to open no more; but the ani- mal walked as before,—groping, as it were, its way for want of vision. It lived nearly six months. All have noticed the independence of the parts of a wasp, after vthe head has been severed from the body. It will try to bite, and, for a considerable time, the abdomen will attempt to sting. An illustrative instance of the kind occurred to Dr. Harlan.1 He cut off the head of a rattlesnake; and, grasping the part of the neck attached to the head with his finger and thumb, the head twisted itself violently, endeavouring to strike him with its fangs. A live rabbit was presented to the head, which immediately plunged its fangs deep into the animal; and when the tail of the snake was laid hold of, the headless neck was bent quickly round as if to strike the experi- menter. The experiments of Dr. Le Conte,2 of Savannah, Georgia, and of Dr. Bennet Dowler,3 of New Orleans, on the Alligator—croco- dilus lucius—exhibit like results, and would lead to the inference, that in that animal, phenomena essentially resembling those which in the 1 Medical and Physical Researches, p. 503, Philad., 1835. ■ New York Journal of Medicine, Nov. 1845, p. 335. 3 Contributions to Physiology, New Orleans, 1849. 308 MENTAL FACULTIES. upper classes of animals are referable to the encephalon, may be more diffused in their origin. In one experiment by the latter gentleman, and Dr. Young, aided by Mr. Barbot, the head of the animal, for more than an hour after decollation, exhibited that it possessed sensation, perception, vision, passion, and voluntary motion. " It saw its ene- mies; opened its mouth to bite at the proper time; and nictated when a foreign body approached the eye;" and for three or four hours the headless trunk, during extensive mutilations by two operators, " mani- fested, in a still higher degree, sensation, intelligence, definite, well- directed muscular actions. There was, as usual, a complete loss of progressive or forward motion. The test used to elicit sensation and voluntary movements were pinching, puncturing and burning. Its sen- sibility and motions appeared to be nearly as acute, quick and varied as in the unmutilated animal. The direction of the limbs was not such as could be deemed habitual, as in walking and swimming. Some of these motions are of difficult execution in the entire animal from its anatomical conformation, such as reaching up between the shoulders or hips to remove an irritant." In another experiment performed in the presence of Drs. Cartwright, Smith, Nutt, Powell, Hire, Mr. Barbot, and Professor Forshey—in which decollation was practised with a dull hatchet, and, in consequence, the hemorrhage was not great, although considerable—Dr. Dowler carried the handle of a knife towards the eye, to ascertain whether it would wink; " whereupon the ferocious, separated head" sprang up from the table with great force at him, passing very near his breast, which re- ceived several drops of blood; and then alighted upon the floor from six to eight feet distant from its original position. It missed him be- cause he was standing at the side, and not in front of the head. "For about two hours,"—says Dr. Dowler—" the headless trunk exhibited such phenomena as are usually attributed to the brain,—namely, sen- sation, volition, and intelligential motion, as tested by the application of bits of ignited paper, wounds, and the like, whereupon the usual indi- cants of pain were elicited with great promptness and precision: it trembled, receded, rolled over, curved, placed its limbs accurately to the exact spot, and removed the offending cause. In certain places, this was exceedingly difficult, as on the spine between or near the shoulders or hips. It always used the limb the best adapted for the purpose. If the fire was too remote, as when applied to the tail, the whole body was thrown into the most favourable position for the pur- pose of reaching and removing the same. If the fire was placed on the table, in a position to annoy, yet without touching, the animal, as if endowed with sight, reached, and always accurately, to the exact spot, and either extinguished the fire, or removed it. As upon former occa- sions, if the animal found that the fire was continued at the same spot, and that it could not remove it, which was sometimes the case, owing to continuous or repeated applications, and carefully manoeuvring, it curved the body,—scratched violently, manoeuvred skilfully, and then, as a last resort, rolled quite over, laterally, always from, never towards the fire and operator." Still, the position, that in man and the upper classes of animals, ENCEPHALIC SEAT OF THE PASSIONS. 309 the brain is the organ through which the mind acts in the production of the different mental and moral manifestations, can scarcely be contested.1 Yet, amongst those who admit the accuracy of this conclu- sion, a difference of sentiment exists,—some conceiving that other organs participate in the function. To each of the known tempera- ments as many intellectual and moral dispositions have been ascribed. It has been affirmed, that if the brain be manifestly the organ of intel- lect the passions must be referred to the organs of internal or organic life; whilst others have regarded the brain as a great central apparatus for the reception and elaboration of the different impressions made upon the external senses;—thus conceiving the latter to be direct agents in the execution of the function, as well as the brain. The influence of the temperaments upon the mental and bodily pow- ers is much less invoked at the present day than it was of old. The ancients esteemed organized bodies to be an assemblage of elements, endowed with different qualities, but associated and combined so as to moderate and temper each other. Modern physiologists mean by tem- perament, the reaction of the different organs of the body upon each other consistently with health; so that if one set or apparatus of organs predominates, the effect of such predominance may, it is conceived, be exerted on the whole economy. In the description of the tempera- ments in different authors we find a particular character of intellectual and moral faculties assigned to each. The man of sanguine tempera- ment is described as of ready conception, retentive memory, and lively imagination; inclined to pleasure, and generally of a good disposition; but inconstant and restless. He of the bilious, on the other hand, is said to be hasty, violent, ambitious, and self-willed ; whilst the lym- phatic temperament bestows feeble passions ; cold imagination; tend- ency to idleness; and the melancholic disposes to dulness of concep- tion, and to sadness and moroseness of disposition. M. Gall2 has animadverted on this assignment of any intellectual or moral faculty to temperament. If we look abroad, he affirms, we find the excep- tions more numerous than the rule itself; so numerous, indeed, as to preclude us from establishing any law on the subject. Moreover, the idiot, who possesses a temperament like other persons, has no intel- lectual faculties. The temperament, doubtless, influences the brain within certain limits, as it does other functions: this, he suggests, it probably does by impressing them with a character of energy or of languor, but without, in any respect, regulating the intellectual sphere of the individual. Bichat,3 again, maintained, that whilst the encephalon is evidently the seat of the intellectual functions, the organic nervous system, and, consequently, the different organs of nutrition, which are supplied by it, are the seat of emotions or passions. That distinguished physiolo- gist, than whom, as M. Corvisart wrote to the First Consul, on an- nouncing his death, "personne en si peu de temps n'a fait tant de 1 Gall, Sur les Fonctions du Cerveau, ii. 69, Paris, 1825 ; Adelon, art. Encephale, Diet de Medec, vii. 517; and Physiologie de l'Homme, ed. cit, i. 496. * Op. citat, ii. 140. 3 Sur la Vie et la Mort, Part i., Paris, 180G. 310 MENTAL FACULTIES. choses et aussi Men,"1 rests his views upon the following considerations: —1st. That while inward feeling induces us to refer intellectual acts to the brain, the passions are referred to the viscera of the thorax or abdomen. 2dly. That the effects of intellectual labour are referred to the encephalon, as indicated by redness and heat of face, and beating of the temporal arteries in violent mental contentions, &c.: whilst the passions affect the organic functions, the heart is oppressed, and its pulsations are retarded or suspended; the respiration becomes hurried and interrupted; the digestion impeded or deranged, &c.; and 3dly. That whilst our gestures and language refer intellect to the encepha- lon, they refer emotions to the nutritive organs. If we wish to express any action of the mind, or are desirous of recalling something that has escaped the memory, the hand is carried to the head; and we are in the habit of designating a strong or weak intellect as a " strong or weak head;" or we say, that the possessor has " much or little brain." On the other hand, if desirous of depicting the passions, the hand is carried to the region of the stomach or heart; and the possessor of benevolent or uncharitable sentiments is said to have a'good or a bad heart. Bichat properly adds, that this idea is not novel, inasmuch as the ancients conceived the seat of the passions to be in the epigastric centre;—that is, in the nervous plexuses situate in that region. He remarks that amidst the varieties presented by the passions, according to age, sex, temperament, idiosyncrasy, regimen, climate, and disease, there is always a ratio between them and the degree of predominance of the different nutritive apparatuses; and he concludes with a de- duction, which ought not to have been hazarded without full reflection, —that as the functions of the nutritive organs, in which he ranges the passions, are involuntary, and consequently uninfluenced by education, education can have no influence over the passions, and the disposition is consequently incapable of modification. The answer of MM. Gall2 and Adelon3 to the views of Bichat appears to us to be irrefragable. How can we conceive, that viscera, whose functions are known, and which differ so much from each other, are agents of moral acts? The passions are sensorial phenomena, and like all phenomena of the kind, must be presumed to be seated in essentially nervous organs. Again;—when an injury befalls the brain, and the intellectual faculties are perverted or suspended by it, the same thing happens to the affective faculties; and if the viscera fulfil the high office assigned to them, why are not the passions manifested from early in- fancy,^ period when the viscera are in existence and active? The argument of Bichat—that the phenomena which attend and follow the passions, are referable to the nutritive organs—is not absolute. The functions of animal life are frequently disturbed by the passions, as well as those of organic life. It is not uncommon for them to induce convulsions, mania, epilepsy, and other affections of the encephalon. The effect here, as M. Adelon remarks, is mistaken for the cause. The 1 Eloge de Xavier Bichat, par Miquel, p. 58, Paris, 1823. 1 Op. citat, i. 94. 3 Art. Enceph. (Physiol.) in Diet de Med., vii. 521, and Physiologie de l'Homme, edit. cit., i. 510. SOURCES OF THE INTELLECTUAL SPHERE. 311 heart certainly beats more forcibly in anger, but the legs fail us in fear; and if we refer anger to the heart, we must, by parity of reasoning, refer fear to the legs. By reasoning of this kind, the passions might be referred to the whole system, as there is no part which does not suffer more or less during their violence. The error arises from our being impressed with the most prominent effect of the passion—the feeling accompanying it—and this is the cause of the gesture and the descriptive language, to which Bichat has given unnecessary weight in his argu- ment. If, then, the views of Bichat, regarding the seat of the passions, be unfounded, the mischievous doctrine deduced from them—that they are irresistible, and cannot be modified by education—falls to the ground. His notion was, that the nutritive organs are the source of irritative irradiations, which compel the brain to form the determinations that constitute the passion, and to command the movements by which it is appeased or satisfied. A similar view is embraced by M. Broussais,1 who, however, conceives, that the passions can be fomented and increased by attention, until they become predominant. Daily experience, indeed, exhibits the powerful effect produced on the passions by well-directed moral restraint. How many gratifying instances have we of persons, whose habitual indulgence of the lowest passions and propensities had rendered them outcasts from society, having become restored to their proper place by exerting due control over their vicious inclinations and habits! We can not only curb the expression of the passions, as we are constantly compelled to do, in social intercourse; but even modify the internal susceptibility by well-directed habits of repression. Lastly. Many physiologists have considered the brain as a great nervous centre for the reception and elaboration of different impressions conveyed thither by the external senses; and absolutely requiring such impressions for the mental manifestations. They consequently rank, amongst the conditions necessary for such manifestations, not only the brain which elaborates them, but the parts that convey to it the impres- sions or materials on which it has to act; and conceive, that a necessary connexion exists between these two orders of parts. The supporters of these opinions ascribe the differences observed in the intellectual and moral faculties of different persons as much to diversity in the number and character of the impressions, as to differences in the encephalon ifself. They do not all, however, agree as to the source of the impres- sions, which they conceive to be the raw material for the intellectual and moral acts. M. Condillac2and his school admit only one kind;—those proceeding from the external senses, which they term external impres- sions. M. Cabanis,3 in addition to these, admits others proceeding from every organ in the body, which he terms internal impressions. The school of Condillac set out with the maxim ascribed to Aristotle, "nihil est in intellectu quod non prius fuerit in sensu;" and they adopt, as an elucidation of their doctrine, the ingenious idea of Condillac—of a statue, devoid of all sensation, which is made to receive each of the ' Examen des Doctrines Medicales, ii. 388, and Physiology applied to Pathology, Drs. Bell and La Roche's translation, p. 136, Philadelphia, 1832. 2 Traite des Sensations, i. 119. 3 Rapport du Physique et du Moral de l'Homme, 4eme edit, par G. Pariset, Paris, 1824. 312 MENTAL FACULTIES. five senses in succession; and which, he attempts to show, from the impressions received, may be able to develope gradually the different intellectual and moral faculties. All these, he affirms, are derived from impressions made on the external senses; and he considers the whole of human consciousness to be sensation variously transformed. The views of M. Condillac have been largely embraced, with more or less modification; and, at the present day, many metaphysicians believe, that impressions on the senses are the necessary and exclusive materials for all intellectual acts. His case of the statue seems, how- ever, to be by no means conclusive. It must, of course, be possessed of a centre for the reception of impressions made upon different senses, otherwise no perception could occur; and if we can suppose it possible for such a monstrous formation as a being totally devoid of external senses to exist; such a being must not only be defective in the nerves which, in the perfect animal, are destined to convey impressions to the brain, but probably in the cerebral or percipient part likewise. From defective cerebral conformation, therefore, the different mental phe- nomena might not be elicited.1 If, however, we admit in such a case the possibility of the cerebral structure,—particularly of those portions that are especially concerned in the function of thought,—being properly organized, it appears to us, that certain mental or moral manifestations ought to exist. Of course, all knowledge of the universe would be pre- cluded, because deprived of the instruments for obtaining such know- ledge; but the brain would act as regarded the internal sensations. In order that such a being may live, he must be supplied with the neces- sary nourishment; possess all those internal sensations or wants that are inseparably allied to organization; and must, consequently, feel the desires of hunger and thirst; but we have seen, that these sensa- tions require the intervention of the brain as much as the external sensations. Supposing him, again, to survive the period of puberty, he must experience the instinctive changes, which occur at this period, and which must furnish impressions to the encephalon. In this assumed ease, then, a certain degree of mental action might exist; and, under the supposition of a properly organized brain, ideas—limited, it is true, in consequence of the privation of the ordinary inlets of knowledge— might be formed; and memory, imagination, and judgment be com- patible within certain limits. The objections to the view, that the intellectual and, moral sphere of man and animals is proportionate to the number and perfection of the external senses are overwhelming. Animals have the same number of senses as man, and, frequently, have them more perfect; yet in none is the mental sphere co-extensive. The idiot has the external senses as delicate as the man of genius, and often much more so; many of those of the greatest talents having the senses extremely obtuse. It has been already remarked, that the superiority of the human intellect has been referred entirely to the sense of touch, and to the happy organization of the human hand; but the case of Miss Biffin, and others, and that of the young artist cited by M. Magendie,2 negative this pre- ' Adelon, op. citat, i. 519-. J See page 140 of this volume. MENTAL SPHERE OF THE DEAF, DUMB, AND BLIND. 313 sumption. The senses are important secondary instruments,—indis- pensable for accomplishing certain manifestations of the mind, but, in no way, determining its power. The example of the deaf and dumb is illustrative of this matter.1 If a child be born deaf, he is necessarily dumb; inasmuch as he is unable to hear those sounds which, by their combination, constitute language; and cannot therefore imitate them;—a connexion between the functions of hearing and speech, which was not well known to the ancients. For a length of time, these objects of compassionate interest were esteemed to be beyond the powers of any kind of intellectual culture, and were permitted to remain in a state of the most profound ignorance. The ingenuity of the scientific philanthropist has, however, devised modes of instruction, by which their mental power has been exhibited in the most gratifying manner, and in a way to prove, that the sense of hear- ing is not indispensable for mental development; but that its place may be supplied, to a great extent, by the proper exercise of others. The deaf and dumb, deprived of the advantages of spoken language, are compelled to have recourse to the only kind available to them,—that addressed to the eye. In this typical way, by a well-devised system of instruction they can be taught to preserve their ideas, and to multiply them, like the perfectly formed, by the spoken and written language,— without one or the other of which the human mind would have remained in perpetual infancy. Thus, the deaf and dumb have not only like ideas ; but the same words to convey them to others. - Yet the deaf and dumb are not so much the objects of our commise- ration as they who have been deprived, from birth or from early in- fancy, of both sight and hearing, and have thus been devoid of two of the most important inlets for the entrance of impressions from the sur- rounding world. In such case, it is obvious, they are shut out from all instruction, except what can be afforded by the senses of touch, smell, and taste; yet even here we have the strongest evidence of independent intellect. One of the most striking cases of the kind is that of the Scotch boy Mitchell, the object of much interest to Spurzheim and to Dugald Stewart,2 both of whom have described his case in their writings. It is matter of uncertainty, whether either his deafness or blindness was total. The evidences of the sensation of hearing were, in a high degree, vague and unsatisfactory; but he gave more con- vincing proofs of the possession of partial vision. He could, for exam- ple, distinguish day from night; and, when quite young, amused himself by looking at the sun through crevices in the door, and by kindling a fire. At the age of twelve, the tympanum of each ear was perforated; but without any advantage. In his fourteenth year, the operation for cataract was performed on the right eye, after which he recognized more readily the presence of external objects; but never made use of sight to become acquainted with the qualities of bodies. Before and after this period, red, white, and yellow particularly attracted his at- 1 Gall, op. cit, i. 119. * Elements of the Philosophy of the Human Mind, &c.; Transactions of the Royal Society of Edinburgh, vol. vii.; and Dr. Gordon, ibid., vol. vi.; also, History of James Mitchell, a boy born blind and deaf, by James Wardrop, London, 1813. 314 MENTAL FACULTIES. tention. The senses, by which he judged of external bodies, were those of touch and smell. His desire to become acquainted with objects was great. He examined every thing he met with, and each action indi- cated reflection. In his infancy, he smelt at every one who approached him; and their odour determined his affection or aversion. He always recognized his own clothes by their smell; and refused to wear those which he found to belong to others. Bodily exercises, such as rolling down a small hill, turning topsy-turvy, floating wood or other objects on the river that passed his father's house; gathering round, smooth stones, laying them in a circle, and placing himself in the middle, or building houses with pieces of turf, &c, were a source of amusement to him. After the operation on his right eye, he could better distinguish objects. His countenance was very expressive; and his natural lan- guage not that of an idiot, but of an intelligent being. When hungry, he carried his hand to his mouth, and pointed to the cupboard where the provisions were kept; and, when he wished to lie down, reclined his head on one side upon his hand, as if he wished to lay it upon the pil- low. He easily recollected the signification of signs that had been taught him; all of which were of course of the tactile kind. To make him comprehend the number of days before an event would happen, they bent his head as a sign that he would have to go to bed so many times. Satisfaction was expressed by patting him on the shoulder or arm; and discontent by a sharp blow. He was sensible of the caresses of his parents; and susceptible of different emotions—hatred, passion, malice, and the kindlier feelings. He was fond of dress, and had great fears of death, of the nature of which he had manifestly correct notions. Mitchell's case has been pregnant with interest to the metaphysician; but it is not so elucidative as it would have been had the privation of the senses in question been total. There is, or was, in the American Asylum at Hartford in Connecti- cut, a being not less deserving of attention than Mitchell.1 Her name is Julia Brace. She is the daughter of John and Rachel Brace, natives of Hartford, and was born in that town in June, 1807; so that she is now (1850) forty-three years old. At four years of age she was seized with typhus fever; was taken sick on the evening of Monday, November 29, 1811; and, on the Saturday morning following, became both blind and deaf. Prior to her illness, she had not only learned to speak, but to repeat her letters, and to spell words of two or three syllables; and, for some time after the loss of her sight and hearing, she was fond of taking a book, and spelling words and the names of her acquaintances. She retained her speech pretty well for about a year; but gradually lost it, and appears to be now condemned to per- petual silence. For three years she could still utter a few words, one of the last of which was "mother." At first she wTas unconscious of her misfortune, appearing to think, that a long night had come upon the world; and often said, <'It will never be day." She would call upon the family to " light the lamp," and was impatient at their seeming 1 Twenty-first Report of the Directors of the American Asylum at Hartford, for the Edu- cation and Instruction of the Deaf and Dumb, p. 15, Hartford, 1837, et seq. CASE OF JULIA BRACE. ' 315 neglect, in not even answering her. At length, in passing a window, she felt the sun shining warmly upon her hand; and pointed with de- light to indicate that she recognized this. From the January after her illness, until the following August, she would sleep during the day, and be awake through the night; and it was not until autumn, by taking great pains to keep her awake during the day, that she was set right. At present, she is as regular in this respect as other persons. From the period of her recovery, she seemed to perceive the return of Sab- bath ; and, on Sunday morning, would get her own clean clothes, and those of the other children. If her mother was reading, she would find a book, and endeavour to do so likewise. The intervention of a day of fasting or thanksgiving confused her reckoning; and some time elapsed before she got right. During the first winter after her recovery, she was irritable almost to madness; would exhibit the most violent passion, and use the most profane language. The next summer she became calmer; and her mother could govern her, to some extent, by shaking her, in sign of disapprobation; and stroking or patting her head, when she conducted herself well. She is now habitually mild, obedient and affectionate. During the first summer after her illness, she was very unwilling to wear clothes, and would pull them off vio- lently. At length, her mother took one of her frocks and tried it on her sister, with a view of altering it for her. Julia had ever been remarked for her sense of justice in regard to property. This seemed to be awakened; and she took the frock and put it on herself. After this she was willing to wear clothes, and even cried for new ones. She has ever since been fond of dress. At nine years of age she was taught to sew; and, since that time, has learned to knit. She has been a resident for several years in the American Asylum at Hartford; where she i's supported in part, by the voluntary contributions of visitors, and, in part, by her own labours in sewing and knitting. A language of palpable signs was early established as a means of communication with her friends; and this has been so improved as to be sufficient for all necessary purposes. Her countenance, as she sits at work, is said to exhibit the strongest evidence of an active mind, and a feeling heart: "thoughts and feelings," says a writer who describes her case, "seem to flit across it like the clouds in a summer sky: a shade of pensiveness will be followed by a cloud of anxiety or gloom; a peaceful look will perhaps succeed; and, not unfrequently, a smile lights up her counte- nance, which seems to make one forget her misfortunes. But no one has yet penetrated the darkness of her prison house, or been able to find an avenue for intellectual or moral light. Her mind seems, thus far, inaccessible to all but her Maker." A still more interesting example is cited by Dr. Abercrombie1 from the Medical Journals of the time. A gentleman in France lost every sense except feeling on one side of his face; yet his family acquired a method of holding communication with him, by tracing characters upon the part which retained its sensation. These cases are not, perhaps, so unfrequent as has been supposed. Dr. Howe, the superintendent of 1 Inquiries concerning the Intellectual Powers, &c, Amer. edit, p. 56, New York, 1832. 316 MENTAL FACULTIES. the Perkins Institution and Massachusetts Asylum for the Blind, stated, some years ago, that four cases in New England, besides that of Julia Brace, had come within his own observation. One of these had been in 1841 upwards of three years under his care; and the results of his diligence and judgment in this instance have furnished more gratifying results to the psychologist and philanthropist than any, perhaps, on record. Laura Bridgman, the subject of the case, wTas born in December, 1829. At two years of age, her eyes and ears inflamed, suppurated, and their contents were discharged. At the expiration of two more years of suf- fering, it was discovered, that her sense of smell was almost wholly destroyed; and, consequently, that her taste was much blunted. She had, therefore, but one sense remaining, that of touch, by which she could become acquainted with the external world. Whilst at home, before her reception into the Asylum, she would explore the house; become familiar with the form, density, weight, and temperature of every article she could lay her hands upon; followed her mother; felt her hands and arms, and endeavoured to repeat every thing herself. She even learned to sew a little, and to knit. She exhibited warm affection towards the members of her family; but the means of com- municating with her were limited. When it was desired that she should go to a place, she was pushed; or that she should approach, she was drawn towards the person. Gently patting on the head signified appro- bation; on the back, disapprobation. She had made, however, a natural language of her own; and had a sign to express her idea of each member of the family,—such as drawing her finger down each side of her face, to allude to the whiskers of one; twirling her hand and arm around, in imitation of the spinning-wheel, for another, &c. In October, 1837, she was received into the Institution for the Blind, in Boston. The first experiments made with her consisted in taking articles in common use; such as knives, forks, spOons, keys, &c, and pasting labels upon them with their names printed in raised letters. These she felt very carefully; and speedily found, that the crooked lines spoon differed as much from the crooked lines key, as the spoon dif- fered from the key in form. Small detached labels, with the same words printed upon them, were then put into her hands, and she soon observed, that they were similar to the ones pasted on the articles. She showed her perception of this similarity by laying the label key upon the key, and the label spoon upon the spoon. In this manner she proceeded to acquire a knowledge of language; used the manual alphabet of the deaf mutes with great facility and rapidity, and increased her vocabu- lary so as to comprehend the names of all common objects. She could soon count to high numbers; and add and substract small ones. But the most gratifying acquirement which she made, and the one which gave her the most delight, was the power of writing a legible hand, and expressing her thoughts upon paper. She writes with a pencil in a grooved line, and makes her letters clear and distinct. The author has a favourable specimen now before him, in a recent well conceived, and well expressed, letter to a friend. She is expert with her needle; knits easily, and can make twine bags and various fancy articles very CASE OF LAURA BRIDGMAN. 317 prettily; is docile; has a quick sense of propriety; dresses herself with great neatness, and is always correct in her deportment. No definite course of instruction could be marked out; for her inquisitiveness was so great, that she was very much disconcerted if any question, which occurred to her, was deferred until the lesson was over. It was deemed best to gratify her, if her inquiry had any bearing on the lesson; and often she led her teacher far away from the objects with which he com- menced. With regard to the sense of touch it is very acute, even for a blind person. It is shown remarkably in the readiness with which she distinguishes persons. There were, a few years ago, forty inmates in the female wing, with all of whom she was acquainted. Whenever she is walking through the passage-way, she perceives by the jar of the floor, or the agitation of the air, that some one is near her, and it is exceedingly difficult to pass her without being recognized. Her arms are stretched out, and the instant she grasps a hand, a sleeve, or even part of the dress, she knows the person, and lets him pass on with some sign of recognition. The details concerning this interesting being, and her gradual pro- gress in moral and intellectual culture, can be learned from the annual reports of the Institution, which Dr. Howe so ably superintends.1 How strongly do these cases demonstrate the independence of the organ of intellect; requiring, indeed, the external senses for its perfect developement, but still capable of manifesting itself without the presence of many, and probably of any, of them; and how inaptly, although humanely, does the law regard such beings! "A person," says Black- stone,2 "born deaf, dumb, and blind, is looked upon by the law as in the same state with an idiot, he being supposed incapable of any under- standing, as wanting all those senses which furnish the human mind with ideas." But if he grow deaf, dumb, and blind, not being born so, he is deemed non compos mentis, and the same rules apply to him as to other persons supposed to be lunatics. With regard to the deaf and dumb, they are properly held to be competent as witnesses, provided they evince sufficient understanding, and to be liable to punishment for a breach of the criminal laws. M. Cabanis3 embraces the views of Condillac regarding the external senses; but thinks, that impressions from these are insufficient to con- stitute the materiel of the mental and moral manifestations. In con- firmation of this opinion, he observes, that the young infant, and animals at the very moment of birth, frequently afford evidences of complicated acts originating in the nervous centres; and yet the external senses can have been but little impressed. How can we, he asks, refer to the operation of the external senses the motions of the foetus in utero, which are perceptible to the mother, for the latter half of utero-gesta- tion; or the act of sucking executed from the first day of existence? Can we refer to this cause the fact of the chick, as soon as it is hatched, pecking the grain that has to nourish it ? or the one, so frequently 1 Annual Reports of the Trustees of the Perkins Institution and Massachusetts Asylum for the Blind to the Corporation, for the years 1837, et seq. 1 Commentaries on the Laws of England, i. 304. 3 Rapport du Physique et du Moral, edit. cit. 318 MENTAL FACULTIES. quoted from Galen, of the young kid, scarcely extruded from the ma- ternal womb, and yet able to select a branch of the cytisus from other vegetables presented to it? Man and animals, continues M. Cabanis, during the course of their existence, experience mental changes as remarkable as they are frequent; yet nothing in the condition of the senses can account for such difference. For example, at the period of puberty, a new appetite is added; and this, even, when the being is kept in a complete state of isolation. This, he argues, it is impossible to refer to any change in the external senses; which, if they furnished the materials at all, must have been doing so from early infancy; and he concludes, that the difference observable in the mental manifestations, according to sex, temperament, climate, state of health or disease, re- gimen, &c, cannot be referable to the senses, as they remain the same; and, consequently, we must look elsewhere for the causes of such differ- ence. These M. Cabanis conceives to be the movements by which the organs of internal life execute their functions. Such movements, he says, although deep-seated and imperceptible, are transmitted to the brain, and furnish that organ with a fresh set of materials. At puberty, when the testicles become developed, and their function is established by the secretion of sperm, the organic movements during the secretion are the materials of the new desires, which appear at that age. These impressions he calls internal, in contradistinction to the external, or those furnished by the five senses; and he considers, that whilst the external senses serve as the basis for all that we include under the term intellect, the internal impressions are the materials of what are called instincts; and, as the organs of internal life, whence the internal im- pressions proceed, vary more than the senses, according to age, sex, temperament, climate, regimen, &c, it is more easy to find in them organic modifications, which coincide with those exhibited by the mind under those various circumstances. In proof of these opinions, he adduces, besides others, the following specious affirmations. First. As the venereal appetite appears in man and animals synchronously with the developement of the testicles, and is never exhibited when they are removed in infancy, we have reason to believe, that the impressions, which constitute the materials for this new catenation of ideas, must proceed from the testicles. Secondly. Numerous facts demonstrate, that the condition of the uterus has much influence on the mental and moral manifestations of the female. The period of the developement of that organ, for example, is the one at which new feelings arise, and all those manifestations assume more activity; and there is generally a ratio between their activity and that of the uterus. If the state of the uterus be modified, as it is at the menstrual period, or during pregnancy, or after delivery, the mind is so likewise. All these facts ought to induce a belief, he thinks, that im- pressions are continually emanating from that organ, which, by their variety, occasion the diversity in the state of mental and moral facul- ties observed in those different cases. Thirdly. It is impossible in the hypochondriac and melancholic constitutions, to mistake the influence exerted upon the mind by the abdominal organs. According as they execute their functions more or less perfectly, the thinking faculty is VIEWS OF CABANIS, GALL, ETC. 319 more or less languid or brilliant; and the affections more or less vivid and benevolent, or the contrary; hence the expressions melancholy1 and hypochondriasis,2 assigned to the states of mind characterizing those constitutions, which denote that the cause must be referred to the abdominal organs. The origin of the alternations of inactivity and energy in the intellect, of benevolent and irascible fits of humour, as well as of insanity, is also referable, he says, to the abdominal viscera. Hence—M. Cabanis concludes—it is evident, that the abdominal organs are the source of fortuitous and abnormous impressions which excite the brain to irregular acts;—and is it not, he asks, probable, that what takes place in excess, in these morbid movements, may happen to a less and more appropriate extent in health; and that thus impressions may emanate in a continuous manner from every organ of the body, which may be indispensable to the production of the mental and moral acts? M. Cabanis, therefore, considers that the axiom of Aristotle should be extended; and that the statue of Condillac is incomplete, in not having internal organs for the emanation of internal impressions, which are the materials of the instincts. In this way he accounts for the instincts, which, by some metaphysicians, have been looked upon as judgments, executed in the ordinary manner, but so rapidly, that the process has ceased from habit to be perceptible. Finally, he remarks, there is a ratio between the duration and intensity of the intellectual results and the kind of impressions, which have constituted their mate- rials. All the mental and moral acts, for instance, that are derived from impressions engendered in the very centre of the nervous system or in the brain,—such as those of the maniac,—are the strongest and most dur- able. After these come the instincts, of which the internal impressions are the materials: they are powerful and constant;—and lastly, the intellectual acts, which are more transient, because they emanate from external impressions, themselves fickle, and somewhat superficial. According to the views, then, of M. Cabanis and his followers, amongst the organic conditions of the mental and moral manifestations must be placed, not only those of the encephalon and external senses, but of the different organs of the body, which furnish the various internal impressions. The influence of the external senses on the intellectual and moral developement has already been canvassed: we have seen, that they are only secondary instruments for making us acquainted with external bodies, and that they in nowise regulate the intellectual and moral sphere. The notion of internal impressions is ingenious, and has led to important improvements in the mode of investigating the different mental and moral phenomena. It was suggested, as has been shown, by M. Cabanis, in consequence of the external senses appearing to him insufficient to explain all the phenomena. By MM. Gall, Adelon,3 and others, however, all these cases are considered explicable by the vary- ing condition of the brain itself. In the foetus in utero; in the new- born animal, there are already parts of the brain, they say, sufficiently developed; and, accordingly, we witness the actions to which reference 1 From ;"£>.*?, "black," and ^oXu, "bile." * Disease of the hypochondres. 3 Physiologie de l'Homme, 2de edit, i. 251. 320 MENTAL FACULTIES. has been made by M. Cabanis; and if the intellectual and moral manifes- tations vary according to sex, temperament, climate, regimen, state of health, &c, it is because the encephalon is, under these circumstances, in different conditions. The chief facts, on which M. Cabanis rests his doctrine, are,—the coincidence between the developement of the testi- cles and the appearance of the venereal appetite; and the suppression of this appetite after castration. It must be recollected, however, that these are not the only changes, that happen simultaneously at puberty. The voice assumes a very different character; but the change in the voice is not a cerebral phenomenon. It is dependent upon the deve- lopement of its organ, the larynx. Yet castration, prior to puberty, has a decided effect upon it; preventing it from becoming raucous and unmelodious. All these developements are synchronous; but not di- rectly consequent upon each other. The generative function has two organs,—one central, the other external; and it is not surprising, that both should undergo their developement at the same period. On the whole, we are perhaps justified in concluding, that the brain alone is the organ of the intellectual and moral faculties. Yet, as before remarked, there is great force in the facts and arguments brought forward by Dr. Carpenter in favour of the emotional acts being seated in what, he terms, the sensorial ganglia : and that as we descend in the animal scale, the cerebrum or organ of the mental manifestations be- comes less and less developed, until we ultimately find an encephalic organization in which a common sensorium for the reception of sensation and the origination of motion may alone exist; without any organ for the recording of impressions like the cerebrum in more highly endowed organisms. In such case, the motions may be mere responses to sen- sations experienced, without the presence of the slightest consciousness on the part of the being, or knowledge of the adaptation of means to ends. Still, it may be a question whether such sensations and responsive motions are not possessed by animals devoid of anything resembling the encephalic sensory ganglia of higher organisms, and which are wholly supplied with nerves of the excito-motory class—as the stomato-gastric. The interesting topic of the various instinctive operations of the frame will be considered in another part of this work. We shall there find, that instinct cannot in all cases be defined, in the language of M. Broussais,1 to consist in sensations originating in the internal and ex- ternal sensitive surfaces, which solicit the cerebral centre to acts neces- sary for the exercise of the functions,—such acts being frequently executed without the participation of mind, and even in its absence,— inasmuch as it is not confined to beings possessed of brain, but exists also in the vegetable. Having now decided upon the organ of the mental and moral facul- ties, it would be necessary, according to the system adopted in this work, to describe its anatomy; but this has been done elsewhere. 1 Physiol, appliquee a la Pathologie, ch. vii.; or Drs. Bell and La Roche's translation, Philad., 1832. INTELLECTUAL AND MORAL FACULTIES. 321 PHYSIOLOGY OF THE INTELLECTUAL AND MORAL FACULTIES. When the organ of the intellect is exposed by accident, and we regard it during the reception of a sensation, the exercise of volition, or during any intellectual or moral operation, the action is found to be too mole- cular to admit of detection. At times, during violent mental conten- tion, a redness of the surface of the brain has been apparent, as if the blood had been forced more violently into the vessels; but no light has been thrown by such examination on the wonderful actions that consti- tute thought. We ought not, however, to be surprised at this, when we reflect, that the most careful examination of a nerve does not convey to us the slightest notion how an impression is received by it from an external body; and how such impression is conveyed to the brain. All that we witness in these cases is the result; and we are, therefore, com- pelled to study the intellectual and moral acts by themselves, without considering the cerebral movements concerned in their production. Such study is the basis of a particular science—metaphysics, ideology, ox philosophy. Apart from organization, this subject does not belong to physiology; but as some of the points of classification, &c, are con- cerned in questions that will properly fall under consideration, it may be well to give a short sketch of the chief objects of metaphysical inquiry; which are, indeed, intimately connected in many of their bear- ings,—as commonly treated by the metaphysician,—with physiology. M. Broussais has considered, that metaphysics and physiology should be kept distinct; and that all the investigations of the metaphysician Bhould be confined to the ideal. " I wish metaphysicians, since they so style themselves," he remarks, somewhat splenetically, "would never treat of physiology; that they would only occupy themselves with ideas as ideas, and not as modifications of our organs; that they would never speak either of the brain, the nerves, the temperaments, or of the influ- ence of climates, of localities, or of regimen; that they would never inquire whether there are innate ideas, or whether they come through the medium of the senses; that they would not undertake to follow their developements according to age or state of health; for I am convinced that they cannot reason justly on these points. Such questions belong to physiologists, who can unite a knowledge of the moral nature with that of the structure of the human body." "It is possible," he adds, "that particular circumstances may oblige them to introduce physiolo- gical considerations into their calculations; as when it is necessary to estimate the influence of certain laws or customs in relation to temper- ature, to the nature of the soil, the prevailing diseases, &c, but then they should avail themselves of the experience of physiologists and physicians."1 A more appropriate recommendation would be that the metaphysician should make a point of becoming acquainted with physio- logical facts and reasoning; and, conversely, that metaphysics should form a part of the study of every physiologist. The cerebral manifestations comprise two very different kinds of acts;—the intellectual and the moral; the former being the source of 1 De l'Irritation et de la Folie, Paris, 1828; or Dr. Cooper's translation, Columbia, S. C, 1831. VOL. I.—21 322 MENTAL FACULTIES. all the knowledge we possess regarding ourselves and the bodies sur- rounding us; the latter comprising our internal feelings, appetites, desires, and affections, by which we are incited to establish a relation with the beings around us:—the two sets of acts respectively embracing the qualities of the mind, and those of the heart.1 If we attend to the different modes in which the intellectual mani- festations are evinced in our own persons, we find, that there are several acts which are by no means identical. We are conscious of the differ- ence between appreciating an impression made upon one of the external senses, which constitutes perception, and the recalling of such impres- sion to the mind, which is the act of memory; as well as the distinction between feeling the relations, that connect one thing with another, con- stituting judgment; and the tendency to act in any direction, which we call will. The consciousness of these various mental processes has induced philosophers to admit the plurality of the intellectual acts, and to endeavour to reduce them all to certain primary faculties; in other words, to faculties which are fundamental or elementary, and by their combination give rise to other and more complex manifestations. To this analytical method they have been led by the fact, that the different acts, which they esteem elementary, exhibit great variety in their degrees of activity: one, for example, may be impressed with a character of en- ergy—as the memory;—whilst another, as the judgment, may be sin- gularly feeble;—and conversely. M. Broussais conceives, that without the memory we cannot exercise a single act of judgment; as it is always necessary, in order to judge, that we should experience two successive perceptions; which we could not do, unless possessed of the faculty of renewing that which we had felt before; in other words, unless we pos- sessed memory. Hence the loss of this faculty, he says, necessarily occasions that of judgment, and reduces man to a state of imbecility. To a certain extent this is true. Total privation of memory must be attended with the results described. If an individual retains no con- sciousness of that which impressed him previously, there can obviously be no comparison. A man may, however, have an unusual memory for certain things and not for others; he may astonish us by the extreme accuracy of his recollection of numbers, places, or persons; and yet he may be singularly deficient in judging of other matters;—his memory suggesting only one train of objects for comparison. In enumerating the faculties, which, by their union, constitute the intellect, we observe great discrepancy amongst metaphysicians. Some admit will, imagination, understanding, and sensibility ; others, sensi- bility, imagination, memory, and reason; others will, intelligence, and memory; and others, again, imagination, reflection, and memory. The views of M. Condillac2 on this subject have perhaps excited more atten- tion than those of any other individual. Professing, as we have seen, that all our ideas are derived from successive operations of the senses and the mind, he admits the following constituent faculties of the in- tellect:—sensation, attention, comparison, judgment, reflection, imagin- 1 Adelon, Facultes de l'Esprit et de l'Ame, in Diet, de Med., viii. 469, Paris, 1S23; and Physiologie de l'Homme, edit, cit, i. 527. a Op. citat. FACULTIES THAT CONSTITUTE THE INTELLECT. 323 ation, and reason. Sensation he defines to be—the faculty of the mind, which affords the perception of any sensitive impression. Attention, the faculty of sensation, applied exclusively to a determinate object; being, as the word imports, the tension of the mind upon a particular object. Comparison, the faculty of sensation, applied to two objects at once. Judgment, the faculty by which the mind perceives the con- nexions, that exist between the objects compared. Reason, the faculty of running through a succession of judgments, which are connected with, and deduced from, each other. Reflection, as the word indicates, the faculty by which the mind returns upon itself, upon its own products, to prove their correctness, and to subject them again to its power; and imagination, to which Condillac attaches memory,—the faculty pos- sessed by the mind of reproducing at will the different impressions, and all the products of its own operations. With regard to the order of catenation of these different faculties, he considers sensation to be first put in play; and if, amongst the perceptions, there is one, of which we have a more lively consciousness, and which attracts the mind to it alone, it is the product of attention: then comes comparison, which is nothing niore than double attention: comparison is irresistibly succeeded by judgment: if, from one judgment, we pass to another deduced from it, we reason; if the mind turns back on its own -production, we reflect: and lastly, if the mind spontaneously awakens its different perceptions imagination is in action. All these faculties are thus made to be de- duced from each other; to originate in the first or sensation; and all are sensation successively transformed. The doctrine of M. Condillac, abstractly considered, has already engaged attention. The division of the faculties, which he conceives, by their aggregation, to form the intellect, is simple and ingenious, and appears to be more easily referable to physiological principles than that of other metaphysicians; accordingly, it has been embraced, with more or less modification, by certain physiological writers. The power of reflection, according to M. Broussais, is the character- istic of the human intellect; and to reflect is to feel. Man not only feels the stimulation produced by external agents, and by the move- ments of his own organs, which constitutes sensation or perception, but he is conscious that he has felt these stimulations: in other words, he feels that he has felt; he has, consequently, a perception of his actual perception, which, M. Broussais says, constitutes mental reflection. This process he can repeat as often as he thinks fit, and can observe all his sensations, and the different modes in which he felt, whilst occupied with his feelings. From this study he derives an idea of his own existence. "He distinguishes himself,"to quote the dry description of M. Broussais, "in the midst of creation, and paying regard only to his own exist- ence, compared with all that is not himself, he pronounces the word J, (moi,) and says, lam; and viewing himself in action, says, I act, I do, &c. Perception of himself and of other bodies procures him what are denominated ideas. This is, therefore, another result of reflection; in other words, of the faculty he possesses of feeling himself feel. But man feels, besides, that he has already felt: this constitutes memory. In comparing two perceptions with each other, which are felt in sue- 324 MENTAL FACULTIES. cession, a third perception results, which is judgment. Consequently, to judge is only to feel." " Hence," he concludes, "sensation, reflection, and judgment are absolutely synonymous, and present to the physiolo- gist nothing more than the same phenomenon. The will, or the faculty by virtue of which man manifests his liberty by choosing, among dif- ferent perceptions, the one he must obey;—the faculty, which gives him the power of resisting, to a certain extent, the suggestions of instinct— is founded on reflection. Consequently, when we consider' it in a physiological point of view, we can only discover in it the faculty of feeling ourselves, and of perceiving that we feel ourselves." Some of the later French metaphysicians have proposed certain modifications of the system of Condillac. M. De La Romiguiere,1 for instance, denies that sensation is the original faculty, and derives all from attention. The mind, he remarks, is passive during the reception of sensation, and does not commence action until directed to some ob- ject, or until it attends. According to him, the intellect consists of three faculties—attention; comparison or double attention ; and reason or double comparison. Judgment, imagination, and memory are not primary faculties: judgment is the irresistible product of comparison; memory is but the trace, which every perception necessarily leaves behind it; and imagination is but a dependence on reason. M. Des- tutt-Tracy,2 again, reduces the number of primary faculties to four— perception, memory, judgment, and will or desire. According to him, attention is not an elementary faculty. It is but the active exercise of the intellectual faculties. The same applies to reflection and reason, which are only a judiciously combined employment of those faculties; and to comparison and imagination, both of which enter into the judg- ment. This division is embraced by M. Magendie.3 Mr. Dugald Stewart's4 classification is into, 1, Intellectual poivers, and, 2, Active and moral powers; including, in the former, perception, attention, con- ception, abstraction, the associating principle, memory, imagination, and reason. Dr. Brown5 reduces all the intellectual states to simple suggestion and relative suggestion,—comprising in the former, concep- tion, memory, and imagination,—in the latter, judgment, reason, ab- straction, and taste. Dr. Abercrombie6 considers the mental operations to be chiefly referable to four heads,—memory, abstraction, imagina- tion, and reason or judgment; whilst Kant has twenty-five primary faculties or forms; pure conceptions or ideas a priori. These are a few only of the discrepant divisions of psychologists. The list might have been extended by the classifications of Aristotle, Bacon, Hobbes, Locke, Bonnet, Hume, Vauvenargues, Diderot, Reid, and others. Perhaps the most prevalent opinion at present is, that the original faculties are—perception, memory, judgment, and imagination. It is impossible, were it even our province, to reconcile these discre- 1 Lecons de Philosophie, torn. i. 4eme lecon. 2 Elemens d'Ideologie, 2de edit, Paris, 1804. 3 Precis Elementaire, i. 196. 4 Elements of the Philosophy of the Human Mind, 3d edit, Lond., 1S08; and Amer. edit, Brattleborough, Vt., 1813. 5 Lectures on the Philosophy of the Human Mind, Amer. edit, Boston, 1826. 6 Inquiries concerning the Intellectual Powers, Amer. edit, p. 91, New York, 1832. AFFECTIVE FACULTIES. 325 pancies. They are too considerable to hope, that this will ever be effected by metaphysical inquiry. We must, therefore, look to physio- logical investigation, if not with well-founded—with the only—hopes, we can entertain, for the elucidation of the subject; and we shall find presently, that the minds of metaphysical physiologists have been turned in this direction, and that many interesting facts and speculations have been the result. A second topic of metaphysical inquiry regards the formation of the intellectual notions. On this, there have been two principal opin- ions; some, as Plato, Des Cartes, the Kantists, Kanto-Platonists, &c, believing in the existence of innate ideas;—others, as Bacon, Locke, and Condillac, denying the existence of such innate ideas, and assert- ing that the human intellect, at birth, is a tabula rasa; and that the mind has tQ acquire and form all the ideas it possesses from impres- sions made on the senses. The truth includes probably both these pro- positions,—the action of the senses and intellectual faculties being alike necessary;—the former receiving the external and internal im- pressions, and transmitting them to the mind, which, through the cerebral organ, produces the latter. Under the terms affective faculties, affections, and passions, are comprehended all those active and moral powers, which connect us with the beings that surround us, and are the incentives to our social and moral conduct. To this class belong,—the feeling, which attaches the parent to the child ; that which attracts the sexes ; and compassion, by which we are led to assist a suffering fellow-creature. They are, in truth, internal sensations, but of a higher cast than those of hunger and thirst;—the latter being purely physical, and announcing physical necessities; the former suggesting social and moral relations. Such affective faculties are the foundation of what are called moral wants; and, like the internal sensations in general, are the source of pleasure, when satisfied,—of pain, when resisted ; and it is only when they are extreme and opposed, that they acquire the name of passions.1 The analysis of these is attended with the same difficulties as that of the intellectual faculties. Their plurality is universally admitted, but still greater discrepancy exists as to their precise number and connexion.2 Many moralists have united the moral faculties under the head of will or desires. Condillac3 is one of those. Every sensation, he observes, has the character of pleasure or pain, none being indifferent; as soon, therefore, as a sensation is experienced, the mind is excited to act. This tendency is at first but slightly marked, and is only an uneasiness (malaise); but it soon increases and becomes restlessness or inquietude;— in other words, a difficulty experienced by the mind of remaining in the same situation. This gradually becomes desire, torment, passion, and finally will excited to the execution of some act. Some have en- deavoured, by ultimate analysis, to derive all the affective faculties from one principal faculty—that of self-love,—the inward feeling, which induces all to attend to themselves, their own preservation, and ' From patior, I suffer. 2 Adelon, art. Affection, Dictionnaire de Medecine, lere edit.; and Physiologie de l'Homme, edit, cit, i. 537. 3 Qp. citat 326 MENTAL FACULTIES. welfare. All the faculties, they assert, are returns of this self-love upon itself; and, as in the case of the intellectual faculties, attempts have been made to classify them ; but scarcely two metaphysicians agree. Some have divided them into the agreeable and distressing; others into those of love and hatred; many—regarding their effects upon society—into the virtuous, vicious, and mixed;—the first com- prising those that are useful to society,—as filial, parental, and con- jugal love, which form the foundation of families ; goodness, pity, and generosity, which, by inducing men to assist each other, facilitate the social condition; and the love of labour, honour, and justice, which have the same result, by constituting so many social guarantees. The vicious passions, on the contrary, are such as injure man individually, and society in general, as pride, anger, hatred, and malice. Lastly, the mixed passions are such as are useful or injurious, according to their use or abuse; as ambition, which may be a laudable* emulation, or an insatiable passion, according to its extent and direction. Again, the passions have been divided into the animal or such as belong to physical man, and the social or such as appertain to man in society. The first are guides for his preservation as well as for that of the species. To them belong fear, anger, sadness, hatred, excessive hunger, the venereal desires when vehement, jealousy, &c. In the second are included all the social wants when inordinately experienced. These vary according to the state of civilization of the individual and the community. Ambition, for instance, it is said, may be regarded, when inordinate, as excessive love of power:—avarice, as an exaggera- tion of the desire for fortune:—hatred, and vengeance, as the natural and impetuous desire of injuring those that injure us, &c. Mr. Dugald Stewart's1 division of the active and moral powers embraces, 1. Instinct- ive principles, and 2. Rational principles,—the former including appe- tites, desires, and affections ; the latter self-love and the moral facidly; all of which Dr. Brown2 comprises under emotions, immediate, retrospect- ive, or prospective;—and lastly, Dr. Abercrombie3 refers all the prin- ciples, which constitute the moral feelings, to the following heads: 1. The desires, the affections, and self-love; 2. The will; 3. The moral principle, and 4. The moral relation of man towards the Deity. It is obvious, that the analysis of the moral faculties has been still less satisfactorily executed than that of the intellectual; and that little or no attempt has been made to distinguish those that are primary or fundamental, from those that are more complex; consequently, the remarks which were made regarding the only quarter we have to look to, for any improvement in our knoAvledge of the intellectual acts, apply a fortiori to the moral; although it must be admitted, that the difficul- ties attendant upon the investigation of the latter are so great as to appear to be almost insuperable. As the brain, then, is admitted to be the organ of the intellectual and moral faculties, it is fair to presume that its structure may be i Op. citat. 2 Op. citat. 3 Philosophy of the Moral Feelings, Amer. edit, p. 35, New York, 1833. SIZE OF THE BRAIN. 327 found to vary according to the number and character of those ; and if there be primary or fundamental faculties, each may be conceived to have a special organ concerned in its production, as each of the exter- nal senses has its organ. According to this view, the cerebral organi- zation of animals ought to differ according to their psychology: where one is simple, the other should be so likewise. This seems, so far as we can observe, to be essentially the fact. " In the series of animals," says M. Adelon,1 "we observe the brain more complicated as the men- tal sphere is more extensive; and in this double respect a scale of gra- dation may be formed from the lowest animals to man. If he has the most extensive moral sphere, if he alone has elevated notions of religion and morality, he also has the largest brain, and one composed of more parts; so that if the physiology of the brain were more ad- vanced, we might be able, by comparing the brains of animals with his, to detect the material condition, which constitutes humanity. If the brain were not constructed a priori for a certain psychology, as the digestive apparatus is for a certain alimentation ; and if the mental and moral faculties were not as much innate as the other faculties, there would be nothing absolute in legislation or morals. The brain and its faculties are, however, in each animal species, in a ratio with the rble, which such species is called upon to play in the universe. If man is, in this respect, in the first rank ; if he converts into the delicate affec- tions of father, son, husband, and country, those brute instincts by which the animal is attached to its young, its female, or kennel; if, in short, he possesses faculties which animals do not,—religious and moral feelings, with all those that constitute humanity,—it is owing to his having a more elevated vocation ; to his being not only king of the universe, but destined for a future existence, and specially intended to live in society. Hence it was necessary, that he should not only have an intellect sufficiently extensive to make all nature more or less sub- ject to him, but also a psychology such, that he might establish social relations with his fellows. It was necessary, that he should have notions of the just and the unjust, and be able to elevate himself to the knowledge of God;—to those sublime feelings, which cause him so to regulate his conduct as to maintain with facility his mortal connexions, and deserve the future life to which he is called." But if the intellectual sphere be regulated by the cerebral develope- ment, can we not, it has been asked, estimate the connexion between them ? And if there be different primary cerebral faculties, each of which must have an organ concerned in its production, can we not point out such organ in the brain ? Several investigations of this cha- racter have been attempted, with more or less success: generally, however, they have added but little to our positive knowledge, and this, principally, from the intricacy of the subject. Until of late years, attention was chiefly paid to the mass and size of the encephalon; and it was, at one time, asserted that the larger it is, in any species or in- dividual, the greater the intellect. Man, however, has not absolutely the largest encephalon, although he is unquestionably the most intelli- gent of beings. The weight of the encephalon of a child six years of 1 Art.Encephale, in Diet de Med., vii. 526 ; and Physiologie de l'Homme, edit, cit, i. 524. 328 MENTAL FACULTIES. age is given by Haller at two pounds three ounces and a half; whilst that of the adult is estimated by Sommering at from two pounds three ounces, to three pounds three ounces and three-quarters 'f by Tiede- mann2 at from three pounds three ounces, to four pounds eleven ounces troy,—the brain of the female weighing, on an average, from four to eight ounces less than that of the male. The average weight, after the meninges have been stripped off, is, in the healthy adult male, according to M. Lelut,3 about 1346 grammes, or three pounds and a half avoirdupois; of which the cerebrum weighs 1170, the cerebellum 176 grammes. In the female, the weight of the encephalon was about J^th less. From the tables of weights of the brain given by Dr. Sims, Clendinning,4 Tiedemann, and Dr. John Reid,5 it was found that in a series of 278 cases the maximum weight of the adult male brain was 65 ounces: the minimum weight 34 oz. In a series of 191 cases, the maxi- mum weight of the brain of the adult female was 56 oz. .*—the minimum weight 31 oz. By taking the mean of all the cases, an average weight was deduced of 49J oz. for the male; and of 44 oz. for the female brahV; and although many female brains exceed in weight particular male brains, it is found that the adult male encephalon is heavier than that of the female, by from five to six ounces on an average.6 The encephalon of the elephant, according to Haller, weighs from seven to ten pounds. The brain of an African elephant, seventeen years old, was found by Perrault to weigh nine pounds; that of an Asiatic elephant, weighed by A. Moulins, was ten pounds. Sir Astley Cooper dissected one that weighed eight pounds one ounce and two grains, avoirdupois.7 These facts, consequently, overthrow the proposition; and, moreover, in certain insects, the bee and the ant, we meet with evidences of singular intel- ligence. The proposition was therefore modified, and it was laid down, that the larger the encephalon, compared with the rest of the body, the greater the mental sphere. When the subject was first investigated in this way, the result, in the case of the more common and domestic animals, was considered so satisfactory, that without farther compari- son, the proposition was considered established. More modern re- searches have shown, that it admits of numerous exceptions; and that several of the mammalia, and many diminutive and insignificant ani- mals have the advantage over man in this respect. It has, indeed, been properly observed by Mr. Lawrence,8 that it cannot be a very satisfactory mode of proceeding, to compare the body, of which the weight varies so considerably, according to illness, emaciation, or em- bonpoint, with the brain, which is affected by none of those circum- 1 Weber's Hildebrandt's Handbuch der Anatomie, Band iii. 423; Rudolphi, Grundriss, u. s. w. ii. 11, Berlin, 1823. 3 Proceedings of the Royal Society for 1836; also Das Him des Negers mit des Eu- ropiters und Orang-outangs vergleichen, Heidelb., 1837, cited in Brit, and For. Med. Rev., for Oct. 1839, p. 374. 3 Gazette Medicale; and Medico-Chirurgical Review for Oct., 1837, p. 507. 4 Medico-Chirurgical Transactions, xix. 353. 6 Lond. and Edinb. Monthly Journal of Medical Science, April, 1843, p. 298. 6 Quain's Human Anatomy, by Quain and Sharpey, Amer. edit, by Leidy, ii. 185, Philad., 1849. 7 Dr. Todd, art Nervous Centres, in Cyclop, of Anat. and Physiol. Pt. xxv. p. 604, Lond., 1844. 8 Lectures on Physiology, Zoology, &c, p. 191, Lond., 1819. SIZE OF THE BRAIN. 329 stances, and appears to remain constantly the same. This is the cause, why, in the cat, the weight of the encephalon compared with that of the body has been stated as 1 to 156 by one comparative ana- tomist ; and as 1 to 82 by another; that of the dog as 1 to 305 by one, and as 1 to 47 by another, &c. The following table, taken chiefly from Haller1 and Cuvier,2 exhibits the proportion borne by the encephalon to the rest of the body, in man and certain animals. Child, 6 years old i 22 Adult 1 3 5 Gibbon . . 1 45 Sapajous, from -1 to -1-4 1 LU 2 2 Apes 4!5 tO ^ Baboons T04 t° 55 Lemurs 54 tO g*r Bat ,(vespertilio) • ifr Mole 1 35 Bear 1 * 205 Hedgehog . • T55 Fox * 20> l32 Eagle * 253 Goose 350" Cock 1 25 Canary Bird 1 T4 Humming Bird3 . 1 ■ 1 1 Turtle ■ 5555 Tortoise . • 3240" Frog T*3 Shark 3435 Pike 1 _ 13 05 Carp sin In 9 males, between 27 and 50 years of age, who died immediately, or within a few hours, after accidents, and other external causes of death, and who had been previously in good health, Dr. John Reid4 obtained the following results;—the weight used being avoirdupois:— Average weight of body (9 weighed) . . . 134 lbs. 3} oz. Average of encephalon (6 weighed) ... 3 lbs. 4 oz. 4| dr. Average of cerebellum (4 weighed) ... 5 oz. 7^ dr. Average of cerebellum with pons and medulla (5 weighed)......... Or, taking the average of the four cases only in which the cerebellum was taken . . Average of heart (9 weighed)..... Relative weight of body to encephalon (6 weighed) . Relative weight of body to heart (9 weighed) . . . Relative weight of encephalon to cerebellum (4 weighed).............as 1 to Relative weight of encephalon to cerebellum, with pons and medulla (5 weighed)......as 1 to 5 6 6 12 oz. 6 dr. oz. 7g dr. oz. 6 dr. as 1 to as 1 to 173i 40* n T3 2 Lecons d'Anat Comp., ix. art. 5. ' Element Physiol., x. sect. 1. 3 On the authority of ex-President Madison. * Lond. and Edinb. Monthly Journal of Med. Science, April, 1843, p. 322. 330 MENTAL FACULTIES. M. Bourgery1 found, that the mean weight of the encephalon being 20393*5 grains troy, the cerebral hemispheres weigh 16940*46 grains; the cerebellum, 2176*7 grains ; the cephalic prolongation of the cere- bro-spinal axis, 1312*2 grains ; of which the optic thalami and corpora striata make 879*9 grains ; the medulla oblongata with the pons Varolii 432*2 grains ; and the spinal cord 710*1 grains. Hence, in man, the cerebral hemispheres include a nervous mass, which is four times greater than the rest of the cerebro-spinal mass; nine times greater than the cerebellum; thirteen times greater than the cephalic stem of the spinal cord; and twenty-four times greater than the spinal cord itself. It has been the general belief, that' the brain of the negro is inferior to that of the white variety of the species; but certain observations of M. Tiedemann led him to the belief, that there is no perceptible differ- ence either in its average weight or average size in the two varieties, and that the nerves compared with the size of the brain are not larger in the former than in the latter. In the external form of the brain of the negro a very slight difference only could be traced; and he affirmed further, that there is absolutely no difference in its external structure, nor does the negro brain exhibit any greater resemblance to that of the ourang outang than the brain of the European, excepting, perhaps, in the more symmetrical disposition of its convolutions. Tiedemann's observations were made, however, upon few subjects ; and his own facts do not bear out all his deductions. He admits, that the anterior part of the hemispheres was something narrower than is usually the case in Europeans, " which,"—says Dr. Combe,2—" as the anterior portion is the seat of intellect, is really equivalent to conceding that the negro is naturally inferior in intellectual capacity to the European !" M. Tiede- mann established that the average capacity of the Ethiopian skull is somewhat less than that of the European, and that a large sized skull is considerably less frequent among them than among any other races of mankind.3 The following table, drawn up by Dr. Morton,4 exhibits the absolute capacity of the cranium or bulk of the brain in cubic inches, obtained by filling the cavity of the crania with leaden shot, one-eighth of an inch in diameter, in different races and families of man.5 It sufficiently exhibits how little can be judged, in this manner, of their relative intel- lectual aptitudes. i Lond. Med. Gaz., Jan., 1845, p. 462. 2 Phrenological Journal, No. liv.,Dec, 1837. 3 Brit, and For. Med. Rev., for Oct., 1839, p. 379. 4 Catalogue of Skulls of Man and the Inferior Animals in the collection of Samuel George Morton, M.D., &c, 3d edit, p. viii., Philad., 1849. 6 For the ingenious process invented by Mr. J. S. Phillips, of Philadelphia, by which these measurements were taken, see Dr. Morton's Crania Americana, p. 253, Philad. and Lond., 1839. SIZE OF THE BRAIN. 331 TABLE, Showing the Size of the Brain in cubic inches, as obtained from the measurements q/"023 Crania of various Races and Families of Man. (N. B.—I. C means Internal Capacity.) RACES AND FAMILIES. No. of Skulls. Largest. I. C. Smallest. i.e. Mean. Mean. MODERN CAUCASIAN GROUP. Teutonic Family. Germans, 18 114 70 90 ) English, 5 105 91 96 L92 Anglo-Americans, 7 97 82 90 j Pelasgic Family. ] Persians, Armenians, 10 94 75 84 Circassians, J x Celtic Family. Native Irish, } 6 I 32 97 78 - 87 Indostanic Family. Bengalees, &c, 91 67 80 Semitic Family. ) Arabs, I 3 98 84 89 Nilotic Family. Fellahs, } 17 96 66 80 ANCIENT CAUCASIAN GROUP. si ■•-* s a 8 < 2-2 fa <3 Pelasgic Family. Grceco-Egyptians, } « 97 74 88 Nilotic Family. ^ Egyptians, | 55 96 68 80 MON 30LIAN GROUP. Chinese Family, 6 91 70 82 MAL AY GROUP. Malayan Family, 20 97 68 86 J 85 Polynesian Family, 3 84 82 83 AME RICAN GROUP. Toltecan Family. 1 -| Peruvians, \ 155 101 ' 58 75 Mexicans, 22 92 67 79 Barbarous Tribes. Iroquois, -79 Lenape', t 161 104 70 84 Cherokee, Shoshoni, &c, . _, NEGRO GROUP. Native African Family, 62 99 65 83 | 83 American-born Negroes, 12 89 73 82 Hottentot Family, 3 83 68 75 Alforian Family. } * Australians, 83 63 75 332 MENTAL FACULTIES. From this table it appears, that the smallest mean cranial capacity is found in the Hottentots and Australians, which is 75 cubic inches; whilst that of the Teutonic races is 92 cubic inches. It may be inte- resting to add, that from the examination of four skulls of the Enge-ena, a quadrumanous animal—Troglodytes gorilla of Savage—from Gaboon in Africa, Dr. Jeffries Wyman1 found the mean capacity, measured according to the method employed by Dr. Morton, to be 28*9-| cubic inches, or considerably less than one-half the mean of the Hottentots and Australians, who afford the minimum average for the human family. The mean cranial capacity of three adult Chimpanzees was even less, or 24 cubic inches. Wrisberg and Sommering2 proposed another point of comparison— the ratio of the mass of the encephalon to that of the rest of the nervous system; and they asserted, that in proportion as any animal possesses a larger share of the former; or, in other words, in proportion as the percipient and intellectual organ exceeds the other or the organ of the external senses—the mental sphere may be expected to be more diversified and developed. But although man is, in general, pre-eminent in this respect, he is not absolutely so. Fig. 134. Facial Line and Angle of Man. It would be still more important to know the ratio, which the cere- brum or brain proper bears to the cerebellum and medulla ob- longata. The first is essentially the organ of intellect; and the most striking character of the human brain is the large deve- lopement of the cerebral hemi- spheres, of which we have no parallel in the animal kingdom. The last is the encephalic part in which the nerves of sense arise or terminate. The assertion, that man has the largest cerebrum in propor- tion to the cerebellum, is not ac- curate. The Wenzels3 found the ratio, in him, to be as Qj^ or 8T422T to 1; in the .horse, 4J to 1; in the cow, 5jff to 1; in the dog, 63% to 1; in the cat, 4T4g to 1; in the mole, 3f to 1; and in the mouse, 6f to 1. Nor is it true that man has the largest cere- brum in proportion to the medulla 1 A description of two additional Crania of the Enge-ena, &c, read before the Boston Society of Natural History, Oct. 3, 1849; and published in the American Journal of Science and Arts, second series, vol. ix. 2 Corpor. Human. Fabric, iv. § 92; and Blumenbach's Comp. Anat. by Lawrence, p. 292, Lond., 1807. 3 De Penitiori Structur. Cerebr. Hominis et Brutorum, tab. iv. camper's facial line and angle. 333 oblongata and medulla spinalis; although to this position there are perhaps fewer objections than to the others. None of them, it is ob- vious, are distinctive between man and animals, or assist us in solving the great problem of the source and seat of the numerous psychological differences we observe. Various plans have been devised for appreciating the comparative size of the cranium,—which is generally in a ratio with that of the brain, —and of the bones of the face. As the former contains the organ of the intellect, and the latter those of the external senses and of mastica- tion, it has been presumed, that the excess of the former would indicate the predominance of thought over sense; and, conversely, that the greater developement of the face would place the animal lower in the scale. One of these methods, first proposed by Camper,1 is by taking the course of the facial line, and the amount of the facial angle. The facial line is a line drawn from the projecting part of the forehead to the alveoli of the incisor teeth of the upper jaw; the facial angle is that formed between this line and another drawn horizontally backwards from the upper jaw. The course of the horizontal line and its point of union with the facial line are not uniform in all the figures given by Camper: sometimes, it is made to pass through the meatus auditorius externus; but it often falls far below it; yet Dr. Bostock thinks2 "we cannot hesitate to admit the correctness of Camper's observations, and we can scarcely refuse our assent to the conclusion that he deduces from them." In man, whose face is situate perpendicularly under the cra- nium,, the facial angle is very large. In animals, the face is placed in front of the cranium; and as we descend from man the angle becomes less and less, until it is finally lost; the cranium and face being in most reptiles and fish on a level. The marginal figure (Fig. 134) exhibits the difference be- tween the facial angle of those of European descent, and that of the negro. By covering with the finger the parts below the nose al- ternately, we have the countenance of the white, and negro, in which the facial angle differs as much as 10°, or 15°. Fig. 135 exhibits the facial line and angle of the ourang-outang. Animals that have the snout long, and the facial angle consequently small, have been proverbially esteemed fool- ish,3—such are the snipe, stork, crane, &c.; whilst superior intelligence has been ascribed to those in which the angle is more largely developed,—as the elephant and the owl; although in them, the large facial angle is caused by the size of the frontal sinuses, or FacialLmeand Angle of the Ourang- ' Dissertation Physique de M. Camper, sur les Differences Reelles que presentent les Traits du Visage, &c, traduit du Hollandois, par D. B. Q. Disjonval Autrecht 1791 » Physiology, 3d edit, p. 804, Lond., 1836. 3 Lawrence, op. citat, p. 168. Fig. 135. 334 MENTAL FACULTIES. by the wide separation between the two tables of the skull, and is necessarily no index of the size of the brain. Yet, from this cause, perhaps, the owl was chosen as an emblem of the goddess of wisdom; and the elephant has received a name in the Malay language, indicating an opinion, that he is possessed of reason. The following table exhibits the facial angle in man and certain animals, taken Ly a line drawn parallel to the floor of the nostrils, and meeting another, drawn from the greatest prominence of the alveoli of the upper jaw to the promi- nence of the forehead:— Man ... 68° to 88° or more Sapajou ...... 65° Ourang-outang . . . 56° or 58° Guenon ...... 57° Mandril.....30° to 42° Coati......28° Polecat , Pug dog Mastiff Hare Ram Horse , 31° 35° 41° 30° 30° 23° The facial angle may, then, exhibit the difference between man and animals; and, to a certain extent, between the species or individuals of the latter; but, farther, it is of little or no use.1 In man, it may be considered to vary from 70° to 85° in the adult; but in children it reaches as high as 90° and upwards; a sufficient proof, that it cannot be regarded as a measure of the intellect. In the European, it has been estimated, on the average, at perhaps, 80°, in the Mongol, 75°, and in the negro, 70°, not many degrees above the Sapajou.2 The following table, drawn up from the average of actual measure- ments of the skulls of different races and families of man, in the col- lection of Dr. Morton,3 will afford more precise information on this matter. Arab (2 cases) European and Anglo-American Egyptian Bengalee Circassian Sandwich Islander (one case) Chinese (one case) Guanche (one case) Negro Indian Hottentot (one case) Peruvian Malay It is found, that the skulls of different nations, and of individuals of the same nation, may agree in the facial angle, whilst there may be striking distinctions in the shape of the cranium and face, in the air and character of the whole head; as well as in the particular features,— the inclination of the facial line being more dependent on the promi- nence of the upper jaw and frontal sinuses than on the general form of ' Dr. Morton, in his splendid work, Crania Americana, Philad., 1839, describes a "Facial Goniometer," originally suggested by Dr. Turnpenny, of Philadelphia, which is admirably adapted for measuring the facial angle. 3 Prichard's Physical History of Mankind, i. 288, 3d edit, Lond., 1836. 3 Catalogue of Skulls of Man, &c, 3d edit, Philad., 1849. FACIAL ANGLE. erage. Highest. L owe 82 88 76 80 85 77 79-3 86 73 79-3 83 76 78-5 81 75 78 78 77 76-8 83 69 76-1 84 70 75 749 81 68 74-6 82 69 CAMPER'S FACIAL LINE AND ANGLE. 335 1 the head. The ancients were impressed with the intellectual air exhi- 1 bited by the open facial angle; for we find in all their statues of legis- ] lators, sages, and poets, an angle of at least 90°, and in those of heroes i and superhuman natures it is as high as 100°. This angle, according 1 to Camper, never existed in nature; and yet he conceives it to be the i beau ideal of the human countenance, and to have been the ancient : model of beauty. It was, more probably, the model of superior intel- lectual endowment, although ideas of beauty might have been connected with it. Every nation forms its notions of beauty, derived from this source, chiefly from the facial angle to which it is accustomed. With the Greeks it was large, and therefore the vertical facial line was highly estimated. For the same reason, it is pleasing to us; but such would not be the universal impression. Savage tribes on our own continent, have preferred the pyramidal shape of the head, and made use of every endeavour, by unnatural compression in early infancy, to produce it; ' whilst others, not satisfied with the natural shape of the frontal bone, have forced back the forehead, either by applying a flat piece of board to it, like the Indians of our own continent, or by iron plates, like the inhabitants of Arracan. By this practice the Caraibs are said to be able to see over their heads. M. Daubenton,1 again, endeavoured, by taking the occipital line and angle, to measure the differences between the skulls of man and ani- mals. A line is drawn from the posterior margin of the foramen magnum of the occipital bone to the inferior margin of the orbit, and another from the top of the head to the space between the occipital condyles. In man, these condyles, as well as the foramen magnum, are so situate, that a line drawn perpendicular to them will be a con- tinuation of the vertebral column; but in animals they are placed more or less obliquely; the perpendicular will, therefore, necessarily be thrown farther forward, and the angle be rendered more acute.2 Blumenbach says, that Daubenton's method may be adapted to measure the degrees of comparison betwixt man and brutes, but not varieties of national character; for he found it even different in the skulls of two Turks, and three Ethiopians. The methods of Camper and Daubenton com- bined, were, also, insufficient to indicate the varieties in national and individual character. He accordingly describes a new method,—which he calls norma verticalis? It consists in selecting two bones; the frontal from those of the cranium, and the superior maxillary from those of the face; comparing these with each other, by regarding them verti- cally, placing the great convexity of the cranium directly before him, and marking the relative projections of the maxillary bone beyond the arch of the forehead. The Asiatic Georgian is found to be character- ized by the great expanse of the upper and outer part of the cranium, 1 Memoires de l'Academie des Sciences de Paris, p. 568, Paris, 1764. a By some writers, Daubenton's method is said to consist of "a line drawn from the pos- terior margin of the occipital foramen to the inferior margin of the orbit; and another drawn horizontally through the condyles of the occipital bone." It is obvious, that little or no com- parative judgment of the cranium and face could be formed from this. 3 Decad. Collectionis sure Craniorum diversarum Gentium; and De Gener. Human. Var. Nativ., edit. 3a, Gotting., 1795. 336 MENTAL FACULTIES. which hides the face. In the Ethiopian, the narrow, slanting forehead permits the face to appear, whilst the cheeks and jaws are compressed laterally and elongated in front; and in the Tungoose, the maxillary, malar, and nasal bones are widely expanded on each side; and the two last rise to the same horizontal level with the space between the frontal sinuses—the glabella. Blumenbach's method, however, only affords us the comparative dimensions of the two bones in one direction. It does not indicate the depth of either, or their comparative areas. The view thus obtained is, therefore, partial. Finding the inapplicability of other methods to the greater part of the animal creation—to birds, reptiles, and fishes, for example—M. Cu- vier1 suggested a comparison between the areas of the face and cranium under the vertical section of the head. The result of his observations is1—that, in the European, the area of the cranium is four times that of the face, excluding the lower jaw. In the Calmuck, the area of the face is one-tenth greater than in the European; in the negro, one- fifth, and in the sapajou, one-half. In the mandril, the two areas are equal; and, in proportion as we descend in the scale of animals, the area of the face gains over that of the cranium; in the hare, it is one- third greater; in the ruminant animals double; in the horse, quad- ruple, &c.; so that the intelligence of the animal appeared to be greater or less as the preponderance of the area of the face over that of the skull diminished or increased. The truth, according to Sir Charles Bell,2 is, that the great differ- ence between the bones of the cranium and face in the European and negro is in the size of the jaw-bones. In the negro, these bear a much greater proportion to the head and to the other bones of the face than in the European; and the apparent size of the bones of the negro face was discovered to proceed solely from the size and shape of the jaw-bones; whilst the upper bones of the face, and, indeed, all that had no relation to the teeth and to mastication, were less than those of the European skull. Other methods, of a similar kind, have been proposed by natu- ralists, as Spigel,3 Herder,4 Mulder,5 Walther,6 Doornik,7 Spix,8 and Oken, but they are all insufficient to enable us to arrive at a satis- factory comparison.9 Blumenbach asserts, that he found the facial and occipital angles nearly alike in three-fourths of known animals. 1 Lecons d1 Anatomie Compar., No. viii. art. i. torn. ii. p. 1. 2 Anatomy of Expression, 3d edit, Lond., 1844. 3 Linese Cephalometricae Spigelii, in Spigel, De Human. Corpor. Fabric, i. 8. * Nackenlinien (Linese nuchales Herderi), in Herder's Ideen zur Philosophie der Geschichte der Menschheit, Th. iii. s. 186, Tubing., 1806. 6 Vorderhauptwinkel (Angulus sincipitalis Mulderi), in art Kopflinien, in Pierer's Anat. Physiol. Real Worterb., iv. 524, Leipz., 1821. 6 Schadelwinkel (Angulus Cianioscopicus Waltheri), in Walther, Kritische Darstellung der Gallschen Anat. Physiol. Untersuch. des Gehirn und Schadelbaues, s. 108, Zurich, 1802. 7 Wijsgeerig Natuurkundig Onderzoek aangande den Oorsprongliken Mensch en de Oorspronglilie Stammen van deszelfs Geslacht, Amsterd., 1808. 8 Cephalogenesis, Monach., 1815. 9 Oken, Lehrbuch der Zoologie, Abth. ii. s. 660. A description of all these methods is given by Choulant, in Pierer, loc. cit. VIEWS OF PHRENOLOGISTS. 337 Moreover, it by no means follows, that, in the same species, there should be a correspondence between the size of the cranium and face. In the European, the face may be unusually large; and yet the mental endowments may be brilliant. Leo X., Montaigne, Leibnitz, Racine, Haller, Mirabeau, and Franklin, had all large features.1 All these methods, again, are confined to the estimation of the size of the whole encephalon; whereas the brain, we have seen, is alone concerned in the intellectual and moral manifestations; although Gall includes the cerebellum. It has already been remarked, that no ani- mal equals man in the developement of the cerebral hemispheres. In the- ape they are less prominent; and below it in the scale of creation, they become less and less; the middle lobes are less arched down- wards; and the posterior lobes are ultimately wanting, leaving the cerebellum uncovered; the convolutions are less and less numerous and deep, and the brain at length is found entirely smooth. The ex- periments of Rolando of Turin, and Flourens2 of Paris, are likewise confirmatory of this function of the brain proper. These gentlemen experimented upon different portions of the encephalon, with the view of detecting their functions;—endeavouring, as much as possible, not to implicate any part except the one which was the subject of investiga- tion ; and they found, that if the cerebral hemispheres were alone removed, the animal was thrown into a state of stupor or lethargy; was insensible to all impressions; to every appearance asleep, and evidently devoid of all intellectual and affective faculties. On the other hand, when other parts of the encephalon were mutilated—the cerebellum, for example—leaving the cerebral hemispheres uninjured, the animal was deprived of certain other faculties—that of moving, for instance—but retained its consciousness, and the exercise of all its senses. M. Desmoulins,3 in his observations on the nervous system of verte- brated animals, is in favour of a view, embraced by M. Magendie,4 that the intellectual sphere of man and animals depends exclusively on the cerebral convolutions; and that an examination of the convolu- tions will exhibit the intellectual differences, not only between different species, but between individuals of the same species. According to him, the cerebral convolutions are numerous in animals in proportion to their intelligence; and, in animals of similar habitudes, have a similar arrangement. In the same species, they differ sensibly, ac- cording to the degree in which the individuals possess the qualities of their nature:—for example, they vary in the foetus and adult; are mani- festly less numerous and smaller in the idiot; and become effaced in protracted cases of insanity. He farther remarks, that the morbid conditions of the encephalon, which occasion mental aberration, are especially such as act upon the convolutions; and that whilst apo- plectic extravasation into the centre of the organ induces paralysis of 1 Gall, Sur les Fonctions du Cerveau, ii. 296. ' Recherches Experimentales sur le Systeme Nerveux, 2de edit, Paris, 1842. 3 Anatomie des Systemes Nerveux des Animaux a Vertebres, Paris, 1825. * Precis Elementaire, edit, cit, i. 185. VOL. I.—22 338 MENTAL FACULTIES. sensation and motion, the slightest inflammation of the arachnoid membrane causes delirium. Hence, he deduces the general principle, that the number and perfection of the intellectual faculties are in a ratio with the extent of the cerebral surfaces. It would seem, however, from some experiments by M. Baillarger,1 that the amount of intel- lectual developement in man, and in the various classes of animals, is far from being proportionate to the extent of surface presented by the brain of each. That of man, for instance, has, in proportion to its volume, a much less extent of surface than the brains of the lower mammalia; and the brain of the rabbit has, in proportion to its volume, an extent of surface two and a half times greater than that presented by the brain of man. The view of M. Desmoulins, so far as regards the seat of the intel- lectual and moral faculties, accords with one to which attention must now be directed; and which has given rise to more philosophical in- quiry, laborious investigation, and, it must be admitted, to more idle enthusiasm and intolerant opposition, than any of the psychological doctrines advanced in modern times: we allude to the views of M. Gall.2 These are, 1st, That the intellectual and moral faculties are innate. 2dly, That their exercise or manifestation is dependent upon organization. 3dly, That the encephalon is the organ of all the appe- tites, feelings, and faculties; and, 4thly, That the encephalon is com- posed of as many particular organs as there are appetites, feelings, and faculties, differing essentially from each other. The importance of Gall's propositions; the strictly physiological direction they have taken—the only one, as we have said, which ap- pears likely to aid us in our farther acquaintance with the psychology of man—require that the physiological student should have them placed before him as they emanated from the author. The work of Gall on the functions of the encephalon comprises, however, six octavo volumes, not distinguished for unusual method or clearness of exposition. Fortunately, the distinguished biologist, M. Adelon, to whom we have so frequently referred, has spared us the necessity of a tedious and difficult analysis, by the excellent and impartial view be has given in the Dictionnaire de MSdecine,3 which has since been trans- ferred to his Physiologie de l'Homme; both being abridgments of the Analyse d'un Cours du Dr. Gall, published by him in 1808. The foundation of this doctrine is, that the encephalon is not a single organ, but is composed of as many nervous systems as there are primary and original faculties of the mind. In the view of Gall, it is a group of several organs, each of which is concerned in the produc- tion of a special moral act; and, according as the encephalon of an animal contains a greater or less number of organs, and of a greater or less degree of developement, the animal has, in its moral sphere, a greater or less number of, or more or less active, faculties. In like 1 Revue Medicale, Mai, 1845. a Sur les Fonctions du Cerveau, Paris, 1825. 3 Art. Encephale (Physiologie), Paris, 1823, and art. Facultes de l'Esprit et de l'Ame, &c, in Diet, de Medecine, viii. 469, Paris, 1823. VIEWS OF PHRENOLOGISTS. 339 manner, as there are as many sensorial nervous systems and organs of sense as there are external senses, so there are, it is maintained, as many encephalic nervous systems as there are special moral faculties or internal senses. Each moral faculty has, in the encephalon, a nervous part concerned in its production; as each sense has its special nervous system; the sole difference being, that the nervous systems of the senses are separate and distinct, whilst those of the encephalon are crowded together in the small cavity of the cranium, and appear to form but one mass. The proofs, adduced by Gall1 in favour of his proposition, are the following:—1st. It has been established as a principle, that differences in the psychology of man and animals correspond to varieties in the structure of the encephalon, and that the latter are dependent on the former. Now, differences of the encephalon consist less in changes of the general form of the organ, than in parts, which are present in some and not in others; and if the presence or absence of such parts is the cause why certain animals have a greater or less number of faculties than others, they ought certainly to be esteemed special organs of such faculties. 2dly. The intellectual and moral faculties are multiple. This every one admits. Each, consequently, ought to have its special organ; and the admission of a plurality of intellectual moral faculties must induce that of a plurality of encephalic organs, in the same man- ner as each external sense has its proper nervous system. 3dly. In different individuals of the same species,—in different men,—much psychological variety is observable. The cause of this is doubtless in the encephalon; but we can hardly ascribe it to a difference in the general shape of the organ, which is sensibly the same. It is owing rather to differences in its separate parts. Are not such parts, there- fore, he asks, distinct nervous systems ? 4thly. In the same individual— in the same man—the intellectual and affective faculties have never the same degree of activity: whilst one predominates, another may be feeble. Now, this fact, which is inexplicable under the hypothesis, that the encephalon is a single organ, is readily intelligible under the theory of the plurality of organs. Whilst the encephalic part, which is the agent of the one faculty, is proportionably more voluminous or more active, that which presides over the other is less so. Why, he asks, may not this happen with the encephalic organs, as with the other organs of the body,—the senses, for example ? Cannot one of these be feeble, and the other energetic ? 5thly. In the same indi- vidual, all the faculties do not appear, nor are they all lost at the same period. Each age has its own psychology. How can we explain these intellectual and moral varieties according to age, under the hypothesis that the encephalon is a single organ ? Under the doctrine of the plurality of encephalic organs, the explanation is simple. Each ence- phalic system has its special period of developement and decay. 6thly. It is a common observation, that when we are fatigued by one kind of mental occupation, we have recourse to another; yet it often happens, that the new labour, instead of adding to the fatigue experienced by • Op. cit, ii. 394. 340 MENTAL FACULTIES. the former, is a relaxation. This, Gall remarks, would not be the case if the encephalon were a single organ, and acted as such; but it is readily explicable under the doctrine of plurality of organs. It is owing to a fresh encephalic organ having been put in action. 7thly. Insanity is frequently confined to one single train of ideas, as in the variety called monomania, which is often caused by the constancy and tenacity of an original exclusive idea. This is frequently removed by exciting another idea opposed to the first, which distracts attention from it. Is it possible, Gall asks, to comprehend these facts under the hypothesis of unity of the encephalon ? 8thly. Idiocy and dementia are often only partial, and it is not easy to conceive, under the idea of the unity of the encephalon, how one faculty remains amidst the abolition of all the others. 9thly. A wound or a physical injury of the encephalon frequently modifies but one faculty, paralyzing, or aug- menting it, and leaving every other uninjured. lOthly, and lastly. Gall invokes the analogy of other nervous parts; and, as the great sympathetic, medulla oblongata, and medulla spinalis are—in his view at least—groups of special nervous systems, it is probably, he says, the same with the encephalon. Such are the main arguments employed by Gall for proving, that the encephalon consists of a plurality of organs, each of which is con- cerned in the production of a special intellectual or moral faculty; and should they not carry conviction, it must be admitted that many of them are ingenious and forcible, and all merit attention. It is a prevalent idea, that this notion of a plurality of organs is a fantasy, which originated with Gall. Nothing is more erroneous: he has adduced the opinions of numerous writers who preceded him, some of whom have given figures of the cranium, with the seats of the dif- ferent organs and faculties marked upon it. To this list might be added numerous others. Aristotle, in whose works are found the germs of many discoveries and speculations, thought that the first or anterior ventricle of the brain, was the ventricle of common sense; because, from it, according to him, the nerves of the five senses branched off. The second ventricle, connected by a minute opening with the first, he designated as the seat of imagination, judgment, and reflection; and the third, as a storehouse into which the conceptions of the mind, digested in the second ventricle, were transmitted for retention and accumulation: he regarded it as the seat of memory. Bernard Gor- don, in a work written in 1296, gives nearly the same account of the brain. It contains, he says, three cells or ventricles. In the anterior part of the first lies common sense; the function of which is to take cognizance of the various forms and images received by the several senses. In the posterior part of the first ventricle he places phantasia; and in the anterior part of the second, imaginativa ; in the posterior part of the middle lies estimativa. It would be a waste of time and space, to adduce the absurd notions entertained by Gordon on this subject. He thinks there are three faculties or virtues—imaginatio, cogitatio, and memoria—each of which has a special organ engaged in its production. VIEWS OF PHRENOLOGISTS. 341 Fig. 136. For many centuries it was believed, that the cerebrum was the organ of perception, and the cerebellum that of memory. Albert the Great, in the thirteenth century, sketched a head on which he represented the seat of the different intellectual faculties. In the forehead and first ventricle he placed common sense and imagination ; in the second intelligence and judgment; and in the third, memory and the motive force. The head in the margin (Fig. 136), is from an old sketch contained in the Book Rarities of the University of Cambridge. Servetus conceived, that the two anterior cerebral cavities are for the reception of the images of ex- ternal objects; the third is the seat of thought; the aqueduct of Sylvius, the seat of the soul; and the fourth ventri- cle that of memory. In 1491, Peter Montagnana published an engraving, in which were represented the seat of the sensus communis, a cellula imagina- tiva, cellula estimativa seu cogitativa, a cellula memorativa, and a cellula ra- tionalis. A head by Ludovico Dolci exhibits a similar arrangement. (Fig. 137.)1 The celebrated Dr. Thomas Willis, in 1681, asserted, that the corpora striata are the seat of perception; the medul- lary part of the brain that of memory and imagination; the corpus callosum that of reflection; and the cerebellum furnished the vital spirits necessary for the involuntary motions.2 It would ap- pear, too, that Swedenborg, half a cen- tury before the promulgation of Gall's theory, maintained the doctrine, that every man is born with a disposition to all sorts of evil, which must be checked by education, and, as far as possible, rooted out; and that the degree of success or failure in this respect would be indicated by the shape of the skull. "The peculiar distinctions of man, will and the understand- ing," he argued, "have their seats in the brain, which is excited by the fleeting desires of the will, and the ideas of the intellect. Near Old Phrenological Head. Fig. 137. Olfactus Gustus Phrenological Head by Dolci, A. D. 1562. 1 See Burton's Anatomy of Melancholy, 11th edit, i. 32, Lond., 1813; and Margarita Philosophica, lib. ix. cap. 40, Basil., 1508, cited by Dr. John Redman Coxe, in Dunglison's American Medical Intelligencer, i. 58, Philad., 1838. * Gall, Sur les Fonctions du Cerveau, ii. 350, Paris, 1835. 342 MENTAL FACULTIES. the various spots where these irritations produce their effects, this or that part of the brain is called into a greater or less degree of activity, and forms along with itself corresponding parts of the skull."1 This view, that exercise of the encephalic organs occasions their develope- ment in bulk, and want of due exercise their decrease, is now main- tained by many phrenologists-; but denied by others. The above examples are sufficient to show, that the attempt to assign faculties to different parts of the brain; and, consequently, the belief, that the brain consists of a plurality of organs, had been long indulged by anatomists and philosophers. The views of Gall are resuscitations of the old; but resembling them little more than in idea. Those of the older philosophers were the merest fantasies, unsupported by ob- servation: the speculations of the modern physiologist have certainly been the result of long and careful investigation, and deep meditation. Whilst, therefore, we may justly discard the former, the latter are worthy of careful and unprejudiced examination. Admitting, with M. Gall, the idea of the plurality of organs in the encephalon, the inquiry would next be,—how many special nervous systems are there in that of man, and what are the primary intellectual and moral faculties over which they preside? This Gall has attempted. To attain this double object, he had two courses to adopt;—either, first to indicate anatomically the nervous systems that constitute the encephalon; and then to trace the faculties of which they are the organs; or, contrariwise, to point out first the primary faculties, and afterwards to assign to each an organ or particular seat. The first course was impracticable. The encephalic organs are not distinct, isolated: and if they were, simple inspection could not indicate the faculty over which they preside, any more than the appearance of a nerve of sense could indicate the kind of sensation for which it is des- tined. It was, only, therefore, by observing the faculties, that he could arrive at a specification of the primary encephalic organs. But here, again, a source of difficulty arose. How many primary intellectual and moral faculties are there in man? and what are they? The classifi- cations of the mental philosophers,—differing, as we have seen they do, so intrinsically and essentially from each other,—could lead him to no conclusion. He first, however, followed the views on which they appeared to be in accordance; and endeavoured to find particular organs for the faculties of memory, judgment, imagination, &c. But his researches in this direction were fruitless. He, therefore, took for his guidance the common notions of mankind; and having regard to the favourite occupations, and different vocations of individuals, to those marked dispositions, which give occasion to the idea, that a man is born a poet, musician, or mathematician, he carefully examined the heads of such as presented these predominant qualities, and endea- voured to discover in them such parts of the encephalon as were more prominent than usual, and might be considered as special nervous systems,—organs of those faculties. After multitudinous empirical researches on living individuals, on collections of crania, and casts * Dr. Sewall, Examination of Phrenology, 2d edit, p. 14, Boston, 1839. VIEWS OF PHRENOLOGISTS. 343 made for the purpose; attending particularly to the heads of such as had one of their faculties predominant, and who were, as he remarks, geniuses on one point,—to the maniac, and the monomaniac;—after a sedulous study, likewise, of the heads of animals, comparing especially those that have a particular faculty with such as have it not, in order to see if there did not exist in the encephalon of the former some part which was wanting in that of the latter; by this entirely experimental method, he ventured to specify, in the encephalon of animals and man, a certain number of organs; and, in their psychology, as many facul- ties, truly primary in their character. But, in order that such a mode of investigation be applicable it must be admitted, 1st. That one of the elements of the activity of a function is the developement of its organ. 2dly. That the encephalic organs end, and are distinct, at the surface of the encephalon. 3dly. That the cranium is moulded to the encephalon, and is a faithful index of its shape; for it is, of course, through the skull and the integuments covering it, that Gall attempts, in the'living subject, to appreciate the state of the encephalon. Within certain limits, these positions are true. In the first place, we judge of the activity of a function, by the size of the organ that executes it: the greater the optic nerve, the more acute we expect to find the sense of sight. In the second place, according to the anato- mical theory of Gall, the encephalic convolutions are the final expansions of the encephalon: if we trace back the original fasciculi, which, by their terminations, form the hemispheres of the brain, they are observed to increase gradually in size in their progress towards the circumference of the organ, and to end in the convolutions. Lastly, to a certain extent the cranium is moulded to the encephalon; and participates in all the changes which the latter undergoes at different periods of life and in disease. For example, during the first days after the formation of the encephalon of the foetus, the cranium is membranous, and has exactly the shape of that viscus. On this membrane, ossific points are deposited, so that, when the membrane has become bone, the cranium has still the shape of the encephalon. In short, nature having made the skull to contain the encephalon has fitted the one to the other, and this so accurately, that its internal surface exhibits sinuosities corresponding to the vessels that creep on the surface; and digitations corresponding to the encephalic convolutions. The encephalon, in fact, rigidly regulates the ossification of the cranium ; and when, in the pro- gress of life, it augments, the capacity of the cranium is augmented likewise; not by the effect of mechanical pressure, but owing to the two parts being catenated in their increase and nutrition. This remark applies not only to the skull andx encephalon, regarded as a whole, but to their separate parts. Certain portions of the encephalon are not developed simultaneously with the rest of the organ; and the same thing happens to the portions of the skull that invest them. The fore- head, for example, begins to be developed after the age of four months; but the inferior occipital fossae do not increase in proportion until the period of puberty. Again; when the encephalon fades and wastes in advanced life, the cavity of the cranium contracts, and its ossification 344 MENTAL FACULTIES. takes place on a less and less outline. In advanced life, however, according to Gall, the correspondence between the encephalon and the inner table of the skull is alone maintained ; the table appearing to be a stranger to all nutritive movement, and preserving its dimensions. Lastly, the cranium partakes of all the variations experienced by the encephalon in disease. If the latter be wanting, as in the acephalous monster, the cranium is wanting also. If a portion of the encephalon exists, the corresponding portion of the cranium exists. If the ence- phalon is smaller than natural, as in the idiot, the cranium is also. If, on the contrary, it is distended by hydrocephalus, the cranium has a considerable capacity: and this, not owing to a separation, at the sutures, of the bones composing it, but to ossification taking place on a larger outline. If the encephalon be much developed in any one part, and not in another, the cranium is protuberant in the former; restricted in the latter; and lastly, in cases of mania, the cranium is often affected, being, for example, unusually thick, dense, and heavy. These reasons, adduced by Gall, may justify the admission, that, within certain limits, the skull is moulded to the encephalon; and, if this be conceded, the method followed by him of specifying the organs of the mental faculties may be conceived practicable. Such is the basis of the system of craniology proposed by Gall. It has also been called eranology, organology, phrenology, and cranioscopy: although, strictly speaking, it is by cranioscopy that we acquire a know- ledge of craniology,—the art of prejudging the intellectual and moral aptitudes of man and animals, from an examination of the cranium. It is, of course, limited in its application. Gall admits, that it is not available in old age, owing to the physiological fact before stated,— that the external table of the skull is no longer modified by the changes, that happen to the encephalon ; and he acknowledges, that its employ- ment is always difficult, and liable to errors. We cannot, for example, touch the cranium directly; for it is covered by hair and integument. The skull is made rough, in parts, by muscular impressions; and these roughnesses must not be confounded with what are termed "protu- berances,"—prominences, formed by a corresponding developement of the encephalon. In this respect, craniology presents more difficulties in animals, owing to their heads being more covered with muscles, and from the inner table of the skull being, alone, in contact with the encephalon beneath. Other errors may be incurred from the frontal and superior longitudinal sinuses; and from the possible separation of the hemispheres at the median line. The difficulty is, of course, extremely great in appreciating the parts of the encephalon, that are situate behind the eyes; and craniology must be entirely inapplicable to those encephalic organs that terminate at its base. Gall has taken especial pains to remark, that by craniology we can only prejudge the dispositions of men, not their actions; and can appreciate but, one of the elements of the activity of organs—their size,—not what belongs to their intrinsic activity, and to the impulse or spring they may receive from the temperament or general formation. Setting out, however, with the principle, that the predominance of a faculty is in a great measure dependent on the developement of the VIEWS OF PHRENOLOGISTS. 345 portion of the encephalon whieh is its organ, he goes so far as to par- ticularize-, in this developement, what is owing to the length of the encephalic fibres, and what to their breadth; referring the activity of Fig. 138. Fig. 139. Fig. 140. Phrenological Organs according to Gall. the faculty to the former, and its intensity to the latter. In applying cranioscopy to animals, he observes, that the same encephalic organ frequently occupies parts of the head, that seem to be very different, on account of the difference between station in animals and man, and of the greater or less number of systems, that compose their encephalon. The following are the encephalic organs enumerated by Gall, with the corresponding faculties:—the numbers corresponding with those of the above illustrations. 1. Instinct of generation, of reproduction ; "> amativeness. Instinct of propagation; Seated in the cerebellum. It is manifesi venereal instinct. I at the surface of the cranium b tWQ rQu rerman.) / e ugu n&s tr i eh. f r,mri1i-10,.Q>™„£, ~„„-----„u „:.i. -r .,. {German.) Zeugungstrieb, Fortpflanzungstrieb Geschlech tstrieb. fested .—nd protuberances, one on each side of the nape of the neck. 346 MENTAL FACULTIES. 2. Love of progeny; phUoprogenitiveness. (G.) Jungenliebe, Kinder 1 i e b e . 3. Attachment, friendship. (G.) Freundschaftsinn. 4. Instinct of defending self and property ; love of strife and combat; combativeness ; courage. (G.) Muth, Raufsinn, Zanksinn. Indicated at the external occipital protube- rance. About the middle of the posterior margin of the parietal bone; anterior to the last. Seated a little above the ears; in front of the last, and towards the mastoid angle of the parietal bone. 5. Carnivorous instinct; inclination to mur- der ; destructiveness ; cruelty. (G.) Wurgsinn, Mordsinn. secretive- 6. Cunning; finesse; ness. (G.)List, Schlauheit, Klug-f h e i t. 7. Desire of property; provident instinct; "] cupidity; inclination to robbery; acqui- I f Greatly developed in all the carnivorous ani- mals ; forms a prominence at the posterior frontal bone, towards the temple, and be- (C.) Knnstsinn, Bausinn. ) hind the organs of music and numbers. 2a Comparative sagacity j ^ ^ midd,e and anterjor of the fromal (G.) Vergleichender S c h a r f - \ b above that of the me of thi Sinn. ") ' 21. Metaphysical penetration; depth of] In part, confounded with the preceding. Indi- mind. I cated, at the outer side of this last, by two (G.) Metaphysischer^ Tief- [ protuberances, which give to the forehead a s i n n. J peculiar hemispherical shape. j At the lateral and outer part of the last; and ir\W- C giving greater width to the frontal promi- » '' 1 z' j nences. 23. Poetical talent. ) On the outer side of the last; divided into two (G.) Dich terge ist. \ halves by the coronal suture. 24. Goodness; benevolence; mildness; com- passion ; sensibility; moral sense; con- science; bonhommie. (G.) G u tmvit higkeit, Mit lei- den, moralischer Sinn, G e w i s s e n . /•/->\ at x f-> fxxmxcry. ( At the outer side of the last. (G-.) JNachahmungssinn. } 26. God and religion ; theosophy. } At the top of the frontal bone and at the supe- ( G.) Theosophisches Sinn. $ rior angles of the parietal bones. 27. Firmness; constancy; perseverance; ) „, /-,,.. .i_ . ■ j , ■ ' 3> r > r 372 MUSCULAR MOTION. Loop-like termination of the Nerves in voluntary muscle.—After Burdach. (Todd and Bowman.) Fig. 158. spinal marrow, forming part of a nerv- ous trunk; turns around one or more muscular fibres, and returns along the same or a neighbouring trunk to the posterior column of the marrow. The red colour of muscles is usually ascribed to the blood distributed to them, as it may be removed by repeated washing and maceration in water or alcohol, without the texture of the mus- cle being modified. By some, it has been thought, that a quantity of red blood remains attached to the fibres, and is extravasated from the vessel: by others, it is presumed with more proba- bility to be contained in the vessels, and according to Mulder,1 who considers the red colour to be wholly due to^ the blood in the capillary system of the muscles, when they are injected with water, every muscle is colourless. Bi- chat2 conceived, that the colour is de- pendent upon some foreign substance combined with the fibre; and he grounded his opinion upon the circumstance that, in the same animal, some of the muscles are always much redder than others, and yet they do not appear to have a greater quantity of blood sent to them; and also, that in dif- ferent classes of animals the colour of the muscles does not appear to correspond with the quantity of red blood circulating through their vessels. The fact, however, that when muscles have been long in a state of inaction they become pale ; and that, on the other hand, the colour becomes deeper when they are exercised, is additional evidence, that their colour is dependent upon the blood they receive, which is found to diminish or increase in quantity, according to the degree of inactivity or exertion. Muscles differ, like the primary fibre, at their extremities and centre; the former being composed of condensed areolar membrane ; the latter of the muscular or fibrous tissue. The centre of a muscle is usually called its venter or belly; and the areolar texture at the extremities is variously termed;-:—that from which it appears to arise being called the head or origin; and that into which it is inserted the tail, termination or insertion. These terms are not sufficiently discriminative. We shall find, that a muscle is capable of acting in both directions; so that the head and the tail—the origin and insertion—may reciprocally change places. In ordinary language, however, the extremity at which the albugineous tissue (if we adopt Chaussier's nomenclature), assumes a rounded form, so as to constitute a cord or tendon, is called the inser- * The Chemistry of Vegetable and Animal Physiology, translated by Fromberg, &c, p. 589, Edinburgh and Lond., 1849. 3 Anat. General., ii. 327, Paris, 1818. COMPOSITION OF MUSCLES. 373 tion. When this tissue is expanded into a membrane it is termed an aponeurosis; and in this state it exists at the head or origin of the muscle ; so that by tendon and aponeurosis the muscles are inserted into the parts, which they are destined to move, if we except those that are inserted into the skin. Fig. 159. "sSks^ ^^......•"--'Q. Compound Ventriform Muscle. Muscles are divided into simple and compound. The simple are those whose fibres have a simi- lar course and arrangement. Fig. 160. * They may be either flat or ventriform, radiated or penni- form. The compound arise from different parts; their origins are, consequently, by distinct fasciculi, or they may terminate by distinct inser- tions. Fig. 159, which is a representation of the biceps— a flexor muscle of the forearm —is one of these. It has, as its name imports, two heads running into one belly. It is, also, an example of a ventriform muscle. In the pectoralis major, Fig. 160, we have an example of the radi- ated muscle, or of one in which the fibres converge toward their tendi- nous insertion. In the penniform muscle, the fibres run in a parallel direction, but are all inserted obliquely into the tendon, like the feathers of a quill. Fig. 161 is a representation of a double penniform muscle. Muscles may, also, be complicated: that is, with one belly, and several tendons having the fibres variously inserted into them ; or having several bellies with the tendons interlaced. Penniform Muscle. Fig. 161. Double Penniform Muscle. They are, again, partitioned into the long, broad, and short. The long muscles are situate chiefly on the limbs, and are concerned in locomotion. The broad generally form the parietes of cavities : they are not so much enveloped as the long by strong fibrous aponeuroses 374 MUSCULAR MOTION. or fasciae, owing to their being obviously less liable to displacement; and the short are situate in parts, where considerable force is required, and but little motion; so that their fibres are very numerous. The number of muscles varies, of course, in different animals, in proportion to the extent and variety of motion they are called upon to execute. In man, it is differently estimated by anatomists; some describing several distinct muscles under one name; and-others di- viding into many what ought to belong to one. According to the arrangement of M. Chaussier, three hundred and sixty-eight distinct muscles are admitted; but others reckon as many as four hundred and fifty. When muscles are subjected to analysis, they are found to consist of fibrin; osmazome; jelly; albumen; phosphates of soda, ammonia, and lime; carbonate of lime; chloride of sodium; phosphate, and lactate of soda; and, according to Fourcroy and Vauquelin,1 sulphur and potassa are present. The great constituents of the pure muscular tissue are,—fibrin, and probably osmazome;—the gelatin met with being ascribable to the areolar membrane that envelopes the muscular fibres and lacerti. The membranous structures of young animals con- tain a much greater quantity of jelly than those of the adult; and it is probably on this account, that the flesh of the former is more gela- tinous ; not because the muscular fibre contains more gelatin. M. The- nard assigns the muscles, on final analysis, the following constituents:— fibrin; albumen; osmazome; fat; substances capable of passing to the state of gelatin; acid (lactic), and different salts: kreatin and krea- tinin have likewise been found in them. They have also been ana- lyzed by Berzelius and Braconnot2 and others. It must be borne in mind, however, as M. Raspail3 has properly remarked, that all these are the results of the analysis of muscle, as we meet with it. The analysis of muscular fibre has yet to be accomplished. In this, too, and every analogous case, the analysis only affords us evidence of the constituents of dead animal matter; and some of the products may even have been formed by new affinities resulting from the operations of the analyst. They can afford but an imperfect judgment of the con- stitution of the living substance. These remarks are especially appli- cable to the efforts at determining the composition of muscle by ulti- mate analysis. Mulder,4 indeed, affirms, that this is impracticable— *' for in this process we burn a mixture of various substances, a very complicated tissue of muscular fibres, ligamentary tissue, coats of bloodvessels and nerves. If, therefore, Playfair and Bockmann have found the composition of muscle to be identical with that of blood,— which is a mixture of various substances, containing some that are en- tirely different from those of muscle, and in which again others are wanting that are present in the latter,—then this may be considered as 1 Annales de Chimie, lvi. 43. 2 Muller's Handbuch der Physiologie, Baly's translation, Part i. p. 369, Lond., 1837; and Dr. T. Thomson, Chemistry of Animal Bodies, p. 273, Edinb., 1843. 3 Op. citat., p. 214. 4 The Chemistry of Vegetable and Animal Physiology, by Fromberg, &c, p. 589. Edinb, and Lond., 1849. COMPOSITION OF MUSCLES. 375 a proof that it is impossible to find out essential differences by means of ultimate analysis :"—and he adds—" Nothing has ever surprised me more than the assertions now so frequently repeated, that muscle and blood are identical in composition—two substances which present, in fact, no other point of resemblance, except this, that they both con- tain protein compounds. But if we proceeded upon this principle, we should be induced at present to apply the term identity to a great num- ber of substances indeed." Muscular structure is liable, under particular circumstances, to a singular kind of conversion, to which it may be well to advert. When, about the latter part of the last century, it was determined, for pur- poses of salubrity, to remove the bodies from the churchyard of Les Innocens at Paris1—which had been the cemetery for a considerable part of the population of Paris for centuries ; the whole area, occupy- ing about seven thousand square yards, was found converted into a mass, consisting chiefly of animal manner, and raising the soil several feet above the natural level. On opening the ground, to remove the prodigious collection of dead bodies, they proved to be strangely al- tered in their nature and appearance. What had constituted the soft parts of the body was converted into an unctuous matter, of a gray colour, and peculiar, but not highly offensive, smell. According to their position in the pits,—for the bodies were deposited in pits or trenches, about thirty feet deep, each capable of holding from twelve hundred to fifteen hundred,—and according to the length of time they had been deposited, this transformation had occurred to a greater or less extent. It was found to be most complete in those that were near- est the centre of the pits, and when they had been buried about three years. In such case, every part, except the bones, hair and nails, seemed to have lost its properties, and to be converted into gras des cimetieres, which was found to be a saponaceous compound, consisting of ammonia, united to adipocire,—a substance, as its name imports, possessing properties intermediate between those of fat and wax. When the adipocire was freed from the ammonia, and obtained in a state of purity, it was found to resemble strongly spermaceti, both in physical and chemical qualities. It was afterwards discovered, that the conversion of muscular flesh into adipocire might be caused by other means. Simple immersion, in cold water, especially in a running stream, was found by Dr. Gibbes2 to produce the conversion more speed- ily than inhumation. It can be caused, too, still more rapidly by the action of dilute nitric acid. The chemical is not the only interest attached to this substance. It has been adduced in a court of justice for the purpose of enabling some judgment to be formed regarding the time that a body may have been immersed in the water. It is probable that this must differ greatly according to various circumstances;—as the period that elapsed between the death of the individual, and the act of immersion; the conditions of the fluid as to rest or motion, temperature, &c.; and the 1 Thouret, Journal de Physique, xxxviii. 255. 1 Philosophical Transactions for 1794 and 1795. 376 MUSCULAR MOTION. temperature of the atmosphere; so that any effort to fix a time for such conversion must be liable to much inconclusiveness. Yet the opin- ion of a medical practitioner on the subject has been the foundation of a juridical decision. At the Lent assizes, holden at Warwick, Eng- land, in the year 1805, the following case came before the court. A gentleman, who was insolvent, left his home with the intention,—as was presumed from his previous conduct and conversation,—of de- stroying himself. Five weeks and four days after that period, his body was found floating down a river. The face was disfigured by putrefac- tion, and the hair separated from the scalp on the slightest pull; but the other parts of the body were firm and white, without any putrefac- tive appearance. On examining the body, it was found that several parts were converted into adipocire. A commission of bankruptcy having been taken out against the deceased a few days after he left home, it became an important question to the interest of his family to ascertain whether or not he was living at that period. From the changes sustained by the body, it was presumed, that he had drowned himself on the day he left home; and to corroborate the presumption, the evidence of Dr. Gibbes was requested, who, from his experiments on this subject, it was thought, was better acquainted with it than any other person. Dr. Gibbes stated on the trial, that he had procured a small quantity of this fatty matter, by immersing muscular parts of animals in water for a month, and that it required five or six weeks to form it in any large quantity. Upon this evidence, the jury were of opinion, that the deceased was not alive at the time the commission was taken out, and the bankruptcy was accordingly superseded!1 Bones. The bones are the hardest parts of the animal frame; and serve as a base of support and attachment to the soft parts. They constitute the framework of the body, and determine its general shape. The principal functions they fulfil are,—to form defensive cavities for the most important organs of the body,—the encephalon, spinal-marrow, &c.—and to act as so many levers for transmitting the weight of the body to the soil, and for the different locomotive and partial movements. To them are attached the different muscles, concerned in those func- tions. In man and the higher classes of animals, the bones are, as a general rule, within the body; his skeleton is, consequently, said to be internal. In the Crustacea, the testaceous mollusca, and certain in- sects, the skeleton is external; the whole of the soft parts being con- tained within it. The lobster and crab are familiar instances of this arrangement. The stature of the human skeleton is various, and may be taken, on the average, perhaps,—in those of European descent,—at about five feet seven and a half inches.2 We find, however, examples of con- siderable variation from this average. A skeleton of an Irish giant, 1 Male, Epitome of Forensic Medicine, in Cooper's Tracts on Medical Jurisprudence, Philad., 1819. 3 Quetelet, Sur l'Homme, &c, Paris, 1835; or translation by Dr. Knox, p.64,Edinb., 1842. BONES. 377 in the museum of the Royal College of Surgeons of London, measures eight feet four inches. On the other hand, Bebe, the dwarf of Stanislaus, King of Poland, was only thirty-three inches high; and a Polish noble- man, Boruwlaski, is said to have measured twenty-eight French inches, at twenty-two years of age. Mr. Mathews, the comedian, states, how- ever, that he measured him late in life and found that his height was three feet three inches; and that he had undoubtedly grown an inch a short time before he was eighty-one, when he measured three feet four.1 He had a sister, whose height was twenty-one inches.2 Sir George Simp- son,3 in one of the villages of Siberia, saw a dwarf, about forty years of age, thickset, with a large head, and barely'two feet and a half high. "For his inches, however," says Sir George, "he was a person of great importance, being the wise man of the place, and the great arbiter in all disputes, whether of love or of business." The celebrated dwarf called General Tom Thumb, was seen by the author in 1847. He was then said to be fifteen years old; weighed at the Mint twenty pounds and two ounces, and was twenty-eight inches high. His intellect was evidently limited, childlike. The bones may be divided into short, broad, or flat, and long. Short bones are met with in parts of the body, which require to be both solid and movable:—in the hands and feet, for example; and in the spine. Flat or broad bones form the parietes of cavities, and aid materially in the movements and attitudes, by affording an extensive surface for the attachment of muscle. Long bones are chiefly intended for locomo- tion ; and are met with only in the extremities. The shape of the body or shaft and of the extremities of a bone, merits attention. The shaft or middle portion is the smallest in diameter, and is usually cylindrical. The extremities, on the other hand, are expanded; a circumstance, which not only adds to the solidity of the articulations, but diminishes the obliquity of the insertion of the tendons, passing over them, into the bones. In their interior is a medullary canal or cavity, which con- tains the medulla, marrow or pith:—a secretion, whose office will be a theme for after inquiry. One great advantage of this canal is, that it makes the bone a hollow cylinder, and thus diminishes its weight. On many of the bones, prominences and cavities are perceptible. The eminences bear the generic name of apophyses or processes. Their great use is to cause the tendons to be inserted at a much greater angle into the bones they have to move. It may be seen, hereafter, that the nearer such insertion is to the perpendicular to the lever, the greater will be the effect produced. The cavities are of various kinds. Some are articular: others for the insertion, reception, or transmission of parts. Those of insertion and reception afford space for attachment of muscles; those of trans- mission, &c, are frequently incrusted with cartilage; converted into canals by means of ligament, and furnished with a synovial membrane, * A Continuation of the Memoirs of Charles Mathews, Comedian, by Mrs. Mathews, Amer. edit., i. 165, Philad., 1839. 3 Lectures on Physiology, Zoology, &c, by W. Lawrence, p. 434, Lond., 1819. 3 An Overland Journey round the World, Amer. edit., Part ii. p. 203, Philad., 1847. 378 MUSCULAR MOTION. which lubricates them; and facilitates the play of the tendons, for the passage of which they are destined. The mechanical structure of bone is a laminated framework incrusted by an earthy substance, and penetrated by exhalant and absorbent vessels, arteries, veins and nerves. M. Herissant1 appears to have been one of the first who stated, that bone is essentially composed of two substances:—the one a cartilaginous basis or parenchyma, giving form to the part;—the other a peculiar earthy matter deposited on this basis, and communicating to it hardness. These two constituents can be readily demonstrated; the first, by digesting the bone in dilute chlorohydric acid, which dissolves the* earthy part, without acting on the animal matter; and the second, by burning the bone until all the animal mat- ter is consumed, whilst the earthy is left untouched. If we take a long bone and divide it longitudinally, we find, that it is composed of three different substances, all of which may, however, be regarded as the same osseous tissue in various degrees of condensa- tion. These are,—the hard or compact substance; the spongy or areolar; and the reticulated. The first is in the most condensed form; it exists at the exterior of the bone, and constitutes almost the whole of the shaft. The second is seen towards the extremities of a long bone, and in almost the whole of the short bones. In it, the laminse are less close, and have a cancellated appearance,—the cellules bearing the name of cancelli. The reticulated substance is a still looser formation; the laminse being situate at a considerable distance; and the space between filled up with a series of membranous cells, which lodge the marrow. The marginal figures represent a longitudinal and a trans- verse section of the same bone, in which this arrangement is well exhibited. We have seen the advantages of the expanded extremities of long bones, as regards the insertion of muscles; but it is obvious, that if these portions of the bone had consisted of the heavy compact tissue, the increased weight would have destroyed the advantages, that would otherwise have accrued; whilst, if the shaft of the bone, exposed, as it is, to external violence, had consisted of the spongy tissue only, it would not have offered the necessary resistance. It is, therefore, formed almost entirely of the compact tissue; so that a section of one inch, taken from the body of the bone, will not differ essentially in weight from an inch taken from the extremity. Nor does the cavity within the bones diminish their strength, as might at first sight be presumed. By en- larging the circumference, the contrary effect is produced; for we shall see, in the mechanical proem to the particular movements, that of two hollow columns, formed of an equal quantity of matter and of the same height, that, which has the larger cavity, is actually the stronger. A very important use of the cancellated or spongy texture of the bones was suggested by a distinguished individual of this country, to whom surgical science, in particular, has been largely indebted. Dr. Physick2 asserts, that it serves to diminish, and, in many cases, to prevent, con- ' Memoir, de l'Academ. des Sciences de Paris, pour 1758, p. 322. ' Horner, Special and General Anatomy, &c, 5th edit., Philad., 1843. ANALYSIS OF BONES. 379 cussion of the brain, and of other viscera, in falls and blows. The demonstration, which he gives of this, is simple and satisfactory. If we suspend a series of six ivory balls by threads; raise the ball at one extremity of the series, and allow it to fall on the next to it, the farthest ball in the series is impelled to a distance which corresponds with the momentum communicated by the first ball to the second. But if we substitute, for the middle ball of the series, a ball made of the cellular structure of bone, almost the whole of the momentum is lost in this osseous structure; especially, if it be pre- viously filled with tallow or well soaked in water, so as to bring it to a closer approxi- mation to the living condition. Bones consist of earthy salts, and animal matter, intimately blended. The latter is chiefly cartilage, gelatin, and the peculiar fatty matter—the marrow. On reducing bones to powder, and digesting them in water, Sections of a Bone. the fat rises and Swims Upon the Surface; 1,2. Longitudinal section of the ex- and the gelatin is dissolved. According to 'Transverse section of the body. the analysis of Berzelius, 102 parts of dry human bones consist of animal matter, 33*3; basic phosphate of lime, 51*04; carbonate of lime, 11-30; fluoride of calcium, 2; phosphate of magnesia, 1*16; soda, chloride of sodium, and water, 1*2. It has been much doubted, however, whether fluoride of calcium is contained in recent bones; whilst it is admitted to have been detected in fossil bones. According to Dr. Daubeny,1 it exists in the former, in about a quarter of the proportion in which it is present in the latter; but the propor- tions in different specimens of both kinds are variable. Dr. Daubeny ascribes the failure of those who have not detected fluorine except in fossil bones and teeth, to the tenacity with which it is retained by animal matter; and to its being carried off with the carbonic acid evolved at the same time, too rapidly to act upon glass exposed to it. He, therefore, before submitting the bones to the action of strong sul- phuric acid, burns away all the animal matters; removes the carbonic acid by dissolving th.em in chlorohydric acid; then throws down the earthy phosphates by caustic ammonia, and dries them. MM. Fourcroy and Vauquelin found in bones oxides of iron and manganese, silica, and albumen. Mr. Hatchett detected, also, a small quantity of sulphate of lime. Schreger gives the following as the pro- portions of the animal and earthy parts: Infants. Adults. Aged. Animal matter .... 47-20 20-18 1220 Earthy matter .... 48-48 74-84 8410 95-68 9502 96-30 1 Philosophical Magazine, Aug., 1844. 380 MUSCULAR MOTION. The following are the average proportions, according to Lehmann,1 from his own analyses, and those of two other observers. Sebastian. Lehmann. Frerichs. Compact Bone. Spongy Bone. Organic . . 63-66 32-28 31-2 37-82 Earthy . . 63-34 67-72 68-8 62-18 Dr. Stark2 affirms, from the results of his experiments, that the mean proportion of animal matter in the bones of all vertebrate animals is 33*91; of earthy 66*09; the mean proportion in the bones of man 33*39 of animal matter; 66*61 of earthy. The bones are enveloped by a dense fibrous membrane, termed, in the abstract, periosteum; but assuming different names according to the part it covers. On the skull, it is called pericranium: and its extensions over the cartilages of prolongation are called perichondrium. The chief uses of this expansion are, to support the vessels in their passage to and from the bone, and to assist in its formation; for we find, that if the periosteum be removed from a bone, it becomes dead at the surface previously covered by the membrane, and exfoliates. In the foetus, it adds materially to the strength of bone, prior to the completion of ossification. In the long bones, ossification commences at particular points; one generally in the shaft, and others at the different articular and other processes. These ossified portions are, for some time, separated from each other by the animal matter, which alone composes the intermediate portions of the bone; and, without this fibrous envelope, they would be too feeble, perhaps, to resist the strains to which they are exposed. The periosteum, moreover, affords a convenient insertion for muscles destined to act upon bones; and enables them to slide more readily when contracting: hence friction is avoided. The cavity of long bones is lined by a membrane—called medullary membrane or internal periosteum—which is supplied Avith numerous vessels; adheres to the internal surface of bone, and is not only con- cerned in its nutrition, but in the secretion of the marrow, and likewise of a kind of oily matter, which differs from marrow in being more fluid, and is contained in cells formed by the spongy substance, and in areolae of the compact substance. This is called oil of bones. Marrow is considered to be lodged in membranous cells, formed by an extension of the internal periosteum; whilst, according to Mr. Howship,3 oil of bones is probably deposited in longitudinal canals—Haversian canals—which traverse the solid substance of the; bone, and through which its vessels are transmitted. If a thin transverse section of long bone be examined under a high magnifying power, the bony matter is observed to be arranged in concentric circles around the orifices of the canals as in Fig. 164. These circles are marked by a number of stel- lated dark spots formerly termed osseous corpuscles; but as they are minute cavities in the bony substance, now more appropriately called lacunae. From these, fine pores or tubes, termed candliculi, proceed, 1 Schmidt's Jahrbucher, No. vi., 1843. 2 Edinburgh Medical and Surgical Journal, April, 1845, p. 313. Medico-Chirurg. Transact., vii. 393. ANALYSIS OF BONES. 381 which traverse the substance of the bone, and communicate irregularly with each other. All the different lacunse communicate by means of the canaliculi with the Haversian canals; so that fluid may pass to every part of the osseous substance, and thus convey fluid for nutrition. They open, likewise, into the great medullary canal, and into the cavities of the cancellated texture. Blood corpuscles cannot pass along them, as their largest diameter has not seemed to be more than from l-20000th to l-14000th of an inch; and the smallest not more than from l-60000th to l-40000th. The nature and fancied uses of marrow and oil of bones will be considered elsewhere. The bones, periosteum, and marrow are, in the sound state, amongst the insensible parts of the frame. They are certainly not sensible to ordinary irritants; but, when morbid, exhibit intense sensibility. This applies, at least, to bones and the periosteum; the sensibility, which has been ascribed to the marrow, in disease, being probably owing to that of the prolonga- tions of the membrane in which it is contained. Fig. 163. Haversian Canals, seen on a Longitudinal Section of the Compact Tissue ofthe Shaft of one of the Long Bones. 1. Arterial canal. 2. Venous canal. 3. Dilatation of another venous canal. Fig. 164. Transverse Section of Compact Tissue of Humerus magnified about 150 diameters. Three of the Haversian canals are seen, with their concentric rings ; also the corpuscles or lacunre, with the canaliculi extending from them across the direction of the lamella;. The Haversian apertures had got filled with debris in grinding down the section, and therefore appear black in the figure, which represents the object as viewed with transmitted light. The number of the bones in the body is usually estimated at two hundred and forty, exclusive of the sesamoid, which are always found 382 MUSCULAR MOTION. in pairs at the roots of the thumb and great toe; between the tendons of the flexor muscles and jqints; and, occasionally, at the roots of the fingers and small toes. _ The bones are connected by means of articulations or joints, which differ materially from each other. To all the varieties, names are ap- propriated, which form a difficult task for the memory of the anatomical student. Technically, every part at which two bones meet, and are connected, is called an articulation, whether any degree, of motion exists or not. This, indeed, is the foundation of the division that pre- vails at the present day,—the articulations being separable into two classes ; the immovable or synarthroses; and the movable or diarthroses. Synarthroses are variously termed, according to their shape. When the articular surfaces are dovetailed into each other, the joint is called a suture. This is the articulation that prevails in the bones of the skull. Harmony is when the edges of bones are even, and merely touch; as in the bones of the head in quadrupeds and birds. When a pit in one bone receives the projecting extremity of another, we have a case of gomphosis. It is exhibited in the union between the teeth and their sockets. Lastly, schindylesis is when the lamina of one bone is received into a groove of another; as in the articulation of the vomer, which separates the nasal fossse from each other. The movable articulations comprise two orders:—amphiarthroses, in which the two bones are intimately united by an intermediate substance, of a soft and flexible character, as in the junction of the vertebrse with each other; and diarthroses, properly so called. The last admit of three subdivisions—enarthroses or ball and socket joints; the condyloid, in which, owing to the head being oval, the movements are not as easy in all directions as when it is spherical; and the ginglymoid or ginglymus, in which the motion can occur in only one direction, as in a hinge. The farther subdivision of the joints belongs more to anatomy than to physiology. The articular surfaces of bones never come into immediate contact. They are tipped with a firm, highly elastic substance, called cartilage; which, by its smoothness, enables the bones to move easily upon each other ; and may have some influence in deadening shocks, and defending the bones, which it covers. The arrangement of cartilage varies ac- cording to the shape of the extremity of the bone. If it be spherical, the cartilage is thick at the centre, and gradually diminishes towards the circumference. In the cavity, the reverse is the case ; the cartilage is thin at the centre, and becomes thicker towards the circumference; whilst on a trochlea or pulley its thickness is nearly every where alike. An admirable provision against displacement of bones at the articu- lations is seen in the ligaments. These, by the French anatomists, are distinguished into twTo kinds—fibrous capsules, and ligaments properly so called. The former are a kind of cylindrical sac, formed of a firm, fibrous membrane; open at each extremity, by which they closely embrace the articular ends of bones; and loose, when the joint admits of much motion. In this way, the articulation is completely enclosed: they generally bear the name of capsular ligaments. The ligaments, properly so called, are bands of the same kind of tissue, which extend PHYSIOLOGY OF MUSCULAR MOTION. 383 from one bone to another; by their resistance preserving the bones in situ; and by their suppleness admitting the necessary motion. The interior of all these articulations is lubricated by a viscid fluid, called synovia. This is secreted by a peculiar membrane of a serous nature ; and its use is to diminish friction, and, at the same time, to favour adhesion. The mode in which it is secreted, and its chief pro- perties and uses, will be the subject of future inquiry. In certain of the movable articulations, fibro-cartilaginous substances, frequently called inter articular cartilages, are found between the articu- lar surfaces, and not adherent to either. These have been supposed to form a kind of cushion, which, by yielding to pressure, and returning upon themselves, may protect the joints to which they belong; and, accordingly, it is asserted, that they are met with in joints, which have to sustain the greatest pressure ; but M. Magendie1 properly remarks, that they do not exist in the hip or ankle-joint, which have constantly to support the strongest pressure. The use, which he suggests, is more specious;—that they may favour the extent of motion, and prevent displacement. The stability of the joints is likewise aided by the manner in which muscles or tendons pass over them. These are contained in an aponeu- rotic sheath, to prevent their displacement; and thus the whole limb becomes well protected, and dislocation unfrequent, even in those joints, as that of the shoulder, which, as regards their osseous arrangement, ought to be very liable to displacement. It has been suggested by Weber, that the head of the thigh-bone is retained in situ, not by the power of the muscles or ligaments, but by the pressure of the surrounding atmosphere ; and Lauer,2 who repeated Weber's experiments under the directions of Fricke, of Hamburg, is of opinion, that atmospheric pressure must be classed among the means by which the lower extremity is kept in apposition with the trunk of the body. PHYSIOLOGY OF MUSCULAR MOTION. By voluntary motion or that effected by the muscular system of ani- mal life, we mean contraction of the muscles under the influence of volition or will. This influence is propagated along the nerves to the muscles, which are excited by it to contraction. The encephalon, spi- nal marrow, nerves, and muscles are, therefore, organs of voluntary muscular contraction. Volition is a function of the encephalon, and might have been with much propriety included under the physiology of the intellectual and moral acts ; but as it is so intimately concerned with muscular motion, it was judged advisable to defer its consideration. That in man and the higher animals, it is a product of encephalic action is proved by many facts. If the brain be injured in any manner;—by fracture of the skull, or by effusion of blood, producing apoplectic pressure ;—or if it be deprived of its functions by a strong dose of any narcotic substance;— 1 Precis Elementaire, 2de edit., i. 292, Paris, 1823. " Zeitschrift fur die gesammte Medicin, Band ii. Heft 3. 384 MUSCULAR MOTION. or if, again, it be in a state of rest, as in sleep;—volition is no longer exerted ; and voluntary motion is impracticable. This is the cause why the erect attitude cannot be maintained during sleep ; and why the head falls forward upon the chest, when somnolency is to such an extent as to deprive the extensor muscles of the back and head of their stimulus to activity.1 That an emanation from the encephalon is necessary is likewise proved by the effect of tying, cutting, compressing, or stupefy- ing a nerve proceeding to a muscle; it matters not that the will may act; the muscle does not receive the excitation, and no motion is pro- duced ; a fact which proves, that nerves are the channels of communi- cation between the brain and the muscles. If, again, we destroy the medulla oblongata and medulla spinalis, we abolish all muscular mo- tion, notwithstanding the brain may will, and the muscles be in a state of physical integrity ; because we have destroyed the parts whence the nerves proceed. In like manner, by successively slicing away the medulla spinalis from its base to the occiput, we paralyse, in succession, every muscle of the body that receives its nerves from the spinal marrow. Experiments of physiologists have confirmed the view, that the ence- phalon is the chief seat of volition. When it has been sliced away to a certain extent, the animal has been thrown into a -state of stupor, attended with loss of sensibility, power of locomotion, and especially spontaneous motion; and in writing, dancing, speaking, &c, we have indisputable evidence of its direction by the intellect. It is not so clear, that the seat of volition is restricted to the encephalon. There are actions of the yet living trunk, which appear to show, that an obscure volition may be exerted even after the brain has been separated from the rest of the body; and acephalous children have not only moved perceptibly when in utero, but at birth. Without referring to the low- est classes of animals, which execute voluntary motions for a long time after they have been bisected, every one must have noticed the motions of decapitated fowls, which continue for a time, to run and leap, and apparently, to suffer uneasiness in the incised part. The feats of the Emperor Commodus are elucidative of this matter. Herodian relates, that he was in the habit of shooting at the ostrich, as it ran across the circus, with an arrow having a cutting edge ; and, even when the shaft was true to its destination, and the head was sev- ered from the body, it usually ran several yards before it dropped. Kaauw Boerhaave—nephew of the celebrated Hermann, himself an emi- nent medical teacher at St. Petersburg—asserts that he saw a cock, thus decapitated, run a distance of twenty-three feet. Cases are also recorded of men walking a few steps after decapitation, striking their breasts, &c. ; but they can scarcely be regarded as authentic.2 In countries where judicial execution consists in decapitation by the sword, sufficient opportunities must have presented themselves for testing this question; but no zealous Naturforscher appears to have been pre- 1 Adelon, art. Encephale (Physiol.) in Dict.de Med., vii. 516, Paris, 1823; and Physiol.de l'Homine.ii. 25, 2de edit., Paris, 1829. 3 Adelon, op. citat., ii. 28; and Dr. J. R. Coxe, in Dunglison's Amer.. Med. Intelligencer, for May 15, 1837. SEAT OF VOLITION. 385 sent to record them. Similar opportunities have likewise occurred under the operations of the guillotine. M. Legallois,1 in some experiments, which he instituted, for the pur- pose of determining the nervous influence on the heart, &c, found that rabbits, which he had deprived of their heads and hinder extremities, but still kept alive by artificial respiration, moved their fore paws when- ever he stimulated them by plucking their hairs. With regard to complete acephali, or those foetuses which are totally devoid of encephalon,—although they may vegetate in utero, they ex- pire after birth, owing to their being devoid of the medulla oblongata in which is the nervous system of respiration. Monsters have been born without the brain, but with part of. the encephalon. These have been called, by way of distinction, anencephali or hemicephali. Where the medulla oblongata exists, they possess the nervous system of the senses, and of respiration, and are, consequently, able to live for a time after birth, and to exert certain muscular movements, as sucking, moving the limbs, evacuating the excretions, &c. M. Adelon asserts, that none of these facts ought to shake the proposition,—that in the superior animals, and consequently in man, the medulla spinalis and nerves are merely the conductors of volition or the locomotive will; and that volition is produced in the encephalon alone. His arguments on this point are not, however, characterized by that ingenuousness and freedom from sophism, for which his physiological disquisitions are generally distin- guished. "First of all," he observes, "the fact of the progression and motions of men and quadrupeds after decapitation is manifestly apo- cryphal ; and even if we admit, that certain animals still execute certain movements after decapitation, are such evidently regular and ordained? And, supposing them to be so, may not this have arisen from the con- formation of the parts, or from habits contracted by the organs? This last appears to us most probable; for if, from any cause whatever, the muscles of a part contract, they cause the part to execute such motions as the joints, entering into its composition, require; and which may, therefore, be similar to those produced by the will." He further at- tempts to deny the facts related of the lower classes of animals, and asserts, that "they are not evinced in the experiments instituted in our day." The cases, recorded to prove the defective sensibility of the lower tribes of animated nature, are, however, as has been elsewhere shown, incontestable.—The trunk of the wasp attempts to sting after the head has been removed; and an experiment made on the rattlesnake by Dr. Harlan,2'in the presence of Capt. Basil Hall, certainly demonstrates something like design in the headless trunk; and the cases, already re- ferred to, on the authority of Drs. Le Conte and Dowler, exhibit almost miraculous phenomena of the kind in the decapitated alligator.3 Our conclusion ought probably to be, from all these cases,—that volition is chiefly seated in the encephalon, but that an obscure action of the kind may originate, perhaps, farther down the cerebro-spinal 1 (Euvres, Paris, 1824. 2 Medical and Physical Researches, Philad., 1835. 3 See p. 307. vol. i.—25 386 MUSCULAR MOTION. axis. This conclusion, of course, applies only to the higher classes of animals; for we have seen, that the polypus is capable of division into several portions, so as to constitute as many distinct beings; and it is probable, that the principal seat of volition may extend much lower down in the inferior tribes of created beings. Successful attempts have been made to discover, whether the whole brain is concerned in volition, or only a part. Portions have been dis- organized by disease, and yet the person has not been deprived of motion; at other times, as in paralysis, the faculty has been impaired; and again, considerable quantities of brain have been lost, owing to accidents (in one case the author knew nineteen tea-spoonfuls), with equal immunity as regards the function in question. Experiments, executed on this subject, go still farther to confirm the idea, that voli- tion is not seated exclusively in the encephalon. MM. Rolando and Flourens1 performed several, with the view of detecting the seat of the locomotive will, or of that which presides over the general movements of station and progression; and they were led to fix upon the cerebral lobes. Animals, from which these were removed, were thrown into a sleepy, lethargic condition; were devoid of sensation and spontaneous motion, and moved only when provoked. On the other hand, M. Magen- die2 affirms, that the cerebral hemispheres may be cut deeply in different parts of their upper surface, without any evident alteration in the movements. Even their total removal, if it did not implicate the cor- pora striata, he found to produce no greater effect; or, at least, none but what might be easily referred to the suffering induced by such an experiment. The results, however, were not alike in all classes of ver- tebrated animals. Those mentioned were observed on quadrupeds, and particularly dogs, cats, rabbits, Guinea-pigs, hedgehogs, and squirrels. In birds, the removal or destruction of the hemispheres—the optic tu- bercles remaining untouched—was often followed by the state of stupor and immobility described by MM. Rolando and Flourens; but, in numerous cases, the birds ran, leaped, and swam, after the hemispheres had been removed, the sight alone appearing to be destroyed. In rep- tiles and fish, the removal of the hemispheres seemed to exert little effect upon their motions. Carps swam with agility; frogs leaped and swam as if uninjured; and their sight did not appear to be affected. Magendie3 properly concludes, from these experiments, that the spon- taneity of the movements does not belong exclusively to the hemi- spheres; that in certain birds, as the pigeon, adult rook, &c, this seems to be the case; but not so in other birds. To mammalia, reptiles, and fish,—at least such of them as were the subjects of experiment,—his conclusion is, however, applicable. Of the nature of the action of the brain in producing volition we know* nothing. It is only in the prosecution of direct experiments on the encephalon that we can have an opportunity of seeing it during the execution of the function; but the process is too minute to admit of observation. Our knowledge is confined to the fact, that the encephalon acts, and that some influence is projected from it along the muscles, 1 Op. citat. * Precis Elementaire. 3 Ibid., i. 336. NERVOUS CENTRE OF MUSCULAR CONTRACTION. 387 which excites them to action; and accurately regulates the extent and velocity of muscular Contraction. Yet volition is not the sole excitant of such contraction. If we irritate any part of the encephalon or spinal marrow, or any of the nerves proceeding from them, muscular movements are excited; but they are not regulated as when under the influence of volition. The whole class of involuntary motions, or rather of those executed by the muscular system of organic life, is of this kind, including the action of many of the most important organs,— heart, intestines, blood-vessels, &c. The involuntary muscles equally require a stimulus to excite them into action; but, as their name imports, they are removed from the influence of volition. In certain diseased conditions, we find, that all the voluntary muscles assume in- voluntary motions; but this is owing to the ordinary volition being interfered with, and to some direct or indirect stimulation affecting the parts of the cerebro-spinal axis concerned in muscular contraction; or, if the effect be local, to some stimulation of the nerve proceeding from the axis to the part. Of this kind of general involuntary contraction of voluntary muscles, we have a common example in the convulsions of children; and one of the partial kind, in cramp or spasm. The will, then, is the great but not the sole regulator of the supply of voluntary nervous influence. This is confirmed by experiment. If a portion of the spinal marrow be divided, so as to separate it from all communication with the encephalon, the muscles cannot be affected by the will; but they contract on irritating the part of the spinal marrow, from w'hich its nerves proceed. It has, hence, been presumed by some physiologists, that volition is only the exciting and regulating cause of the nervous influx; and that the latter is the immediate agent in pro- ducing contraction; and they affirm, that as, in the sensations, the im- pression is made on the nerve, and perception effected in the brain,—so, in muscular motion, volition is the act of the encephalon, and the nerv- ous influx to a part corresponds to the act of impression. With regard to the seat of this nervous centre of muscular contrac- tion, much discrepancy has existed amongst modern physiologists. It manifestly is not in the whole encephalon, as certain portions of it may be irritated in the living animal without exciting convulsions. Parts of it, again, may be removed without preventing the remainder from exciting museular contraction when irritated. In the experiments of M. Flourens, the cerebral lobes were taken away, yet the animals, when stimulated, were susceptible of motion; and, whenever the medulla oblongata was irritated, convulsions were produced. Its seat is not, therefore, in the whole encephalon. M. Rolando refers it to the cere- bellum. He asserts, that on removing the cerebellum of living animals, without implicating any other part of the encephalon, they preserved their sensibility and consciousness, but were deprived of the power of motion. This occurred to a greater extent in proportion to the severity of the injury inflicted on the cerebellum. If the injury was slight, the loss of power was slight; and conversely. Impressed with the resem- blance between the cerebellum of birds and the galvanic apparatus of the torpedo; and taking into consideration the lamellated structure of the cerebellum, which, according to him, resembles a voltaic pile; and 388 MUSCULAR MOTION. the results of his experiments, which showed, that the movements diminished in proportion to the injury done to the cerebellum, Rolando drew the inference, that this part of the encephalon is an electro-motive apparatus for the secretion of a fluid analogous to the galvanic. This fluid is, according to him, transmitted along the nerves to the muscles, and excites them to contraction. The parts of the encephalon con- cerned in volition would, in this view, regulate the quantity in which the motive fluid is secreted; and govern the motions; whilst the medulla oblongata, which, when alone irritated, always occasions convulsions, would put the encephalic extremity of the conducting nerves in direct or indirect communication with the locomotive apparatus. This ingenious and simple theory is, however, far from being corro- borated, by the fact, mentioned by M. Magendie,1 that he is annually in the habit of exhibiting to his class animals deprived of cerebellum, which are capable of executing regular movements. For example, he has seen the hedgehog and Guinea-pig, deprived not only of brain but of cerebellum, rub the nose with its paw, when a bottle of strong acetic acid was held to it; and he remarks, that a single positive fact of the kind is worth all the negative facts that could be adduced. He farther observes, that there could be no doubt of the entire removal of the brain in his experiments. The experiments of Magendie are, however, equally adverse to the hypothesis of M. Flourens, that the cerebellum is the regulator or balancer of the movements. Some anatomical ob- servations by Mr. Solly2 would seem to show, that there is a direct communication between the motor tract of the spinal marrow and the cerebellum. The corpora pyramidalia have been generally supposed to be formed by the entire mass of the anterior or motor columns of the spinal cord, but Mr. Solly shows, that not more than one-half of the anterior column enters into the composition of these bodies; and that another portion, which he terms " antero-lateral column," when traced on each side in its progress upwards, is found to cross the cord below the corpora olivaria, forming, after mutual decussation, the surface of the corpora restiformia; and being ultimately continuous with the cere- bellum. Others, again, have estimated the encephalon to be the sole organ of volition, and have referred the nervous action, which produces the "locomotive influx," as it is termed, exclusively to the spinal marrow; and hence they have termed the spinal marrow, and the nerves issuing from it, the "nervous system of locomotion." It is manifest, however, that the encephalon must participate with the medulla spinalis in this function; inasmuch as not only does direct irritation of several parts of the former excite convulsions, but we see them frequently as a con- sequence of disease of the encephalon; yet, as has been remarked, there is some reason for believing, that, in the upper classes of animals, an obscure volition may be exercised for a time, even when the ence- phalon is separated from the body. It need scarcely be said, that we ' Precis, &c, i. 340. 7- Transactions of the Royal Society for 1836 ; and Solly on the Brain, Amer. edit., Phila., 1848. ENCEPHALIC SEAT OF MUSCULAR MOTION. 389 are as ignorant of the character of this influx, as we are of that of the nervous phenomena in general. The parts of the encephalon and spinal marrow, concerned in mus- cular motion, are very distinct from those that receive the impressions of external bodies. The function of sensibility is comprised in the medulla oblongata and in the posterior column of the spine, whilst the encephalic organs of muscular motion appear to be the corpora striata, the thalami nervorum opticorum, at their lower part; the crura cerebri; the pons Varolii; the peduncles ofthe cerebellum; the lateral parts of the medulla oblongata, and the anterior column of the medulla spi- nalis. This is proved by direct experiment, as will be shown presently; and, in addition to this, pathology furnishes us with numerous examples of their distinctness. In various cases of hemiplegia or palsy of one side of the body,—which is of encephalic origin,—we find motion almost lost; yet sensibility may be slightly or not at all affected; and, on the other hand, instances of loss of sensation have been met with, in which the power of voluntary motion has continued. Modern dis- coveries in the system of vertebral nerves exhibit how this may hap- pen. A considerable space may exist between the roots of a nerve, one of which shall be destined for sensation, the other for motion; yet both may pass out enveloped in one sheath;—the same nervous cord thus conveying the two irradiations, if they may be so termed. Ac- cording to Sir Charles Bell's system the spinal column is divided into three tracts; the anterior for motion; the posterior for sensibility; and the two are kept separate and united by the third—the column for respiration. The existence of the last column is now admitted by few.1 The experiments performed by the French physiologists especially,— for the purpose of discovering the precise parts of the encephalon con- cerned in muscular motion, have attracted great and absorbing interest. We wish it could be said, that the results have been such as to afford determinate notions on the subject. According to those of M. Flou- rdns, the cerebral lobes preside over volition, and the medulla oblon- gata over the locomotive influx : to the latter organ he assigns, also, sensibility. We have seen, that the results of his experiments have been contested; and with them, of course, his deductions. The facts and arguments, already stated, throw doubts on all except the last pro- position, which.refers sensibility to the medulla oblongata; and even it is not restricted to that organ, or group of organs, whichsoever it may be considered. MM. Foville and Pinel Grand-Champ2 have affirmed that the cere- bellum is the seat of sensibility. To this conclusion they were led by the remarks they had made, in the course of their practice, that the cases of paralysis of sensibility, which fell under their notice, suc- ceeded more especially to morbid conditions of the encephalon. In this view they conceive themselves supported by the discovery of columns in the spinal marrow destined for particular functions ; and, as the posterior column is found to be the column of sensibility, and the cerebellum seems to be formed from this column, they think it ought to be possessed of the same functions. M. Adelon3 remarks, that ' See page 89. a Sur le Systeme Nerveux, Paris, 1820. 3 Op. citat., ii. 38. 390 MUSCULAR- MOTION. Willis professed a similar notion, and that he considered the cerebral lobes to be the point of departure for the movements, and the cere- bellum the seat of sensibility. In his first volume, however, he had cited more correctly the views of Willis. " Willis says positively," he remarks, " that the corpora striata are the seat of perception; the medullary mass of the brain, that of memory and imagination; the corpus callosum, that of reflection ; and the cerebellum, the source of the motive spirits." "Willis, in truth, regarded the cerebellum as supplying animal spirits to the nerves of involuntary functions, as the heart, intestinal canal, &c. The opinions of Foville and Pinel Grand- Champ are, however, subverted by the experiments of Rolando, Flourens, and Magendie, which show, that sensation continues, not- withstanding serious injury to, and even entire removal of, the cere- bellum. By other physiologists, the two functions have been assigned re- spectively to the cineritious and medullary parts of the brain; some asserting, that the seat of sensibility is more especially in the latter, and the motive force in the former. According to Treviranus, the more medullary matter an animal has in its brain and spinal marrow, in proportion to the cineritious, the greater will be its sensibility. To this, however, M. Desmoulins1 properly objects, that in many animals, the spinal marrow is composed exclusively of medullary matter [?]; and consequently they ought not only to be the most sensible of all, but to be wholly devoid of the power of motion. Others, again, as MM. Foville and Pinel Grand-Champ have reversed the matter; assigning sensibility to the cineritious substance, and motility to the medullary. From these conflicting opinions, it is obviously impossible to sift any- thing categorical; except that we are ignorant of the special seat of these functions. A part of the discrepancy, in the results, must be ascribed to organic differences in the animals which were the subjects of the experiments. This was strikingly exemplified in those instituted by M. Magendie, which have been cited. Similar contrariety exists in the experiments and hypotheses, regarding the particular parts of the encephalon, that are concerned in determinate movements of the body. The results of many of those are, indeed, so strange, that did they not rest on eminent authority they might be classed among the romantic. It has been already remarked, that Rolando considered the cerebel- lum to be an electro-motive apparatus, producing the whole of the gal- vanic fluid necessary for the motions. M. Flourens, on the other hand, from similar experiments, independently performed, and without any knowledge of those of Rolando, affirmed it to be the regulator and balancer of the locomotive movements; and he asserted, that, when removed from an animal, it could neither maintain the erect attitude, nor execute any movement of locomotion; nor, although possessing all its sensations, could it fly from danger it saw menacing it. The same view has been advocated by M. Bouillaud, who has detailed eighteen experiments, in which he cauterized the cerebellum, and found that, in ' Anatomie des Systemes Nerveux, &c., Paris, 1825. ENCEPHALIC SEAT OF MUSCULAR MOTION. 391 all, the functions of equilibration and progression were disordered. The experiments of M. Magendie1 on this subject, are pregnant with import- ant novelty. We have already referred to those that concern the cere- bral hemispheres and cerebellum as the encephalic organs of the general movements, in the mode suggested by MM. Rolando and Flourens, and others. M. Magendie affirms, in addition, " that there exist, in the brain, four spontaneous impulses or forces, which are situate at the extremity of two lines, cutting each other at right angles; the one impelling forwards ; the second backwards ; the third from right to left, causing the body to rotate; and the fourth from left to right, occasion- ing a similar movement of rotation." The first of these impulses he fixes in the cerebellum and medulla oblongata ; the second in the cor- pora striata ; and the third and fourth in each of the peduncles of the cerebellum. 1. Forward Impulse.—It has often been observed by those who have made experiments on the cerebellum, that injuries of it cause animals to recoil manifestly against their will. M. Magendie2 asserts, that he has frequently seen them, when wounded in the cerebellum, make an attempt to advance, but be immediately compelled to run back ; and he says that he kept a duck for eight days, the greater part of whose cere- bellum he had removed, which did not move forwards during the whole of that time, except when placed on water. Pigeons, into whose cerebella he thrust pins, constantly walked and flew backwards, for more than a month afterwards. Hence, he concludes, that there exists, either in the cerebellum or medulla oblongata, a force of impulsion, which tends to cause animals to go forward. He thinks it not impro- bable, that this force exists in man; and states that Dr. Laurent, of Versailles, exhibited to him, and to the AcadSmie Royale de Medecine, a young girl, who, in the attacks of a nervous disease, was obliged to recoil so rapidly, that she was incapable of avoiding bodies or pits behind her; and was, consequently, exposed to serious falls and bruises. This force, he affirms, exists only in the mammalia and birds ;—certain fish and reptiles, on which he experimented, appearing to be unaffected by the entire loss of the cerebellum. 2. Backward Impulse.—M. Magendie found,3 when the corpora stri- ata were removed, that the animal darted forward with great rapidity ; and, if stopped, still maintained the attitude of running. This was particu- larly remarked in young rabbits; the animals appearing to be impelled forward by an inward and irresistible power, and passing over obstacles without noticing them. These effects were not found to take place, unless the white, radiated part of the corpora striata was cut: if the gray was alone divided, no modification was produced in the movements. If only one of the corpora was removed, the rabbit remained master of its movements, directed them in different ways, and stopped when it chose ; but, immediately after the removal of the other, all regulating power over the motions appeared to cease, and it was irresistibly im- pelled forwards. In the disease of the horse, called, by the French, immobility, the animal is often capable of walking, trotting, and gallop- 1 Op. citat., i. 345. 2 Precis, i. 341. 3 Op. cit., i. 337. 392 MUSCULAR MOTION. ing forward with rapidity; but he does not back; and frequently it is impracticable to arrest his motion forwards. M. Magendie1 asserts, that he has opened several horses that died in this condition ; and found, in all, a collection of fluid in the lateral ventricles, which had produced a morbid change on the surface of the corpora striata, and must have exerted a degree of compression on them. Similar pathological cases occur in man. M. Magendie relates the case of a person, who became melancholic, and lost all power over his movements ; continually executing the most irregular and fantastic antics ; and frequently compelled to walk exclusively forwards or back- wards until stopped by some obstacle. In this case, recovery occurred; and, accordingly, there was no opportunity for investigating the ence- phalic cause. M. Itard describes two cases, in which the patients were impelled, in paroxysms, to run straight forward, without the power of changing their course, even when a river or precipice was before them. A case is related by M. Piedagnel,2 which is more to the purpose as an opportunity occurred for post mortem examination. The subject of it also was irresistibly impelled to constant motion. " At the time of the greatest stupor," says M. Piedagnel, " he suddenly arose; walked about in an agitated manner; made several turns in his chamber, and did not stop until fatigued. On another occasion, the room did not satisfy him ; he went out, and walked as long as his strength would permit. He remained out about two hours, and was brought back on a litter." M. Piedagnel adds, "that he seemed impelled by an insur- mountable force," which kept him in motion, until his powers failed him. On dissection, several tubercles were found in the right cerebral hemisphere, especially at its anterior part; and at the side of the cor- pora striata. These had produced much morbid alteration in that hemi- sphere ; and had, at the same time, greatly pressed on the other. From these facts, M. Magendie infers it to be extremely probable, that, in the mammalia and in man, a force of impulsion always exists, which tends to impel backwards, and is, consequently, the antagonist to the force seated in the cerebellum. 3. Lateral Impulse.—If the peduncles of the cerebellum—crura cerebelli—be divided in a living animal, it immediately begins to turn round, as if impelled by some considerable force. The rotation or cir- cumgyration is made in the direction of the divided peduncle—M. Longet says, in the opposite direction—and, at times, with such rapidity, that the animal makes as many as sixty revolutions in a minute. The same kind of effect is produced by any vertical section of the cerebellum, which implicates from before to behind the whole substance of the me- dullary arch formed by that organ above the fourth ventricle; but the movement is more rapid, the nearer the section is to the origin of the peduncles; in other words to their point of junction with the pons Varolii. M. Magendie3 affirms, that he has seen this movement continue eight days without stopping, and apparently without any suffering. When an impediment was placed in the way, the motion was arrested; and, * Op. cit., i. 338. 3 Magendie, Journal de Physiologie, torn. iii.; and Precis Elementaire, i. 338. 3 Precis, &c, i. 343. ENCEPHALIC SEAT OF MUSCULAR MOTION. 393 under such circumstances, the animal frequently remained with its paws in the air, and ate in this attitude. What he conceives to have been one of his most singular experiments was,—the effect of the division of the cerebellum into two lateral and equal halves: the animal ap- peared to be alternately impelled to right and left, without retaining any fixed position: if he made a turn or two on one side, he soon changed his motion and made as many on the other. M. Serres1—who is well known as a writer on the comparative anatomy of the brain, and must have had unusual opportunities for observation at the Hospital La Pitie to which he was attached—gives the case of an apoplectic, who presented, amongst other symptoms, the singular phenomenon of turn- ing round, like the animals in those experiments; and, on dissection, an apoplectic effusion was found in that part of the encephalon. On di- viding the pons Varolii vertically, from before to behind, M. Magendie2 found, that the same rotary movement was produced: when the section was to the left of the median line, the rotation was to the left, and con- versely; but he could never succeed in making the section accurately on the median line. From these facts he concludes, that there are two forces, which are equilibrious by passing across the circle formed by the pons Varolii and cerebellum. To put this beyond all question, he cut one peduncle, when the animal immediately rolled in one direction; but on cutting the other or the one on the opposite side, the movement ceased, and the animal lost the power of keeping itself erect, and of walking. From the results of all his experiments, M. Magendie infers, that an animal is a kind of automatic machine, wound up for the performance of certain motions, but incapable of producing any other. The figure of the base of the brain in the margin, will explain, more directly, the impulses described by this physiologist. The cor- pora striata are situate in each hemisphere, but their united impulses may be represented by the arrow A; the impulse seated in the cerebellum, by the arrow B; and those in each peduncle of the cerebellum, p, p, by the arrows C and D respectively. When the impulse backwards is from any cause destroyed, the animal is given up to the forward impulse, or that represented by the arrow B; and conversely. In like manner, the destruction of one lateral impulse leaves the „,i -xl i. i. -j. j Direction of Encephalic Impulses, according to other without an antagonist, and Magendie. Fig. 165. 1 Magendie's Journ. de Physiol., iv. 405. 3 Precis, &c, p. 344. 394 MUSCULAR MOTION. the animal moves in the direction of the arrow placed over the seat of the impulsion that remains. In a state of health, all these impulsions being nicely antagonized, they are subjected to the influence of volition; but in disease they may be so modified as to be entirely withdrawn from its control. These four are not the only movements excited by particular injuries done to the nervous system. M. Magendie1 states, that a circular move- ment to the right or left, similar to that of horses in a circus, was caused by the division of the medulla oblongata, to the outer side of the cor- pora pyramidalia anteriora. When the section was made on the right side, the animal turned, in this fashion, to the right; and to the left, if the section was made on that side. Pathology has, likewise, indicated the brain as the seat of different bodily movements. Diseases of the encephalon have been found not only to cause irregular movements or convulsions, but, also, paralysis of a part of the body, leaving the rest untouched. Hence it has been concluded, that every motion of every part has its starting point in some portion of the brain. The ancients were well aware, that in cases of hemiplegia, the encephalic cause of the affection is found in the opposite hemisphere. Attempts have been made to decide upon the precise part of the encephalon in which the decussation takes place. Many have conceived it to be in the commissures; but the greater num- ber, perhaps, have referred it to the corpora pyramidalia. These, the researches of Gall and Spurzheim2 and others, had pointed out as de- cussating at the anterior surface of the marrow, and as being apparently continuous with the radiated fibres of the corpora striata; and an opinion has prevailed, that the paralysis is of the same side as the encephalic affection, or of the opposite, according as the affected part of the brain is a continuation of fasciculi, which do not decussate—of the corpora olivaria, for example—or of the corpora pyramidalia, which do. M.' Serres,3 however, affirms, that affections of the cerebellum, pons Varolii, and tubercula quadrigemina, exert their effects upon the oppo- site side of the body, and he supports his statement by pathological cases and direct experiment. M. Magendie4 divided one pyramid from the fourth ventricle; yet no sensible effect was produced on the move- ments ; certainly, there was no paralysis, either of the affected or oppo- site side: he then divided both pyramids about the middle, and no apparent derangement occurred in the motions—a slight difficulty in progression being alone observable. The section of the posterior pyra- mids was equally devoid of perceptible influence on the general move- ments; and to cause paralysis of one half the body, it was necessary to divide the half of the medulla oblongata, when the corresponding side became,—not immovable, for it was affected by irregular move- ments; and not insensible, for the animal moved its limbs when they were pinched,—but incapable of executing the determinations of the will. These views are not exactly in accordance with the general idea, 1 Precis, &c, p. 345. 3 Recherches sur le Systeme Nerveux, &c, sect, vi., Paris, 1809. 9 Anatomie Comparee du Cerveau, Paris, 1824. 4 Op. cit. ENCEPHALIC SEAT OF MUSCULAR MOTION. 395 that disease, confined to one hemisphere of the brain, or cerebellum, and to one side of the mesial plane in the tuber annulare, constantly affects the opposite side; whilst disease, confined to one of the lateral columns of the medulla oblongata and medulla spinalis, affects the corresponding side of the muscular system;—the encephalon having a crossed,—the medulla a direct effect.1 The crossing of the fibres at the anterior surface of the marrow would not, however, account for the loss of sensation in hemiplegia. Mr. Hilton2 has examined care- fully the continuation upwards of the anterior and posterior columns of the spinal marrow into the medulla oblongata, and found, that the decussation at the upper part of the marrow belongs in part -to the column for motion, and in part to the column for sensation; and farther, that the decussation is only partial with respect to either of the columns. The result of the examination of morbid cases has induced some physiologists to proceed still farther in their location of the encephalic organs of muscular motion; and to attempt an explanation of para- plegia, or cases in which one half the body, under the transverse bi- section, is paralyzed. MM. Serres, Foville, and Pinel Grand-Champ assert, that the anterior radiated portion of the corpora striata presides over the movements of the lower limbs; and the optic thalami over those of the upper; and that according as the extravasation of blood, in a case of apoplexy, occurs in one of these parts, or in all, the para- lysis is confined to the lower or to the upper limbs, or extends over the whole body. In 1768, M. Saucerotte3 presented a prize memoir to the Academic Royale de Chirurgie, of Paris, in which a similar view was expressed. He had concluded, from experiments, that affections of the anterior parts of the encephalon paralyse the lower limbs, whilst those of the posterior parts paralyse the upper. M. Chopart,—in a prize essay, crowned in 1769, and contained in the same volume with the last—refers to the results of experiments by M. Petit, of Namur, which appeared to show, that paralysis of the opposite half of the body was not induced by injury of the cerebral hemisphere, unless the corpora striata were cut or removed. The experiments by Saucerotte were repeated by M. Foville, and are detailed in a memoir, crowned by the AcadSmie Royale de Medecine, of Paris, in 182G. They were attended with like results. In cats and rabbits, he cauterized, in some, the anterior part of the encephalon; in others, the posterior: in every one of the former, paralysis of the posterior, and in the latter, of the anterior extremities succeeded. Having in one animal mutilated the whole of the right hemisphere, and only the anterior part of the left, he found that the animal wras paralysed in the hinder extremities, and in the paw of the left fore-leg; but that the paw of the right re- mained active.4 1 Lectures on the Nervous System and its Diseases, by Marshall Hall, M.D., &c, Lond., 1836, p. 34, or Amer. edit., Philad., 1836. 2 Proceedings of the Royal Society, No. 34, for 1S37-8; also, Solly on the Brain, p. 145, Lond.. 1836; and Dr. John Reid, Edinb. Med. and Surg. Journ., Jan., 1841, p. 12. 3 Prix de TAcademie Royale de Chirurgie, vol. iv. p. 373, Paris, 1819. * Adelon, Physiologie de l'Homme, edit, cit., ii. 44. 396 MUSCULAR MOTION. Lastly, the motions of the tongue or of articulation are sometimes alone affected in apoplexy. The seat of this variety of muscular motion has been attempted to be deduced from pathological facts. M. Foville places it in the cornu ammonis and temporal lobe; and M. Bouillaud1 in the anterior lobe of the brain, in the medullary substance, —the cineritious being concerned, he conceives, in the intellectual part of speech. It is sufficiently obvious, from the whole of the preceding detail, that the mind must still remain in doubt, regarding the precise part of the encephalon engaged in the functions of muscular motion. The experiments of M. Magendie are, perhaps, more than any others, en- titled to consideration. They appear to have been instituted without any particular bias; to subserve no particular theory; and are supported by pathological facts furnished by others. He is, withal, a practised experimenter, and one to whom physiology has been largely indebted. His vivisections have been more numerous, perhaps, than those of any other individual. His investigations, however, on this subject clearly show, that owing to the different morphology of animals, we cannot draw as extensive analogical deductions from comparative anatomy and physiology as might be anticipated. The greatest source of discre- pancy, indeed, between his experiments and those of MM. Rolando and Flourens, appears to have been the employment of different animals. Where the same animals were the subjects of the vivisections, the results were in accordance. The experiments demand careful repe- tition, accompanied by watchful and assiduous observation of patho- logical phenomena ; and, until this is effected, we can, perhaps, scarcely feel justified in deducing, from all these experiments and investigations, more than the general propositions regarding the influence of the cerebro-spinal axis on muscular motion, which we have enunciated. It has been already shown, however, that strong evidence may be adduced in favour of the view of M. Flourens, that the cerebellum is the regu- lator or co-ordinator of the muscular movements,2 and it is the one now embraced by the generality of physiologists; although it must be ad- mitted, with M. Longet,3 that " the precise determination of the uses of the cerebellum is one of the most embarrassing problems in physi- ology." The nerves, it has been shown, are the agents for conducting the locomotive influence to the muscles. At one time, it was universally believed, that the same nerve conveys both sensation and volition; but the pathological cases, that not unfrequently occurred, in which either sensation or voluntary motion was lost, without the other being neces- sarily implicated; and, of late years, the beautiful additions to our knowledge of the spinal nerves, for which we are mainly indebted to Sir Charles Bell,4 and M. Magendie,5 have satisfied the most sceptical, that 1 Magendie's Journal de Physiologie, torn, x.; also, Belhomme, Archiv. General, de Mede- cine, Mai, 1845. 2 Longet, Anatomie et Physiologie du Systeme Nerveux, i. 703, Paris, 1842. 3 Traite de Physiologie, ii. 272, Paris, 1850. * The Nervous System, &c, 3d edit, Lond., 1837, and Narrative of the Discoveries of Sir Charles Bell in the Nervous System, by A. Shaw, London, 1839. 5 Precis Elementaire, &c, 2de edit., i. 216. NERVES OF MOTION. 397 there are separate nerves for the two functions, although they may be enveloped in the same neurilemma or nervous sheath; and may consti- tute one nervous cord. We have more than once asserted, that the posterior part of the spinal marrow, with the nerves proceeding from it, has been considered to be chiefly concerned in the function of sen- sibility; and the anterior column, and the nerves connected with it, to be inservient to muscular motion; whilst a third intervening column, in the opinion of Sir Charles Bell, is the source of all the respiratory nerves, and of the various movements connected with respiration and expression. It is proper, here again, to observe, that although these two distinguished physiologists agree in their assignment of function to the anterior and posterior columns of the spinal marrow, Bellingeri1 has deduced very different inferences from like experiments. He asserts, that having divided, on living animals, either the anterior roots of the spinal nerves, and the anterior column of the medulla spinalis— or the posterior roots of these nerves, and the posterior column of the marrow, he did not occasion, in the former case, paralysis of motion, and in the latter, loss of sensation; but only, in the one, the loss of all movements of flexion; and in the other, of those of extension. In his view, the brain and its prolongations,—crura cerebri, corpora pyra- midalia, anterior column of the spinal marrow, and the nerves con- nected with it, preside over the movements of flexion; and, on the contrary, the cerebellum and its extensions, as the posterior column of the medulla spinalis, and the nerves connected with it, preside over those of extension: he infers, in other words, that there is an antago- nism between these sets of nerves. The primd facie evidence is against the accuracy of Bellingeri's experiments. The weight of authority in opposition to him is, in the first place, preponderant; and in the second place, it seems highly improbable, that distinct nerves should be employed for the same kind of muscular action. Moreover, in experiments on the frog, Professor Miiller established the correctness of the views of Bell. It seems, that the different physiologists, who engaged in the inquiry before he did, employed warm-blooded animals in their experiments, and he imagines, that the pain, resulting from the necessarily extensive wounds, may have had such an effect on the nervous system as to modify, and perhaps even counteract, the results. Miiller employed the frog, whose sensibility is less acute, and tenacity ,of life greater. If the spinal marrow of this animal be exposed, and the posterior roots of the nerves of the lower extremities be cut, not the least motion is perceptible when the divided roots are touched by mechanical means, or galvanism. But if the anterior roots be touched, the most active movements are instantly observed. These experiments, Miiller2 remarks, are so readily made, and the evidence they afford is so palpable, that they leave no doubt as to the correctness of the views of Sir Charles Bell. 1 Exper. Physiol, in Med. Spinal. August, Taurin., 1825; Ragionamenti, Sperienze, &c, oomprovanti lAntagonismo Nervoso, &c. Torino, 1833; and an Analysis of the same, in Edinb. Med. and Surg. Journ., Jan., 1835, p. 160. 2 Elements of Physiology, by Baly, p. 644, Lond., 1838. 398 MUSCULAR MOTION. Experiments, by M. Magendie, and by Dr. Kronenberg,1 of Moscow, have shown, that a portion of the fibres of the sensitive roots extends to the point of union between them and the anterior roots, and is re- flected to the anterior column of the spinal marrow;—the return or reflection of the fibres taking place near the junction of the two roots. This arrangement of the fibres accounts for the fact, often noticed by physiologists, that some degree of sensibility appears to be manifested, in experiments on animals, when the motor roots of the nerves are irritated. The sensibility of the portio dura, a motor nerve, has been long known, and properly ascribed to its receiving filaments of the fifth pair. Motions can be excited by irritating the posterior root, which are owing to its connexion with the spinal cord. This irritation does not act immediately upon the muscles through the trunk of the nerve, which the posterior root contributes to form; but it excites a motor impulse in the spinal cord, which is propagated through the anterior roots to the periphery of the system. In the ordinary case of the action of a voluntary striped or striated muscle, the nervous influence, emanating from some part of the cerebro- spinal axis, under the guidance of volition, proceeds along the nerves with the rapidity of lightning, and excites the muscle to contraction. The muscle, which was before smooth, becomes rugous; the belly more tumid; the ends approximate, anjd the whole organ is rendered thicker, firmer, and shorter. The researches of Mr. Bowman2 have shown, that in the state of contraction the transverse strise, before described as ex- isting in each fibre, approach each other; whilst its diameter is increased; hence the solid parts are more closely approximated, and the fluid which previously existed between them is pressed out so as to form bullse in the sarcolemma, as represented in Fig. 166, from Mr. Bowman. The Fig. 166. Muscular Fibre of Dytiscus in contraction. (Bowman.) marginal representations, Fig. 167, of the muscular fibre of the skate, at rest and in contraction, are also from Mr. Bowman. It is proper to remark, however, that these representations are of muscular fibres when in an unnatural condition,—separated, that is, from the rest of the economy, and it cannot be considered established, that contraction ex- cited by the agency of the nerves is accomplished in precisely the same manner. With regard to the degree of contraction or shortening, which a muscle experiences, some difference of sentiment has prevailed. Ber- ' Muller's Archiv., Heft v. 1839. 2 Art. Muscular Motion, in Cyclop, of Anat. and Physiol.,Part xxiv. p. 525, London, July, 1842; and Philosophical Transactions for 1840-1841. STATE OF MUSCLES IN ACTION. 399 93 nouilli and Keill1 estimated it at one-third of the length; and Dumas2 carried it still higher. It must, of course, be proportionate to the length'of the fibres,—being greater, the longer the fibres. It has, also, been a subject of ex- periment and speculation, whether the bulk and the specific gravity of a muscle be aug- mented during contraction. Borelli3 and Sir Anthony Carlisle4 affirm, that its bulk is in- creased. In the experiments of the latter, the arm was immersed in a jar of water, with which a barometrical tube was connected; and when the muscles were made to contract strongly, the level of the water in the tube was raised. Glisson, however, from the same experiment, deduced opposite conclusions; Swammerdam and Ermann5 appear to be of their opinion; but Sir Gilbert Blane,6 Mr. Mayo,7 Barzellotti,8 MM. Dumas and PreVost,9 and Valentin,10 during the most careful ex- periments could see no variation in the level of the fluid; and, consequently, do not believe, Muscular Fibre of Skate. that the Size Of a muscle is modified by COn- In a state of rest (1), and in three traction. Sir Gilbert enclosed a living eel in ^"(Bownfan.fcontraction <2>3' a glass vessel filled with water, the neck of which was drawn out into a fine tube; he then, by means of a wire introduced into the vessel, irritated the tail of the animal, so as to ex- cite strong contraction, during which he noticed, that the water in the vessel remained stationary. He, likewise, compared the two sides of a fish, one of which had been crimped, and thus brought into a state of strong contraction;—the other left in its natural condition: their specific gravity was the same. The experiment of Barzellotti was the following. He suspended, in a glass vessel, the posterior half of a frog; filled the jar with water, and closed it with a stopper, traversed by a narrow, graduated tube. The muscle was then made to contract by means of galvanism, but in no case was the level of the liquid in the tube changed. It may, then, be concluded, that the bulk of a muscle is not much, if at all, greater when contracted than when relaxed. Professor E. Weber, who repeated the experiments of Ermann, detected an increase of bulk, but it was exceedingly small.1* ' Tentamina-Medico-Physica, Lond., 1718. 3 Principes de Physiologie, &c., 2de edit., Paris, 1806. 3 De Motu Animalium, addit. J. Bernouillii, Medit. Mathem. Mnscul., L. B. 1710. * Philos. Transact, for 1805, pp. 22, 23. s Gilbert's Annalen, p. 40, 1812. 6 A Lecture on Muscular Motion, &c, Lond., 1778 ; and Select Dissertations, &c, p. 239. 7 Anatomical and Physiological Commentaries, i. 12; and Outlines of Human Physiology, 3d edit., p. 35, Lond., 1833. 8 Esame di alcune moderne Teorie intorno alia Causa prossima della Contrazione mos- colare, Siena, 1796. 9 Op. citat., and Magendie, Precis, &c, i. 222. 10 Lehrbuch der Physiologie des Menschen, s. 42, Braunschweig, 1844; and Grundriss der Physiologie, s. 218, Braunschweig, 1846. " Art. Muskelbewegung, in Wagner's Handworterbuch der Physiologie, 15te Lieferung, s 52 und 121, Braunschweig, 1846. 400 MUSCULAR MOTION. During contraction, the muscle is sometimes so rigid and elastic as to be capable of vibration when struck. The ordinary firm state is well exhibited by the masseter, when the jaws are forcibly closed; and some men possess the power of producing sonorous vibrations by striking the contracted biceps with a metallic rod. It has been a matter of dispute whether the quantity of blood circu- lating in a muscle is diminished during contraction. At one time, it was universally believed, that such diminution existed, and that it ac- counted for the diminished size of the muscle during contraction. This last allegation we have shown to be inaccurate; and no correct deduc- tion can, consequently, be drawn from it. Sir Anthony Carlisle1 adopted the opinion, that the muscles become pale during contraction; but he offers no proof of it. The probability is, that he implicitly obeyed, in this respect, the dicta of his precursors, without observing the incongruity of such a supposition with his idea, that the absolute size of the muscle is augmented during contraction. The truth is, we have no evidence, that the colour of a muscle, or the quantity of blood circulating in it, is altered during contraction. Bichat,2 who adopted the opinion, that the blood is forced out during this state, relies chiefly upon the fact, known to every one, that in the operation of blood-letting from the arm the flow of blood is augmented by working the muscles; but the additional quantity expelled is properly ascribed by Dr. Bos- tock3 to the compression of the large venous trunks by the swelling out of the bellies of the muscles. The prevalent belief, amongst phy- siologists of the present day, is, that there is no change of colour in the muscle during contraction. When the extremities of a muscle are made to approximate, the belly, of course, swells out; and would probably expand to such an extent, that the fasciculi, of which it is composed, would separate from each other, were it not for the areolar membrane and aponeuroses, with which they and the whole muscle are enveloped. The phenomena attendant upon the relaxation of a muscle are the reverse of those that accompany its contraction. The belly loses its rugous character; becomes soft, and the swelling subsides; the ends recede, and the organ is as it was prior to contraction. It is obvious, however, that after a part, as the arm, has been bent by the contrac- tion of appropriate muscles, simple relaxation would not be sufficient to restore it to its original position; for although the relaxation of a muscle has been regarded by Bichat and others to be, in part at least, an active effort; and to consist in something more than the mere ces- sation of contraction, the evidence in favour of the view is extremely feeble and unsatisfactory. The arrangement of the muscular system is, in this, as in every other respect, admirable, and affords signal evi- dence of Omnipotent agency. The arm, as in the case selected above, has not only muscles to bend, but also to extend it; and, accordingly, when it has been bent, and it becomes necessary to extend it, the flexor muscles are relaxed and rest, while the extensors are thrown into • Op. citat, p. 27. 9 Anat. General., torn. iii. § 2. 3 Physiology, 3d edit., 94, Lond., 1836. PHENOMENA OF MUSCULAR CONTRACTION. 401 action. This disposition of antagonist muscles prevails in almost every part of the frame, and will require notice presently. Muscles are not, however, the sole agents in replacing parts. Many elastic textures exist, which, when put upon the stretch by muscular contraction, have a tendency to return to their former condition, as soon as the extending cause is removed. Of this a good example occurs in the cartilages of prolongation, which unite the ribs to the sternum. During inspiration, these elastic bodies are extended; and, by returning upon themselves, they become active agents of expiration, and tend to restore the chest to its unexpanded state. The production of the phenomena of muscular contraction is, so far as is known, unlike any physical process with which we are acquainted. It has, therefore, been considered essentially organic and vital; and, like other operations of the kind, will probably ever elude our researches. Yet here, as on every obscure subject, hypotheses have been innumera- ble; varying according to the fashionable systems of the day, or the views of the propounder. They, who formerly believed that the mus- cular fibre is hollow, or vesicular, ascribed its contraction to distension by the influx of "animal spirits" or of blood; and relaxation to the withdrawal of those. Such were the hypotheses of Borelli,1 Stuart,2 and others. Independently, however, of the objection to these views, that we have no positive evidence of the existence of such vesicles, it is obvious, that the explanation is defective, inasmuch as we have still to look to the cause that produces this mechanical influence. Again, how are we to account, under this hypothesis, for the surprising efforts of strength executed by muscles? The mechanical influence of animal or other spirits—granting for a moment their existence—might develope a certain degree of force; but how can we conceive them able, as in the case of the muscles inserted into the foot, to develope such a force as to project the body from the ground? In all these cases, a new force is generated in the brain; and this, by acting on the muscular fibre, is the efficient cause of the contraction. Moreover, what an inconceivable amount of fluids would be necessary to produce the contraction of the various muscles, that are constantly in action; and what, it has been asked, becomes of these fluids when relaxation succeeds to contraction? Some have affirmed, that they are absorbed by the venous radicles; others, that they run off by the tendons; and others, again, that they become neutralized in the muscle, and communicate to it the greater size it attains under" exercise. These fantasies are too abortive to require comment. When chemical hypotheses were in fashion in medicine, physiology participated in them largely. At one time it was imagined, that an effervescence was excited in the muscle by the union of two substances, one of which was of an acid, the other of an alkaline nature. Willis, Mayow, Keill,3 Bellini,4 &c, supported opinions of this kind; some ascribing the effervescence to a union of the nervous fluid with the arte- 1 De Motu Animalium, Lugd. Bat., 1710. 3 De Structura et Motu Musculari, Lond., 1738. 8 Tentamin. Medico-Physic, No. v., Lond., 1718. 4 Bostock, op. cit., p. 111. VOL. I.—26 402 MUSCULAR MOTION. rial blood; others to a union of the particles of the muscular fibre with the nervous fluid; and others, to the disengagement of an elastic gas, primitively contained in the blood, and separated from it by the nerv- ous spirits. It would, however, be unprofitable, as well as uninterest- ing, to repeat the different absurdities of this period—so prolific in physical obscurities. Medicine has generally kept pace with physics, and where the latter science has been dark and enigmatical, the former has been so likewise. In physiology, this is especially apparent; most of the natural philosophers of eminence having applied their doctrines in physics to the explanation of the different functions of the human frame. Newton, Leibnitz, and Des Cartes, were all speculative physi- ologists. The discovery of electricity gave occasion to its application to the topic in question; and it was imagined, that the fibres of the muscle might be disposed in such a manner as to form a kind of battery, capable of producing contraction by its explosions; and after the dis- covery of galvanic electricity, Valli1 attempted to explain muscular contraction, by supposing that the muscles have an arrangement simi- lar to that of the galvanic pile. Haller2 endeavoured to resolve the problem by his celebrated doctrine of irritability, which will engage attention hereafter. He conceived, that the muscles possess, what he calls, a vis insita; and that their contraction is owing to the action of this force, excited by a stimulus, which stimulus is the nervous influx directed by volition. This, although a true doctrine we think, sheds no new light on the mysterious process. It is, in fact, cutting the Gor- dian knot. We should still have to explain the precise mode of action of the vis insita:3 but that it is not in any way derived from the nerv- ous system will be shown when treating of Life. The hypothesis of Prochaska4 is entirely futile. He gratuitously presumes, that minute ramifications of arteries are every where con- nected with the ultimate muscular filaments, twining around them, and crossing them in all directions. When these vessels are rendered turgid by an influx of blood,—by passing among the filaments, they must, he conceives, bend the latter into a serpentine shape, and thus diminish their length, and that of the muscle likewise. Sir Gilbert Blane,5 again, throws out a conjecture—deduced from experiments, in which he found that the actual bulk of a muscle is not changed during contraction, but that it gains in thickness exactly what it loses in length;—that this may be owing to the muscle being composed of particles of an oblong shape; and that when the 'muscle is contracted, the long diameter of the particle is removed from a perpendicular to a transverse direction. But the same objection applies to this as to other hypotheses on the subject; that it is entirely gratuitous,—resting on no histological observation whatever. Two views have been, perhaps, the most prevalent; one which con- siders muscular contraction to be a kind of combustion ; another that it i Experiments in Animal Electricity, Lond., 1793. 2 Element. Physiol., xi. 214; and Oper. Minor., torn. i. 3 M. Hall, art. Irritability, Cyclop, of Anat. and Physiol., July, 1840. 4 De Carne Musculari, § ii., Vienn., 1778. 6 Op. citat. ELECTRICAL THEORY OF MUSCULAR CONTRACTION. 403 is produced by electricity. The former, which was originally propounded by Girtanner,1 and zealously embraced by Dr. Beddoes, who was more celebrated for his enthusiasm than for the solidity of his opinions, has now few supporters. This hypothesis supposes, that muscular contrac- tion depends upon the combustion of the combustible elements of the muscle, hydrogen and carbon, by the oxygen of the arterial blood; the combustion being produced by the nervous influx, which acts in the man- ner of an electric spark;—at least, such is the view adopted by M. Richerand,2 one of the most fanciful of physiological speculators. Of course, we have neither direct nor analogical evidence of any such com- bustion, which, if it existed at all, ought to be sufficient, in a short space of time, to entirely consume the organs that furnish the elements. The idea is as unfounded as numerous others that have been enter- tained, and is worthy only of particular notice, from its being professed in one of the well-known works on physiological science. The second hypothesis refers muscular contraction to electricity. Attention has been already directed to the electroid or galvanoicl cha- racter of the nervous agency; and we have some striking examples on record of the analogous effects produced by the physical and the vital fluid on the phenomena under consideration. It has been long known, that when nerves and muscles are exposed in a living animal, and brought into contact, contractions or convulsions occur in the latter. Galvani3 was the first to point this out. He decapitated a living frog; removed the fore-paws, and quickly skinned it. The spine was divided, so as to leave the spinal marrow communicating only with the hinder extremities by means of the lumbar nerves. He then took, in one hand, one of the thighs of the animal, and the vertebral column in the other, and bent the limb until the crural muscles touched the lumbar nerves. At the moment of contact the muscles were strongly convulsed. The experiment was repeated by Volta,4 Aldini,5 Pfaff,6 Humboldt,7 and others; and with like results. Aldini8 caused convulsions in the mus- cles by the contact of those organs with nerves, not only in the same frog, but in two different frogs. He adds, that he remarked them when he put the nerves of a frog in connexion with the muscular flesh of an ox recently killed. Humboldt made numerous experiments of this kind on frogs, and found convulsions supervene when he placed upon a dry plate of glass a posterior extremity whose crural nerves had been exposed, and touched the nerves and muscles with a piece of raw muscular flesh, insulated at the extremity of a stick of sealing-wax. Convulsions likewise occurred, when, instead of one piece of flesh, he used three different pieces to form the chain, one of which touched the nerve; the other the thigh, and the third the two others. The expe- riments were repeated by Ritter with similar results; but they were 1 Journal de Physique, xxxvii. 139. 2 Elements of Physiology, § 163. 3 Mem. sull' Elettricita Animale, Bologn., 1797. 4 Memoria sull' Elettricita Animale, 1782. 6 Essai Theoretique et Experiment, sur le Galvanisme, Paris, 1804. 6 Ueber thierische Electricitilt und Reizbarkeit, Leipz., 1795. 7 Versuche liber die gereizte Muskel und Nervenfaser, Posen und Berlin, 1797. 8 Traite complet de Physiologie de l'Homme, par Tiedemann, traduit par Jourdan,p. 559, Paris, 1837. 404 MUSCULAR MOTION. only found to succeed, when the frogs were in full vital activity,—espe- cially in spring, after pairing; when the animal was of sufficient size, and its preparation for the experiment had been rapidly effected. From all these experiments it might be inferred, that parts of an ani- mal may form galvanic chains, and produce a galvanic effect, which, independently of any mechanical excitation, may give rise to the con- traction of muscles. This excitation of electricity in chains of animal parts, M. Tiedemann thinks, ought not to be esteemed a vital act. Its effects only—the contractions excited in the muscles—are dependent on the vital condition of the muscles and nerves. He considers, that elec- tricity, excited in chains of heterogeneous animal parts, may be modi- fied and augmented by the organic or living forces ; and that, more- over, in certain animals, organs exist, the arrangement of which is such as to excite electricity during their vital action as in the different kinds of electrical fishes ; but in some experiments, instituted by M. Edwards,1 the effects above referred to were produced by touching a denuded nerve with a slender rod of silver, copper, zinc, lead, iron, gold, tin, or platinum, and drawing it along the nerve for the space of from a quar- ter to a third of an inch. He took care to employ metals of the great- est purity, as they were furnished him by the assayers of the mint. But it was not even necessary that the rod should be metallic : he suc- ceeded with glass or horn. All metals, however, did not produce equally vigorous contractions. Iron and zinc were far less effective than the others ; but no accurate scale could be formed of their respect- ive powers. Much difference is found to exist, when electricity is employed, ac- cording as the nerve is insulated or not; for as the muscular fibre is a good conductor of electricity, if the nerve be not insulated, the electri- city is communicated to both nerve and muscle, and its effect is conse- quently diminished. It became, therefore, interesting to M. Edwards to discover, whether any difference would be observable, when one metal only was used, whether the nerve Avas insulated or not. In the expe- riments above referred to, the nerve was insulated by passing a strip of oiled silk beneath it. A comparison was now instituted between an animal thus prepared, and another whose nerves instead of being insu- lated, rested on the subjacent flesh. He made use of small rods, with which he easily excited contractions when he drew them from above to below along the denuded portion of nerve that was supported by the oiled silk ; but he was unable to cause them when he passed the rod along the nerve of the other animal which was not insulated. His experiments were then made on two nerves ofthe same animal; and he found that after having vainly attempted to produce contractions by the contact of a nerve resting upon muscle, they could still be induced if the oiled silk were had recourse to; and he was able to command their alternate appearance and disappearance by using a non-conductor or a conductor for the support of the nerve. Somewhat surprised at these results, M. Edwards was stimulated to the investigation, — whether 1 Appendix to Edwards on the Influence of Physical Agents on Life,—Hodgkin and Fisher's translation, Lond., 1832. ELECTRICAL THEORY OF MUSCULAR CONTRACTION. 405 some degree of contraction might not be excited by touching the unin- sulated nerve, and having remarked, that contractions were most con- stantly produced in the insulated nerve by a quick and light touch, he adopted this method on an animal whose nerve was not insulated, and frequently obtained slight contractions. All his experiments on this subject seemed to prove, that, caeteris paribus, muscular contractions, produced by the contact of a solid body with a nerve, are much less considerable, or even wholly wanting, when the nerve, in place of being insulated, is in communication with a good conductor; and it would seem to follow, as a legitimate conclusion, that these contractions are dependent on electricity; facts, which it is well to bear in mind, in all experiments on animals where feeble electrical influences are employed.1 Galvanic electricity, it will be seen hereafter, is one of the great tests of muscular irritability, and is capable of occasioning contractions for some time after the death of the animal, as well as of maintaining, for a time, many of the phenomena peculiar to life. This is the reason why muscular contraction, excited by this nervous, electroid fluid, has been regarded as an electrical phenomenon. Much discrepancy has, however, arisen amongst the partisans of this opinion regarding its modus operandi. Rolando, we have seen, assimilates the cerebellum to an electro-motive apparatus, which furnishes the fluid that excites the muscles to contraction. Some have compared the spinal column to a voltaic pile, and have supposed the contraction of a muscle to be owing to an electric or galvanic shock. The views of MM. Dumas and Provost2 are amongst the most striking. By a microscope, magnifying ten or twelve diameters, they first of all examined the manner in which the nerves are arranged in a muscle; and found, as has been already ob- served, that their ramifications always enter the muscle in a direction perpendicular to its fibres. They satisfied themselves, that none of the nerves really terminate in the muscle; but that the final ramifications embrace the fibres like a noose, and return to the trunk that furnishes them, or to one in its vicinity,—the nerve setting out from the anterior column of the spinal marrow, and returning to the posterior. On farther examining the muscles at the time of their contraction, the parallel fibres composing them were found, under the microscope, to bend in a zigzag manner, and to exhibit a number of regular undulations; such flexions forming angles, which varied according to the degree 5of con- traction, but were never under fifty degrees. The flexions, too, always occurred at the same parts of the fibre, and to them the shortening of the muscle was owing, as MM. Dumas and Prevost proved by calculat- ing the angles. The angular points were always found to correspond to the parts where the small nervous filaments enter or pass from the muscles. (See page 371.) They therefore believed, that these filaments, by their approximation, induce contraction of the muscular fibre; and this approximation they ascribed to a galvanic current running through them; which, as the fibres are parallel and in proximity, they thought, ought to cause them to attract each other, according to the law 1 Coldstream, art. Animal Electricity, in Cyclop. Anat. and Physiol., P. ix. p. 93, Jan., 1837; and J. Miiller, Elements of Physiology, by Baly, p. 261, London, 1838. 1 Journal de Physiologie, torn. iii. 301; and Magendie, Precis, i. 220. 406 MUSCULAR MOTION. laid down by M. Ampere, that two currents attract each other when they move in the same direction. The living muscles are, consequently, regarded by them as galvanometers, and galvanometers of an extremely sensible kind, on account of the very minute distance and tenuity of the nervous filaments. They moreover affirm, that, by anatomical ar- rangement, the nerve is fixed in the muscle in the very position required for the proper performance of its function; and they esteem the fatty matter, which envelope!* the nervous fibres, and which was discovered by M. Vauquelin, as a means of insulation for preventing the electric fluid from passing from one fibre to another. Soon after hearing of M. Ampere's discovery of the attraction of elec- trical currents, it occurred to Dr. Roget,1 that it might be possible to render the attraction between the successive and parallel turns of heli- acal or spiral wires very sensible, if the wires were sufficiently flexible and elastic; and, with the assistance of Dr. Faraday, his conjecture was put to the test of experiment in the laboratory of the Royal Insti- tution of London. A slender harpsichord-wire, bent into a helix, being placed in the voltaic circuit, instantly shortened itself whenever the electric stream was sent through it; but recovered its former dimensions the moment the current was intermitted. From this experiment it was supposed, that possibly some analogy might hereafter be found to exist between the phenomenon and the contraction of muscular fibre. The views of MM. Dumas and Prevost were altogether denied by M. Raspail,2 on the ground, that it is impossible to distinguish, by the best microscope, the ultimate muscular fibre from the small nervous fibrils by which those gentlemen consider them to be surrounded loop- wise. He farther affirmed, that the zigzag form is the neeessary result of the method in which they performed their experiments, and is produced by the muscular fibre adhering to the glass on which it was placed. His own idea, founded on numerous observations, is, that the contraction of the fibre in length is always occasioned by its extension in breadth under the influence of the vital principle. Independently, however, of M. RaspaiTs objection, the circumstance, that, in this mode of viewing the subject, the muscle itself is passive, and the nerve alone active, is a stumbling-block in the way of the views of MM. Dumas and Prevost, and of Dr. Roget. It is proper, too, to remark, that M. Person3 was unable to detect any longitudinal galvanic currents in the nerves by the most sensible galvanometer; and that other stimuli besides galvanism are capable of exciting the muscular fibre to contraction. This we daily see in experiments on the frog, by dropping salt on the de- nuded muscle. Prof. Miiller4 hence infers, that a nerve of motion, dur- ing life, and whilst its excitability or irritability continues, is so circum- stanced, that whatever suddenly changes the relative condition of its molecules excites a contraction at the remote end of the muscle, and 1 Electro-Magnetism, p. 59, in 2d vol. of Nat. Philosophy, Library of Useful Knowledge, London, 1832. 3 Chimie Organique, p. 212, Paris, 1833. 3 Journal de Physiologie, torn. x. Paris, 1830. 4 Art. Electricitat (thierische) in Encyclopad. Worterb. der Medicin. Wissensch., x. 545, Berlin, 1834. ELECTRICAL THEORY OF MUSCULAR CONTRACTION. 407 that electrical, chemical, and mechanical irritants are, in this respect, similarly situate. Interesting electro-physiological researches have been made by Pro- fessor Matteucci of Pisa, from which he has deduced the following results. First. Muscle is a better conductor of electricity than nerve; and nerve conducts better than brain. The conducting power of muscle may be taken as four times greater than that of brain or nerve. Secondly. In the muscles of living animals, as well as of those recently killed, an electric current exists, which is directed from the interior of each muscle to its surface. The duration of this muscular current corresponds with that of contractility; in cold-blooded animals, there- fore, it is greatest: in mammalia and birds very brief. Temperature has a considerable influence on the intensity of the current,—a small amount of electricity being developed in a cold medium; a larger one when the medium is moderately warm. Any circumstance that enfeebles the frogs (the animals experimented on) and deranges their general nutrition, diminishes the power of the muscles to generate electricity, as it likewise impairs the contractile force. The muscular current appears to be quite independent of the nervous system. It is unin- fluenced by narcotic poisons in moderate doses, but is destroyed by large doses, such as would kill the animal. The developement of this muscular current seems evidently to depend on the chemical action constantly taking place as an effect of the changes accompanying nutri- tion. Thirdly. In frogs an electric current exists, which is distinct from the muscular current. It proceeds from the feet to the head, and is peculiar to batrachian reptiles. Fourthly. Singular results are obtained by applying electricity in various ways to nerves. On making experiments on the sciatic nerves of rabbits, he found that on closing the circuit of the direct electric current, or the current passing from the brain to the nerves, contractions in the muscles of the posterior limbs were produced; whilst opening this circuit was followed by marked signs of pain, with contraction of the muscles of the back, and feeble contractions of the posterior limbs. On closing the circuit of the inverse current, or that directed from the nerves to the brain, signs of pain, contractions of the muscles of the back, and feeble contractions of the posterior limbs were produced. On opening it, contractions of the pos- terior limbs followed.1 With regard to the hypotheses which ascribe muscular contractility to the chemical composition of the fibre, and that which maintains, that the property is dependent upon the mechanical structure of the fibre, they are undeserving of citation, notwithstanding the respectability of the individuals who have written and experimented on the subject. They merely seem to show, that here, as in every case, a certain che- mical and mechanical constitution is necessary, in order that the vital operation, peculiar to the part, may be accomplished. But not only is it necessary, that the muscle shall possess a proper 1 For an account of Matteucci's researches, see Todd and Bowman, Physiological Ana- tomy and Physiology of Man, vol. i., Lond., 1845, and, especially, Matteucci, Lectures on the Physical Phenomena of Living Beings, by Pereira, Amer. edit., pp. 176 and 224, Philad., 1848. 408 MUSCULAR MOTION. physical organization, it must, likewise, be endowed with a property essentially vital; in other words, with irritability or contractility. The cause of the ordinary contraction of muscles is, doubtless; the nervous influx; but if we materially alter the condition of the muscle, although the nervous influx may be properly transmitted to it, there will be no contraction. This applies to the living animal; but not apparently to the dead; for Valentin1 found, that after tying the femoral artery or vein, or dividing the sciatic nerve in frogs, the full strength of the muscle remained unaltered for several days,—in one case for twelve. We moreover find, that after a muscle has acted for some time, it be- comes fatigued, notwithstanding volition may regularly direct the nerv- ous influx to it; and that it requires repose, before it is again capable of executing its functions. In the upper classes of animals, contractility remains for some time after dissolution; in the lower, especially in the amphibia, the period during which it is evinced on the application of appropriate stimuli is much greater. From experiments on the bodies of executed criminals, M. Nysten found that irritability ceased in the following order of parts. The left ventricle of the heart first; the intestinal canal at the end of forty-five or fifty-five minutes; the urinary bladder at nearly t\he same time; the right ventricle after the lapse of an hour; the oesophagus at the end of an hour and a half; the iris a quarter of an hour later; the muscles of animal life somewhat later; and lastly, the auricles of the heart, especially the right, which, in one instance, under the influence of galvanism, contracted sixteen and a half hours after death. These results are singular; and the experiments merit repetition. It is, in- deed, strange, that muscles of organic life, apparently circumstanced so much alike, should vary so greatly in the length of time during which they retain their irritability. One of the most interesting of the many experiments that have been made on the bodies of criminals recently deceased, for the purpose of exhibiting the effects of galvanism on muscular irritability, is detailed by Dr. Ure.2 The subject was a murderer, named Clydesdale; a middle- sized athletic man, about thirty years of age. He was suspended from the gallows nearly an hour, and made no convulsive struggle after he dropped. He was taken to the theatre of the Glasgow University about ten minutes after he was cut down. His face had a perfectly natural aspect, being neither livid nor tumefied; and there was no dislocation of the neck. In the first experiment, a large incision was made into the nape of the neck, close below the occiput, and the spinal marrow was brought into view. A considerable incision was made, at the same time, into the left hip, through the glutaeus maximus muscle, so as to expose the sciatic nerve;3 and a small cut was made in the heel; from 1 Lehrbuch der Physiologie des Menschen, ii. 176-92, Braunschweig, 1844. 2 Art. Galvanism, in Diet, of Chemistry, Hare and Bache's Amer. edit., Philad., 1821. 3 It is not indispensable, in these experiments, to expose the nerve. The author has long known, that, in the case of the frog, it is needless; and, in his experiments, he has been in the habit of acting under this knowledge. The experiments made on three criminals,—two of whom were executed at Philadelphia, and the third at Lancaster, Pennsylvania—showed, indeed, that the effect was even greater when the nerves were not exposed. It was found, too, to be more marked when the current was transmitted from the peripheral extremity of • ACTION OF GALVANISM ON MUSCLES. 409 neither of which any blood flowed. A pointed rod, connected with one end of a galvanic battery, of two hundred and seventy pairs of four- inch plates, was now placed in contact with the spinal marrow, whilst another rod, connected with the other end, was applied to the sciatic nerve. Every muscle of the body was immediately agitated with con- vulsive movements, resembling a violent shuddering from cold. The left side was most powerfully convulsed at each renewal of the electric contact On removing the second rod from the hip to the heel, the knee being previously bent, the leg was thrown out with such violence as nearly to overturn one of the assistants, who in vain attempted to prevent its extension. In the next experiment, the left phrenic nerve was exposed at the outer edge of the sterno-thyroideus muscle. As this nerve is distributed to the diaphragm, and communicates with the heart through the pneu- mogastric nerves, it was expected that, by transmitting the galvanic fluid along it, the respiratory process might be renewed. Accordingly, a small incision having been made under the cartilage of the seventh rib, the point of one rod was brought into contact with the great head of the diaphragm, whilst that of the other was applied to the phrenic nerve in the neck. The diaphragm, which is a main agent in respira- tion, was instantly contracted, but with less force than wTas expected. "Satisfied," says Dr. Ure, "from ample experience on the living body, that more powerful effects can be produced in galvanic excitation by leaving the extreme commtfhicating rods in close contact with the parts to be operated on, while the electric chain or circuit is completed by running the end of the wires along the top of the plates* in the last trough of either pole, the other wire being steadily immersed in the last cell of the opposite pole, I had immediate recourse to this method. The success of it was truly wonderful. Full, nay laborious breathing instantly commenced. The chest heaved and fell; the belly was pro- truded and again collapsed, with the relaxing and retiring diaphragm. This process was continued, without interruption, as long as I continued the electric discharges. In the judgment of many scientific gentlemen who witnessed the scene, this respiratory experiment was perhaps the most striking ever made with a philosophical apparatus. Let it also be remembered, that for full half an hour before this period, the body had been well-nigh drained of its blood, and the spinal marrow severely lacerated. No pulsation could be perceived, meanwhile, at the heart or wrist; but it may be supposed, that but for the evacuation of the blood,— the essential stimulus of that organ,—this phenomenon might also have occurred." In a third experiment, the supra-orbital nerve was laid bare in the forehead. The one conducting rod being applied to it, and the other to the heel, most extraordinary grimaces were exhibited. Every muscle in the face was simultaneously thrown into fearful action. "Rage, horror, despair, anguishj and ghastly smiles, united their hideous ex- pression in the murderer's face, surpassing far the wildest representa- a nerve towards its centre. See Bell's Select Medical Library, for Oct., 1839; Amer. Journ. of Med. Sciences, May, 1840, p. 13; and Medical Examiner, Jan. 23d and 30th, 1841. I 410 MUSCULAR MOTION. tion of a Fuseli or of a Kean." At this period, several of the spectators were forced to leave the room from terror or sickness; and one gentle- man fainted. The last experiment consisted in transmitting the electric power from the spinal marrow to the ulnar nerve as it passes by the internal con- dyle at the elbow; when the fingers moved nimbly, like those of a violin performer; and an assistant who tried to close the fist, found the hand open forcibly in spite of every effort to prevent it. When one rod was applied to a slight incision in the tip of the forefinger, the fist being previously clenched, the finger was instantly extended; and from the convulsive agitation of the arm, he seemed to point to the different spectators, some of whom thought he had come to life. The experiments of Dr. lire have been several times repeated in this country on the bodies of criminals, and with analogous results.1 « What important reflections are suggested by the perusal of such cases! The great resemblance between the galvanic and the nervous fluids, and the absorbing idea, to the philanthropist, that galvanism might be found successful in resuscitating the apparently dead, in cases where other means may have failed! Unfortunately, it can rarely happen, that the means will be at hand, so as to be available; and, moreover, when the heart has ceased to beat for a few minutes, it is generally impracticable to cause it to resume its functions. An experiment, described by Dr. George Fordyce,2 exhibits the power of contractility resident in the tissue. He slightly scratched, with a needle, the inside of a heart removed from the body, when it contracted so strongly as to force the point of the needle deep into its substance. This experiment has been often cited for the purpose of showing, that the mechanical effect, in such cases, is infinitely greater than the mechanical cause producing it; and hence, as we have endea- voured already to show, that all mechanical explanations must be in- sufficient to account for the phenomena of muscular contraction: we are compelled, indeed, to infer, that a new force must always be gene- rated. In the year 1806, a cause was tried before the Court of Exchequer in England, in which a better knowledge of the properties of muscle might have led to a different result.3 According to the English law, where a man marries a woman seised of an estate of inheritance, and has, by her, issue born alive, which was capable of inheriting her estate,—in such case he shall, on the death of his wife, hold the lands for his life as tenant by the courtesy of England. It has, consequently, been a point of moment for the husband to show, that the child was born alive; and the law authorities have, with singular infelicity, attempted to define what shall be regarded evidences of this condition. According to Blackstone,4 "it must be born alive. Some have had a notion that it must be heard to cry, but that is a mistake. Crying, 1 Dunbar, in Baltimore Med. and Surg. Journal, i. 245, Bait., 1833, and the Journals re- ferred to in the preceding pages. 2 Philos. Transact, for 1788, p. 25. 3 Taylor, Medical Jurisprudence, Amer. edit., by R. E. Griffith, p. 480, Philad., 1845. 4 Commentaries, B. ii. 127. MUSCULAR SENSE. 411 indeed, is the strongest evidence of its being born alive, but it is not the only evidence." According to Coke,1 "if it be born alive it is suf- ficient, though it be not heard to cry, for peradventure it may be born dumb.2 It must be proved that the issue was alive; for mortuus exitus non est exitus; so that the crying is but a proof that the child was born alive; and so is motion, stirring, and the like." This latitudinarian definition has given occasion to erroneous decisions, as in the trial alluded to, in which the jury agreed that the child was born alive; because, although, when immersed in a warm bath immediately after birth, it did not "cry, or move, or show any symptoms of life;" yet, according to the testimony of two females,—the nurse and the cook,— there twice appeared a twitching and tremulous motion ofthe lips; and this was sufficient to make it fall under Lord Coke's definition. It is manifest, that, granting such motion to have actually occurred, it was of itself totally insufficient to establish the existence of somatic life. We have seen, that on the application of stimuli, the muscles of a body may be thrown into contraction for two hours after the cessation of respiration and circulation or after somatic death. Instead, therefore, of referring the irritability to the existence, at the time, of somatic life, it must be regarded simply as an evidence of the persistence of mole- cular life in parts that had previously and recently formed part of a living whole. The contraction of a muscle is followed by its relaxation ;—the fibres- returning to their former condition. This appears to be a passive state; and to result from the suppression of the nervous influx by the will;— in other words, from the simple cessation of contraction. Some have, however, regarded both states to be active, but without proof. Barthez3 maintains, that the relaxation of a muscle is produced by a nervous action the reverse of that which occasions its contraction ;—the will re- laxing the muscles as well as contracting them. The muscle is the only part susceptible of contraction. The tendon conveys the force deve- loped by it, passively to the lever, which has to be moved. It has been ascertained by MM. Becquerel and Breschet,4 that a muscle during contraction augments in temperature. This increase is usually more than one degree of Fahrenheit; but at times when the exertion has been continued for five minutes,—as in the case of the biceps of the arm, in saw7ing wood,—it has been double that amount.5 Lastly, a sensation instructs the mind that a muscle has contracted, and this has given rise to the notion of a muscular sense, and a sensa- tion of motion:—Muskelsinn, Bewegungssinn or muscular sense of Gruithuisen, Lenhossek,6 Brown,7 Sir C. Bell,8 and other 1 Institutes, 30, a. * It need scarcely be said that the deaf-dumb cry at the moment of birth the same as other children. The natural cry is effected by them as well as by the infant that possesses all its senses. It is the acquired voice, alone, which they are incapable of attaining. 3 Nouveaux Elemens de la Science de l'Homme, Paris, 1806. 4 Archiv. du Museum, torn. i. p. 402, and Annales des Sciences Naturelles, nouv. serie, iii. 272. 6 See on this subject Helmholtz, in Muller's Archiv., H. ii. s. 144, Berlin, 1848. 6 Rudolphi, Grundriss der Physiologie, 2te Band, lste Abtheil., s. 318, Berlin, 1823. 7 Lectures on Moral Philosophy. B The Hand, &c, Amer. edit., p. 145, Philad., 1833. 412 MUSCULAR MOTION. writers. It appears to be an internal sensation, produced by the muscle pressing on the sensible parts surrounding it, which convey the sensation to the brain. It is by this muscular sense that the brain learns to adapt the effort to the effect to be produced. Without it no precision could exist in the movements of the muscles, and every manual effort—whether of the artist or the mechanic—would be confused and disorderly. The step, too, would be unsteady and insecure. "In chewing our food," says Dr. A. Combe,1 "in turning the eyes towards an object looked at, in raising the hand to the mouth, and, in fact, in every variety of muscular movement which we perform, we are guided by the muscular sense in proportioning the effect to the resistance to be overcome; and where this harmony is destroyed by disease, the extent of the service rendered us becomes more apparent. The shake of the arm and hand which we see in drunkards, and their consequent incapability of carrying the morsel directly to the mouth, are examples of what would be of daily occurrence, unless we were directed and assisted by a muscular sense." It enables us to form ideas of force and resistance, by conveying to our minds a distinct idea of the effort re- quired. The force or intensity of muscular contraction is dependent upon two causes,—the physical condition of the muscle, and the energy of the brain. A muscle, which is composed of large, firm fibres, will con- tract,—the energy of the brain being equal,—more forcibly than one with delicate, loose fibres. Volition generally determines the degree of power developed by the voluntary motions; and is accurately regulated so as to raise a weight of one pound or one hundred. We notice astonishing efforts of strength in those that are labouring, at the time, under strong cerebral excitement; mania, rage, delirium, &c. In such cases, the delicate muscles of the female are capable of contracting with a force far transcending that of the healthy male. The power of muscular contraction is, therefore, in a compound ratio with the strength of the organization of the muscle, and the degree of excitation of the brain. When both are considerable, the feats of strength sur- pass belief; and where both are small, the results are insignificant. The extensors of the knee and foot occasionally contract with so much violence as to fracture the patella and tendo Achillis, respectively. The force, developed in the calf of the leg, must be great, when a per- son stands on tiptoe with a burden on his head or shoulders; or when he projects his body from the soil, as in leaping. Rudolphi2 asserts, that he has seen a horse, which fractured its under-jaw by biting a piece of iron. It has been a question, whether the power of a muscle is greater or less at different degrees of contraction, the same stimulus being applied. To determine this, Schwann3 invented an apparatus, which should accu- rately measure the length of the muscle, and the weight it would balance by its contraction; and, from his experiments it appeared, that a uniform 1 Principles of Physiology, 5th edit., p. 131, Edinb., 1836. ' Op. cit., p. 303. » J. Miiller, Physiology, p. 903. FORCE OF MUSCULAR CONTRACTION. 413 increase of force is attended with a nearly uniform increase in the length of the muscle. The explanation of this by Dr. Carpenter1 is probably correct;—that, as the observations of Mr. Bowman have clearly shown, there must be a considerable displacement of the con- stituents of every fibre during contraction, it is easy to understand, that the greater the contraction the more difficult must any farther contraction become. "If, between a magnet and a piece of iron attracted by it, there were interposed a spongy elastic tissue, the iron would cease to approach the magnet at a point, at which the attraction of the magnet would be balanced by the force needed to compress still farther the intermediate substance." We have a number of feats of surprising strength on record, several of which have been collected by Sir David Brewster.2 Of these, the cases of John Charles Van Eckeberg, who travelled through Europe under the appellation of Samson, and of Thomas Topham, are the most authentic and extraordinary. Dr. Desaguliers saw Topham, by the strength of his fingers, roll up a very strong and large pewter dish. He broke seven or eight short and strong pieces of tobacco-pipe with the force of his middle finger, having laid them on his first and third fingers. Having thrust under his garter the bowl of a strong tobacco- pipe, his leg being bent, he broke it to pieces by the tendons of his hams without altering the flexure of his knee. He broke another such bowl between his first and second fingers, by pressing his fingers to- gether sideways. He lifted a table six feet long—which had half a hundred weight hanging at the end of it—with his teeth, and held it in a horizontal position for a considerable time, the feet of the table resting against his knees. He took an iron kitchen poker, about a yard long, and three inches in circumference, and, holding it in his right hand, he struck upon his bare left arm, between the elbow and wrist, till he bent the poker nearly to a right angle. He took such another poker, and holding the ends of it in his hands, and the middle against the back of his neck, he brought both ends of it together before him; and afterwards pulled it nearly straight again. He broke a rope about two inches in circumference, which was in part wound about a cylinder of four inches in diameter, having fastened the other end of it to straps that went over his shoulders. Lastly, he lifted a rolling- stone, eight hundred pounds in weight, with his hands only, standing in a frame above it, and taking hold of a chain that was fastened to it. An equally remarkable example is given by a recent well-known traveller3 as having been witnessed by him in Paris. In the Place du Carrousel, a large coarse French woman made the following exhibition in the presence of a great crowd of spectators. A rough block of stone, weighing more than three hundred pounds, and which two men could barely lift from the ground, was fastened round with several turns of rope. The long black hair of the woman, which was divided into seven traces, tightly platted and fastened at the end, was then brought 1 Human Physiology, § 394, Lond., 1842. 2 Letters on Natural Magic, Amer. edit., p. 222, New York, 1832. 3 J. S. Buckingham, Travels in France, Piedmont, &c, ii. 63, Lond., 1849 414 MUSCULAR MOTION. down, and attached to these ropes, whilst the woman herself bent her head back towards the stone for the purpose of admitting of the traces being fastened. When this was done, she slowly rose to her erect position^ lifting the stone entirely from the ground, its weight being borne by the seven traces of her hair, and the pressure resting wholly on her scalp. She then began to turn herself slowly round, swinging the stone just fastened to her hair, until, by the progressively increas- ing motion, she twirled round as rapidly as the spinning dervishes, or an opera dancer in a pirouette, but for a longer period,—the stone all this while going out farther and farther from her person till it swung round almost horizontally, and with a velocity that made it fearful to look upon, relaxing gradually from the highest point of motion till it rested at her feet. It was then loosened from the hair and the cords; and her next feat was to place two rush-bottomed chairs at a distance of about four feet and a half from each other, when she placed her head on one, and her heels on the other, thus lying horizontally between the two, without any support for her back or loins in the centre, and neither her head nor her heels being more than six inches from the outer edge of the chairs. Whilst in this condition, two men were invited to come from the crowd and lift up the stone, so as to place it on her stomach. Two persons came from amongst the bystanders, and one of them not being a strong man, they were unable to lift it, when a third came to their assistance ; but not till after at least twenty persons had tried to lift the stone a little from the ground, to be assured it was not hollow, and that there was no deception, and each had failed to lift it half an inch from where it stood. The three men, however, raised it up, and placed it on the woman's stomach, as she lay in this horizontal position; when another person, at her request, placed a smaller stone on the large one, and with a heavy iron sledge-hammer broke it into twenty pieces. All this occupied about a quarter of an hour, during the whole of which time the woman evinced no appearance of shrinking; and in conversing with her after she rose there was not the slightest evidence of any inconvenience being felt by her from the exertion. That much depends upon physical organization, as regards the force of muscular contraction, is evinced by the fact of the great difference in the various races of mankind. On our own continent, numerous opportunities have occurred for witnessing the inferiority, in strength, of the aborigines to the white settlers. Pdron1 took with him, in his voyage round the world, one of Regnier's dynamometers, which indicate the relative force of men and animals. He directed his attention to the strength of the arms and loins, making trial on several individuals of different nations ; twelve natives of Van Diemen's Land; seventeen of New Holland; fifty-six of the island of Timor; seventeen Frenchmen belonging to the expedition, and fourteen Englishmen in the colony of New South Wales. The following was the mean result :— 1 Voyage, &c, torn. i. chap. xx. p. 446; and t. ii. p. 461; and Lawrence's Lectures on Physiology, &c, p. 404, Lond., 1819. DURATION OF MUSCULAR CONTRACTION. 415 STRENGTH Of the Arms. Of the Loins. Kilogrammes.1 Myr, •agrammes. 50-6 • 50-8 10-2 5S-7 11-6 . 69-2 152 71*4 16-3 1. Van Diemen's Land, 2. New Holland, .... 3. Timor, ..... 4. French, ..... 5. English, ..... The highest numbers, in the first and second divisions, were respect- ively 60 and 62 ; the lowest in the fifth, 63 ; in the highest 83, for the strength of the arms. In the power of the loins, the highest amongst the New Hollanders was 13; the lowest of the English, 12*7.2 The force of muscular contraction is also largely increased by the proper exercise of the muscles. Hence the utility of the ancient gym- nasia. In early times, muscular energy commanded respect and admira- tion. It was the safeguard of individuals and families, and the protection of nations; and it was esteemed a matter of national policy to encou- rage its acquisition. In modern times, the invention of gunpowder having altered the system of warfare, and given to skill the superiority which strength communicated in personal combats, institutions for the developement of the muscular system have been abandoned, until of comparatively late years. They afford us striking examples of the value of muscular exertion, not only in giving energy and pliancy to the frame, but as a means of preserving health. The mean effect of the labour of an active man, working to the greatest possible advantage, and without impediment, is usually esti- mated to be sufficient to raise ten pounds, ten feet in a second for ten hours in a day; or to raise one hundred pounds, which is the weight of twelve wine gallons of water, one foot in a second, or thirty-six thou- sand feet in a day; or three millions, six hundred thousand pounds, or four hundred and thirty-two thousand gallons, one foot in a day. Dr. Desaguliers affirms, that the weakest men who are in health, and not too fat, lift about one hundred and twenty-five pounds; and the strong- est of ordinary men four hundred pounds. Topham lifted eight hun- dred. The daily work of a horse is estimated to be equal to that of five or six men. In insects, the force of muscular contraction appears to be greater in proportion to their size than in any other animals. The Lucanus cer- vus or Stag Beetle has been known to gnaw a hole of an inch diameter in the side of an iron canister in which it had been confined, and many striking examples of a similar kind are given hereafter under the head of Flying. In the duration of muscular contraction we notice considerable dif- ference between the voluntary and involuntary muscles; the latter being much more rapid and alternating. The. same remark applies to the 1 The approximate value of a kilogramme is about two pounds avoirdupois:—of a myria- gramme about twenty. a See Quetelet, Sur l'Homme, &c, Paris, 1835, or English edit., by Dr. R. Knox, p. 67, Edin- burgh, 1842. Prof. Forbes, of Edinburgh, in London and Edinburgh Phil. Magazine, for March, 1837, p. 197; and in Dunglison's American Med. Intelligencer, for May 15, 1837, p. 74; in which are detailed experiments on the weight, height, and strength of above eight hundred individuals, natives of England, Scotland, Ireland, and Belgium. 416 MUSCULAR MOTION. voluntary muscles, when excited by another stimulus than that of the will. Contraction, excited by volition, can be maintained for a con- siderable time: of this we have examples in bearing a burden; the act of standing; holding the arm extended from the body, &c. In all these cases, the contractility of the muscles is sooner or later exhausted; fatigue is experienced; and it becomes necessary to give them rest; the power of contractility, however, is soon resumed, and they can be again put in action. This law of intermission in muscular action appears absolute;—relaxation being followed by contraction, in every organ, from the commencement of life until its final cessation. The inter- mission, has, indeed, by many physiologists, been held to prevail—to a slight extent only, it is true—during what we are in the habit of con- sidering continuous, muscular contraction. In proof of this, they cite the fact, that when we put the tip of the finger into the meatus audi- torius externus, we hear a kind of buzzing or humming, which does not occur when an inert body is introduced'.1 There are, however, other actions going on in the finger besides muscular contraction; and the buzzing might, with as much propriety, be referred to the noise made by the progression of fluids in the vessels, as to the oscillations of mus- cular contraction and relaxation. We know not, in truth, whence the sound immediately proceeds. In the velocity of muscular contraction, much difference exists, accord- ing to the stimulus which sets it in action. If we apply galvanism to a muscle, we find the contractions at first exceedingly rapid; but they become progressively feebler, and require a stronger stimulus, until their irritability appears to be exhausted. Irritating the nerve in these cases is found to produce a greater effect, than when the stimulus is applied directly to the muscle. The velocity of voluntary contraction is, of course, variable, being regulated entirely by the will. We have, in various classes of the animal kingdom, remarkable instances of this velocity. The motions of the racer, greyhound, practised runner, the fingers in playing on musical instruments—as the violin, flute, piano- forte,—and in writing; of the voice in enunciation, and of the upper and lower limbs in striking, leaping, and kicking, convey a general notion of this rapidity of contraction; and how nicely, in many cases, it must be regulated by volition. The fleetest race-horse on record was capable of going, for a short distance, at the rate of a mile per minute; yet this is trifling, when compared with the velocity of certain birds, which can, with facility, wheel round and round the most rapid racer in circles of immense diameters,—and with that of numerous small insects, which accompany us, with apparent facility, when we travel with great rapidity, even against the wind. It has frequently excited surprise, how the migratory birds can sup- port themselves so long upon the wing as to reach the country of their migration; and, at the same time, live without food during their aerial voyage. The difficulties of the subject have impelled many to deny the fact of their migration, and excited others to form extravagant theories to account for the preservation of the birds during the winter 1 Wollaston, in Philosoph. Transact, for 1810, p. 2. VELOCITY OF MUSCULAR CONTRACTION. 417 months; but if we attend to their excessive velocity, the difficulties, in a great measure, vanish. "Nothing," says Wilson,1 "is more common in Pennsylvania than to see large flocks of the bluebirds, in spring and fall, passing at considerable heights in the air,—from the south in the former, from the north in the latter season. The Bermudas are said to be six hundred miles from the nearest part of the continent. This may seem an extraordinary flight for so small a bird; but it is a fact that it is performed. If we suppose the bluebird to fly only at the rate of a mile a minute, which is less than I have actually ascertained them to do over land, ten or twelve hours would be sufficient to accomplish the journey." Montagu, a celebrated ornithologist, estimates the rapidity with which hawks and many other birds occasionally fly to be not less than one hundred and fifty miles an hour; and that one hundred miles per hour is certainly not beyond a fair computation for the continuance of their migration. Major Cartwright, on the coast of Labrador, found by repeated observations, that the flight of the eider duck is at the rate of ninety miles an hour; yet it has not been esteemed very remarkable for its swiftness. Sir George Cayley computes the rate of flight of the common crow at nearly twenty-five miles an hour. Spallanzani found that of the swallow about ninety-two miles an hour; and he conjectures, that the velocity of the swift is nearly three times greater. A falcon belonging to Henry IV. of France escaped from Fontainbleau, and was in twenty-four hours afterwards at Malta,—a distance computed to be not less than one thousand three hundred and fifty miles, making a velocity of nearly fifty-seven mile's an hour, supposing the falcon to have been on the wing the whole time; but, as such birds never fly by night, if we allow the day to have been at the longest, his flight was perhaps at the rate of seventy-five miles per hour. It is not probable, however, as Montagu observes, that it had either so many hours of light in the twenty-four to perform its journey, or that it was retaken at the moment of its arrival.2 A society of pigeon-fanciers from Antwerp despatched ninety pigeons from Paris, the first of which returned in four hours and a half, at a rate of nearly fifty miles an hour. Out of one hundred and ten pigeons, carried from Brussels to London in the summer of 1830, and let fly from London on July 19th, at a quarter before nine A.M., one reached Antwerp, one hundred and eighty-six miles distant, at eighteen minutes past two, or in five and a half hours,—being at the rate of nearly thirty-four miles an hour. In another case, one went from London to Maestricht, two hundred and sixty miles, in six and a quarter hours. In January, 1831, two pigeons, carried from Liskeard to London, were let loose in London. One reached Liskeard, two hun- dred and twenty miles distant, in six hours; the other in a quarter of an hour more.3 There is an instance of the migratory or passenger pigeon—Columba migratoria of Wilson—having been shot in Fifeshire, in Scotland. It was the first ever seen in Great Britain, and had been forced over, it was imagined, by unusually strong westerly gales.4 1 American Ornithology, ii. 178. * Fleming's Philosophy of Zoology, ii. 42, Edinb., 1822. 3 Turner's History of the World, Amer. edit.,i. 259, New York, 1832. 4 New Monthly Magazine for 1826. vol. i.—27 418 MUSCULAR MOTION. The velocity of the contraction of the muscles of the wings, in these rapid flights, is incalculable. The possible velocity, in any case, must be greatly dependent upon habit. Nothing can be more awkward th,an the first attempts at writing, drawing, playing on musical instruments, or performing any mechanical process in the arts; and what a con- trast is afforded by the astonishing celerity, which practice never fails to confer, in any one of those varieties of muscular contraction ! In running, leaping, wrestling, dancing, or any other motion of the body, one person can execute with facility what another, with equally favour- able original powers, cannot effect, because he has not previously and fre- quently made the attempt. Prize-fighting affords an instance of this kind of muscular velocity and precision acquired by habit,—the prac- tised boxer being able to inflict his blow and return his arm to the guard so quickly as almost to elude the sight. By considering the mus- cular motions, employed in transporting the body of the fleetest horse, Haller concluded, that the elevation of the leg must have been performed in ^th of a second. He calculates, that the rectus femoris,—the large muscle which is attached to the knee-pan and extends the leg,'—is short- ened three inches in the ^gth of a second in the most rapid movements of man. But, he adds, the quickest motions are executed by the mus- cles concerned in the articulation of the voice. He himself, in one experiment, pronounced fifteen hundred letters in a minute ; and as the relaxation of a muscle occupies as much time as its contraction, the con- traction of a muscle, in pronouncing one of these letters, must have been executed in 3^*u^th part of a minute; and fn much less time in some letters, which require repeated contractions of the same muscle or mus- cles as r. If the tremors, that occur in the pronunciation of this let- ter, be estimated at ten, the muscles concerned in it must have con- tracted in Haller's experiment, in 3^00^ Part 0I* a nainute.1 It has been calculated, that all the tones of which the human vdice is capable are produced by a variation of not more than one-fifth of an inch in the length of the vocal cords ; and that in man the variation required to pass from one interval to another will not be more than yo^th of an inch. These cases are, however, far exceeded by the rapidity of the vibrations of the wings of insects, which can be estimated from the musi- cal tone they induce, experiment having shown the number of vibrations required to produce any given note. The vibrations of their wings have thus been found to amount to several thousands per second. It has been the opinion of many physiologists and metaphysicians, that muscular contraction is only directed by volition within certain limits of velocity; and that when it exceeds a certain velocity it depends upon habit. The effects of volition have, in this respect, been divided into the immediate and remote. Of the first we have examples in the formation of certain vocal and articulate sounds ; and in certain mo- tions of the joints, as in the production of voice, speech, and locomo- tion. In the second, those actions are included which we conceive to be within our power, but in which we think of the end to be obtained, without attending to the mechanical means. " In learning a language, 1 Elementa Physiologia', &c, lib. xi. 2, Lausan., 1757-1766. ELEMENTARY PRINCIPLES OF MECHANICS. 419 for example," says Dr. Bostock,1 "we begin by imitating the pronun- ciation of the words, and use a direct effort to put the organs of speech in the proper form* By degrees, however, we become familiar with this part of the operation, and think only of the words that are to be employed, or even the meaning that is to be conveyed by them. In learning music, we begin by imitating particular motions of the fingers, but at length the fingers are disregarded, and we only consider what sounds will follow from certain notes, without thinking of the mechani- cal way in which the notes are produced." In these, however, and in all other cases that can be brought forward, it is difficult to conceive how the effect can be produced without the agency of volition,—obscure it is true, but still in action. The case of reading is often assumed, as confirming the view that invokes habit; yet, if a letter be inverted, we immediately detect it; and although, by habit, we may have acquired extreme facility in playing the notes of a rapid musical movement, no doubt, we think, ought to exist, that an effort of volition is exerted on each note composing it,—inasmuch as there is no natural sequence of sounds; and hence there appears no cogent reason, why one should follow rather than another, unless a controlling effort of the will were exerted. With regard to the extent of muscular contraction, this must of course be partly regulated by volition; but it is also greatly owing to the length of the muscular fibres. The greater the length, of course the greater the decurtation during contraction. We shall see, likewise, that this depends upon the kind of lever, which the bone forms, and the dis- tance at which the muscle is inserted from the joint or fulcrum. Before passing to the examination of special movements, it will be necessary to consider briefly certain elementary principles of mechanics, most of which are materially concerned in every explanation, and with- out some knowledge of which such explanation would, of course, be obscure or unintelligible. Were we, as M. Magendie2 has remarked, to investigate narrowly every motion of the body, we should find the ap- plicability of almost all the laws of mechanics to them. If we take a rod of wood or metal, of uniform matter throughout, and support it at the middle, either like the beam of a balance, or on a pointed body, we find, that the two ends accurately Fj 16g balance each other; and if we add weights at corre- sponding parts of each arm of the beam, that is, at parts equidistant from the point of suspension, the balance will still be maintained. The point by which the beam is suspended, or at Avhich it is equilibrious, is called its centre of gravity; and, in every mass of matter, there is a point of this kind, about which all the parts balance or are equilibrious; or, in other words, they have all a centre of gravity or inertia. The centre of gravity, in a mass of regular form and uniform substance, as in the parallelograms, Figs. 168 and 169, is easily determined, inasmuch as it must necessarily occupy the centre c; but in bodies that are irregular, either as regards density or Centre of Gravity. ' Physiology, edit, cit., p. 774, Lond., 1836. a Precis, &c, edit, cit, i. 276. 420 MUSCULAR MOTION. Fig. 169. Centre of Gravity. 170. form, it has to'be determined by rules of calculation, to be found in all works on physics; but which it is unnecessary to adduce here. The nearer the centre of gravity is to the soil on which the body rests, the more stable is the equilibrium. In order that the Figures 168 and 169 shall be overturned from left to right, the whole mass must turn upon e as upon a pivot; the centre of gravity describing the curve c b, and the whole mass being lifted in the same degree. In Fig. 168, the curve is nearly horizontal, owing to the narrowness of the base and the height of the centre of gravity. In Fig. 169, on the other hand, whose base is broad and the centre of gravity low, the curve rises considerably; the resistance to overturn- ing is consequently nearly equal to the whole weight of the body, and the equilibrium necessarily firm. The condition of equilibrium of a body resting upon a plane is such, that a perpendicular, let fall from the centre of gravity, shall fall within the points by which it touches the plane. This per- pendicular is called vertical line or line of direction, being that in which it tends naturally to descend to the earth; and the space comprised between the points by which the body touches the soil is called base of sustentation. We can now understand, why a wagon, loaded with heavy goods, may pass with safety along a sloping road; whilst, if it be loaded to a greater height with a lighter substance, it may be readily overturned. When the wagon is loaded with metal, the centre of gravity is low, as at c, Fig. 170; the vertical line c p falls considerably within the base of sustentation; and the centre describes a rising path; but in the other case the centre is thrown higher, to a; and the vertical line falls very near the wheel, or on the outside of it, and consequently of the base, whilst the centre describes a falling path. Of two hollow columns, formed of an equal quantity of the same matter, and of the same height, that which has the largest cavity will be the stronger; and of two columns of the same diameter, but of dif- ferent heights, the higher will be the weaker. All bodies tend to continue in the state of motion or of rest, so as to render force necessary to change their state. This property is called the inertia of motion, or of rest, as the case may be. When a carriage is about to be moved by horses, considerable effort is necessary to over- come the inertia of rest; but if it moves with velocity, effort is required to arrest it, or to overcome the inertia of motion. We can thus under- stand why, if a horse start unexpectedly, it is apt to get rid of its burden; and why an unpractised rider is projected over his horse's head if it stops suddenly. In the former case, the inertia of rest is the cause of his being thrown; in the latter, the inertia of motion. The danger of attempting to leap from a carriage, when the horses have taken fright, is thus rendered apparent. The traveller has acquired the same velocity as the vehicle; and if he leaps from it, he is thrown Condition of Equi- librium. ELEMENTARY PRINCIPLES OF MECHANICS. 421 Fig. 171. to the ground with that velocity; thus incurring an almost certain injury to avoid one remotely contingent. The force, momentum, or quantity of motion in a body is measured by the velocity, multiplied into the quantity of matter. A cannon-ball, for example, may be rolled so gently against a man's leg, as not even to bruise it; but if it be projected by means of gunpowder, it may mow down a dense column of men, or penetrate the most solid substance. If a man be running, and strike against another who is standing, a certain shock is received by both; but if both be running in opposite directions with the same velocity, the shock will be doubled. The subject of the direction of forces applies to most cases of mus- cular movement. Where only one force acts upon a body, the body proceeds in the direction in which the force is exerted, as in the case of a bullet fired from a gun; but if two or more forces act upon it at the same time, the direction of its motion will be a middle course be- tween the direction of the separate forces. This course is called the resulting direction, that is, resulting from the composition of the forces. Let us suppose two forces a T and b T in Fig. 171, acting upon the body T, which may be regarded as the ten- don of a muscle, and the two forces as the power developed by muscular fibres holding the same situation; the result will be the same, whether they act together or in succession. For example, if the force a T is sufficient to draw T to a, and immediately afterwards the force b T be exerted upon it, the tendon will be at c, the place towards which it would be drawn by the simultaneous action of the two forces or fibres. If, therefore, we complete the figure, by drawing a c equal and parallel to T b, and c b equal and parallel to a T, we have the parallelogram of forces, as it is called, of which the diagonal shows the resultant of the forces, and the course of the body on which they act. In the case, assumed in Fig. 171, the forces are equal. If not, the parallelogram may result as in Fig. 173; in which T c will, again, be the resultant of the forces a T and T b, or we may have the arrangement in Fig. 172. By these parallelograms, we are enabled, also, to resolve the resultant into its component forces. Suppose, for example, we desire to know the quan- tity of force in the resultant, T c, Fig. 171, which is capable of acting in the directions T a and T b; it is only necessary to draw, from the point c, c a parallel to T b, and c b parallel to T a ; and the lines Composition of Forces. T a and T b, cut off by these, will be the forces into which it may be resolved. The same applies to Figs. 172 and 173, and to every other of the kind. Friction is the resistance necessary to be overcome in making one Composition of Forces. Fig. 172. 422 MUSCULAR MOTION. body slide over another; and adhesion the force, which unites two polished bodies when applied to each other, — a force, which is measured by the perpendicular ef- fort necessary for separating the two bodies. The more polished the surfaces in contact, the greater is the adhesion, and the less the fric- tion; so that where the object is merely to facilitate the sliding of one surface over another, it will be always advantageous to make the Composition of Forces. Fig. 174. Lever of the first kind. surfaces polished, or to put a liquid between them. A beam or rod of any kind, resting at one part on a prop or support, which thus becomes its centre of motion, is a lever. The ten inch beam, PW, Fig. 174, is a lever, of which F may be considered the prop orfulcrum; P, the part at which the power is applied, and W, the point of application of the weight or resistance. In every lever we distinguish three points;— the fulcrum, power, and resistance; and, according to the relative position of these points, the lever is said to be of the first, second, or third kind. In a lever of the first kind, the fulcrum is between the resistance and power, as in Fig. 174; F being the fulcrum on which the beam rests and turns; P, the power; and W, the weight or resistance. We have numerous familiar examples of this lever;—the crowbar in elevating a weight; the handle of a pump; a pair of scales; a steelyard, &c. A lever of the second kind has the resist- ance W, Fig. 175, between the power P and the fulcrum F; the fulcrum and power occupying each one extremity. The rudder of a ship, a wheelbarrow, and nut-crackers, are varieties of this kind of lever. In a lever of the third kind, the power P is between the resistance W, and the fulcrum F, Fig. 176; the resistance and the fulcrum occupying each one extremity of the lever. In the last two levers, the weight and the power change places. Tongs and shears are levers of this kind; also, a long ladder raised against a wall by the efforts of a man: here the fulcrum is at the part of the ladder which rests on the ground; the power is exerted by the man; and the resistance is the ladder above him. Fig. 175. Lever of the second kind. ELEMENTARY PRINCIPLES OF MECHANICS. 423 iimmmiiiwiiH mnuiniMiiniiuiiiiiiiiiiiiiiiiiiH iiiiuiihiiuii jP w Lever of the third kind. In all levers are distinguished,—the arm of the power and the arm of the resistance. The former is the distance Fig.176 comprised between the ,-Ci.. power and the ful- crum, P F, Figs. 174, 175, and 176; and the latter is the dis- tance W F, or that between the weight and the fulcrum. When, in the lever of the first kind, the ful- crum occupies the middle, the lever is said to have equal arms; but if it be nearer the power or the resistance, it is said to be a lever with unequal arms. The length of the arm of the lever gives more or less advantage to the power, or the resistance, as the case may be. In a lever of the first kind, with equal arms, complete equilibrium would exist, provided the beam were alike in every other respect. But if the arm of the power be longer than that of the resistance, the resistance is to the power as the length of the arm of the power is to that of the arm of the resistance; so that if the former be double or triple the latter, the power need only be one-half or one-third of the resistance, in order that the two forces may be in equilibrium. A reference to the figures will exhibit this in a clear light. The three levers are all presumed to be of equal substance throughout, and to be ten inches, or ten feet, in length. The arm of the power, in Fig. 174, is the distance P F, equal to eight of those divisions; whilst that of the resistance is W F, equal to two of them. The advantage of the former over the latter is, consequently, in the proportion of eight to two, or as four to one; in other words, the power need only be one-fourth of the resistance, in order that the two forces may be equilibrious. In the lever of the second kind, the proportion of the arm P F of the power is to that of the resistance, W F, as ten—the whole length of the lever—to two; or five to one; whilst, in the lever of the third kind, it is as two to ten, or as one to five; in other words, to be equilibrious, the power must be five times greater than the resistance. We see, therefore, that in the lever of the second kind, the arm of the power must neces- sarily be longer than that of the resistance, since the power and the fulcrum are separated from each other by the whole length of the lever; hence this kind of lever must always be advantageous to the power; whilst the lever of the third kind, for like reasons, must always be unfavourable to it, seeing that the arm of the resistance is the whole length of the lever, and, therefore, necessarily greater than that of the power. It can now be understood why a lever of the first kind should be most favourable for equilibrium; one of the second for overcoming re- sistance; and one of the third for rapidity and extent of motion: for whilst, in Fig. 176, the power is moving through the minute arc at P, 424 MUSCULAR MOTION. in order that the lever may assume the position indicated by the dotted lines F w, the weight or resistance is moving through the much more considerable space W w. The direction in which the power is inserted into the lever likewise demands notice. When perpendicular to the lever, it acts with the greatest advantage,—the whole of the force developed being employed in surmounting the resistance; whilst if inserted obliquely a part of the force is employed in tending to move the lever in its own direc- tion; and this part is destroyed by the resistance of the fulcrum. Lastly: the general principles of equilibrium in levers consist in this;—that whatever may be the direction in which the power and re- sistance are acting, they must always be to one another inversely as the perpendiculars drawn from the fulcrum to their lines of direction. In Fig. 176, for example, the line of direction of the upper weight is W w; that of the power P p; and, to keep the lever in equilibrium in this position, the forces must be to one another inversely as F w to Fp. In applying these mechanical principles to the illustration of muscu- lar motion, we must, in the first place, regard each movable bone as a lever, whose fulcrum or centre of motion is in its joint; the power at the insertion of the muscle; and the resistance in its own weight and that of the parts which it supports. In different parts of the skeleton we find the three kinds of levers. Each of the vertebrae of the back forms, with the one immediately beneath it, a lever of the first kind,— the fulcrum being seated in the middle of the under surface of the body of the vertebra. The foot, when we stand upon the toe, is a lever of the second kind,—the fulcrum being in the part of the toes resting upon the soil; the power in th6 muscles inserted into the heel, and the resistance in the ankle-joint, on which the whole weight of the body rests. Of levers of the third kind we have numerous instances; of which the deltoid, to be described presently, is one. In this, as in other cases, the applicability of the principle, laid down regarding the arms of the lever, &c, is seen, and we find, that, in the generality of cases, the power is inserted into the lever so near to the fulcrum, that considerable force must be exerted to raise an inconsiderable weight;— that so far, consequently, mechanical disadvantage results; but such disadvantage enters into the economy of nature, and is attended with so many valuable concomitants as to compensate richly for the expense of power. Some of these causes, that tend to diminish the effect of the forces, we shall first consider, and afterwards attempt to show the advantages resulting from these and similar arrangements in effecting the wonderful, complicate operations of the muscular system. In elucidation of this subject, we may take, with Haller,1 the case of the deltoid—the large muscle, which constitutes the fleshy mass on the top of the arm, and whose office it is to raise the upper extremity. Let W F, Fig. 177, represent the os humeri, with a weight W at the elbow, to be raised by the deltoid D. The fulcrum F is necessarily, in this case, in the shoulder joint; and the muscle D is inserted much * Elementa Physiologiae, lib. xi. 2. APPLICATION OF MECHANICAL PRINCIPLES. 425 Fig. 177. nearer to the fulcrum than to the end of the bone on which the weight rests; the arm of the power P F,—(supposing, for a moment, that it is acting at this part with every advantage, which we shall see pre- sently it is not,)—is, consequently, much shorter than that of the resist- ance W F, which, as in all levers of the third kind, occupies the whole length of the lever. In estimating the effect from this cause alone upon the power to be exerted by the del- toid, we may suppose, that the arm of the power is to that of the resist- ance as 1 to 3;—the deltoid being inserted into the humerus about one- third down. Now, if we raise a weight of fifty-five pounds in this way, and add five pounds for the weight of the limb—(which may be conceived to act entirely at the end of the bone)—the power, which the deltoid must exert to produce the effect, is equal not to sixty pounds, but to three times sixty or one hundred and eighty pounds. Fig. 178. Action of the Deltoid. Action of the Deltoid. A. The scapula. B. The os humeri. C The deltoid. Figures 177 and 178 exhibit the disadvantages of the deltoid, so far as regards the place of its insertion into the lever; but many muscles have insertions much less favourable than it. The biceps, D, for exam- ple, in Fig. 179,—the muscle which bends the forearm on the arm,—is attached to the forearm ten times nearer the elbow-joint or fulcrum than to the extremity of the lever; and if we apply the argument to it,—supposing the weight of the globe, in the palm of the hand, to be fifty-five pounds and the weight of the limb five pounds,—it would have to act with a force equal to sixty times ten, or six hundred pounds, to raise the weight. Muscles, again, are attached to the bones at unfavourable angles. If they were inserted at right angles in the direction P P, Fig. 177, the whole power would be effectually applied in moving the limb. On the other hand, if the muscle were parallel to the bone, the resistance would be infinite, and no effect could result. In the animal it rarely 426 MUSCULAR MOTION. happens, that the muscle is inserted at the most favourable angle: it is generally much smaller than a right angle. Reverting to the deltoid, this muscle is inserted into the humerus at an angle of about ten de- Fig. 179. Action of the Biceps. A. The os humeri. B. The ulna. C. The radius. D. The biceps. E. Insertion of the bicep» into the radius. grees. Now, a power acting obliquely upon a lever, is to one acting perpendicularly, as the sine of inclination, represented by the dotted line F s, Fig. 177, to the whole sine P P. In the case of the deltoid, the proportion is as 1,736,482 to 10,000,000. Wherefore, if the muscle had to contract with a force of one hundred and eighty pounds, owing to the disadvantage of its insertion near the fulcrum, it would have, from the two causes combined, to exert a force equal to 1,058 pounds. Again, the direction in which the fibres are inserted into the tendon has great influence on the power developed by the muscle. There are few straight muscles, in which all the fibres have the same direction as the tendon. Fig. 180 will exhibit the Fis- 180. loss 0f power, which the fibres must sustain in proportion to the angle of insertion. The fibre t F would, of course, exert its whole force upon the tendon, whilst the fibre t 90°, by its contraction, would merely displace the tendon. Now, the force exerted is, in such case, to the effective force,— that is, to that which acts in moving the limb,—as the whole sine t F is to the sines of the angles at which the fibres join the tendon represented by the dotted lines. Borelli and Sturm have calculated these proportions as follows:—At an angle of 30°, they are as 100 to 87; at 45° as 100 to 70; at 26° as 100 to 89; at 14° as 100 to 97; and at 8° as 100 to 99. The largest angle, formed by the outer fibres of the deltoid, is esti- mated "by Haller at 30°: the smallest about 8°. If this disadvantage 90 70' Insertion of Fibres into Tendon. APPLICATION OF MECHANICAL PRINCIPLES. 427 be taken into account, the deltoid will have to contract with a force equal to 1,284 pounds, to raise fifty-five pounds at the elbow. It is farther contended by Borelli, Sturm, and Haller, that the force of the muscle, as estimated in the preceding calculations, must be doubled, seeing that it has to exert as much force in resisting the bone which affords a fixed point at one extremity, as in elevating the weight at the other. This estimate, if admitted, would elevate the force, to be exerted by the deltoid in raising the fifty pounds, to 2,568 pounds. Lastly: Much force is spent when a muscle passes over many joints; antagonist muscles must, likewise, exert an influence of the kind, consuming a cer- tain portion of the force developed in the contraction of the muscle. On the other hand, there are arrangements that augment the power developed by muscles ;—as the thick articular extremities of bones; the patella and sesamoid bones in general; all of which enlarge the angle, at which the tendon is inserted into the bone or lever. The projecting processes for muscular attachments, as the trochanters, protuberance of the os calcis, spinous processes of the vertebrae, &c, augment the arm of the lever, and are thus inservient to a like valuable purpose. The smoothness of the articular surfaces of bones,—tipped, as they are, with cartilage,—and the synovia, which lubricates the joints, by dimin- ishing friction, as well as the bursse mucosae, which are interposed wher- ever there is much pressure or friction, also aids the power. Trochleae or pulleys act only in directing the force, without augmenting its amount; and the same may be said of the bony canals and tendinous sheaths, by which the tendons of the muscles, especially those passing to the fingers and toes, are kept in their proper course. Still, it must be admitted, that, as regards the effort to be exerted by muscles, it must, in almost all cases, be much greater than the resistance to be overcome. The very fact of the lever of the third kind being that which prevails in our movements shows this. The mere mechanician has conceived this to be an unwise construction: and that there is a needless expense of force for the attainment of a determinate end. In all cases we find, that the expense of power has been but little regarded in the construction of the frame ; nor is it necessary that it should have been. It must be recol- lected, that the contraction of the muscle is under the nervous influ- ence, and that, within certain limits, the force, to be employed, is regu- lated by the influx sent by it into the muscle. The great object in the formation of the body appears to have been—to unite symmetry and convenience with the attainment of great velocity and extent of motion, so that whilst the power is moving through a small space, the weight or resistance shall move rapidly through one more extensive. We have seen that, in these respects, the lever of the third kind is most fitting. With the others less power might be required ; but there would be less extent of motion and velocity, whilst the symmetry and convenience of the body would be destroyed. Suppose, for example, that in Fig. 179, the biceps—instead of being inserted at E, near the elbow—had passed on to the wrist,—:or, to simplify the matter, to the extremity of the member; it would assuredly have acted with more force—the lever having been changed into one of the second kind,—but the hand would have lost that velocity and extent of motion, which are so important to 428 MUSCULAR MOTION. Tendon of the Great Toe. with more force it; and the course of the mus- cle would have been so modi- fied as to convert the conve- nient and symmetrical mem- ber into a cumbrous, webbed instrument, badly adapted for the multitudinous purposes to which it has to be applied. The same effect results, as Sir Charles Bell1 has remark- ed, from the course of ten- dons and their confinement by sheaths, strengthened by liga- ments. If the tendon A, Fig. 181, took the shortest course to its termination at B, it but the toe would lose its would draw up the toe velocity of movement. To favour this velocity, we find that the majority of muscles are in- serted obliquely into Fig. 182. Gr_________JS__________H. A [iHii.viViiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiijiiiiiiiiiilllllliiiiiiiiiiiiiiiiffiiiiiMiiiiiifiii'l'R Action of Intercostal Muscles. their levers, and the fibres into the ten- dons. By this ar- rangement, as we have proved, consi- derable loss of power results; but in the majority of cases, the motion is effected by a less degree of decurtation than if the muscles were straight. Let A B and C D, Figs. 182 and 183, be parts of two ribs that are parallel, and continue parallel till brought into contact by the action of the straight muscle E F ; or by that of the oblique muscles F G and F H. Now it is obvious, that when the point E comes in contact Fis-183* with F, the length of the straight mus- cle E F must be null; whilst that of the oblique muscles will only have expe- rienced a decurta- tion equal to G g andH h, Fig. 182; and to F g and F h, Fig. 183. It is clear, also, that, in these cases, the straight muscles can never so con- Action of Intercostal Muscles. » Animal Mechanics, Library of Useful Knowledge, p. 27, Lond., 1829. APPLICATION OF MECHANICAL PRINCIPLES. 429 tract as to admit of a close approximation of the ribs; whilst the oblique muscles will admit of this to a much greater extent. We can, therefore, understand, why the intercostal muscles pass obliquely from one rib to another, as at D and B C, Fig. 184, instead of in a direction perpendicular to the two ribs as at A. There are cases, however, in which a straight muscle may pass between two parallel ribs, and carry them through a given space, with less decurtation of fibres, than any oblique muscle, which has the same origin; but is inserted at a greater distance from the centre of motion, Fig. 184. and acts through the medium of a longer lever. Moreover, a mus- cle, with a less degree of obliquity, may be so situate as to carry the bones through a given space, with a less decurtation of fibres than any other muscle having the same origin but a much greater de- gree of obliquity. Suppose A B and C D, Fig. 185, to be two parallel ribs, of which A B is movable about A as a centre ; and sup- pose it to be brought Fig. 185. F Gr Action of Intercostals. A C 8lllllll!i'|i|)llTlllllllllll)IIIUIIIII|[llllMlMlllllH[|[llllllllllll[IIIHIIMIMIIIIIIIIIIIIIIIIIllMlllllllllll1"l Action of Intercostals. by the action of the straight muscle E F, and of the oblique muscles E G and E H, into the position A/. The points of insertion of the mus- cles will now be at a, c, and e, after having traversed the spaces F a, G c, and II e. If we now, from the point E, as a centre, describe the arcs c b and e d; the spaces d H and b G will indicate the degree of decurtation, which the oblique muscles have experienced, and a F that of the straight mus- cle. This figure also shows, that when the muscles change the relative position of any two bones, they at the same time change the direction of their own action, and vary their lever. When the rib A B is brought into the position A /, the muscles E G and E H, by being brought down to c and e, have assumed the positions E c and E«; and have, con- sequently, changed their length, situation, obliquity, and leverage. Again, of the muscles, which are attached to ribs that are parallel, equally movable, and situate at right angles to the spine, those which pass perpendicularly from one rib to the other will act upon each with equal leverage; and each will approach the other with the same velo- city; whilst those that pass obliquely from one to the other, will make them approach with different velocities;—a principle which is strikingly applicable to the intercostal muscles. Let us suppose A B and C D, Fig. 186, to be two parallel ribs, articulated with the spine at A and C, and equally movable on these centres of motion. Let D B repre- 430 MUSCULAR MOTION. Or B iiiMiiiiiiiiiiiii/imtiinii Fig. 186. sent a straight mus- cle, passing directly from the one rib to the other; and D E an oblique muscle. The levers of D B, according to the mechanical princi- ples laid down, will be AB and CD,per- pendiculars drawn from the centres of motion to the line of direction of the power. These levers being pa- rallel are of course equal; but the levers of D E will be C F and A G, —also perpendiculars drawn from the centres of motion to the line of direction of the power. Fig. 187. il»'liiiiiiniiiiiiiiiiiiiiiiiiiiiiiiiiiiin|[iliii[iiiiMiiiiiiiiiiiiim»iiiiiiiiiiiiiiimiii03iiiii nnno Action of Intercostals. .n\ Action of Biceps. These levers are of dif- ferent lengths; and, ac- cordingly, the muscle must act with different degrees of force on the two ribs; so that it will cause C D, on which it acts with the longest lever, to approach A B faster than it makes the latter approach the for- mer,—in the ratio of C F to A C, or with three times the velocity. In all muscular mo- tions, the levers of the power and resistance are undergoing variations; so that the degree of power, necessary to be developed in one position of the member, may be much less than in another. The case of the biceps already referred to, elucidates this. Let E C, Fig. 187, represent the os humeri; E A the forearm; E the elbow-joint; W, a weight or resist- ance hung at the wrist, and D the biceps muscle, inserted at b, a tenth of the distance down the forearm. It is manifest, that the force, necessary for bending the arm, must be much greater when it is in the position A E than in that of E a. The lever of the resistance, in the former case, is the whole length of the forearm; or, in other words, the perpendicular drawn from the fulcrum to the line of direction of the weight W; but, when the arm is raised to a, the lever of the resistance is no-longer E A, but E H: but not only is the lever of the resistance shortened; that of the power is augmented. The lever of the biceps, when the forearm is horizontal, is the dotted perpendicular drawn from the fulcrum at the elbow to the line of direction of the muscle; but when the forearm is bent to the position E a, the disposition of the muscle is also modified. It assumes the position occupied by the dotted APPLICATION OF MECHANICAL PRINCIPLES. 431 Fig. 188. 33 line, which is farther distant from the fulcrum; and the lever of the power is consequently increased. In this case, then, of the action of the biceps, in proportion as we raise the arm, the mechanical disadvantages become less and less; the lever of the power increasing, whilst that of the resistance diminishes. In many of the changes of position of a body, whilst a bone is turn- ing upon its centre of motion, the centre itself is often describing a curve at the same time. In Fig. 188, let A B represent the foot, B C the tibia, C D the thigh-bone, and D E the trunk; and let us suppose it is required to bring the body to the erect position B F; so that B C shall cor- respond to B G, C D to G I, and D E to I F. The point C will describe the curve C G; and, whilst it is accomplishing this, the point D is likewise moving; so that the latter, in- stead of describing the curve D H, which it would do, were the centre of motion C fixed, proceeds along the curve D I: the point E, again, is subjected to the like influence; and instead of describing the curve.E K, which it would do if the centre D were fixed, rises along E F. The motions produced by the muscles may be either simple or compound. The simple muscles admit-of variety; some being straight, composed of parallel fasciculi; others reflected in their course, and others, again, are circu- lar. In the straight muscles, each fibre, by its contraction, draws the tendon in its own direction; and the effect of the whole is to bring it towards the centre of the muscle. whole contractile effort is concentrated on the tendon, in consequence of the course of the fibres being parallel to that of the tendon. In most of the broad muscles, on the other hand, as the attachments at both extremities are usually at different points, all the fibres do not concur in one effort. Different sets of fibres may have a very different action from others, and are capable of being thrown separately into con- traction. The ordinary direction in which a muscle acts is from its ten- dinous, back to its aponeurotic, attachment,—that is, from the movable to the more fixed part; and, in a straight muscle, this direction can be accurately appreciated. It must be borne in mind, however, that the muscle can act in an inverse direction also. When the whole of the fibres composing a broad muscle are brought to act on the tendon, as in the case of the deltoid, we find, by the com- position of forces, that the middle line of direction must be taken for the purpose of estimating their line of action. A part, however, may act and carry the arm upwards and outwards; whilst the opposite fibres may move it upwards and inwards. Where a muscle is reflected, like the superior oblique of the eye, ai.d Combined Muscular Movements in Rising. In a long muscle, the 432 MUSCULAR MOTION. the peronei muscles,—the line of motion will be from the insertion to the point of reflection; precisely as a rope passing over a pulley raises the weight in a line drawn from the weight to the pulley. The circular muscles, which have no precise origin or insertion, are inservient to the contraction of the apertures around which they are placed. In executing the complex movements of any part of the frame, a combination of the action of the different muscles attached to the part, generally occurs,—rendering the process one of a complicated charac- ter. This, if no other cause existed, would render it extremely difficult to calculate the precise degree of force, which particular muscles, alone or in combination, are capable of exerting. The mathematical physi- ologists made multifarious attempts in this direction; but their con- clusions were discrepant. When we bear in mind, that the force, capa- ble of being exerted by any muscle, is dependent upon the proper organization of the muscle, and likewise upon the degree of energy of the brain, it will be apparent, that all attempts of the kind must be futile. We can determine with nicety the effect of which the parts are capable, supposing them inanimate structures. We can calculate the disadvantages, caused by the insertion of the power near the fulcrum; by the obliquity of the line of action of the power, &c.; but we have not the slightest data for estimating the effect produced by the nervous influx,—by that mysterious process, which generates a new force, and infuses it into the muscles, in a manner so unlike that in which the ordinary mechanical powers are exerted. The data necessary for such a calculation would be the precise influx from the brain,—the irrita- bility of the muscle,—the mechanical influences, dependent on the straight or oblique direction of the fibres composing it, as regards the tendon,—the perpendicular or oblique direction in which the tendon is attached to the bone,—the particular variety of lever,—the length of the arm of the power and that of the resistance,—the loss sustained from friction, and the diminution of such loss caused by the cartilages that tip the bones, and by the synovia, &c.—data, which it is impossi- ble to attain; and hence the solution of the problem is impracticable. One great source of the combination of muscular motions is the necessity for rendering one of the attachments fixed, in order that the full force may be developed on the other. In but few of the muscles is the part, whence the muscle originates, steady. To these few, the muscles of the eye, which arise from the inner part of the orbit and pass forward to be inserted into the organ, belong. To show how dis- tant muscles may be concerned in this fixation of one end of a muscle, when it is excited to the developement of plenary power, we may take the case of the deltoid, which arises from the scapula and clavicle, and is inserted into the os humeri: but the scapula and clavicle, themselves, are not entirely fixed; and, accordingly, if the deltoid were to contract alone, it would draw down the scapula and clavicle, as well as elevate the humerus. If, therefore, it be important to produce the latter effect only, the scapula and clavicle must be fixed by appropriate muscles; as by the rhomboidei, trapezius, &c. These muscles, however, arise from various vertebrae of the neck, which are themselves movable. It PREPONDERANCE OF FLEXORS. 433 becomes necessary, therefore, that the neck should be fixed by its extensors, which arise from the lumbar and dorsal regions. By the united action of all these muscles, the deltoid is able to exert its full effect in elevating the humerus. But the deltoid, like other muscles, is capable of acting inversely; as in the case of a person lying on the ground, and attempting to raise himself by laying hold of any object above him. The hand and forearm are thus rendered firm, and the deltoid now contracts from origin to insertion, and, consequently, ele- vates the scapula and clavicle. Again, if a person, in the recumbent posture, endeavours to bend the head forwards, the recti muscles of the abdomen are firmly contracted for the purpose of fixing the sternum, whence the sterno-cleido-mastoidei muscles in part arise, which can then exert their full power in bending the neck forwards. These instances will be sufficient to exemplify the mode in which muscular motions are combined. The same principle prevails over the whole body; and where a greater number of parts has to be moved, the case must, necessarily, be more complex. When a part, movable in various directions, is drawn towards any point, it must be rendered steady, and be prevented from deviating, by the muscles on each side; and the extent of its motion may be partly regulated by the action of antagonist muscles. Supposing, for instance, that the head is inclined forwards, there must be muscles not only to move it in that direction, but also to prevent it from inclining to the right or left, and to limit the motion forwards; although doubt may arise, whether this be not entirely effected by the nervous influx sent by volition to the flexors of the head. Hence, some anatomists have considered, that there must, in these cases, be movers, directors, and moderators. In sleep, the muscles are perhaps in the most complete state of re- laxation ; and, accordingly, this condition has been invoked, as affording evidence of the comparative preponderance of particular antagonizing muscles,—flexors and extensors, for example. In perfect sleep, when no volition is exercised over the muscles, the body reposes in a state of semiflexion,—which seems to show, that the flexor muscles have slightly the advantage over the extensors. M. Richerand1 has assigned the fol- lowing reasons for this preponderance. First. The number of flexors is greater than that of extensors. Secondly. The fibres, composing them, are more numerous and longer:—take, for example, the sartorius, gra- cilis, semi-tendinosus, semi-membranosus, and biceps, which are flexors of the leg, and the rectus and triceps cruris, which are its extensors. Thirdly. Their insertion is nearer the resistance and farther from the centre of motion, which adds to their force. Fourthly. Their insertion into the bones is at a larger angle, and nearer the perpendicular; and Fifthly. Their arrangement is such, that the continuation of the move- ment of flexion renders them perpendicular to the bones to be moved. The explanation, afforded by M. Richerand, applies, on the whole, to the case he has selected; but there are many exceptions to it. The 1 Recueil des Memoires de la Societe Medicale de Paris, an vii. (1799), and Elemens de Physiologie, 13eme edit., par M. Berard, aine; edit. Beige, p. 253, § clx., Bnixelles, 1837. VOL. I.—28 434 MUSCULAR MOTION. extensors of the thigh, foot, and jaw, are decidedly predominant; and, according to M. Adelon,1 experiments, instituted by Regnier with his dynamometer, make the extensors some kilogrammes more powerful than the flexors. In our various attitudes, the movements of the flexors certainly prevail largely; but as the power of contraction is regulated by volition, it is unnecessary to inquire, whether there be any physical predominance in the flexors over the extensors, as has been attempted by M. Richerand. We have already seen, that we can in no way attain a knowledge of the degree of force, which any one muscle of the body is capable of developing. TABLE OF THE MUSCLES, ARRANGED AFTER THE MANNER OF DR. BARCLAY, ACCORDING TO THEIR ACTIONS. Forwards by Platysma myoides, Sterno-mastoideus, Rectus amicus major, " " minor, Assisted (when the lower jaw is fia;ed) by Mylo-hyoideus, Genio-hyoideus, Genio-hyo-glossus, Digastrici. Forwards by Platysma myoides, Sterno-mastoideus, Digastricus, Mylo-hyoideus, Genio-hyoideus, Genio-hyo-glossus, Omo-hyoidei, Sterno-hyoidei, Thyro-hyoidei, Rectus anticus minor, Longus colli. THE HEAD IS MOVED Backwards by Part of trapezius, Splenius capitis, Complexus, Trachelo-mastoideus, Rectus posticus major, " " minor, Obliquus capitis superior. THE NICK IS MOVED Backwards by Part of trapezius, Rhomboideus minor, Serratus posticus superior, Splenius capitis, " colli, Complexus, Trachelo-mastoideus, Transversalis colli, Inter-spinales colli, Semi-spinales colli, Rectus posticus major, " " minor, Obliquus capitis superior, " " inferior, Scaleni postici, Levator scapulae. To either side by Platysma myoides, Sterno-mastoideus, Part of trapezius, Splenius capitis, " colli, Trachelo-mastoideus, Complexus. Laterally by Various combinations of those muscles which separately move it forwards and backwards, assisted by the scaleni, inter-transversales, and recti laterales. Forwards by Rectus abdominis, Pyramidalis, Obliquus externus abdominis, Objiquus internus, Psoas magnus, " parvus, Assisted (when the arms are carried forwards) by Pectoralis major, " minor, Serratus magnus. THE TRUNK IS MOVED Backwards by Trapezius, Rhomboideus major, Latissimus dorsi, Serratus posticus superior, " " inferior, Sacro-lumbalis, Longissimus dorsi, Spinales dorsi, Semi-spinales dorsi, Multiiiaus spinee, Inter-transversales dorsi et 1 umbo rum. Laterally by Obliquus externus, " internus, Quadratus lumborum, Longissimus dorsi, Sacro-lumbalis, Serrati postici, Latissimus dorsi. 1 Physiologie de l'Homme, 2de <2dit., ii. 117, Paris, 1829 • and art. Dynamometre, in Diet des Sciences Medicales. TABLE OF MUSCLES. 435 THE SCAPULA 18 MOVED Upwards by Downwards by Forwards by Backwards by Trapezius, Lower part of trape- Pectoralis minor, Part of trapezius, Levator scapulee, zius, % Serratus magnus. Rhomboidei, Rhomboidei. Latissimus dorsi, Latissimus dorsi. Pectoralis minor. Forwards by Part of deltoid, Part of pectoralis ma- jor, Assisted in, some cir- cumstances by Biceps, Coraco-brachialis. THE HUMERUS IS MOVED Backwards by Part of deltoid, Teres major, " minor, Long head of triceps, Latissimus dorsi. Inwards by Part of pectoralis ma- jor, Latissimus dorsi. Rotated inwards by Subscapularis, Assisted occasionally Pectoralis major, Latissimus and teres major. Outwards by Supra-spinatus, Infra-spinatus, Teres minor. Forwards by Biceps, Brachialis anticus, Pronator teres, Assisted by Flexor carpi radialis, " sublimis, " ulnaris, Supinator longus. THE FOREARM IS MOVED Backwards by Rotated inwards by Triceps, Anconeus. Pronator teres, Flexor carpi radialis, Palmaris longus, Flexor sublimis, Pronator quadratus. Outwards by Biceps, Supinator brevis, Extensor secundi inter- nodii. Forwards by Flexor carpi radialis, Palmaris longus, Flexor sublimis, " carpi ulnaris, " profundus, " longus pollicis. Inwards and for- wards, across the palm, by Opponens pollicis, FleXor brevis, " longus. Forwards, or flexed, by Flexor sublimis, " profundus, Lumbricales, Interossei, Flexor brevis digiti minimi, Abductor digiti mini- mi. THE CARPUS Backwards by Extensor carpi radialis longior, Extensor carpi radialis brevior, Extensor secundi in- temodii, Indicator, Extensor communis digitorum, Extensor proprius pol- licis. IS MOVED Outwards by Flexor carpi radialis, Extensor carpi radialis longior, Extensor carpi radialis brevior, Extensor ossis meta- carpi, Extensor primi inter- nodii. THE THUMB IS MOVED Outwards and back- wards by Extensor ossis meta- carpi pollicis, Extensor primi inter- nodii, Extensor secundi in- ternodii. Upwards and for- wards, away from the other fingers, by Abductor, Assisted by part of the Flexor brevis. THE FINGERS ARE MOVED Backwards, or ex- tended, by Extensor communis, " minimi digiti, Indicator. Outwards, to radial border, by Abductor indicis, " digiti minimi, Interossei. Inwards by Flexor sublimis, " carpi ulnaris, " profundus, Extensor communis digitorum, Extensor minimi di- r,giti' Extensor carpi ulnaris. Backwards and in- wards, to the other fingers, by Adductor, Extensor primi inter- nodii, Extensor secundi in- ternodii. Inwards by Abductor digiti mini- mi, Interossei. , 436 MUSCULAR MOTION. THE THIGH IS MOVED Forwards by Psoas magnus, Iliacus, Tensor vaginas femo- ris, Pectineus, Adductor longus, " brevis. Backwards by Gluteus maximus, Part of gluteus me- dius, Pyriformis, Obturator internus, Part of adductor mag- nus, Long head of biceps, Semi-tendinosus, Semi-membranosus. Inwards by Psoas magnus, Iliacus, Pectineus, Gracilis, Adductor longus, " brevis, " magnus, Obturator externus, Quadratus femoris. Outwards by Tensor vagina? femo- ris, Gluteus maximus, " medius, " minimus, Pyriformis. THE THIGH IS ROTATED Inwards by Tensor vaginae femo- ris, Part of gluteus me- dius, And, when the leg is extended, by Sartorius, Semi-tendinosus. Outwards by Gluteus maximus, Part of gluteus medius, Pyriformis, Gemellus superior, Obturator internus, Gemellus inferior, Quadratus femoris, Obturator externus, Psoas magnus, Iliacus, Adductor longus, " brevis, " magnus, Biceps cruris, slightly. THE LEG IS MOVED Backwards, or flexed, by Extended by Forwards, or flexed, by Tibialis anficus, Extensor proprius pol- licis, Extensor longus digi- torum, Peroneus tertius. Semi-tendinosus, Biceps, Semi-membranosus, Gracilis, Sartorius, Popliteus. Rectus, Crureus, Vastus externus, " internus. THE FOOT IS MOVED Backwards, or extend- ed, by Gastrocnemius, Plantaris, Soleus, Flexor longus digi- torum, Flexor longus pollicis, Tibialis posticus, Peroneus longus, " brevis. Inclined inwards by Extensor proprius pol- licis, Flexor longus digi- torum, Flexor longus pollicis, Tibialis posticus. Outwards by Peroneus. longus, " brevis, Extensor longus digi- torum, Peroneus tertius. Backwards, or flexed, by Abductor pollicis, Flexor brevis digi- torum, Abductor minimi di- giti, Flexor longus pollicis, " digitorum, " accessorius, Lumbricales, Flexor brevis pollicis, Adductor pollicis, Flexor brevis minimi digiti, Interossei. THE TOES ARE MOVED Forwards, or extend- Inclined inwards by ed, by Extensor longus digi- Abductor pollicis, - torum, Interossei. Extensor proprius pol- licis, Extensor brevis digi- torum. Outwards by Adductor pollicis, " digiti minimi, Interossei.' 1 Quain's Human Anatomy, by Quain and Sharpey; Amer. edit, by Leidy, i. 466, Phila- delphia, 1849. ATTITUDES—STANDING. 437 ATTITUDES. The attitudes, which man is capable of assuming, are of different kinds. They may, however, be reduced to two classes—the active and the passive; the former including those that require a muscular effort; and the latter comprising only one variety,—that in which the body is extended horizontally on the soil, and no effort needed to maintain its position. We shall begin with the most ordinary attitude;—that of standing on both feet. This requires considerable muscular effort to preserve equilibrium. The base of sustentation—the space comprised between the feet plus that occupied by the feet themselves—is small; whilst the centre of gravity is high. The body, again, does not consist simply of one bone, but of many; all of which have to be kept steady by muscular effort; and it is necessary, that the vertical line shall fall within the base of sustentation, in order that equilibrium may be pre- served. That standing is the effect of the action of the different extensors is proved by the fact, that if an animal be killed suddenly, or stunned, so that volition is no longer exerted over the extensors, it immediately falls forward. The head, which is intimately united with the atlas or first vertebra of the neck, forms with it a lever of the first kind; the fulcrum being in the articulation of the lateral parts of the atlas and vertebra dentata; whilst the power and the resistance occupy the extremities of the lever; and are situate—the one at the face, the other at the occiput. The ful- crum being nearer the occiput than to the anterior part of the face, the head has a tendency to fall forwards. This can be readily seen by sup- porting a skull on the condyles; yet Mr. Abernethy1 affirms, that "the condyles are placed so exactly parallel in the centre of gravity, that when we sit upright, and go to sleep in that posture, the weight of the head has a tendency to preponderate equally in every direction, as we see in those who are dozing in a carriage''! In the living subject, the preponderance anteriorly is not so great as it is in the skeleton, because the greater part of the encephalon is lodged in the posterior portion; but the fact, that when we go to; sleep in the upright position the head drops forward is sufficient evidence that it exists; and that in the waking state the head is kept in equilibrium on the vertebral column by the contraction of the extensor muscles of the head, which are situate at the back part of the neck, and inserted into the head;—as the splenius, complexus, trapezius, and posterior recti. These muscles are inserted perpendicularly into the lever or bone to be moved,—an advantage, and some compensation for the shortness of the arm of the lever by which they act. In quadrupeds, the head not being in equilibrium on the spine these muscles are large and strong; the spinous and transverse processes of the vertebrae and the occipital depressions are larger; and, in addition, ' Physiological Lectures, exhibiting a general view of Mr. Hunter's Physiology, &c, Lect 3, 2d edit., p. 115, London, 1822. 438 MUSCULAR MOTION. they have a strong ligament—posterior cervical or ligamentum nuchse, (N, Fig. 189,)—which extends from the spinous processes of the ver- tebrae to the occiput, and aids in supporting the head. Fig. 189. Ligamentum Nuchse. The vertebral column supports the head, and transmits the weight to its lower extremity. The tendency of the column is to bear for- wards ;—the upper limbs, neck, thorax with its contents, the greater part of the contents of the abdomen, and the head itself, by reason of its tendency to fall forwards, either directly or indirectly exert their weight upon it. Hence the necessity for its great firmness and solidity, which are readily appreciated, if we examine the mode of junction of the different vertebrae, with the strong, ligamentous bands connecting them, the whole having the form of a pyramid, whose base rests upon the sacrum, with three curvatures in opposite directions, which give it more resistance than if it were straight, and enable it to support very heavy burdens in addition to the weight of the organs pressing upon it. (Fig. 5, p. 77.) The tendency of the spine to fall forward is resisted by the extensor muscles, which fill the vertebral fossae or gutters—sacro- lumbalis, longissimus dorsi, multifidus spinae, &c.—and pass from the sacrum to the lower vertebrae of the spine, and from the lower to the upper. Each vertebra, in this action, constitutes a lever of the first kind; the fulcrum of which is in the intervertebral cartilage; the power in the ribs, and other parts that draw the body forwards; and the resistance in the muscles attached to the spinous and transverse pro- cesses. The vertebral column, regarded as a whole, may be considered a lever of the third kind; the fulcrum of which is in the union between the last lumbar vertebra and , sacrum, the power in the parts drawing the Extremity of transverse process. 8. spine forward, and the resistance m the Superior articular processes. 9. In- r . » ,, -, i T, . ,i i„„„- ferior articular processes. mUSCleS 01 the back. It IS On tne lOWer Lateral View of a Dorsal Vertebra. ATTITUDES—STANDING. 439 part of the lever that the power acts most forcibly; and it is there that the pyramid is thicker, and that the spinous and transverse processes are larger, and more horizontal. We can accordingly comprehend why fatigue should be experienced in the loins and sacrum, when we have been, for a long time, in the erect attitude. It need scarcely be said, that the longer and more horizontal the spinous processes, the greater will be the arm of the lever; and the less the muscular force necessary to produce a given effect. The weight of the whole of the upper part of the body is transmitted to the pelvis; which, resting upon the thigh-bones as on pivots, repre- sents a lever of the first kind, the fulcrum being in the ilio-femoral articulations; the power and resistance situate before and behind. The pelvis Supports the weight of a part of the abdominal viscera; and the sacrum that of the vertebral column, which, by reason of its shape, transmits the weight equally to the ossa femorum, through the medium of the ossa ilii. When the pelvis is, therefore, in equilibrium on the heads of the thigh-bones, this is owing to many causes. The abdominal viscera, pressing upon the anterior part of the pelvis, which is naturally inclined for- wards, tend to depress the os pubis; whilst the vertebral column by its weight tends to press down the sacrum. As the weight of the latter is more considerable than that of the former, muscles would seem to be required to keep it in equilibrium, as well as Others passing from the femur Lateral View of a Lumbar Vertebra. to be inserted into the os pubis, by the 1. Body. 5. spinous process. 6. Trans- , ,• /. 1 • i ,1 /»__ ■ 1, verse process. 7. Superior articular pro- COntraCtlOn 01 Which the excess Ot Weight cesses. 8. Inferior articular processes. of the vertebral column may be counter- balanced. Such muscles do exist; but, as M. Magendie1 remarks, they are not the great agents in producing the equilibrium of the pelvis on the thigh-bones; for the pelvis, instead of having a tendency to be depressed posteriorly, would appear to bear forwards, inasmuch as the muscles, that resist the tendency which the spine itself has to bear forwards, have their fixed point on the pelvis; and consequently exert a consider- able effort to draw it upwards. The strong glutaei muscles, which form the nates, and are inserted into the os femoris, are the great agents of the equipoise; and as the hip-joint is nearer the pubis than it is to the sacrum, these muscles act with a greater leverage. The thigh-bones transmit the weight of the trunk to the tibia; and here we see the advantage of the neck of the thigh-bone, which, as represented in Fig. 192, B, joins the shaft at a considerable angle. The trochanters D and C are for muscular attachments; and are, of course, advantageous to the muscles, which are inserted into them. The cervix femoris directs the head of the bone, A, obliquely upwards and inwards, so that, whilst it supports the vertical pressure of the pelvis, it resists the separation of the ilia, which the pressure of the sacrum, with its superincumbent weight, has a tendency to produce. * Precis, &c, edit, cit., i. 296. 440 MUSCULAR MOTION. But another and important advantage is that of affording additional strength in adventitious cir- cumstances. When we are standing perfectly erect, the necks of the thigh-bones are very oblique, compared with the line of direction of the body; but if we are thrown forcibly to one side, the line of direction of gravitation corresponds more nearly with that of the neck of the thigh-bone, and frac- ture is rarely produced in this manner. The most common cause of fracture of the neck of the thigh- bone is slipping from a curbstone, or any slight elevation, with one foot, upon a firm substance beneath ; and the fracture in such case, is general- ly transverse. The advantage of this arrangement of the neck of the thigh-bone has been compared not inaptly to that resulting from the dishing of a wheel; or the-oblique position of the spokes from the nave outward to the felly, which strengthens the wheel against the strains produced by its sink- ^°Bone.01 ing with foi*ce into a rut or other hollow.1 The femur transmits the weight of the body to the large bone of the leg^—the tibia; but, from the mode in which the pel- vis presses upon it, its lower extremity has a tendency to bear forwards. This is prevented by the action of the extensors of the leg—rectus and triceps cruris—whose power is augmented by the presence of the patella —a sesamoid bone, seated behind their tendon. The muscles of the posterior part of the leg, which are attached to the condyles of the thigh-bone, aid also in preserving the equilibrium. The tibia is the sole agent for the transmission of the superincumbent weight to the foot. Its upper' extremity has, however, a tendency to bear forwards like the lower part of the os femoris. This is prevented by the contraction of the gastrocnemii, tibialis posticus, and other mus- cles on the posterijor part of the leg. The foot sustains the whole weight of the- body; and its shape and structure are well adapted for the purpose. The sole has some extent, which contributes to the firmness of the erect attitude. The skin and epidermis are thick ; and beneath the skin is a thick, adipous stratum, in greater quantity at the parts of the foot which come in contact with the soil. This fat forms a kind of elastic cushion, adapted for deaden- ing or diminishing the effect of pressure. The whole of the sole of the foot does not come in contact with the ground. The weight is trans- mitted by the heel, the outer margin, the part corresponding to the anterior extremity of the metatarsal bones, and the extremities or pulps of the toes. The tibia transmits the weight to the astragalus; and from this bone it is distributed to the others that compose the foot; but the heel conveys the largest share. When the foot rests upon a flat surface, it is entirely passive ; but when upon a slippery soil, the flexors of the toes, especially of the great toe, are firmly contracted, so * See Fig. 170; also, Sir C. Bell, Animal Mechanics, p. 21, Library of Useful Knowledge, Lond., 1829. Fig. 192. ATTITUDES—ON THE KNEES, ETC. 441 as to fix the shoe, as far as possible, and render the attitude more sta- ble. The use of shoes interferes largely with the exercise of the toes, which, in the savage, are capable of diversified and considerable action. The use of the fibula is, to serve the purpose of a clasp, as its name imports. The tibia exerts its pressure chiefly towards the inner part of the foot, and, consequently, were it not for the fibula, which passes down below the articulation, dislocation outwards would be constantly menacing us. The fibula has no participation in the transmission of the weight to the ground. The conditions for equilibrium, as applicable to man, have been already indicated. If the base of sustentation be rendered extensive in any one direction, as by widely separating the feet, the attitude is more firm in one direction, but less so in the other. It is as firm as possible in every direction, when the feet are turned forwards parallel to each other, and are separated by a space equal to the length of one. What- ever diminishes the base of sustentation, diminishes, in like proportion, the stability of the erect attitude. Hence the difficulty of walking on stilts or wooden legs, on the toes, tight rope, '&c. It seems that the inhabitants of Les Landes,1 in the south-west of France, are enabled by habit to use stilts with singular facility. The sandy plains, that bear this name, afford tolerable pasturage for sheep; but, during one part of the year, they are half covered with water; and during the remainder, they are very unfit walking ground, on account of the deep, loose sand, and thick furze. The natives, in consequence, habituate themselves to the use of stilts or wooden poles, the former of which are put on and off as regularly as parts of their dress. With these they walk readily over the loose sand or through the water, with steps eight or ten feet long. The difficulty, in this kind of progression, does not arise solely from the smallness of the base of sustentation, but from the greater height to which the centre of gravity is thrown, which renders the equilibrium unstable. Standing on one foot is necessarily more fatiguing, as it requires the strong and sustained contraction of the muscles that surround the hip- joint, to keep the pelvis in equilibrium on the os femoris; especially as the body has a strong tendency to fall to the side that is unsupported. The muscles, that prevent the trunk from falling in this direction, are the glutaei, gemelli, tensor vaginae femoris, pyramidalis, obturators, and quadratus femoris. The use of- the neck of the thigh-bone and the great trochanter is here manifest. The base of sustentation, in this case, is the space occupied by the foot which is in contact with the soil; and it need hardly be said, that if this be still farther diminished, by attempting to stand on the toes, the attitude cannot be sustained. In the attitude on the knees, the centre of gravity is brought lower, but the base of sustentation is smaller than on the feet. The patella has to bear the chief pressure; and as it is not provided with a fatty cushion such as exists at the sole of the foot, the position becomes pain- ful, and the surface soon abraded. These remarks apply to the case, in which the knees only come in contact with the soil. When the feet 1 Arnott, Elements of Physics, 3d Amer. edit., i. 15, Philad., 1835. 442 MUSCULAR MOTION. are allowed to touch also, by the points of the toes, the attitude is much more easy and firm, as the base of sustentation is largely augmented, and comprises the space between the knees and toes plus the space occupied by those parts. The sitting posture admits of variety, and its physiology is easily intelligible. In every form in which the back is unsupported, the weight of the body is conveyed to the soil by the pelvis; and the broader this base the firmer the attitude. When we sit upon a stool without any back, and with the legs raised from the ground, the whole of the weight is conveyed by the parts in contact with the seat; but if the feet touch the ground, the weight of the lower extremities is transmitted to the soil by the feet, whilst the pelvis transmits that of the upper part of the body. In both cases, if the attitude be long maintained, fatigue is felt in the back, owing to the continued action of the extensor muscles in keeping the body erect. Sitting in an ordinary chair differs some- what, in a part of the body being supported. Fatigue is felt in the neck, which is unsupported, and requires the sustained contraction of the extensor muscles of the head. To support all the parts, as far as possible, long-backed chairs have been introduced, which sustain the whole body and head; and, when they are provided with rockers, a position approaching to the easiest of all attitudes can be assumed. To produce a similar effect in a common chair, the body is often thrown back until the chair rests on its hinder legs only. When the feet of the individual are on the ground, this position is stable; the base of sustentation being large, and comprised between the legs of the chair and the feet of the individual, added to tha space occupied by the parts themselves, that are in contact with the soil; but as soon as he raises his feet, the equilibrium is destroyed from the impracticability of mak- ing the vertical line fall within the base of sustentation, which is now reduced to the space occupied by the legs of the chair plus the space between them. In all the varieties of the sitting posture, equilibrium is facilitated by the centre of gravity being brought nearer to the ground. Lastly. The horizontal posture is the only one that requires no mus- cular effort. Hence it is the attitude of repose, and of the sick and the feeble. The base of sustentation is here extremely large; and the centre of gravity very low. Accordingly, the attitude can be maintained for a long time; the only inconvenience being that which results to the skin from prolonged pressure on those parts that chiefly convey the weight to the bed,—as the back of the pelvis, the region of the great trochanter, &c.—an inconvenience, which attracts the attention of the physician, more or less, in all protracted and consuming maladies. The reason, why we prefer soft, elastic beds, is not simply to prevent abrasion of those parts of the body that are most exposed to pressure, but to enable a greater portion of the body to transmit the weight; and thus occasion a more equable partition of the pressure. There are numerous other attitudes, which maybe assumed; as, upon one knee, on the head, astride, &c.; but they do not need explanation,— their physiology being obvious after what has been said. MOVEMENTS. 443 MOVEMENTS. The movements, of which the body is susceptible, are of two kinds,— partial and locomotive; the former simply changing the relative situa- tion of parts of the body; the latter the relation of the whole body to the soil. Many of the partial movements constitute an inherent part of the different functions, and are considered under them. In the erect attitude, whilst the body holds the same correspondence with the soil, the position of the upper parts of the body may be greatly varied, provided the vertical line falls within the base of sustentation. Accordingly, to produce this effect, if the upper part of the body be inclined in one direction, the lower will have to be thrown more to the opposite. The head may be turned forwards, backwards, or to one side; and it is capable of a rotatory motion to the right and left. The three first movements, when slight, occur in the articulation of the occipital bone and atlas ; but if to a greater extent, the whole of the cervical vertebrae participate. The rotatory motion is effected essentially in the articu- lation between the first and second vertebrae; the latter of which has an arrangement admirably adapting it for this purpose. A toothlike or odontoid process arises from its anterior part, on which the poste- rior surface of the anterior part of the atlas or first vertebra turns as on a pivot. This arrangement has obtained the second vertebra the name vertebra dentata, and its function, that of axis. Rotation to the right is effected by the contraction of the left sterno-mastoid and splenius, and of the right complexus,—to the left by the action of the opposite muscles of the same name. The motions of the head aid the senses of sight, hearing, and smell; and are useful in the production of the different vocal tones, by occasioning elongation or decurtation of the trachea and vocal tube. They are, likewise, inservient to ex- pression. The spine, as a whole, and each of the vertebrae composing it, are capable of flexion, extension,, lateral inclination, and circumduction. These motions occur in the fibro-cartilages between the vertebrae; and they are more easy and extensive, in proportion to the thickness and width of the cartilages. This is one cause why the motions of the cervical and lumbar portions of the vertebral column are freer than those of the dorsal. The intervertebral substances or fibro-cartilages possess a remarkable degree of elasticity. They yield somewhat, however, to prolonged pressure; and hence, after long continuance in the erect attitude, our stature may be sensibly curtailed. We can thus understand, that at night we may be shorter than in. the morning. Buffon asserts, that the son of one of his most zealous collaborateurs, M. Gueneau de Montbeillard,—a young man of tall stature,—lost an inch and a half after having danced all night. The loss must be partly ascribed to the condensation of the adipous tissue beneath the foot. During the flexion of the spine, these cartilages are depressed on the side ofthe flexure, but they rise on the other; and, by their elasticity, are important agents in the restoration of the body to the erect posi- tion. Where they are thickest the greatest extent of motion is per- 444 MUSCULAR MOTION. mitted, and this is a cause why the spine admits of the greatest mo- tion anteriorly. In rotation, the whole is pressed upon and undergoes elongation in the direction of its constituent laminae. In old age, the cartilages become shrivelled; and this, with the loss of muscular power, is one of the causes why old people bend forwards. * When we assume different positions with the trunk, the centre of motion of the vertebrae becomes modified. If we bend forwards, it is thrown on the anterior part of the body of the vertebrae; if to one side, on the articulating processes, &c. Each vertebra, we have seen, is a lever of the first kind; and as the centre of motion becomes altered the leverage must be so likewise. It is when the body has been bent forwards, and the object is to restore it to the erect position, that the power acts with the greatest advantage,—the fulcrum being thrown to the anterior part of the body of the vertebra, and the arm of the power being the distance between this point and the extremity of the spinous process into which the power is inserted. Each vertebra has but a slight degree of motion;. but the sum of all their motions is considerable, and is estimated by multiplying the single motion by the number of vertebrae. The result, however, can only be regarded as approximate, as the extent of motion, of which the different vertebras are capable, necessarily varies. The arrangement of the spinous processes of the. vertebrae—especially of the dorsal— prevents any considerable flexion of the body backwards: and when we find the tumbler bending his body back until his head touches his heels, it is owing to- the arrangement of the spine having been modified in early life by constant efforts of the. kind, until there are no longer obstacles to the movement. The motions of the vertebrae are frequently united to those of the pelvis on the thigh-bones, so that they seem to be more extensive than they really are. This is the case when we make a low bow. The motions of the spine are inservient to those of the head, and of the superior and inferior extremities. The upper limbs are capable of various motions; some of which have been already described ; others will, be hereafter. They are useful in the different attitudes•; and, at times, by transmitting tq the soil a part of the weight of the body, and thus enlarging the base of sustentation, —as when we employ a stick, rest on the hands and knees, or support the head on one or both elbows. They are of great use, likewise, in preserving equilibrium when we walk on a very narrow base; serv- ing in part the purpose of the pole employed by the dancer on the tight-rope. The lower extremities are, of course, locomotive organs; but they are susceptible of partial movements likewise; as when we kick with one foot, try the consistence of the ground, cross the legs, tread the foot-board of a lathe, &c. Thus much for the attitudes. We shall now consider the mode in which the relation of the body to the soil is altered, comprising the physiology of walking, leaping, running, swimming, flying, &c, which constitute the different varieties of locomotion or progression. WALKING. 445 LOCOMOTIVE MOVEMENTS.' a. Walking. Walking is motion on a fixed surface, the centre of gravity being alternately moved by one of the extremities and sustained by the other, without the latter being, at any time, completely off the ground. It consists of a succession of steps, which are effected—in the erect atti- tude and on a horizontal surface—by bending one of the thighs upon the pelvis and the leg upon the thigh, so as to detach the foot from the ground by the general decurtation of the limb. The flexion of the limb is succeeded by its being carried forward; the heel is then brought to the ground, and, successively, the whole of the inferior surface of the foot. If the bones of the leg were perpendicular to the part which first touches the ground, we should experience a jolt; but, instead of that, Fig-193. the foot descends in an arc of a circle, the centre of which is the point of the heel. In order that the limb shall be thus carried forward, the pelvis must have described a movement of rotation on the head of the thigh-bone of the limb that has not been moved, and must have Carried forward the COr- Movement of the Foot in Walking. responding side of the body. As yet, only one limb has advanced. The base of sustentation has been modi- fied, but there has been no progression. The limb, remaining behind, has now to be raised and brought forward, so as to pass the other, or to be on the same line with it, as the case may be; and this finishes the step. In order to bring up the limb that is behind, the foot must be successively detached from the soil, from the heel to the toe. In this way, an elongation of the limb is produced, which assists in advancing the corresponding side of the trunk, and excites the rotation of the pelvis on the head of the thigh-bone first carried forward. A succes- sion of these movements constitutes walking; the essence of which con- sists in the heads of the thigh-bones forming fixed points, on which the pelvis turns alternately, as upon a pivot, describing arcs of circles, which are more extensive in proportion to the size of the steps. Walking in a straight line requires that the arcs of circles described by the pelvis, and the extension of the limbs when carried forward, shall be equal; otherwise, the body will be directed towards the side opposite to that of the limb whose movements are more extensive. Without the aid of vision, it would he impracticable for us to make the arcs equal, or to walk straight forward. Walking backwards differs somewhat from this. The step is coin- 1 On the whole subject of Animal Motion, Animal Dynamics, Locomotion, or Progressive Motion of Animals, see an elaborate article by J. Bishop, in Cyclopaedia of Anatomy and Physiology, Part xxiii. p. 407, London, April, 1842, and Prof. E. Weber, Art Muskelbewe- (ning, in Wagner's Handworterbuch der Physiologie, I5te Lieferung, s. 1, Braunschweig, 1846. 446 MUSCULAR MOTION. menced by bending the thigh upon the pelvis, and, at the same time, the leg upon the thigh. The extension of the thigh on the pelvis suc- ceeds, and the whole limb is carried backward; the leg is afterwards extended upon the thigh, the point of the foot is brought to the ground, and the remainder of its under surface in succession. The other foot is then raised on its point, by which the corresponding limb is elon- gated; the pelvis, being pushed backwards, makes a rotation on the limb which is Behind, and is, by the action of appropriate muscles, car- ried on a level with, or behind, the other, to afford a new pivot in ita turn. Walking laterally is different from the two last in no arcs being described. In this case, one of the thighs is first slightly bent upon the pelvis, in order to detach the foot from the ground; the whole limb is then moved away by the action of the. abductors, and is brought down to the ground* The other limb follows. If we walk up hill, the fatigue is much augmented; because the flexion of the limb, first carried forward, has to be more considerable; and the limb, that remains behind, has not only to cause the pelvis to execute the movement of rotation, but it has to raise the whole weight of the body, in order to transport it upon the limb which is in advance. To aid in throwing the weight forward, the body is bant forward, so that the centre of gravity may be as favourably disposed as possible; and the extensor muscles of the leg carried forward are powerfully con- tracted to raise the trunk; hence, the feeling of fatigue, which we expe- rience in the knee and anterior part of the thigh, on ascending a long flight of stairs. Fatigue is likewise felt in the calf of the leg, on ac- count of the strong efforts developed in extending the foot, and pro- jecting the body forward. Walking down hill is more fatiguing than on level ground. In this case, there is a tendency in the body to fall forward; great effort is, consequently, required to keep the vertical line within the base of sustentation; and, accordingly, the muscles, employed in the extension of the head and vertebral column, experience fatigue. In all these kinds of progression, the character of the soil is a mat- ter of importance. It must be firm enough to afford support to the limb that presses upon it, otherwise fatigue is experienced, and pro- gression slow and laborious. This occurs, whenever the soil is too soft or too smooth; the former yielding to th& foot, and the latter present- ing no inequalities to which the foot can attach itself. The soil, too, has some influence, in particular cases, by virtue of its elasticity. Such, at least, is the opinion of Borelli;1 but Ba^thez2 thinks, that the influ- ence of the soil is limited to the degree in which it furnishes a firm support. If the soil, again, be movable, as the deck of a vessel, the line of gravity is apt to fall outside the base of sustentation; and to avoid this, the base is enlarged by separating the legs so as to give a characteristic air to the gait of the mariner;—and, lastly, if the base be very narrow, as on the tight-rope, the steps are obliged to be rapid, and the arms are aided in modifying the centre of gravity as may be required, by the use of a long and heavy pole. 1 De Motu Animalium, &c, Lugd. Bat., 1710. a Nouveaux Elemens de la Science de l'Homme, Paris, 1806. LEAPING. 447 b. Leaping. In the action of leaping, the whole body is raised from the ground; and, for a short period, suspended in the air. It consists, essentially, in the sudden extension of the limbs, after they have undergone an unusual degree of flexion. Leaping may be effected directly upwards, forwards, backwards, or laterally. In the ordinary case of the vertical leap, the head is slightly bent on the neck; the vertebral column curved forwards; the pelvis bent upon the thigh; the thigh upon the leg; and the leg upon the foot; the heel generally pressing lightly on the soil, or not touching it at all. This state of general flexion is suddenly succeeded by a quick extension of all the bent joints; so'that the different parts of the body are rapidly elevated, with a force surpassing their own gravity, and to an extent dependent upon the force developed. In this general muscular move- ment, the muscles that form the calf of the leg, and are inserted into the heel, have to develope the greatest force, inasmuch as they have to raise the whole body, and to give it the impulse, which surmounts its gravity. They are, however, favourably circumstanced for the pur- pose;—being remarkably strong; inserted perpendicularly into the heel; and having the advantage of a long arm of a lever. Figure 188 will show, that whenever the body is bent in the position it assumes prelimi- nary to a leap, opposite impulses must be communicated by the restora- tion of the different parts to the vertical line B F. The leg B will tend to impel the body backwards, by following the curved line C G. CD, on the other hand, by describing the curve D I, will tend to impel it forward; whilst the head and trunk, represented by the line D E, will describe the curve E F, and give an impulse backward. Every vertical leap must, therefore, be a mean between these different impulses, or rather the backward and forward impulses must destroy or neutralize each other; and that which is concerned in the elevation of the trunk be alone effective. In the forward leap, the movement of rotation of the thigh predomi- nates over the impulses backward, and the body is projected forward. On the other hand, the impulses of the vertebral column, and of the leg on the foot, prevail in the backward leap. The length of the lower limbs is favourable to the extent of the leap. The forward leap, in particular, is greatly dependent upon the length of the femur, in which the forward impulse is situate. It does not appear, that any kind of impulse is communicated to the body, at the moment of leaping, by the surface on which we rest, unless it be very elastic. In this last case, however, its reaction is added to the effort of the muscles, that occasion the elevation of the body; hence, the wonderful leaps of the performers in circuses and on the tight-rope. On the other hand, if the soil does not afford the necessary resistance, and yields to the feet, leaping is almost or wholly impracticable. The upper extremities are not without their use in leaping. They are brought close to the body, whilst the joints are bent, and are sepa- rated from it at the moment when the body leaves the ground. By being held firmly in this manner, they allow the muscles, that pass from 448 MUSCULAR MOTION. the os humeri to the trunk, to exert a degree of traction upwards, and thus to assist the extensors of the feet in the projection of the body. It is with this view, that the ancients employed their dxr^pr$, or poisers in leaping; and that the moderns use bricks, stones, or other solid heavy bodies with a like intent. It is likewise manifest, that by steadying the arms, and then moving them rapidly backwards, a backward im- pulse may be given to the upper part of the trunk. The effect of a run before we leap is to add to the force developed by muscular contraction that of the impulse acquired by the body whilst running. The leap is, under such circumstances, necessarily more extensive. Some of the smaller animals surprise us by the extent of their leaps. The jumping maggot, found in cheese, erects itself upon its anus, forms its body into a circle, by bringing its head and tail into contact, and, having contracted every part as much as possible, unbends with a sud- den jerk, and darts forward to an astonishing distance. Small animals leap much farther than the larger in proportion to their size; and, as Mr. Sharon Turner has remarked,1 "exhibit muscular powers still more superior to those of the greatest animals than their comparative minds.'* He has given amusing representations of this difference: for example, Linnaeus observes,, that if an elephant were as strong in proportion as a stag beetle, he would be able to tear up rocks and level mountains. A cock-chafer is, for its size, six times as strong as a horse.2 The flea and locust leap two hundred times their own length, as if a man should leap three times as high as St. Paul's.3 The cuckoo-spit froghopper sometimes leaps two or three yards, which is more1 than two hundred and fifty times its own length, as if a man should vault at once a quarter of a mile.4 Mouffet5 relates, that an English mechanic made a golden chain as long as a finger, with a lock and key, which was dragged by a flea; and Latreille6 mentions a flea of moderate size dragging a silver cannon on wheels, that was twenty-four times its own weight. TEis cannon was charged with powder and fired, without the flea seeming to be alarmed. c. Running. This variety of progression consists of a series of low leaps per- formed by each leg in alternation. It differs from walking, in the body being projected forward at each step, and in the hind-foot being raised before the fore-foot touches the ground. It is more rapid than the quickest walk, because the acquired velocity is preserved and increased, at each bound, by a new velocity. Running, therefore, cannot be in- stantaneously suspended, although a stop may be put to walking at any moment. In running, the body is inclined forward, in order that the centre of gravity may be in a proper position for receiving an impulse in that ' Sacred History of the World, Amer. edit., p. 372, New York, 1832. 3 Kirby and Spence, Introduction to Entomology, Amer. edit., p. 486, Philad., 1846. 3 Nat. History of Insects, i. 17. 4 Insect Transformations, v. 6, p. 179 6 Theatr. Insect., 275. 6 Nouv. Diet. d'Histoire Natur., xxviii. 249, and Kirby, op. cit. SWIMMING. 449 direction from the hind-leg; and the fore-leg is rapidly advanced to keep the vertical line within the base of sustentation, and thus prevent the body from falling. There is, consequently, in running, a moment in which the body is suspended in the air. d. Swimming. Although M. Magendie1 affirms that the human body is, in general, specifically heavier than water; and that consequently, if left to itself in a considerable quantity of that fluid, it would sink to its lowest por- tion, the question respecting its specific gravity has not been rigorously determined; and many eminent practical philosophers have even held an opinion the reverse of that of Magendie. Borelli2 accords with him; and a writer of a later period, Mr. Robertson,3 who details a set of experiments on this subject, seems to have originally coincided with him also. He weighed, however, ten different individuals in water, comparing the weight with that of the fluid displaced by their bodies; and he affirms, that, with the exception of two, every man was lighter than his equal bulk of water, and much more so than his equal bulk of sea water;—"consequently," he says, "could persons, who fall into water, have presence of mind enough to avoid the fright usual on such accidents, many might be preserved from drowning." In corrobora- tion of this inference, Mr. Robertson relates a circumstance connected with his own personal knowledge. A young gentleman, thirteen years of age, little acquainted with swimming, fell overboard from a vessel in a stormy sea; but having had presence of mind enough to turn im- mediately upon his back, he remained a full half hour, quietly floating on the surface of the water, until a boat was lowered from the vessel. He had used the precaution to retain his breath whenever a wave broke over him, until he again emerged. A case is given in the Rev. Mr. Maude's Visit to Niagara, in 1803, which is corroborative of Mr. Robertson's view of this matter. The author was on board a sloop on Lake Champlain, when a boy, named Catlin, who was on deck cutting bread and cheese with a knife, was knocked overboard by the captain jibbing the boom. He missed catch- ing hold of the canoe, which was dragging astern, and an attempt of Mr. Maude's servant to. untie or cut the rope, which fastened it, that it might drift to his assistance, also failed. Catlin was known to be unable to swim. It was in the night and very dark, and it was with difficulty that the captain, who considered that there was no hope of saving his life, was at last prevailed upon to go in the canoe to attempt it. He succeeded, however, in picking, the boy up, and brought him on board again in about a quarter of an hour. "Catlin's relation," proceeds Mr. Maude, "almost exceeds probability. He had heard my exclamation to seize the canoe, which he was on the point of doing, when it gave a sudden swing and baffled him; but, finding he could support his head above water, he dismissed all fear, expecting that the canoe would come every moment to his assistance. When he no longer 1 Precis Elementaire, i. 333. l De Motu Animalium, c. 23, de Natat. Prop., 217. 8 Philos. Transact., vol. 1.; also, Dr. Dalton, in Manchester Memoirs, vol. x. VOL. I.—29 450 MUSCULAR MOTION. heard our cheers from the sloop, hope began to fail him, and he was on the point of resigning himself to a watery grave, when he heard the captain's life-restoring voice. On telling Catlin that we despaired of his safety, as we understood that he could not swim, he replied: 'Nor can I. I was never before out of my depth; but I am fond of bathing, and have often seen lads what they call tread the water; that's what I did.' The truth of this account was made manifest, by the boy not only retaining his hat on his head, but its being perfectly dry; and what adds to the singularity of this event, the boy never quitted his grasp of the knife that he was eating his bread and cheese with." Mr. Knight Spencer found, that he was buoyant on the surface of the sea, even when he held stones, weighing six pounds avoirdupois, in his hands. In the water, however, the stones lost two pounds five ounces in weight, so that he was really freighted with, no more than three pounds eleven ounces. . He himself weighed one hundred and thirty pounds.1 Dr. Franklin,2 whilst he considered the detached members of the body, and particularly the head, as of greater weight than their bulk of water, acknowledged the body in the aggregate to be of less specific gravity, by reason of the hollowness of the trunk. He thought, that a body immersed in water would sink up to the eyes, but that if the head were inclined back, so as to be supported by the water, the mouth and nostrils would remain above,—the body rising one inch at every inspiration, and sinking one inch at every expiration; and also, that clothes give additional weight in the water, although, in stepping out of it, the case is quite otherwise. He concluded, there- fore, that if a person could avoid struggling and plunging, he might remain in the posture described with safety. That the body is to a certain degree buoyant, he refers to the -experience of every one who has ever attempted to reach the bottom of deep water,—the effort re- quired sufficiently proving that something resists our sinking. The truth would appear to be, that there is only a slight difference between the specific gravity of the human body and that of water; the former being something greater, otherwise there would be no reason why the dead body should sink to the bottom, as it is known to do. It would seem, however, where the deposition of fat is excessive, the body may be of less specific gravity than water.3 The old notion was, that, in the living state, the specific gravity of the body is decidedly less; but that, in death from drowning, a quantity of water always enters the lungs and stomach, and thus these cavities being no longer occupied with air, buoyancy is lost and the body sinks. Nothing is now better established than that no water gets into the stomach, ex- cept what is accidentally swallowed during the struggling; and that no water must be looked for in the lungs; a quantity of frothy mucus being all that is generally perceptible there. Yet, in courts of justice, the absence of water in these situations has been looked upon as evi- dence, where a body has been found in the water, that death had not occurred from drowning; and attention has consequently been directed 1 Fleming's Philos. of Zoology, vol. i., Edinb., 1822. 3 Works, iii. 374, Philad., 1808 ; and Sparks's edit., vi. 289, Boston, 1838. 3 See vol. ii., under Adipous Exhalation. SWIMMING. 451 to other causes, which might have produced it; the presumption being, that the person had been first killed, and then thrown into the water for the purpose of averting suspicion. Another erroneous opinion, at one time prevalent, was, that if a person be thrown alive into water he will sink; if dead, he will swim; and, therefore, it is necessary, that some weight should be attached to a body, when committed to the deep, to make it sink. All these fallacious notions are dwelt upon in a case, full of interest to all jurists, medical and others;—that of Spencer Cowper, Esq., a member of the English bar, and afterwards one of the judges ofthe Court of Common Pleas; who, with three other individuals, was tried at Hertford Assizes, in 1699, for the murder of Mrs. Sarah Stout.1 The speeches of the counsel, with the evidence of1 many of the medical witnesses, sufficiently testify the low condition of medico-legal knowledge at that period.2 Mr. Jones—the counsel for the prosecution—affirmed, that "when her (Mrs. Stout's) body came to be viewed, it was very much wondered at; for, in the first place, it is contrary to nature, that any persons, that drown themselves, should float upon the water." "We have sufficient evidence," he adds, "that it is a thing that never was: if persons go alive into the water, then they sink; if dead, then they swim." In confirmation of this strange opinion, two seamen were ex- amined, one of whom deposed as follows:—" In the year '89 or '90, in Beeehy fight, I saw several thrown overboard during the engagement, but one particularly I took notice of, that was my friend and killed by my side. I saw him swim for a considerable distance from the ship, &c. Likewise in another engagement, where a man had both his legs shot off and died instantly, they threw over his legs; though they sunk, I saw his body float; likewise I have seen several men, who have died natural deaths at sea; they have, when they have been dead, had a con- siderable weight of ballast made fast to them and so were thrown over- board ; because we hold it for a general ruie that all men swim if they be dead before they come into the water, and, on the contrary, I have seen men when they have been drowned, that they have sunk as soon as the breath is out of their bodies," &c. The weights are, however, attached to the dead, when they are thrown into the sea, not for the purpose of facilitating their descent, but to prevent them from rising, when putrefaction renders them buoyant, by the disengagement of air in the splanchnic cavities. On the same trial, Drs. Coatsworth, Burnet, Nailor, and Woodhouse deposed, that when a person is drowned, water will be taken into the stomach and lungs; and as none was found in the case of Mrs. Stout, they were of opinion, that she came to her death by other means. From all that has been said, it would appear, that the great requisite for safety to the inexperienced who may fall accidentally into the water is a firm and sufficient conviction of the fact, that the living body natu- rally floats, or that it can be easily made to do so. This conviction being acquired, no more than a common share of presence of mind 1 Hargrave's State Trials, vol. v.; Beck's Medical Jurisprudence, 6th edit., ii. 205, Albany, 1838. ' Lives of the Lord Chancellors, by Lord Campbell, Amer. edit., iv. 240, Philad., 1848. 452 MUSCULAR MOTION. would seem to be necessary to insure, that the portion of the body, which is the great outlet of the respiratory organs, shall be above the surface. The movements, adapted to the progression of the body, are to be acquired in the same manner as a child learns to walk; proficiency in this, as in every thing else, being the result of practice. Swimming nearly resembles leaping, except that the effort in it does not take place from a fixed surface. Both the upper and lower extre- mities participate in it. Whilst the former are brought to a point anterior to the head, and form a kind of cut-water, the lower extremities are drawn up, and suddenly extended, as in leaping. The water, of course, yields to their impulse; but not as rapidly as it is struck, and hence the body is projected forwards. The upper limbs are now sepa- rated, and carried circularly and forcibly round to the sides of the body, by which the impulse is maintained; the legs are in the meantime drawn up; and, by a succession of these movements, progression is effected—the hands and feet being turned outwards to present as large a resisting surface as possible. The chest is, at the same time, kept dilated, to augment the bulk of the body, and, of course, to render it specifically lighter, and the head is raised above the surface to admit of respiration. This action is analogous to that of the propulsion of a boat by oars. The body resembles the boat; and the upper and lower extremities are the oars or sculls. The practised swimmer can execute almost as many movements in the water as he can on land. e. Flying. If the human body sinks in the water, how little can it be susceptible of suspension in the air by its own unassisted muscular powers! This is a mode of progression which is denied to man; and accordingly, most of the attempts at flying, since the mythical exploits of Daedalus and Icarus, have been confined to enabling the body to move from one place to another by.means of ropes arid appropriate adjuncts. Years ago, a native of this country exhibited a curious variety of progression, at Dover, England. He was called the "flying phenomenon;" and his plan, so far as we can recollect, was to have a rope extending from the heights to the beach beneath, along which he descended by means of rings attached to different parts of his person, which had the rope pass- ing through them. The sources of difficulty, in flying, are;—the great weight of the body, and the insufficient force which the muscles are capable of exert- ing. It is by no means impossible, however, that by some contrivance, of which the lightest gases might form a part, and by an imponderous apparatus, which would enlarge the surface of the upper extremities, progression, in this manner, might be effected;—but to a limited and unmanageable extent only. f. Other Varieties of Muscular Action. Connected with this subject we may refer briefly to some varieties of muscular action, the nature of which will be easily intelligible. OTHER VARIETIES OF MUSCULAR MOTION. 453 In bearing a load, we have simply a variety of walking in the erect attitude, with this addition, that the extensor muscles of the head, neck, or back,—according to the part on which the burden may be placed,—have to contract forcibly to support it. The position of the individual has, also, to be so regulated, that the centre of gravity shall always be over the base of sustentation. Hence, if the load be on a man's back, he leans forward; if borne before him, he leans backward; and this is the cause of the portly and consequential appearance of the corpulent. If the load be on his head he stands as upright as possible, for a like reason. hi propelling a body forwards, either by the hands or shoulders, the feet are firmly fixed on the ground; the limbs are in a state of semi- flexion, and the centre of gravity is directed forward, so as to aid the force that has to be developed by the muscles. The limbs are then suddenly extended; the body is thrown forward, and the whole power exerted on the obstacle which has to be moved. On the other hand, when we drag a weight after us, or attempt to dislodge a stake from the earth, the feet are equally fixed firmly on the ground, but the body is in a state of extension, and is directed as far as practicable backwards, in order that the tendency to fall, owing to the centre of gravity overhanging the base of sustentation, may aid the force that has to be developed by the flexor muscles of the arms, which are then powerfully contracted, and the whole force is exerted upon the object. As, in both these cases, there is danger of falling should the body yield suddenly, the feet are so placed as to obviate this, as far as possible, by being separated in the direction in which the force is exerted. Squeezing consists in laying hold of the object, either between the arms and body, or by the fingers; and then forcibly contracting the flexor muscles. In all these, and other varieties of strong muscular contraction, the respiration is interrupted, in order that the thorax may be rendered fixed, and serve as an immovable point of origin for the muscles of the head, shoulders, and arms. This is effected by taking in a full inspiration; strongly contracting the respiratory mus- cles, and, at the same time, closing the glottis to prevent the exit of the air. Lastly: as organs of prehension, the upper extremities are of admi- rable organization, possessing great mobility, and at the same time solidity. The joint at the shoulder allows of extensive motion; and the bones, to which the arm is attached at this joint—scapula and clavicle—are themselves movable. The forearm is likewise susceptible of various movements on the arm, of which those of pronation and supination are not the least important; whilst the hand possesses every requisite for an organ of prehension. It is composed of numerous bones, and is capable of being applied to the most irregular surfaces. The great superiority of the human hand arises from the size and strength of the thumb, which can be brought into a state of opposition to the fingers; and is, therefore, of the highest use in enabling us to seize hold of, and grasp spherical bodies; to take up any object; to lay firm hold of whatever we seize, and to execute the various useful, 454 MUSCULAR MOTION. and ornamental processes of the arts. These processes require the most accurate, quick, and combined movements of the muscles. How quick, for example, is the motion of the hand in writing, and in execut- ing the most rapid movements on the piano-forte! How accurate the muscular contraction, which stops the precise part of the violin-string to bring out the note or semi-tone in allegro movements; and what a multitude of combinations must be invoked in all these cases! As an organ of touch, the advantages of the upper extremity have already been depicted; and much of what was then said applies to it as an organ of prehension. " In this double respect," observes M. Adelon,1 "man is the best provided of animals. How much, in fact, does he stand in need of an ingenious instrument of prehension! As we have several times remarked, he has, in his organization, neither the offensive nor defensive arms, that are bestowed on other animals. Naked from birth, and exposed to the inclemencies of the atmosphere, without means of attack or defence against animals, he must inces- santly labour to procure what he requires. It was not, consequently, enough that he should possess an intellect, capable of making him ac- quainted with, and of appropriating to himself, the universe. He must have an instrument adapted for the execution of a.11 that his intellect conceives. Such instrument is his upper extremity. In short, whilst other animals find every thing in nature—necessary for their different wants—more or less prepared; man, alone, is obliged to labour to pro- cure what he requires. He must make himself clothes, construct his habitations, and prepare his food. He is the labouring and producing animal par excellence; and hence needs not only an intellect to con- ceive, but an instrument to execute," FUNCTION OF EXPRESSION OR LANGUAGE. Under this head will be included those varieties of muscular con- traction, by which man and animals exhibit the feelings that impress them, and communicate the knowledge of such feelings to each other. It comprises two different sets of actions:—those addressed to the ear— or phenomena of voice: and those appreciated by the senses of sight and touch—or gestures. Of these we shall treat.consecutively. a. Ofthe Voice. By the term voice—or phonation, a term proposed by Chaussier— is meant the sound produced in the larynx, whilst the air is passing through it, either to enter, or issue from, the trachea. 1. ANATOMY OP THE VOCAL APPARATUS. The apparatus, concerned in the production of voice, is composed, in man, of the muscles concerned in respiration ; the larynx ; the mouth and nasal fossae. The first are merely agents for propelling the air through the instrument of voice. They will fall under consideration under Respiration; whilst the anatomy of the mouth and nasal fossse has been, or will have to be, described in other places. The larynx, 1 Physiologie de l'Homme, ii. 201, 2de edit., Paris, 1839. VOICE—ANATOMY OF THE VOCAL APPARATUS. 455 Fig. 194. and its primary dependencies, which are immediately concerned in the production of voice, will alone engage us at present. The larynx is situate at the anterior part of the neck, and forms the projection so perceptible in that of the adult male,calledpomumAdami. An attentive examination of the various parts which compose it, so far as they concern its physiological relations, will be necessary. This will exhibit the imperfect knowledge of several writers on the voice, and the false and insufficient views that have been entertained on the subject. If we look along the larynx from the trachea of which it is a continuation, we find that the tube becomes gradually narrower from side to side; and, at length, presents an oblong cleft, called glottis, the sides of which are the essential oro-an of voice. The larynx is composed of four cartilages— the cricoid, thyroid, and two arytenoid. The cricoid is the lowest of these, and is the inferior part of the organ;—that by which it joins the trachea. It is shaped like a ring, whence its name, but is much deeper behind than before. The thyroid is situate above the cricoid, with Lateralv'ew ofthe Larynx. which it is articulated in a movable manner bv i,1'-?B,Mroides/ 2- Thyreo- /••,•«•• xi- i*7 hy°ld ligament. 3. Cornu means ot its interior cornua. In this way, the majus of thyroid cartilage. 4. lower front margin of the thyroid, which is com- mLunsg ^Vterai portion of monly separated by a short space from the upper of tach£niIage" 7' Rings margin of the cricoid, may be made to approach to or recede from it; as may be ascertained by placing the finger against the small depression felt externally, and observing its change of size when various tones are sounded. It will be observed, that the higher the tone the more the cartilages approximate, and that they separate in proportion to the depth of the tone. A ligament unites these cartilages—the crico-thyroid, which can be traced, although in a very thinned condition, over the whole of the periphery of the ventri- cle of the larynx, even as far as the pedicle of the epiglottis. This membrane is composed of the yellow elastic tissue—tissu jaune,—and, according to Dr. Leidy,1 it presents, under the microscope, a good example of that substance, which enabled him to detect its presence in the ventricles of the larynx. The thyroid is the large cartilage that occupies the anterior, promi- nent, and lateral part of the larynx. The arytenoid cartilages are two in number. They are much smaller than the others, and are articu- lated with the posterior part of the cricoid in a movable manner. Around this articulation is a synovial capsule. Before it is the thyro- arytenoid ligament; and, behind, a strong, ligamentous fascia, called, by M. Magendie,2 from its attachments—crico-arytenoid. Three fibro-car- 1 Amer. Journ.of the Medical Sciences, July, 1846, p. 142. * Precis Elementaire, i. 235. 456 MUSCULAR MOTION. tilages, likewise, enter into the constitution of the larynx. These are,— the epiglottis ; and two small bodies, that tip the arytenoid cartilages, and are met with only in man—capitula Santorini, supra-arytenoid cartilages or capitula cartilaginum arytenoidarum. Fig. 195. Fig. 196. . On examining the interior of the larynx, two clefts are seen—one above the other; the uppermost being usually oblong-shaped; ten or eleven lines long, and two or three broad; having the shape of a tri- angle, the apex forwards. It is circumscribed, anteriorly, by the thy- roid cartilage and epiglottis ; posteriorly, by the arytenoid cartilages; and, laterally, by two folds of mucous membrane, which pass from the epiglottis to-each arytenoid cartilage, and are called superior ligaments of the glottis and superior vocal cords. A few lines below this is a second cleft, also oblong from before to behind and of a triangular shape, the base of which is behind. It is bounded anteriorly by the thyroid cartilage; posteriorly, by a muscle extending from one aryte- noid cartilage to the other—the arytenoideus; and, laterally, by two folds, formed of the thyro-arytenoid ligament, passing from the ante- rior part of the arytenoid cartilage to the posterior part of the thy- VOICE—ANATOMY OF THE VOCAL APPARATUS. 457 Fig. 197. roid, and of a muscle of the same name. These folds are called infe- rior ligaments or lips of the glottis or inferior vocal cords. They are represented by T V, in Fig. 196, and B B, Fig. 197. Between these two clefts are the sinuses or ventricles of the larynx, V V, Fig. 197. The inferior, exterior, and superior sides of these are formed by the thyro-arytenoid muscles. By means of these ligaments—superior and inferior—the lips of the superior and inferior aperture are perfectly free, and unencumbered in their action.1 Anatomical descriptions will be found to give different significations to the word glottis. Some have applied it to the upper cleft; others to the lower; some to the ventricles of the larynx; and others to the whole space comprised between the inferior liga- ments and top of the larynx. It is now, gene- rally perhaps, restricted to the part of the larynx engaged in the production of voice, or usually considered to be so engaged,—that is, the space between the inferior ligaments plus the liga- ments themselves*-—and in this signification it will be employed here. The mucous membrane, which lines the larynx, is continuous above with that of the mouth; below, with that of the trachea. It contains several mucous follicles, some of which are ag- glomerated near the superior ligaments of the glottis and the environs of the ventricles of the larynx, seeming to constitute distinct organs, which have been called arytenoid glands. A similar group exists between the epiglottis be- hind, and the os hyoides and thyroid cartilage before, which has been termed the epiglottic gland. The uses of this body are not clear. M. Magendie2 conceives, that it favours the frequent slidings of the thyroid cartilage over the posterior surface of the os hyoides; keeps the epi- glottis separated above from thisjbone; and, at the same time, furnishes it a very elastic support, which may aid it in the functions it has to execute, connected with voice and deglutition. The larynx is capable of being moved as a whole, as well as in its component cartilages. It may be raised, depressed, or carried forwards or backwards. The movements, however, which are most concerned in the production of voice, are those effected by the action of the intrinsic muscles, as they have been termed. These are, 1st. The crico-thyroid, a thin, quadrilateral muscle, which arises from the anterior surface of the cricoid cartilage, and is inserted into the lower and inner border of the thyroid. M. Magendie3 affirms, that its use is not, as generally ima- gined, to depress the thyroid on the cricoid, but to elevate the cricoid, approximate it to the thyroid, and even make it pass slightly under its in- ferior margin. The effects of its contraction must be to render the vocal 1 Hilton, Guy's Hospital Reports, No. v. October, 1837, p. 519, and Leidy, American Journal ofthe Medical Sciences, p. 142, July, 1846. * Precis, &c, i. 237. » Ibid., i. 236. Scheme of the Lar ynx. 458 MUSCULAR MOTION. 198. ligaments tense. 2dly. Thecrico-arytenoideipostici, and crico-arytenoidei laterales; the former of which pass from the posterior surface of the cri- coid to the outer angle of the base of the arytenoid; and the latter from the upper border of the side of the cricoid to the outer angle of the base of the arytenoid. The use of the crico-arytenoidei postici is to carry the arytenoid cartilages backwards, separating them at the same time from each other, and thus opening the glottis; the action of the crico-arytenoidei laterales is like that of the arytenoidei to bring together the inner edges of the arytenoid cartilages, and close the glottis. 3dly. The arytenoidmuscle —of which there is only one. It extends across from one arytenoid cartilage to the other; and, by its contraction, brings them towards each other. 4thly. The thyro-arytenoid muscle, which, according to M. Magendie,1 is the most important to be known of all the muscles of the larynx, as its vibrations produce the vocal sound. It forms the lips of the glottis, and Magendie describes it as constituting, also, "the inferior, superior, and lateral parietes of the ventricles of the larynx." Generally, it is considered to arise from the posterior surface of the thyroid cartilage, and the ligament connecting it with the cricoid, and to be inserted into the anterior edge of the base of the ary- tenoid. By drawing the point of the thyroid back, it must relax the vocal ligaments. Lastly.—The muscles of the epiglottis—the thyro-epiglottideus, aryteno-epiglottideus supe- rior, aryteno-epiglottideus inferior (Hilton's muscle),2 and some fibres,that may be looked upon as vestiges of the glotto-epiglotticus, which exists in many animals. These mus- cles,—the position' of which is indicated by the name,—modify by their contraction, the situation of the epiglottis. The principal governors of the pitch of the voice, which is almost wholly regulated by the degree of tension of the vocal ligaments, are the crico-thyroid and thyro-arytenoid. 1, 3, 4. Medulla oblongata. 1. Corpus pyramidale of one side. 3. Corpus olivare. 4. Corpus resti- forrae. 2. Pons Varolii. 5. Facial nerve, 6. Origin of glosso-pharyngeal nerve. 7. Ganglion of Andersch. 8. Trunk of the nerve. 9. Spinal accessory nerve. 10. Ganglion of pneumogastric nerve. 11. Its plexiform ganglion. 12. Its trunk. 13. Its pharyngeal branch forming the pharyngeal plexus (14), assisted by a branch from the glosso-pharyngeal (8), and one from the superior laryngeal nerve (15). 16. Cardiac branches. 17. Recurrent laryngeal branch. 18. Anterior pulmonary branches. 19. Pos- terior pulmonary branches. 20. (Esophageal plexus. 21. Gastric branches. 22. Origin of spinal accessory nerve. 23. Its branches distributed to sterno-mastoid muscle. 24. Its branches to the trapezius muscle. Origin and Distribution of the Eighth Pair of Nerves. 1 Precis, &c, 236, and his Memoire sur l'Epiglotte. ' Wilson's Anatomist's Vade Mecum, Amer. edit., p. 483, Philad., 1843. VOICE—ANATOMY OF THE VOCAL APPARATUS. 459 The respective action of the different muscles has been given in a tabular form.1 Govern the Pitch of the Notes. "*> f Cricothyroidei ( Depress the front of the thyroid cartilage on the cricoid and stretch ■^ • Sterno-thvroidei i t,le voca' ligaments; assisted by the arytenoideus and crico- c j t arytenoidei postici. Thyroarytenoidei ( Elevate the front of the thyroid, and draw it towards the arytenoid, Thyro-hyoidei ( relaxing the vocal ligaments. Govern the Aperture of the Glottis. Crico-arytenoidei postici . . . Open the Glottis. | I Crico-arytenoidei laterales C Press together the inner edges of the ary- ■ 470 MUSCULAR MOTION. is first excited at the embouchure, which throws the column of air, within the instrument, into vibration. Every sound, indeed, produced at the orifice of a column of air, throws it into vibration, provided its dimensions be adapted to the length of the waves produced directly:— hence the utility of a musical pipe having parietes susceptible of vary- ing in size and tension, whatever may be the character of its embou- chure. Lastly.—The fundamental note of a tube closed at one end, whose diameter is every where the same, is an octave lower than the sound of the same tube, when open at both extremities. But this is not the case with tubes that are of unequal diameter, conical and pyra- midal, &c, when made to vibrate at their narrowest part. The tone' produced in such case increases in graveness, according to the difference between its narrow and expanded portions. These different physical conditions M. Savart invokes to account for the different tones of the human voice,—under the theory, that the vocal organ—composed of the larynx, pharynx, and mouth—forms a conical tube, in which the air is set in vibration by a movement similar to that which prevails in organ pipes. The trachea is terminated above by a cleft—the glottis—which is the inferior aperture of the vocal instru- ment. This cleft, which is capable of being rendered more or less nar- row, plays the same part as the lumiere des tuyaux a bouche or narrow space in the organ pipe, at the edge of the biseau or languette, along which the air passes. The air clears it, traverses the ventricles of the larynx or cavity of the instrument, and strikes the superior ligaments. These surround the upper aperture of the instrument, and fulfil the same function as the biseau of the organ pipe. The air, contained in the interior of the larynx, now vibrates, and sound is produced. This sound acquires intensity, from the waves that constitute it extending into the vocal tube above the larynx, and exciting in the column of air filling it, a movement similar to that occasioned in the tube of a flute; except, that the tone is susceptible of much variation, because the larynx, being a short tube, can give rise to various tones by simple modification in the velocity of the air sent through it: moreover, the vocal tube has the same power, its parietes being membranous, of a vibratory nature, and capable of different degrees of tension. The inferior or outer part of the vocal tube is equally constituted of elastic parietes, susceptible of varied tension; and the mouth, by modifying the dimensions of the column of air within the tube, exerts an influence on the number of vibrations, which the column is capable of experiencing; whilst the lips can convert the channel at pleasure into an open or closed conical tube. Certain sounds, M. Savart affirms, are produced alto- gether in the ventricles ofthe larynx, as those of pain, and the falsetto voice, for example. They can be elicited when the vocal tube has been removed; and there are animals, in which the vocal organ is reduced to the ventricles of the larynx,—frogs for example. Savart, consequently, considers, that the human vocal organ bears in its essential parts, C C, B B, Fig. 197, a striking analogy to the action of the bird-call; and, in this way, he explains the use of the superior ligaments C C, which are entirely overlooked in the different theories of the voice previously propounded. VOICE—TIMBRE. 471 We have given M. Savart's view at some length, in consequence of its ingenuity, and of its seeming to explain as well as any other theory the varied tones of which the human voice is susceptible. It cannot, however, be esteemed established, inasmuch as it is diametrically op- posed, in many of its points, to the observations and vivisections of distinguished physiologists; who, it has been seen, affirm, that voice is produced solely by the inferior ligaments; that all the parts above these may be destroyed, and yet voice continue; and that a wound in the ventricles, which permits the exit of air through the parietes of the larynx, does not destroy the function. Our notions on this point must not, therefore, be considered definite. Farther experiments are neces- sary; and, in all deductions from them, great importance will have to be attached to the vital action of the organs, especially of the intrinsic muscles, which are capable of modifying the situation of parts, and the character of the function in myriads of inappreciable ways. It may be added, that, more recently, Mr. J. Bishop,1 from his numerous investigations, has arrived at the conclusion, that the human voice results from the vibration of membranous ligaments, in obedience, first, to the laws of musical strings; secondly, to those of reed instru- ments; and thirdly to those of membranous pipes; and that the vocal organs combine in reality the actions of each of these instruments, and exhibit in conjunction the perfect type of every one of them. 3. Timbre or Quality of Voice. In the preliminary essay on sound, attached to the physiology of audition, it was remarked, that the cause of the different timbres of sound, in the various musical instruments, has. hitherto remained un- explained. The same remark is applicable to the timbre of the voice. Each individual has his own, by which he is distinguished from those around him; anxl it is the same with each sex and period of life. In this the larynx is, doubtless, concerned; but in what manner is not clear. The feminine timbre or stamp, that characterizes the voice of the child and the eunuch, would appear to be generally connected with the cartilaginous condition of the larynx; whilst the masculine voice, which is sometimes met with in the female, is connected with the osseous condition of the parts, and especially of the thyroid cartilage. An infinity of modifications may also be produced by changes in the thick- ness, elasticity, and size of the 'lips of the glottis. The vocal tube probably exerts great influence in this respect by its shape, as well as by the nature of the material composing it. Such conditions, at least, appear to modify the timbre of our wind instruments. The timbre of a flute, made of glass or brass, is very different from that of one formed of wood, although the instruments may resemble each other in every other respect. The form of the body of the instrument has, also, con- siderable effect. If it be conical, and wider towards its outlet, as in the clarionet,.or hautboy, the quality of the sound is shrill. If it be entirely cylindrical, as in the flute, we have the soft quality, which cha- 1 Proceedings of the Royal Society, No. 65, Lond., 1847. 472 MUSCULAR MOTION. racterizes that instrument; and on the other hand, if the tube be ex- panded at its middle portion, the quality of the sound is raucous and dull. It is probable, therefore, that Ave must reckon, amongst the ele- ments of the varying character of the timbre or stamp of the voice, the different conditions of the vocal tube, as to length, width, and form; and that we must likewise include the position and shape of the tongue, of the velum palati, mouth and nose, the presence or want of teeth, &c, all which modify the voice considerably. The first modification takes place, probably, in the ventricles of the larynx, in which the voice acquires more rotundity and expansion. It was remarked by Dr. Isaac Parrish,1 that a peculiar change was induced in two cases by the excision of the tonsils. The voice was rendered shrill and whistling. By the generality of physiologists, it is conceived, that the voice enters the different nasal fossae, and, by resounding in them, a timbre or character is given to it, which it would not otherwise possess. Ac- cording to this view, when it is prevented from passing through the nose, from any cause, it acquires the nasal twang; or, by a singular in- accuracy of language, we are said "to talk through the nose." M. Ma- gendie,2 however, considers, that whenever the voice passes through the nasal fossae, it becomes disagreeable and nasal. The simple experiment of holding the nose exhibits, that, in the enunciation of the true vocal sounds, unmodified by the action of the organs of articulation, the timbre or quality is materially altered; and we shall see, hereafter, that there are certain letters, that do not admit of enunciation, unless the nasal fossae be pervious—the m, the n, and ng, for example. It would seem that, under ordinary circumstances, the sound, after it is produced in the larynx, flows out by both channels; and that, if we either shut off the passage through the nose altogether, or attempt to pass it more than usually through the nasal fossae, the voice becomes nasal. The fine, sharp voice prior to puberty is especially owing to the narrowness of the glottis, the shortness of the ligaments, and, according to M. Mal- gaigne,3 the want of developement of the nasal cavities. At puberty, the size of the opening of the larynx is doubled; the ligaments enlarge, and the size of the passages of the nose is augmented. The timbre now becomes raucous, dull, and coarse; and for a time the harmony of the voice is lost. M. Bennati,4 himself an excellent theoretical and prac- tical musician, whose voice marks three octaves, advises, that the voice should not be much exerted during" this revolution. He has known perseverance in singing at this time in several instances completely destroy the voice. Not only does the voice, when produced in the larynx, pass out by the vocal tube, but it resounds along the tracheal and bronchial tubes, giving rise to the resonance or thrill, audible in certain parts of the chest, more especially, when the ear or the stethoscope is placed over them; and, when cavities exist in the lungs, in the consumptive, if the 1 Quarterly Summary of the Transactions of the College of Physicians of Philadelphia, Nov. and Dec, 1841, and Jan., 1842. 3 Precis Elementaire, i. 254. 3 Archives Generales de Medecine, pp. 201 and 214, Fevrier, 1831. 4 Recherches sur le Mecanisme de la Voix Humaine, Paris, 1832. VOICE—TIMBRE. 473 ear be placed upon the chest, immediately over one of them, the voice will appear to come directly up to the ear. The same thing happens, if the stethoscope be used. In this case, when the extremity of the instrument is applied over the vomica, the voice appears to pass directly through the tube to the ear, so as to give rise to what has been termed pectoriloquy. M. Adelon1 conceives, that this distribution of the sound along the trachea orporte-vent and the lungs may suggest that the condition of these organs has some effect on the quality of the voice. In speaking of the timbre of the voice in different individuals, we have had in view the natural quality,—-not that which is the result of imitative action, and which can be maintained for a time only. Many of the conditions, which have been described as regulating the timbre, are voluntary, especially that of the shape of the vocal tube. In this way we can modify the timbre and imitate voices different from our own. The table d'hdte of many of the hotels of continental Europe is enlivened by the presence of individuals, capable of not only imitating various kinds of birds, but the timbres of different musical instruments; and the success which attended th*e personation of the voices of public speakers, by Matthews, Yates, and others, is sufficient evidence of the fidelity of their representations. We see the difference between the natural and imitative voice strongly exemplified in one of the feathered songsters of our forests, turdus poly glottis or mocking-bird, which is capable of imitating, not only the voices of different birds, but sounds of other character, which cannot be regarded in the light of accomplishments. There is a singular variety of the imitative voice, now employed only for purposes of amusement—but, of old, perhaps, used in the Pagan temples, by the priests, to infuse confidence in the oracular dicta of the gods—which requires notice : this is engastrimism or ventriloquism. Both these terms, by their derivation, indicate the views at one time entertained of its physiology, namely, that the voice of the ventriloquist is made to resound in the abdomen, in some inexplicable manner, so as to give rise to the peculiarity it exhibits. This singular view seems to have been once embraced by M. Richerand.2 " At first," says he, " I had conjectured, that a great part of the air expelled by expiration did not pass out by the mouth and nostrils, but was swallowed and carried into the stomach; and, being reflected in some part of the digestive canal, gave rise to a real echo ; but, having afterwards more attentively observed thisk curious phenomenon on Mr. Fitzjames, who exhibits it in its greatest perfection, I was soon convinced that the name of ventrilo- quism is by no. means applicable." M. Richerand was probably the last remnant of the supporters of the ancient vague hypothesis; and his views soon underwent conversion. Another, equally unfounded notion, at one time entertained, was, that the ventriloquist possesses a double or triple larynx. It is now admitted, that the voice is produced at the ordinary place, and is modi- 1 Physiologie de l'Homme, edit, cit., ii. 204. 3 Elemens de Physiologie, edit. 13eme, par M. Berard aine, edit. Beige, cxciv. p. 300, Bruxelles, 1837. 474 MUSCULAR MOTION. fied in intensity and quality by actions of the larynx and vocal tube, so as to give rise to the deceptions we experience. It is known, that our appreciation of the distance and nature of a sonorous body is formed from the intensity and quality of the sound proceeding from it. We instinctively believe, that a loud sound proceeds from a near object, and a feeble sound from one more remote ; accordingly, if the intensity and quality of the sound from a known body be such as to impress us with the idea that it is more remote than it really is, we incur an acous- tic illusion. The ventriloquist takes advantage of this source of illu- sion ; and, by skilfully regulating the force and timbre of his voice, leads us irresistibly into error. Mr. Dugald Stewart1 gives some exam- ples of this kind of illusion. He mentions having seen a person, who, by counterfeiting the actions of a performer on the violin, whilst he imi- tated the music by his voice, riveted the eyes of the audience on the instrument, although every sound they heard proceeded from his own mouth. Mr. Savile Carey, who imitated the whistling of the wind through a narrow chink, told Mr. Stewart, that he had frequently practised the deception in the corner of a coffee-house, and that he sel- dom failed to see some of the company rise to examine the tightness of the windows; whilst others, more intent on the newspapers, contented themselves with putting on their hats, and buttoning their coats.2 It is to account for the mode in which this is effected, that different hypo- theses have been from time to time entertained. Haller, Nollet, Mayer,3 and others, believed, that the voice is formed during inspiration; but this does not seem to be the case. Voice can certainly be effected during inspiration; but it is raucous, unequal, and of trifling extent only. MM. Dumas and Lauth4 considered ventriloquism to be a kind of rumination of sounds ; the voice, formed in the larynx, being sent into the interior of the chest, attaining there a peculiar timbre, and issuing of a dull character. M. Richerand is of opinion, that the whole mechanism consists in a slow, gradual expiration, which is always preceded by a deep inspiration. By means of this, the ventriloquist introduces into his lungs a considerable quantity of air, the exit of which he carefully regulates; and a similar view is embraced by Prof. J. Miiller,5 who asserts that the sounds uttered by the ventriloquist can be perfectly elicited by a method, which, he is convinced, must be adopted by ven- triloquists. This method consists in inspiring deeply so as to protrude the abdominal viscera by the descent of the diaphragm, and then speak- ing, whilst expiration is performed very slowly through a narrow glottis by means of the lateral parietes of the thorax alone, the diaphragm maintaining its depressed position; and M. Colombat confirms the general accuracy of Professor Muller's view, remarking that by con- tinually practising in a manner somewhat similar to that pointed out by him he was enabled to attain considerable skill in the production of 1 Elements of the Philosophy of the Human Mind, 3d edit., Lond., 1808; Amer. edit., Brattleborough (Vermont), 1813. a Brewster, Natural Magic, Amer. edit., p. 158, New York, 1832. 3 Lepelletier, Physiologie Medicale, &c, iv. 213, Paris, 1833. * Memoir, de la Societe des Sciences Agricol. de Strasbourg, i. 427. * Elements of Physiology, by Baly, p. 1054, Lond., 1838. VOICE—TIMBRE. 475 this variety of voice.1 Mr. Gough2 attempts to explain the phenomenon upon the principle of echoes :—the ventriloquist, he conceives, selects a room, well disposed for echoes in various parts of it, and produces false voices, by directing his natural voice in a straight line towards such echoing parts, instead of in a straight line towards the audience, who are supposed, by Mr. Gough, to be placed designedly by the ventrilo- quist on one or both sides of him. A sufficient answer to this is, that the practised ventriloquist is careless about the room chosen for his exhibitions ; and habitually performs where this system of echoes would be totally impracticable. But it is well to inquire what the ventriloquists themselves say of the mechanism of their art. We pass over the explanation of Baron von Mengen, an Austrian colonel, who forms a kind of vocal organ between his tongue and his left cheek, if we understand his description correctly, and keeps a reservoir of air in his throat to throw the organ into vibra- tion. His object must evidently have been to mislead. In 1811, M. L'Espagnol, a young physician, maintained a thesis on this subject before the Faculte de Medecine of Paris, which may be regarded as at least an honest exposition of his belief regarding the mode in which the phenomenon was effected in his own person. Ac- cording to him, the whole is dependent upon the action of the velum pendulum palati. In ordinary voice, he remarks, a part of the sound passes directly through the mouth, whilst another part resounds in the nasal fossae. If we are near the person who is speaking, these two sounds strike equally and almost synchronously upon the ear; but if at a distance, we hear only the first of the two sounds; when the voice appears more feeble, and, especially, has another timbre, which experi- ence makes us judge to be that of the voice at a distance. The differ- ence, says M. L'Espagnol, between the voice that proceeds from a near, and that from a more distant object is, that in the former we hear the mixture of the two sounds; whilst in the latter we hear that sound only, which issues directly from the mouth. Now, the secret of the ventriloquist is, to permit this direct sound only to pass to the ear, and prevent the nasal sound from being produced, or at least from being heard; and this is done by the elevation of the velum pendulum palati: the vocal sound does not then resound in the nasal fossae; the direct sound is alone produced; the voice has the feebleness and timbre that belong to the distant voice, and is judged to proceed from a distance; and if, during the performance, it seems to come from any determinate place, it is owing to the ventriloquist attracting attention to it: the voice itself need only appear to proceed from a distance; and this it does more or less, according as the pendulous veil has more or less com- pletely prevented the sound from issuing by the nasal fossae. The ventriloquist thus, according to M. L'Espagnol, makes the voice appear nearer or more remote at pleasure, by raising or depressing the velum palati. He denies, that he speaks with his mouth closed; and affirms, that he articulates, but to a trifling extent only. ' Baly and Kirkes, Recent Advances in the Physiology of Motion, the Senses, Generation, and Developement, p. 11, Lond., 1848. 2 Manchester Memoirs, 2d edit., v. 622, Lond., 1789. 476 MUSCULAR MOTION. M. Comte, another ventriloquist, and of some celebrity, who has endeavoured to explain the physiology of his art, affirms, that voice takes place as usual in the larynx; but is modified by the action of other parts of the apparatus; that inspiration directs it into the thorax, where it resounds; and that both strength and flexibility are required in the organ to produce this effect. This, however, is no explanation. It is now universally admitted, that the voice of the ventriloquist is produced in the larynx; and that its character and intensity are modi- fied by the action of other parts of the apparatus, but the particular agency that produces it is not elucidated by any of these attempted explanations of the ventriloquist. About forty years ago (1810), Dr. John Mason Good,1 in some lec- tures delivered before the Surrey Institution of London, suggested that the larynx alone, by long and dexterous practice, and, perhaps, by a peculiar modification in some of its muscles or cartilages, may be capa- ble of answering the purpose, and of supplying the place of the asso- ciate organs of the mouth. In confirmation of this view, he remarks, that, in singing, the glottis is the only organ made use of, except where the notes are articulated; and it is apparently the sole organ employed in the mock articulations of the parrot and other imitative birds; some of which have exhibited unusual powers. A parrot belonging to a Colo- nel O'Kelly, could, it is said, repeat twenty of the most popular English songs, and sing them to their proper tunes. The larynx, too, is the sole organ of all the natural cries; and hence, it has been imagined by Lord Monboddo2 to have been the chief organ of articulate language, in its rudest and most barbarous state. " As all natural cries," he observes, " even though modulated by music, are from the throat and larynx, or-knot of the throat, with little or no operation of the organs of the mouth, it is natural to suppose, that the first languages were, for the greater part, spoken from the throat; and that what consonants were used to vary the cries, were mostly guttural; and that the organs of the mouth would at first be but very little employed." Certain it is, that privation of the tongue does not necessarily induce incapacity of articulation; whether the defect be congenital, or caused after speech has been acquired. Professor John Thomson of Edinburgh found the speech but little impaired after bullets had carried away more or less of the tongue.3 Under the Sense of Taste, several authentic cases were stated of individuals, who were deprived of this organ, and yet possess- ed the faculty of speech. To these we may add one other, which ex- cited unusual interest at the time, and was examined under circumstances that could admit of no deception. The case forms the subject of various papers, by Dr. Parsons, in the Philosophical Transactions of London.4 A young woman, of the name of Margaret Cutting, of Wickham Market, near Ipswich, in Suffolk, when only four years old, lost the whole of her 1 Book of Nature, ii. p. 238, Lond., 1834; see also his Study of Medicine, Physiological Proem to Class ii., Amer. edit., i. 296, Philad., 1824. 3 Origin and Progress of Language, i. 322, Edinb., 1773. 3 Report of Observations made in trie British Hospital, in Belgium, after the Battle of Waterloo, Edinb., 1816. « Philosoph. Transact, for 1742 and 1747. VOICE—VENTRILOQUISM. 477 tongue, together with the uvula, from a cancerous affection; she still, however, retained the power of speech, taste, and deglutition without any imperfection; articulating as fluently and correctly as other persons; and even those syllables that commonly require the aid of the tip of the tongue for accurate enunciation. She also sang admirably; articulat- ing her words whilst singing; and could form no conception of the use of a tongue in other people. Her teeth were few; and rose scarcely higher than the surface of the gums, owing to the injury to the sockets from the disease that had destroyed the tongue. The case, when first laid before the Royal Society, was attested by the minister of the parish, by a medical practitioner of repute, and by another respectable indivi- dual. The Society, however, were not satisfied, and appointed commis- sioners to inquire into the case, whose report coincided minutely with the first; and, to set the matter completely at rest, the young woman was shortly afterwards conveyed to London, and examined, in person, before the Royal Society.1 These cases are not so extraordinary as they appear at first sight; when we consider, that the tongue is not the sole organ of articulation, but that it shares the function with the various parts that compose the vocal tube. In reality, of the twenty-four articulate sounds, wThich our common alphabet comprises, there are few in which the tongue takes a distinct lead, as I, d, t, r, &c, though it is auxiliary to several others* but the guttural or palatine, g, h, k, q; the nasal, m, and n; the labial, b, p, f, v; and most of the dental, together with all the vowels, are little indebted to its assistance. From these, and other concurrent facts, Dr. Good2 concludes, that ventriloquism appears to be an imitative art, founded on a close atten- tion to the almost infinite variety of tones, articulations, and inflexions, which the glottis is capable of producing in its own region alone, when long and dexterously practised upon; and in a skilful modification of these vocal sounds, thus limited to the glottis, into mimic speech, passed for the most part, and whenever necessary, through the cavity of the nostrils, instead of through the mouth. It is possible, he adds, though no opportunity has hitherto occurred of proving the fact by dissection, that they who learn this art with facility, and carry it to perfection, possess some peculiarity in the structure of the glottis, and particularly in respect to its muscles or cartilages. MM. Magendie3 and Rullier,4 however, affirm, that the quiescence of the lips, observed in the practised ventriloquist when enunciating, is more apparent than real; and that if he be capable of pronouncing without moving his lips, it is because he is careful to make use of words in which there are no labial consonants, or which do not absolutely require the movement of the lips in their for- mation. M. Rullier, indeed, denies positively, that the ventriloquist can speak without opening his mouth and moving his lips; but he affirms, that he uses his jaws, mouth, and lips, as little as possible in articula- tion; and he ascribes the common belief in their perfect quiescence to 1 Elliotson's Human Physiology, p. 507, Lond., 1840. See a curious chapter on the L^se of Tongues in Southey, The Doctor, vii. L Lond., 1847. " Op. citat. 3 Precis, &c, i. 265. 4 Art. Engastrimysme, in Diet, de Medecine, torn, viii., Paris, 1823. 478 MUSCULAR MOTION. the habit, acquired by him, of restraining their movements, united to the care he takes in concealing them; and of giving to his face an im- passive expression, or one foreign to the verbal expression to which he is giving utterance. On the whole, the explanation of Dr. Good appears the most satisfac- tory:—the larynx or glottis affords some individuals'a facility in acquir- ing the art, which others do not possess, in the same manner as it makes some capable of singing, whilst others, are forever incapacitated. It is probable, however, that there may be a greater degree of obscure action about the parts composing the vocal tube than Dr. Good is disposed to admit; and that this may be materially concerned in giving the voice its peculiar quality and intensity; and eliciting some of the sounds which might not be so easily produced by the action of the glottis alone. Sir David Brewster1 observes, that when the ventriloquist utters sounds from the larynx without moving the muscles of his face, he gives them strength by a powerful action of the abdominal muscles; and Bennati affirms, that the ventriloquist uses chiefly the pharyngeal voice, of which mention will be made under the head of Singing. Such is the history of the simple voice, as effected in the larynx. Articulate sounds may, however, be produced in the vocal tube alone. ^Whistling, for example, is caused by the expired air being broken or divided by the lips, which act the part of the lips of the larynx in the production of voice. Whispering consists in articulating the air of expiration. It is wholly accomplished in the vocal tube; and, hence, the impracticability of sing- ing in a whisper; singing being produced in the glottis. The sound of sighing is produced by the rushing of air along the air passages, and especially along the vocal tube. In laughing, crying, and yawning, voice is concerned; but the physiology of these functions of expression will fall more appropriately under Respiration. Having described the different views, that have been entertained, with regard to the production of voice, we shall now inquire into the function in connexion with expression. In this respect, it admits of division into the natural or inarticulate voice, and the artificial or articulate. 3. NATURAL OR INARTICULATE LANGUAGE. This, which is sometimes termed the cry or native voice, is an inap- preciable sound, entirely produced in the larynx, and requiring few or none of the organs of articulation to aid in its formation. As, how- ever, it is caused by different degrees of contraction of the intrinsic muscles of the larynx, it is susceptible of a thousand different tones. It is elicited independently of all experience or education; seems to be inseparably allied to organization; and, consequently, occurs in the new-born infant, the idiot, the deaf from birth, and the wild man, if any such there be, as well as in the civilized individual. The natural voice differs as much as the sentiments it is employed to express. Each * Letters on Natural Magic, p. 169, Amer. edit., New York, 1832. VOICE—INARTICULATE LANGUAGE. 479 moral affection has its appropriate cry;—the cry of joy is very distinct from that of grief;—of surprise from that of fear, &c; and the patho- logist finds, in the diseases of children more especially, that he can occasionally judge of the seat of a disease by the character of the cry, to which the little sufferer gives utterance; that there is, in the language of M. Broussais, a cry peculiar to the suffering organ. By the cry, our vivid sensations are expressed, whether they be of the external or internal kind; agreeable or painful; and by it we exhibit all our natural passions, and most simple instinctive desires. Generally, the most intense sounds, to which the organ of voice can give utter- ance, are embraced in the natural cry; and, in its character, there is frequently something, that annoys the ear and produces more or less effect on those within hearing. It is, by its agency, that sympathetic relations are established between man and his fellows; and between animals of the same kind. The' language, possessed by the greater part of animals, is this natural voice differing according to varying organization, and, therefore, instinctive; hence the various notes of birds; and the ranges, which we find the voice to possess in different species. Yet each species has one, by which it is distinguished and which it possesses, even when brought up in the same cage with one of another species; or when hatched, and attended to, by a foster mother endowed with very different vocal powers. In the case of a goldfinch and chaffinch, this has been put directly to the proof; and it is well known, that the cuckoo, which is never hatched or nurtured by its own parent, still retains the note, that has acquired it its name in almost every language of the globe. It is, probably, by this natural cry, and not by any signs addressed to the eye, that the process of pairing is effected, and that the female is induced to select her mate. The voca- bulary of the common cock and hen is quoted as perhaps the most extensive of that of any tribe of birds with which we are acquainted; or rather, as Dr. Good remarks,1 we are better acquainted with the extent of its range than with that of any other. The cock has his watchword for announcing the morning; his love-speech and terms of defiance. The voice of the hen, when leaving her nest, after laying, is different from that which she assumes when the brood is hatched, and both are very different from her cries, when her young are placed in jeopardy. Even the chick exhibits a variety in its voice, according to the precise emotion it experiences. All these sounds are such as the larynx of the animal alone admits of; and hence we can understand why, so far, they should be mere modifications of the natural voice; but it is more than probable, that the chick learns the adoption of a particular sound by the parent to express a particular emotion, as an affair of education. It can scarcely be conceived, that the clucking of the hen, when she meets with food proper for her offspring, can be understood at first by the chick. But as soon as it, traces the connexion between the sound produced and the object of such sound, it comprehends the signification ever afterwards. There are sounds, which, from their discordant and harsh characters, • Book of Nature, ii. 277, Lond., 1826. 480 MUSCULAR MOTION. affect most animals perhaps independently of all experience. The cry of terror or pain appears to occasion sympathetically disagreeable effects on all that are within its sphere. 4. ARTIFICIAL OR ARTICULATE LANGUAGE. Speech, likewise, is a vocal sound; but it is articulated, in its passage through the vocal tube; and is always employed to convey ideas, that have been attached to it by the mind. It is a succession of articulate sounds, duly regulated by volition, and having determinate significations connected with them. The faculty of speech has been assigned by some philosophers chiefly to the organ of hearing. It is manifest, however, that this, like the musical ear, is referable to a higher organ. The brain must attach an idea to the impression made upon it by the sounds that impinge upon the organ of hearing; the sound thus becomes the sign of such idea, and is reproduced in the larynx at the will of the individual. Of the intellectual character of the process, we have -decisive evidence. The infant of tender age has the ear and voice well developed, yet it is long before it is capable of speech; this does not happen until it discovers the meaning of the sounds addressed to it, and finds its own larynx capable of producing similar sounds, which can be made subservient to its wishes. It is thus, by imitation, that it acquires the faculty of speech. Again, the idiot, notwithstanding his hearing may be acute, and voice strong, is incapable of speech; and, in the maniacal and delirious, the language participates in the derangement and irregularity of ideas. The brain must, therefore, be regarded as the organ of the faculty of language; and the ear, larynx, and vocal tube as its instruments. Man, who is endowed with the most commanding intellect, has the vocal appa- ratus happily organized for expressing its various combinations; and, according to Gall, if the ourang-outang and other animals are incapable of speech, it is because they have not the intellectual faculty of lan- guage. In proof, that it is not to the vocal organ that this deficiency must be ascribed, he remarks, that animals may be made to enunciate several of the words of human speech, and to repeat them with music. The case of the far-famed parrot of Colonel O'Kelly has already been referred to. Mr. Herbert1 saw this parrot, about the year 1799: it then sang perfectly about fifty different tunes, solemn psalms, and humorous or low ballads; articulating every word as distinctly as man, without a single mistake; beating time with its foot; turning round upon its perch, and marking the time as it turned. If a person sang part of a song it would take it up where he left off; and when moulting and unwilling to sing, turned its back and said, "Poll's sick." Gall, amongst other cases, cites that of a dog mentioned by Leibnitz, which could articulate some German and French words. This dog, of which Leibnitz was an "eye-witness," was at Zeitz, in Misnia. A young child had heard it utter some sounds, which it thought resembled German, and this led him to teach it to speak. At the end of about eight years, it had learned thirty words, some of which were, tea, coffee, chocolate, and assembly. 1 In a note to the Rev. Gilbert White's Natural History of Selborne, p. 227. VOICE—ARTICULATE LANGUAGE. 481 It spoke only after its master had pronounced the word, and appeared to do so only on compulsion, although it was not ill used.1 In the "Dumfries Journal," Scotland, for January, 1829, mention is made of a dog, then living in that city, which could utter distinctly the word "William," the name of the young man to whom it was much attached.2 There is no doubt, however, that in numerous animals speech would be impracticable, owing to defective organization, even were they gifted with adequate intellect. It is difficult—perhaps impossible—to say, how man came to select certain sounds as the types of certain intellectual acts ; nor is it a mat- ter which strictly concerns the physiologist. It may be remarked, however, that whilst some contend, that speech is a science which was determined upon, and inculcated, at' an early period of the world, by one or more superior persons acting in concert, and inducing those around them to adopt their articulate and arbitrary sounds; others affirm, that it has grown, progressively out of the natural language, as the increasing knowledge and wants of mankind demanded a more extensive vocabulary.3 The first view is that of Pythagoras and Plato; but it was opposed by Lucretius and the Epicureans, on the ground, that it must have been impossible for any one person or synod of per- sons to invent the most difficult and abstruse of all human sciences with the paucity of ideas, and of means of communicating them, which they must have possessed; and that even allowing they could have invented such a science, it must still have been utterly impossible for them to teach it to the barbarians around them. The opinions of those philosophers who confine themselves to the phenomena of nature, and hold themselves uncontrolled by other au- thority, accord with those of the Epicureans. In the origin of language, it is probable, that words were suggested to mankind by sounds heard around;—by the cries of quadrupeds;—notes of the birds of the forest;—noises emitted by the insect tribe;—audible indications from the elements, &c. These, being various, probably first of all suggested discriminative names, deduced from the sounds heard. It is this imitation of the noise made by objects, that consti- tutes the figure of speech called onomatopoeia,—the "vox repercussa naturae" or "echo of nature," as Wachter4 has defined it. Daily ex- perience shows us, that this source of words is strictly physiological. Children designate a sonorous oBject by an imitation of the sounds rendered by it; and the greater number of sonorous bodies have had names, radically similar, given to them in languages differing most from each other. We say the serpents "hiss;" the bees " hum;" the storm "blusters;" the wind "whistles;" the hogs "grunt;" the hen "cackles;" the man "snores," &c, words used, originally, not perhaps in these very shapes, but varying according to the varying idiom of language, to imitate the sounds elicited by those objects. Such words 1 Letter to the Abbe Saint Pierre, Oper. ii. 180. 3 Sharon Turner's Sacred History of the World, p. 280, Amer. edit.. New York, 1832. 3 Harris's Hermes, 3d edit., Boole iii. p. 3l4,London, 1771; Beattie's Theory of Language, p. 246, London, 1803, and Good's Book of Nature, ii. 254, London, 1834. * Glossarium Germanicum, Lips., 1737. VOL. I.—31 482 MUSCULAR MOTION. are numerous in all languages, and have been adopted to depict both the sound emitted, and the sonorous body itself; but, in some cases, the word imitating the sound has survived its transmission from lan- guage to language to the most modern times, whilst the name of the object whence it proceeded has experienced considerable mutation. The Sanskrit, the antiquity of which will not be contested, has a num- ber of such words—as wilala, cat—kukada, hen—and waihu, wind; in the last of which the sound of the w (oo), imitates that of the pas- sage of the air, and is found in the word corresponding to wind, (ooind,) in many languages. The Hebrew and the Greek have numerous pho- netic words; but no language is richer, in this respect, than the Teu- tonic in all its ramifications, including the English. The animal kingdom, affords us many examples, of which the following is one:— Cuckoo.—This word is nearly the same in almost all languages. Greek, xoxxv%; Latin, cucullus;. Irish, cuach; Bask, cucua; Sclavonic, kukulka, kukuscka, &c; Hungarian, kukuk; Hebrew, cacatha ; Syriac, coco ; Arabic, cuchem ; Persian, kuku; Koriak, kaikuk ; Kamtscha- dale, koakutschith; Kurile, kakkok; Tartar, kauk; German, kuckucks or guckguck; Dutch, koekoek; whence our words cuckoo and cuckold, and the Scottish gouckoo, gowk, or golk; French, cocu; &c. In the greater part of languages, words, expressive of the cries of animals, are accurate imitations. Of this, the following are a few examples. leafing of sheep.—Greek, (Sxn^ao^ai; Latin, balare; Italian, belare; Spanish, balar; French beler ; German, bloken ; Dutch, bleeten; Saxon, bicefan, &c. Holding of wolves.—Greek, o/\oXufa>; Latin, ululare; German,, heulen; Dutch, huilen; Spanish, aullar ; French, hurler, &c. Hence the word oibl. Neighing of the horse.—Latin, hmnire ; French, hennir; German, wiehern; Saxon, hnsegan, &c. * . , Clocking or clucking of hens.—Latin, glocire; French, ghusser; Greek, xaxxa^w; German, glucken; Dutch, klokken ; Saxon, clo&an, &c. To crow, like a cock.—Greek, xfa^ai; German, krahen; Dutch, kraayen; Saxon, craw, &c, whence the word crow, the bird. The Latin words tinnimentum, tinnitus, tintinnabulum, &c, from tinnio, " I ring," are all from the radical tin, and imitate the sound ren- dered on striking a metallic vessel. The gurgling of water; the clang- ing of arms; the crash of falling ruins ; are of the same character; and the game trictrac, formerly tictac, seems to have been so called from the noise made in putting down the men or dice. In whatever manner language was first formed, it is manifest that the different sounds could make but transient impression, until they were reduced to legible characters, which could recal them to mind. On our continent, the fact has often been noticed of a tribe of Indians separat- ing themselves into two parties, and remaining distinct for years. In such case, the language has become so modified, that after the lapse of a considerable period they have scarcely been able to comprehend each other. Hence, the importance of the art of writing,—certainly the most valuable of human inventions. Of this, there have been two kinds, —imitative or alphabetical,—and symbolical, allegorical, or emblemati- cal, the latter consisting of hieroglyphics, designs representing external objects, or symbolical allegories. The former, or the written represen- tation of spoken sounds, alone concerns us. To attain this, every com- VOICE—ARTICULATE LANGUAGE. 483 pound sound has been reduced to certain elementary sounds, which are represented by signs, called letters. These elementary sounds, by com- bination, form syllables ; and the syllables, by combination, words. The number of elementary sounds, admitted in each language, constitutes its alphabet, which differs more or less in certain languages ; but 'as it is entirely a matter of human invention, and as the elementary sounds, of which the human voice is capable, are alike in the different races of mankind, we see readily, that the alphabets of the different languages must correspond, although the combinations of letters constituting syl- lables and words may vary essentially. Into the origin of written legible language, it is not necessary to inquire. We may remark, that the invention has been considered so signally wonderful as to transcend human powers ; and hence, St. Cyril, Clement of Alexandria, Eusebius, Isidore, and, in more modern times, Messrs. Bryant, Costard, &c.,' have been of opinion, that the knowledge of letters was first communicated to Moses by the Almighty himself, and that the decalogue was the earliest specimen of alphabetic writing. Many passages in the writings of Moses, show unequivocally, however, that written records must have existed prior to his time. In the passage in which writing is first mentioned in the sacred volume, the art is alluded to a,s one of standing:—" And the Lord said unto Moses, i Write this for a memorial in a book or table ;' " and in a sub- sequent chapter—"And thou shalt make a plate of pure gold, and grave upon, like the engravings of a signet, Holiness to the Lord."1 The English alphabet is considered to consist of twenty-six letters. It may, however, by ultimate analysis, be reduced to twenty-five sim- ple sounds—A, B, D, E, F, G, H, I, J, K, L, M, N, 0, P, R, S, T, U, V, Z, Ch, Sh, Th, and Ng. To these letters arbitrary names have been assigned, as Bee (B,) See (C,) Dee (D,) &c, which express very different sounds from those that belong to the letter when it forms part of a word or syllable. The word bad is not pronounced bee-a-dee, as the child, just escaped from learning his alphabet, must imagine ; hence, he has to unlearn all that he has acquired ; or to imagine, that different letters have very different sounds, according to the situation in which they are placed. To obviate this inconvenience, some persons are in the habit of teaching their children syllabically from the very first, by which they acquire the true sound attached to each letter of the alpha- bet. In the preceding enumeration of the simple sounds, that consti- tute the alphabet, C, Q, W, X, and Y, have been excluded, for the fol- lowing reasons. C has always the sound of either S or K, as in cistern or consonant. Q has the sound of koo, as in quart, (kooart;) W of oo, as in word (oourd;) X of ks, or Z, as in vex, (vecks,) or Xerxes, (zerk- ses;) whilst Y has the sound of I or E, as in wry or yard, {tori or eeard.) Ch, Sh, and Th, have been added, as being true alphabetic or simple sounds. Letters have been usually divided into two classes, vowels and conso- nants. The vowels or vocal sounds are so called, because they appear to be simple modifications of the voice formed in the larynx, uninter- ' Good, op. citat., ii. 273. 484 MUSCULAR MOTION. rupted by the tongue and lips, and passing entirely through the mouth. Such at least is the case with those that are reckoned pure vowels. These, in the English alphabet, are five in number,—A, E, I, 0, and U. W and Y are, likewise, vowel sounds in all situations. In enunciating A, as in fate, the tongue is drawn backwards and slightly upwards, so as to contract the passage immediately above the larynx. In sounding E, the tongue and lips are in their most natural position without exer- tion. I is formed by bringing the tongue nearly into contact with the bony palate ; 0, by the contraction of the mouth being greatest imme- diately under the uvula, the lips being also somewhat contracted. In the production of U, the contraction is prolonged beneath the whole of the soft palate. From these principal vowels, all the other vowel sounds of the language may be formed, by considering them as partak- ing more or less of the nature of each. They are, in our language, fourteen in number: besides compound sounds, as in oil and pound. Of these fourteen, four belong to A ; two to E ; two to I; three to 0; and three to U. fFate. . . J Far. A> as m ' * * i Fast. [Fall. „ . 5 Me. E, as in - - - *j Met_ C Pine. I, as in - - - ^Pin. O^as in U, as in The vowels are more easy of pronunciation than the consonants. They merely require the mouth to be opened ; and howsoever it may be arranged in the enunciation of the different vowels, the vocal tube is simply modified, to vary the impression, which has to be made on the organ of hearing. The shape of the cavity is altered; but the passage of the air continues free, and the voice, consequently, issues in an unrestrained manner. Hence, perhaps, the physiological origin of the Danish word Aa, " a river"—a generic term, which became after- wards applied to three rivers in the Low Countries, three in Switzer- land, and five in Westphalia,—the sound of the two broad A's flowing without obstacle, like a river. Time passes away in a similar manner; hence, for a like reason, the Greek ati which signifies "always, per- petually ;" and the German je, which has the same signification. The consonants are more difficult of enunciation than the vowels; as they require different, and sometimes complex, and delicate movements of the vocal tube; and, on this account, they are not acquired so early by children. The term consonant is derived from one of its uses,—that of binding together vowels, and being sounded with them. By most, and according to Mr. Walker,1 by the best grammarians, w and y are con- sonants when they begin a word; and vowels when they end one. Dr. Lowth,2 however, a man of learning and judgment, who certainly would not suffer in a comparison with any of his opponents, regards them, as the author does, to be always vowels. Physiologically, it is not easy to look upon them in any other light. Yet Mr. Walker exclaims:—" How 1 Preface to his Dictionary. 3 Introduction to English "Grammar, p. 3. VOICE—ARTICULATE LANGUAGE. 485 so accurate a grammarian as Dr. Lowth could pronounce so definitely on the nature of y, and insist on its being always a vowel, can only be accounted for by considering the small attention which is generally paid to this part of grammar." No stronger argument, however, could be used against the useless expenditure of time on this subject, than the conclusion to which Mr. Walker himself has arrived-; and for which he can find no stronger reasons, than that "if w and y have every pro- perty of a vowel, and not one of a consonant; why, when they begin a word, do they not admit of the euphonic article an before them?"! The consonants are usually divided into mutes, 'semi-vowels, and liquids. Mutes are such as emit no sound without a vowel,—b, p, t, d, k, and c and g hard. Semi-vowels are such as emit a sound, without the concurrence of a vowel, as/, v, s, z, x, g soft or j. Liquids are such as flow into, or unite easily with, mutes, as I, m, n, r. These letters issue without much obstacle; hence perhaps their name. In tracing the modes in which the different consonants are articulated, we find, that certain of them are produced by an analogous action of the vocal tube; so that the physiology of one will suffice for the other. For instance, the following nearly correspond:— .p f t s k ch &'&&&&& b v d z g j B and P are produced when the lips, previously closed, are suddenly opened. B differs from P in the absence, in the latter, of an accom- panying vocal sound. F and V are formed by pressing the upper incisor teeth upon the lower lip. They are, consequently, not well enunciated by the aged, who have lost their teeth. F differs from V only in the absence of an accompanying vocal sound. T and D are formed by pressing the tip of the tongue against the gums behind the upper incisor teeth. D is accompanied by a* vocal sound; T not. S and Z are'produced by bringing the point of the tongue nearly in con- tact with the upper teeth, and forcing the air against the edges of the teeth with violence. S differs from Z in the absence of the vocal sound. K and G are formed by pressing the middle of the tongue against the roof of the mouth, near the throat; separating the parts a little more rapidly to form the former, and more gently to form the latter of those letters. In K, the accompanying vocal sound is absent. Ch and J are formed by pressing t to sh; and d to zh. In Ch, there is no ac- companying vocal sound. SH and ZH are formed in the same part of the tube as s and z. TH is formed by protruding the tongue between the incisor teeth, and pressing it against the upper incisors to produce its sound in think. Its sound in that is effected by pressing the tongue behind the upper incisor teeth. In the former case, it is unaccompanied by a vocal sound. In M, the lips are closed, as in B and P; and the voice issues by the nose. N is formed by resting the tongue against the gums, as in the enunciation of t and d; breathing through the nose with the mouth open. In L, tl>e tip of the tongue is pressed against the palate, the sound escaping laterally. In forming the letter K, the middle and point of the tongue strike the palate with a vibratory mo- tion; the tip being drawn back. Lastly, in the formation of H, the 486 MUSCULAR MOTION. breath is forced through the mouth, which is every where a little con- tracted. It need hardly be said, that the enunciation of these letters requires, that the vocal tube, or the parts concerned in the function, shall be in a sound condition.1 A few years ago, (1846,) an ingenious German, named Faber, ex- hibited publicly in Philadelphia a speaking automaton, in the construc- tion of which he found that the alphabet can be simplified still further.- The precise mechanism he did not unfold; but affirmed that the parts were made of elastic materials to resemble as nearly as possible the human vocal organs. These parts were susceptible of varied move- ments by means of keys. The author was mueh struck by the distinct- ness with which the automaton could enunciate various letters and words. The combination three was well pronounced; the th less perfectly; but astonishingly well. It also enunciated, diphthongs and numerous diffi- cult combinations of sounds. Sixteen keys were sufficient to produce all the sounds. It sang " God save the Queen" and "Hail Columbia"— the words and air combined. The following is the alphabet of the automaton. 1. Five simple vowels: for example—a as in father; o as in home; u as in ruin; i as e and e as a. 2. Nine consonants, I, r, w (the German w—the English w is oo), /, s, sh in shall, and b, d, g hard, as in give. 3. A nasal sound and an aspirate; making in all sixteen simple sounds. From these the compound sounds are formed, as in the following examples: b and the nasal form m; d and the nasal, n: if the nasal sound be pre- vented, me becomes be; not becomes dot; g and the nasal form ng; b and the aspirate formp; d and the aspirate, t; g and the aspirate, k; sh and the nasal, th; wf or uf form v; d and sh,j and g soft; t and sh, ch in chin. The diphthongs admitted by Mr. Faber are ai i, eu u; and au sounded as in how. Wolfgang von Kempelen,2 in a work on the mechanism of human speech, which is considered classical in Germany,—and in which he treats of a speaking automaton (Sprachmaschine) of his inven- tion,—divides the consonants into four classes. 1. Mutes, (ganz s t u m m e,) as K, P, T. 2. Explosives, (W i n d m i 11 a u t e r,) as F, H, Ch, S, and Sh. 3. Vocal consonants, (Stimmitlauter,)asB, D, G, L, M, and N; and 4. Vocal Explosives, (Wind und Stimm- lauter zugleich,) as R, I, W, V, Z. Dr. Thomas Young has, likewise, divided the English consonants into classes; of which he enu- merates five. 1. Pure semi-vowels, as L, R, V, Z, and J. 2. Nasal semi-vowels, as M and N. 3. Explosive letters, as B, D, and G. 4. Susurrant letters, as H, F, X, arid S; and 5. Mutes, as P, T, K; but the most satisfactory classification, in a physiological, as well as philo- logical point of view, is according to th| parts of the vocal tube more immediately concerned in their articulation. 1 See Mayo, Outlines of Human Physiology, 3d edit., p. 357, Lond., 1833; also, Haller, Element. Physiol., lib. ix. § 4, Lausan. 1766. 3 Mechanismus der Menschlichen Sprache, s. 228, Wien, 1791; and Rudolphi, Grundriss der Physiologie, 2ter Band, lste Abtheil. s. 398, Berlin, 1823. VOICE—ARTICULATE LANGUAGE. 487 Labial. Dento-labial. Linguo-dental. Linguo-palatal. Guttural. B M P F V Th D J L N R S T Z Ch Sh Ng G K That this physiological arrangement has had much to do with the formation of congenerous tongues more especially is exhibited by facts connected with the permutation or change of letters;—when a word passes, for example, from one of the Teutonic or Romanic lan- guages to another. "The changes of vowels," says Mr. Lhuyd,1 "whether by chance or affectation, are so very easy and so common in all languages, that in etymological observations, they need not, indeed, be much regarded; the consonants being the sinews of words, and their alterations therefore the most perceptible. The changes of consonants also into others of the same class, (especially labials, palatals, and Un- guals,) are such obvious mistakes, that there is no nation where the common people in one part or other of their country do not fall into some of them." A few.examples will show to what extent this permu- tation occurs between letters of the same class in different languages. In this view, we may regard the labials and dento-labials as belonging to the same. P into B.—Greek, <})Xf 4.; Latin, phlebs. Latin, (and Greek,) episcopus; English, bishop; Anglo-Saxon, biscop ; German, b i s c h o f. Pinto F and V.—Latin, pater; German, vater; Dutch, vader ; English, father. T into S.—German, b e s s e r ; English, better. German, w a s s e r; English, water. D into Th.-^German, das; Dutch, dat; English, that. T into Z,—German, zung; Dutch, tong; English, tongue. German, z w e i g; English, twig. , - . L into R.—Spanish, Gil Bias; Portuguese, Gil Bras. Latin, arbor*; Spanish, albero. C or K into G.—Latin, hemicranium ; French, migraine. Latin, cibarium; French, gibier. Latin, acer ; Italian, agro. Latin, alacer.; Italian, allegro. Greek, xuxvc?; Latin, cygnus. The most harmonious languages are such as have but few consonants in their words, compared with the number of vowels; hence the musical superiority of the Greek and Italian, over the English, German, &c. "Among certain northern nations," says M. Richerand,2 "all articu- lated sounds appear to issue from the nose or the throat, and make a disagreeable pronunciation, doubtless because it requires greater effort; and he who listens, sympathizes in the difficulty, which seems to be felt by him that speaks;"-—and he adds:—"would it not seem that the inb.abitan.ts of cold countries have been led to use consonants rather than vowels, because as the pronunciation does not require the same opening of the mouth, it does not afford the same space for the continual admission of cold air into the lungs?"! The whole of Richerand's re- marks on this topic are singularly fantastic and feeble, and unworthy of serious discussion. In regard to consonants, it has been presumed, that some common imitative principle must have existed with all nations, so as to cause them to conform in adopting such as produce a certain sound to convey ' Archaeologia Britannica, Oxford, 1707. 1 Eletnens de Physiologie, edit, cit., p. 298. 488 MUSCULAR MOTION. the same effect to the ear. Dr. John Wallis1 turned his attention to this matter, chiefly as regards the English language, and he has col- lected a multitude of examples to show, that a certain collocation of consonants at the commencement of a word generally designates the class of ideas intended to be conveyed by it. For instance, he re- marks that:— Str, always carries with it the idea of great force and effort:—as strong, strike, stripe, strife, struggle, stretch, strain, &c. St, the idea of strength, but in less degree—the vis inertia, as it were :—as stand, stay, stop, stick, stutter, stammer, stumble, stalk, steady, still, stone, &c. Thr, the idea of violent motion :—as throw, thrust, throb, threat, throng, &c. Wr, the idea of obliquity or distortion:—as wry, wreathe, wrest, wring, wrestle, wrench, wrig- gle, wrangle, &c. Br, the idea of violent—chiefly sonorous—fracture or rupture:—as break, brittle, brust, or burst, brunt, bruise, broil, &c. Cr, the idea of straining or dislocation, chiefly sonorous:—as crack, creak, crackle, cry, crow, crisp, crash. Other words, beginning with these consonants, communicate the idea of curva- ture, as if from curvus:—as crook, cringe, crouch, creep, crawl, cripple, crumple, crotchet, &c. Others, again, denote decussation, as if from crux:—as cross, cruise, crutch, crosier. Shr, the idea of forcible contraction :—as shrink, shrivel, shrug, shrill, &c. Gr, the idea of the rough, hard, onerous and disagreeable, (either owing to the letter of roughness r, or from gravis,)—as grate, grind, gripe, grapple, grieve, grunt, grave, &c. Sw, the idea of silent agitation or of gentle lateral motion :—as sway, swag,swerve, sweat, swim, swing, swift, &c. Sm, a very similar idea to the last:—as smooth, small, smile, smirk, &c. CI, the idea of some adhesion or tenacity:—as cleave, clay, cling, climb, cloy, cluster, close, &c. Sp, the idea of some dispersion or expansion, generally quick, (especially with the addi- tion of the letter r,)—as spread, spring, sprig, sprinkle, split, splinter, spill, &c. SI, the idea of a gently gliding or slightly perceptible motion :—as slide, slip, slippery, slime, sly, slow, sling, &c. Lastly: Sq, Sk, Scr, denote violent compression:—as squeeze, squirt, squeak, squeal, skreek, screw, &c. Other interesting observations on the collocation of consonants, at the termination, and in the body, of words, are contained in the gram- mar of Wallis. His remarks,, however, are chiefly confined to his own tongue. The President de Brosses2 has taken a wider range, with a similar object, and endeavoured to discover why certain consonants, or a certain arrangement of'consonants in a word, should designate certain properties, in all languages. Why, for instance, the st should enter into most words signifying firmness and stability:—as, in the Sanskrit, stabatu, to stand, stania, a town, &c.; in the Greek, atrj^, a column, etsotos, solid, immovable, ffr-^po, sterile, remaining constantly without fruit, ffT^p-^co, " I fix firmly," &c.; in the Latin, stare, to stand; stirps, a stem; stupere, to be astonished; stagnum, stagnant water, &c.; and he might have added, in the German, still-stehend, stagnant; stad t, a town; stand, condition; sterben,to die; still-stand, cessation, &c, besides the English words, commencing with st, already quoted from Wallis. He farther inquires, why words, commencing with sc, denote hollowness, as oxarttu, I dig; axaftj, skiff or boat, in the Greek; scutum, a shield; scyphus, a large jug; sculpere, to engrave; scrobs, a ditch, in the Latin;—ecuelle, formerly escuelle, a dish; scarifier, to scarify; scabreux, scabrous; sculpture^ &c, in the French; and simi- 1 Grammatica Linguae Anglicana?, &c, edit. 6, Lond., 1765. 3 Traite de la Formation Mechanique des Langues et des Principes Physiques de l'Ety- mologie, i. 199, Paris, 1765. VOICE—ARTICULATE LANGUAGE. 489 lar words might be added from our own language. Ecrire, formerly escrire, the French for "to write," is from the Latin scribere; and, anciently, a kind of style was used for tracing the letters in wax; which instrument, by a like analogy, was called, by the Greeks, exaf>t.$o$. M. de Brosses1 accounts for these, by supposing, that the teeth, being the most immovable of the organic apparatus of the voice, the firmest of, what he calls the dental letters, T, has been mechanically employed to denote stability; and to denote hollowness, the K or C has been adopted,—which are produced in the throat, the most hollow of the vocal organs. The letter S serves, he conceives, merely as an augmen- tative; as the sound can, by its addition, be made continuous. It is itself, however, a letter expressive of softness, when combined, as we have seen, with certain other consonants; or when employed alone at the commencement of a word. In the same manner, the letters fl are used to designate the motion of fluids more especially,—as in the Greek, $\o%, a flame; $\f\, a vein; ixtytQw, a burning river in the infernal regions:—in the Latin, flamma, flame; fluo, I flow; flatus, wind; fluctus, wave, &c.:—in the German, fibs sen, to float; flbten,to play on the flute; fluss,a river; flug, flight, &c; and in the French and English words of the same meaning. Lastly, the idea of roughness and asperity is conveyed by the letter r, as in the words rough, rude, rock, romp, he. How different, for example, in smoothness are the two following lines, in which the S predominates, from those that succeed them, where the R frequently, and perhaps designedly, occurs: " Softly sweet in Lydian measures, Soon he soothed his soul to pleasures;" And:— " " Now strike.the golden lyre again, A louder yet, and yet a louder strain; Break liis bands of sleep asunder; And rouse him like a rattling peal of thunder." Dryden's " Alexander's Feast.'' The foregoing remarks, suggested by those of Wallis and M. de Bros- ses, must not, however, be received too absolutely.' In the condition in which we find languages at the present day, it would be impossible that they should hold good universally; but they will tend to show, that the physiology of the voice is intimately connected with this part of philo- logy; and that the sounds emitted by the agency of particular parts of the vocal tube, may have led to the first employment of those sounds, according to the precise idea it may have been desired to convey;— gutturals, for example, for sounds conveying the notion of hollowness: —resisting dentals, that of obstacles, &c. The words mamma and papa are composed of a vowel and consonant, which are the easiest of enun- ciation ; and which the child, consequently, pronounces and unites earlier than any other. Hence they have become the infantile appella- tions for mother and father with many nations. President de Brosses2 affirms—and he has brought forward numerous examples to prove his position—that in all ages, and in every country, a labial, or, in default * Op. cit., i. 261. 3 Op. cit., i. 244. 490 MUSCULAR MOTION. of it, a dental, or both together, are used to express the first infantile words "papa" and "mamma;" but it is scarcely necessary to say, that the child, when it first pronounces the combinations, attaches no such meaning to them as the parent fondly imagines. There is a rhetorical variety of onomatopoeia, frequently considered under the head of alliteration, but by no means deriving its chief beau- ties from that source. It happens when a repetition of the same letter concurs with the sonorous imitations already described; as in the fol- lowing line in one of the books of the iEneid of Virgil;— " LucZantes venZos ZempesZaZesque sonoras," in which the frequent occurrence of the letter of firmness and stability, T, communicates the idea of the striking of the wind on objects. In the " Andromaque" of Racine, a line of this character occurs: " Pour qui sont ces serpens qui sifflent sur vos tetes,"1 in which the sound impressed on the ear has some similarity to the hissing of serpents: and in the *'Poeme des Jardins" of the Abbe" De- lille, there is the following example:— " Soit que sur le Zimon une riviere fente, Derou/e en paix les pfis de son onde indoZente; Soit qu'a travers les rocs un torrent en courroux Se brise avec fracas.:'2 In the first two lines, the liquid L denotes the tranquil flow of the river; whilst in the two last, the letter of roughness and asperity, R, resembles the rushing of the stream like a torrent. The remarks already made will have exhibited the radical difference in the ideas communicated by the sound of those letters, by the common consent of languages. In the German this variety of expression is often had recourse to; and by none more frequently than by the poet Burger.3 The English language affords a few specimens, but not as many as might be imagined. Of simple alliteration there are many; some that give delight; others that do violence to the' suggestive principle; but there are comparatively few where the words are selected, which by their sound convey to the mind the idea to be communicated. The galloping of horses may be assimilated by a frequent succession of short syllables ;'slow, laborious progression by the choice of long; but in the onomatopoeia in question, the words themselves must consist of such a collocation of one consonant, or of particular consonants, as adds force to the idea communicated by the words collectively. Of this, we have a good example in the lines before cited, in which the 1 " For whom are those serpents that hiss o'er your heads ?" 2 Which may be translated as follows:— " If o'er deep slime a river laves In peace the folds of its sluggish waves; Or o'er the rocks.a torrent breaks In wrath obstrep'rous." 3 Art. Alliteration, and Onomatopoeia, in Encyclopedic, par Diderot, D'Alembert, &/c., and in Allgemeine Deutsche Real-Encyclopadie fur die gebildeten Stande, (Conversations Lexi- kon,) Aufl. 8, Leipz., 1837. VOICE—SINGING. 491 repetition of the letter R, in the phonetic words, adds considerable force to the idea intended to be conveyed by the passage— "Break his bands of sleep asunder; And rouse him like a rattling peal of thunder," and in Byron's "Darkness," "Forests were set on fire—but hour by hour They fell and faded—and the crackling trunks Extinguish'd with a crash—and all was black." 5. SINGING. The singing voice differs from other vocal sounds in consisting of appreciable tones, the intervals of which can be1 distinguished by the ear, and admit of unison. Under the sense of hearing we endeavoured to show, that the musical ear is an intellectual faculty; and that the ear is only the instrument for attaining a knowledge of sounds, which are subsequently reproduced by the larynx, under the guidance of the intellect. In this respect, therefore, there is a striking resemblance between music and spoken language. Like the latter, singing admits of considerable difference, as regards intensity, timbre, &c. Voices are sometimes divided into the grave and acute ; the difference between thetn amounting to about an octave. The former is the voice of the adult male; but he is capable of acute sounds, by assuming the falsetto, which M. Savart1 conceives to be pro- duced in the ventricles ofthe larynx; M. Bennati in the pharynx; and more recently, Mr. J. Bishop2 lias suggested, that it may arise either from the partial closing of the glottis, or from a nodal division of the vocal chords, "the pitch of the sound in the production of this peculiar modification of. the voice being such, that the column of air in the vocal tube is of the precise length requisite to vibrate in unison with the larynx." The mode, however, in.which the falsetto voice is produced is by no means determined. It has given rise to great diversity of views.3 The acute voice is that of the grown female, children, and eunuchs. According to M. Pouillet,4 the gravest sound of the male voice makes 190 vibrations per second; the most acute 678 per second; whilst the female voice makes 572 vibrations for the gravest, and 1606 for the most acute. By adding all the tones of an acute to those of a grave voice, they are found to embrace nearly three octaves; but, according to M. Magendie, it does not appear, that such a compass of voice, in pure and agreeable tones, has ever existed, in one individual.5 On the other hand, M. Biot'calculated three octaves and a half to be the ex- treme range; this, Mr. Bishop6 says, he knows from experience is too low an estimate. Independently of the falsetto, the compass of the natural voice would seem to rarely exceed two octaves; but in some cases, as in those of Catalani and Malibran, it has extended beyond * Magendie's Journal de Physiologie, torn, v., Paris, 1825.' 3 Proceedings of the Royal Society, No. 65, London, 1847. 3 Miiller, Physiology, P. iv., p. 1032, Lond., 1838. * Elemens de Physiologie Experimentale, torn. iii. 130, Paris, 1832. s Precis Elementaire, i. 262. « The Lond. and Edinburgh Philosophical Magazine, for October, 1836, p. 272. 492 MUSCULAR MOTION. three. Some singers can descend sixteen tones below, others can rise sixteen above, the medium. The former are called tenor bass; the latter soprano; but hitherto no example has occurred of a person, who could run through the thirty notes. The musician establishes certain distinctions in the voice; such as counter, tenor, treble, bass, &c. We find it, also, differing considerably in strength, sweetness, flexibility, &C.1 The singing voice, according to M. Bennati,2 is not limited to the larynx,—the pharynx being likewise concerned. ■ The voice, produced in those two different parts, has long been termed voce di petto, and voce di testa. M. Bennati calls the former laryngeal notes or notes of the first register; the latter supra-laryngeal or notes of the seeond register; and M. Lepelletier designates them laryngeal and pharyngeal respect- ively;—comprising, in the dependencies of the pharynx, the tongue, tonsils, and velum palati, by means of which the latter class of sounds is elicited. The laryngeal voice, which is always more elevated by an octave in the* female than the male, is most commonly met with. It furnishes the types called, 1. Alt or soprano ; 2. Counteralt; 3. Tenor; 4. Tenor Bass. The pharyngeal voice presents only modifications of these types. It is met with in but few persons in its finest develope- ment. It has usually been supposed to be formed by the superior ligaments of the larynx, or in the ventricles; but these gentlemen esteem it demonstrated, that it is formed at the guttural aperture, cir- cumscribed by the base of the tongue, velum palati, its pillars, and the tonsils. By it is produced the baritenor, the contraltino tenor, and the soprano sfogato. Bennati concludes his memoir on the human voice by remarking,—that not only are the muscles of the larynx inservient to the modulation of the notes • of song, but those of the os hyoides, tongue, and the superior, anterior, and posterior, part of the vocal tube are called into action, without the simultaneous and properly associated operation of which the degree of modulation requisite for song could not take place. When the voice is raised in the scale from grave to acute, a corre- sponding elevation takes place in the larynx towards the base of the cranium. By placing the finger on the pomum Adami, this motion can be easily felt; at the same time, the thyroid cartilage is drawn up within the os hyoides, and presses on the epiglottis; the small space between the thyroid and cricoid closes; the pharynx is contracted; the velum pendulum depressed and carried forwards; the tonsils approach each other; and the uvula is folded on itself. The reverse of these phenomena takes place during the descent of the voice.3 It has been already remarked, that the natural voice or cry is con- nected with the organization of the larynx. So far as it can be modified into tones independently of the participation of the intellect, a natural singing voice may be said to exist. To repeat, however, any song, requires both ear and intelligence; and, therefore, singing may be said 1 Magendie's Jour, de Physiologie, x. 179. ' Recherches sur le Mecanisme de la Voix Humaine, Paris, 1832. 3 Bishop and Bennati, in op. cit. GESTURES. 493 to have originated in social life. It can be employed, as it is in many of our operas, to depict the different intellectual and moral conditions, " And bid alternate passions fall and rise." When the air is accompanied by the words, or is articulated, we are capable of expressing, by singing, any of the thoughts or feelings, that can be communicated by ordinary artificial language. Declamation is a kind of singing, except that the intervals between the tones are not entirely harmonic, and the tones themselves not wholly appreciable. With the ancients—it has been imagined—it dif- fered much less from singing than with the moderns, and probably re- sembled the redtative of the operas. The ingenious work of Dr. James Rush of Philadelphia,1 may be consulted on all this subject, with great advantage. b. Cfestures. Under this appellation, and that of muteosis, are included those functions of expression, that are addressed to the sight and touch. It comprises not only the partial movements of the face, but also those of the upper extremities; besides the innumerable outward signs that cha- racterize the various emotions. In many tribes of animals, the con- ventional language appears to be almost, if not entirely, confined to the gestures; and even in man—favoured beyond all animals in the facility of communicating his sentiments by the voice—the language of gestures is rich and comprehensive. It is in the gestures of the face chiefly, that he far exceeds other animals. This is, indeed, in him, the great group of organs of expression. In animals, the function is dis- tributed over different parts of the body, the face assuming but little expression, whilst the animal is labouring, under any emotion, if we make exception of the brute passion of anger and of one or two others. Hence it is, that, by some naturalists, man has been defined, by way of distinction, "a laughing and erying animal." In animals, almost all the facial expression of internal feeling is confined.to the eye and mouth, but, in addition, the attitude of the body is variously modified, and the hair is raised by the panniculus carnosus, as we see on the back of the, dog when enraged. In the human countenance, alone, in the state of society, can the passions be read,—the rest of the body being covered by clothing; and even were it not, the absence of a coat of hair, and of a panniculus carnosus, would enable it to minister but little to expression. The skin of the face is very fine, and on certain parts, as the lips and cheeks, is habitually more or less florid, and admits of considerable and expressive variations in its degree of colour. The union of the different parts composing the face gives occasion to numerous reliefs, which are called traits or features; and beneath the skin are muscles, capable, by their contraction, of modifying the features in a thousand ways. To comprehend fully the physiology of the facial expression of the 1 Philosophy of the Human Voice, 3d edit., Philad., 1845. 494 MUSCULAR MOTION. Fig. 201. passions, a few observations on the muscles of the human face will be ne- cessary. (Fig. 201.) The eyebrow is greatly concerned in expression; and certain muscles are attached to it for the purpose of moving it. The fasciculus of fibres which der scends from the frontal muscle, and is attached to the side of the nose, has been esteemed, by some, a separate mus- cle, and to have a distinct operation. It draws the inner extremity of the eyebrow downwards, When the orbicu- laris palpebrarum, and the last muscle act, there is a heavy lpwering expres- sion. If they yield to the action of the frontal muscle, the eyebrow is arched, and there is a cheerful, inquiring ex- pression. If the corrugator supercilii acts, there is more or less of mental an- guish, or of painful exercise of thought. If it combines with the frontalis, the forehead is furrowed, and there is an upward inflection of the inner extremity of the eyebrow, which indicates more of querulous and weak anxiety. " The arched and polished forehead," says Sir Charles Bell—of whose elegant and accurate Essays1 the author will occa- sionally avail himself on this branch of the subject—" terminated by the distinct • line of the eyebrow, is a table, on which we may see written, in perishable cha- racters, but distinct while they continue, the prevailing cast of thought; and by the indications here, often the mere animal activity, displayed in the motions of the lower part of the face, has a meaning and a force given to it. Independent of the actions of the muscles, their mere fleshiness gives character to this part of the face. The brow of Hercules wants the elevation and form of intelligence; but there may be observed a fleshy fulness on the forehead, and around the eyes, which conveys an idea of dull brutal strength, with a lower- ing and gloomy expression, which accords with the description in the Iliad." Sir Charles separates the orbicularis palpebrarum into two muscles;— the outer, fleshy, circular band, which runs round the margin of the orbit; and the lesser band of pale fibres, which lies upon the eyelids. The latter is employed in the act of closing the eyelids, but the former is only drawn into action in combination with the other muscles of the Muscles of the Head and Face. 1. Frontal portion of occipito-frontalis. 2. Occipital portion. 3. Aponeurosis. 4. Orbicularis palpebrarum, which conceals corrugator supercilii and tensor tarsi. 5. Pyramidalis nasi. 6. Compressor nasi. 7. Orbicularis oris. 8. Levator labii superioris alaeque nasi. The figure is plac.ed on nasal portion. 9. Levator labii superioris.proprius; the lower paTt of the levator anguli oris" is Been between muscles 10 and 11. 10. Zygo- maticus minor. 11. Zygomaticusmajor. 12. Depressor labii inferioris. 13. Depressor anguli oris. 14. Levator labii inferioris. 15. Superficial portion of masseter. 16. Its deep portion. 17. Attrahens aurem. 18. Buccina- tor. 19. Attollens aurem. 20. Temporal fascia which covers temporal muscle. 21. Retrahens aurem. 22. Anterior belly of'di- gastricus muscle; the tendon seen passing through its aponeurotic pulley. 23. Stylo- hyoid muscle pierced by posterior belly of digastricus. 24. Mylo-hyoideus muscle. 25. Upper part of sterno-mastoid. 26. Upper part of trapezius. The muscle between 25 and 26 is the splenius. (Wilson.) 1 Essays on the Anatomy and Philosophy of Expression, 3d edit., Lond., 1844. GESTURES—MUSCLES OF THE FACE. 495 face in expressing passion, or in some convulsive excitement of the organ. In laughing and crying, the outer and more powerful muscle is in action, gathering up the skin about the eye, and forcing back the eyeball itself. In drunkenness, the power of volition over this muscle is diminished; and there is an attempt to raise the upper eyelid by a forcible elevation of the eyebrow. The muscles of the nostrils are; 1st, levator labii superioris alaeque nasi, which, as its name imports, raises the upper lip and nostril; 2dly, compressor nasi, a set of fibres which compresl the nostril; and 3dly, depressor aloe nasi, which lies under orbicularis oris, and whose function is indicated by its name. The three muscles serve to expand and con- tract the opening or canal of the nostril, moving in consent with the muscles of respiration, and thus the inflation of the nostrils indicates general excitement, and animal activity. The muscles of the lips are; 1st, levator labii proprius, which raises the upper lip; 2dly, levator anguli oris, which raises the angle of the mouth; and 3dly, the zygomatic muscle, which is inserted into the angle of the mouth. Sometimes an additional muscle of the name exists:— zygomaticus minor. These last muscles raise the upper lip and angle of the mouth, so as to expose the canine teeth. If they be in action contrary to the orbicularis oris, there is a painful and bitter expression; but if they be influenced along with the orbicularis oris, and orbicularis palpebrarum,—if the former of these muscles be relaxed, and the latter contracted,—there is a fulness of the upper part of the face, and a cheerful, smiling expression of countenance. The orbicularis oris closes the mouth; and, when allowed to act fully, purses the lips. The nasalis labii superioris draws down the septum of the nOse. The triangularis Oris or depressor. labiorum indicates, by its name, its function. The quadratus menti is a depressor of the lower lip. The levatores menti, by their action, draw up the chin, and project the lower lip; and the buccinator is chiefly for turning the alimentary bolus in the mouth; and, in broad laughter, retracts the lips. The orbicularis muscle is affected in the various emotions of the mind; trembling and relaxing in both grief and joy: it relaxes pleasantly in smiling. The union of these various muscles at the angle of the mouth pro- duces the fleshy prominence noticed in those who have thin faces ; and who are, at the same time, muscular. When the cheeks are fat and full, the action of these muscles produces the dimpled cheek. The angle of the mouth is full of expression, according as the orbicularis, or the superior or inferior muscles inserted into it have the preponder- ance. Lastly; the temporal is a strong muscle, which raises the lower jaw. It is assisted by the masseter, a deep-seated muscle, which lies on the outside of the lower jaw; arises from the jugum, and is inserted into the angle of the jaw. Two different nerves are distributed to these muscles,—the fifth pair, and portio dura or facial of the seventh; the latter of which, according to the experiments of Sir Charles Bell, is concerned in the instinctive movements of expression; and comparative anatomy exhibits, that the number and intricacy of these nerves vary in proportion to the animal's 496 MUSCULAR MOTION. Distribution of Facial Nerve. Fig. ^02. power of expression. The nerves of the face and neck of the monkey are numerous, and have frequent connexions; but on cutting the seventh pair, or respiratory nerve of the face of Sir Charles Bell's system, the features are found to be no longer influenced by the passions. Yet the skin continues sensible, and the muscles of the jaws and tongue are capable of the actions of chewing and swallowing. If the respiratory nerve of one side be cut, the expression of that side is destroyed; whilst the chattering, grinning, and other movements of expres- sion continue on the other. In a dog, too, if the respira- 1. Facial nerve, escaping from stylo-mastoM foramen, tory nerve Of the face be Cut, and crossing ramus of lower jaw; the parotrd gland has foe will fight aS Jbitterlv, but been removed in order to see the nerve more distinctly. . O > i-T 2. Posterior auricular branch; the digastric and stylo- With no retraction 01 hlS lipS, mastoid filaments are seen near origin or this branch. 3. -, -.. n ,, j Temporal branches, communicating with (4) branches of Sparkling 01 the eye, Or OraW- frontal nerve. 5. Facial branches communicating with • hQr>L- nf +k0 0„0 rpu0 (6) infra-orbital nerve. 7. Facial branches, communicat- lu& ud'^K- "A ^u« edIS. -LUC ing with (8) mental-nerve. 9. Cervico-facial branches face is inanimate, although the communicating with (10) superficial^ colli nerve, and ' °. forming a plexus (11) over submaxillary gband. Distribu- mUSCleS Ot the face and jaWS, tion of branches of the facial in a radiated direction over r o +li 1* W +n side of face constitutes the pes anserinus. 12. Auricularis SO lar aS tney are liaDie tO magnus nerve, one of ascending branches of cervical V.p inflnpnpprl thrnno-h nthpr plelus. 13. Occipitalis minor, ascending along posterior Ue lUUUeilCeU inrOUgU Oilier border of sterno-mastoid muscle. 14. Superficial and nerveS, Continue their office. deep descending branches of cervical plexus. 15. Spinal m, l • i accessory nerve, giving off a branch to external surface of lhe game-COCK, 1U the pOSl- trapezius muscle. 16 Occipitalis major nerve, posterior .• f fiay.f:n„ ,„«„(], „ rnflp branch of second cervical nerve. I-10" Ol ngnting, SpreaaS a HUT of feathers around his head. The position of his head and the raised feathers are the expressions of hostile excitement; but on the division of the respiratory nerve, the feathers are no longer raised, although the pugnacious disposition con- tinues. It has been found, moroover, that if the galvanic influence be passed from one divided extremity of the respiratory nerve to the other, the facial expression returns; and, in certain cases of incomplete hemi- plegia, in which the movements of expression of the face were alone rendered impracticable, the disease was found to have implicated only the respiratory or facial nerve. The views of Sir Charles Bell regard- ing the connexion alleged by him to subsist between the seventh pair and the associated movements of respiration have, however, been con- tradicted by the experiments of Mr. Mayo,1 and his inferences regard- ing the fifth pair as being jointly a nerve of sensation and of voluntary motion have been considered to require qualification. By dividing the 1 Outlines of Human Physiology, 4th edit., p. 254, London, 1837. GESTURES—NERVES OF THE FACE. 497 portio dura of the seventh pair in the ass, and on both sides instead of one, as done by Sir Charles Bell, Mr. Mayo found, that the nerve pre- sides over simple voluntary motion only; and by a similar division of the second and third branches of the fifth, at their points of con- vergence, he showed, that the lips were deprived of sensation, not of motion. "No doubt, I believe," says Mr. Mayo, "is now enter- tained, that the inference which I drew from these experiments is correct;—namely, that the portio dura of the seventh pair is a simple voluntary nerve, and that the facial branches of the fifth are exclusively sentient nerves." In the prosecution of• his inquiries, Mr. Mayo ob- Fig. 203. Plan of the Branches of the Fifth Nerve, modified from a sketch by Sir C. Bell. n. Submaxillary gland, with the submaxillary ganglion above it. 1. Small root of the fifth nerve, Which joins the lower maxillary division. 2. Larger root, with the Gassenan ganglion. J. Oph- thalmic nerve. 4. Upper maxillary nerve. 5. Lower maxillary nerve. 6. Chorda tympani. 7. tacial nerve. served, that the masseter muscle, temporal, pterygoids, and circumflexus palati receive no branches from any nerve except the fifth, and yet that they receive no twigs from the ganglionic portion of the nerve; and thence he concludes, that almost all the branches of the large or gan- glionic portion of the fifth pair are nerves of sensation, whilst those of the small fasciculus or ganglionless portion are nerves of motion. This smaller portion of the fifth pair issues from the peduncles of the brain; constitutes a gangliform plexus with the inferior maxillary only; pre- sents the common aspect of most nerves of the body, and is distributed to the chief muscles concerned in the process of mastication. Hence vol. I.—32 498 MUSCULAR MOTION. it was termed by Bellingeri1 nervus masticatorius; and by Sir Charles Bell, long afterwards, motor or manducatory portion of the fifth nerve. To this smaller fasciculus of the fifth, twigs from the ganglionic portion of the nerve are distributed. The ganglionless portion, and portio dura of the seventh, Mr. Mayo conceives to be voluntary nerves to parts, which receive sentient nerves -from the larger or ganglionic portion of the fifth. The facial nerve, however, after it has passed through the parotid gland, becomes sensory also, owing to its having received a twig from the fifth pair. Pathology affords numerous examples of injury done to the facial nerve. In some of these, the nerve itself may be in a morbid condi- tion in a portion of its Fig. 204. course; in others, the part of the encephalon, whence the nerve originates, may be the seat of the lesion. The prognosis will, of course, vary according to the seat; but, as a general rule, paralysis of the facial nerve is not of great mo- ment. The author has seen several cases of partial paralysis of this kind; some of which have wholly disappeared; but in others the loss of power appears to be permanent. In a case, which presented itself to him in the Baltimore Infirmary, the mischief was probably seated near the origin of the nerve, as it resulted from serious injury to the head. A carriage- horse, belonging to a friend, by exerting considerable power, forced its head through an aperture in the partition of the stall, and was unable to withdraw it, in consequence of the under jaw catching the sides of the aperture. During the efforts to extract it, so much pressure was made upon the portio dura of one side, that the animal lost all power of expression in the corresponding side of the head; the soft parts about the mouth dropped, and the ear no longer associated with that of the opposite side in expression; yet the movements of mastication and deglutition were scarcely affected. This state of paralysis continued for a, few days, and gradually disap- peared. Fig. 204 represents a case of paralysis of this nerve, produced Paralysis of the Facial Nerve. (Marshall Hall.) 1 Dissert. Inaugur., Turin., 1823; cited in Edinb. Med. and Surg. Journ., July, 1834. GESTURES—NERVES OF THE FACE. 499 by the pressure of a tumour beneath the ear: the orbicularis palpebrarum was paralysed so that the patient was unable to close his eyelids. Independently of the various muscular actions which modify the expression of the human countenance, there are certain others that mark the different mental emotions. The skin varies in colour, be- coming pale or suffused, and frequently alternating rapidly between these two conditions. The changes are more especially witnessed on the forehead, cheeks, and lips; and arise from an augmented or dimi- nished flow of blood into the capillaries of the part, under the influence of the existing emotion. Under such circumstances, the eye may par- ticipate in the suffusion. The skin may, also, vary in its degree of moisture or heat; it may be dry, or bathed in perspiration; and the perspiration may be warm or cold;—the two conditions occasionally alternating. Particular parts of the face, again, are more susceptible of this "sweat of expression," as it has been termed,—the forehead and temples for example. The heat of the head is also occasionally modi- fied; a sudden glow is felt in the countenance; and the expression is sometimes evident to a second person. The expression of, the human eye, connected with the action of the oblique muscles, has been referred to under Vision. It was there asserted, that in insensibility, the organ, it has been presumed, is given. up to the action of the oblique muscles, and is drawn up under the upper eyelid. The eye itself is, however, capable of various expres- sions, depending upon varied positions of its tutamina; and especially of the secretion from its mucous covering—the conjunctiva,—and from the lachrymal gland; so that it may be swimming, or the tears may flow over the cheeks and constitute weeping. In addition to these, which may be esteemed sources of expression in the human countenance, may be added the action of osculation or kissing; which, wherever practiced, is employed as an expression of love and friendship;—confined with us to those of the female sex, or of opposite sexes; but, in some countries, employed as an expression of regard between males also. It is impracticable to describe all the facial expressions—Proso- posis, as they have been collectively termed—of which the human countenance is susceptible. They are commonly classed under two heads; the exhilarating, in which the face is flushed, and the counte- nance expanded;—the muscles being contracted from within to without; and the depressing, in which, on the contrary, the face is pale, and the features are drawn inwards and sunken. Let us inquire into the physiology of a few of these expressions; beginning with the play of the features in broad laughter, (Fig. 205,) as being, perhaps, the most easy of explanation. In laughing, it is in vain that we endeavour to confine the lips; a complete relaxation of the orbicularis oris gives uncontrolled power to the opponent muscles inserted into the angles of the mouth and upper lip. Hence, the late- ral retraction of the angles of the mouth; the elevation of the upper lip disclosing the teeth; the peculiar elevation of the nostrils without their being expanded, and the dimple of the cheek, where the acting muscles congregate: hence, also, the fulness ofthe cheeks, rising so as 500 MUSCULAR MOTION. Fig. 205. Broad Laughter. (Sir Charles Bell.) to conceal the eye, and throw wrinkles about the lower eye- lids and temples. In this expression, the whole of the movable features are raised upwards. The orbicularis palpebrarum does not partake of the relaxation of the or- bicularis oris. It is excited, so as to contract the eyelids, and sink the eye, whilst the struggle of a voluntary effort of the muscles to open the eyelids, and raise the eye- brow, gives a twinkle to the eye, and a peculiar obliquity to the eyebrow, the outer part of. which is most ele- vated. At the same time, the individual holds his sides to control the contractions of the muscles of the ribs. The diaphragm is violently agitated. The same influence spreads to the throat, and the sound of laughter is as distinct as the signs in the face. In this movement Fig. 206. Faun "Weeping. (Sir Charles Bell.) of expression we have an instance of the associated action of different parts, which are considered to be under the influence of the respiratory system of nerves of Sir Charles Bell. The facial expression is under the direction of the portio dura or respiratory nerve of the face. In the face of a faun, (Fig. 206,) sketched by Sir Charles Bell, we have the expression of weeping from pain. In the violence of weeping, accompa- nied with lamenta- tion and outcry, the face is flushed or suf- fused from stagna- GESTURES—CRYING. 501 tion of blood in the vessels. The muscles of respiration are affected from the commencement, and the return of blood from the head is somewhat impeded. The muscles of the cheeks are in movement. Those that depress the angles of the mouth are powerfully con- tracted, and the orbicularis oris is not relaxed, but drawn open by the predominant action of its opponents. A-convulsive move- ment in the muscles about the eyes attends ; the eyebrow is drawn down ; the eyes are. compressed by the eyelids; the cheek is raised ; the nostril drawn out, and the mouth stretched laterally. In weep- ing, also, unless the convulsive movement of the muscles is very strong, the expression of grief affects that part of the eyebrows next the nose. It is turned up with a peevish expression, which corresponds with the depression of the corners of the mouth. This depression gives , an air of despondency and languor to the countenance, when accompa- nied by general relaxation of the muscles. When the corrugator co- operates, there is mingled in the expression something of mental energy, moroseness, or pain. If the frontal muscle unites its action, an acute turn upwards is given to the inner part of the eyebrow, very different from the effect of the general action of the frontal muscle, and charac- teristic of anguish, debilitating pain, or discontent, according to the prevailing cast of the rest of the countenance. The depression, how- ever, of the angle of the mouth, that indicates languor and despondency, must be slight; as the depressor anguli oris cannot act forcibly, with- out the action of the superbus participating—a muscle, which quickly produces a revolution in the expression, and makes the under lip pout contemptuously. The expression at the angles of the mouth demands the careful study of the painter; the most opposite characters being communicated to the countenance by their elevation or depression. When Peter of Cor- tona was engaged on a picture, of the iron age for the royal palace of Pitti, Ferdinand II., who often visited him, and witnessed the progress of the piece, was particularly struck with the exact representation of a child in the act of crying. " Has your majesty," said the painter, "a mind to see how easy it is to make this very child laugh ?" The king assented: and the artist, by merely elevating the corner of the lips and inner.extremity of the eyebrows, made the child, which at first seemed breaking its heart with weeping, seem equally in danger of bursting its sides with immoderate laughter, after which, with the same ease, he restored to the figure its proper expression of sorrow.1 It is at the angle of the mouth and the inner extremity of the eye- brow, that the expression which is peculiarly human is situate. These are the most movable parts of the face. On them the muscles are con- centrated, and it is upon their changes that expression is acknowledged chiefly to depend. All the parts, however, of an impassioned counte- nance are in accordance with each other. When the angles of the mouth are depressed in grief, the eyebrows are not elevated at the outer angles as in laughter. When a smile plays around the mouth, or when the cheek is elevated in laughter, the eyebrows are not ruffled as in 1 Good's Book of Nature, iii. 291, Lond., 1834. 502 MUSCULAR MOTION. grief. In real emotion, these opposite actions cannot be combined; and, when united by the mimic, the expression is farcical and ridicu- lous. Dr. Wollaston1 has shown, that the same pair of eyes may appear to direct themselves either to or from the spectator, by the addition of other features in which the position of the face is changed. The nose principally produces the change of direction, as it is more subject to change of perspective than any other feature; and Dr. Wollaston has shown, that even a small portion of the nose will carry the eyes along with it. He obtained four exact copies of the same pair of eyes look- ing at the spectator, by transferring them upon copper from a steel plate, and having added to each of two pairs of them a nose—in one i case directed to the right, and in the other to the left, and to each of the other two pairs a very small portion of the upper part of the nose— all the four pairs of eyes lost their front direction, and looked to the right or to the left, according to the direction of the nose, or of the portion of it that was added. But the effect thus produced is not limited to the mere change in the direction of the eyes ; for a total dif- ference of character may be given to the same eyes by a due represent- ation of the other features. A lost look of devout abstraction in an uplifted countenance may be exchanged for an appearance of inquisi- tive archness in the leer of a younger face turned downwards and obliquely towards the opposite side. This, however, as Sir David Brewster has remarked, is not perhaps an exact expression of the fact. The new character, which is said to be given to the eyes, is given only to them in combination with the new features; or what is probably more correct, the inquisitive archness is in the other features, and the eye does not belie it. Sir David adds, that Dr. Wollaston has not noticed the converse of these illusions, in which a change of direction is given to fixed features by a change in the direction of the eyes. This effect is seen in some magic "lantern sliders, where a pair of eyes is made to move in the head of a figure, which invariably follows the motion of the eyeballs. In bodily pain, the jaws are pressed together, and there is grinding of the teeth ; the lips are drawn laterally, so as to expose the teeth and gums; the nostrils are distended to the utmost, and at the same time drawn up ; the eyes are largely uncovered, and the eyebrows elevated; the face is turgid with blood, and the veins of the temple and forehead are distended; the breath being suspended, and the descent of the blood from the head impeded. In anguish, conjoined with bodily suffering, the jaw falls, the tongue is seen-, and, in place of the lateral retraction of the lips, the lower lip falls; the eyebrows are knit, whilst their inner extremities are ele- vated ; the pupils of the eyes are in part concealed by the upper eye- lids, and the nostrils are agitated. Agony of mind is here added to the bodily suffering, which is particularly indicated by the change in the eyebrow, and forehead. 1 Philosophical Transact, for 1824, p. 247; see, also, Letters on Natural Magic, by Sir D. Brewster, Amer. edit., p. 115, New York, 1832. GESTURES—FACIAL EXPRESSION. 503 In rage, the features are unsteady; the eyeballs are largely seen, roll, and are inflamed. The forehead is alternately knit and raised in furrows by the motion of the eyebrows ; and the nostrils are inflated to the utmost; the lips are swelled, and, being drawn, open the corners of the mouth. The action of the muscles is strongly marked. The whole countenance is at times pale ; at others, inflated, dark and almost livid; the words are passed forcibly through the fixed teeth, and the hair is on end. Fear has different degrees. Mere bodily fear resembles the mean anticipation of pain. The eyeball is largely uncovered; the eyes are staring, and the eyebrows elevated to the utmost stretch. To these are added a spasmodic affection of the diaphragm and muscles of the chest, which affects the breathing, and produces a gasping in the throat, with an inflation of the nostrils, convulsive opening of the mouth, and drop- ping of the jaw ;—the lips nearly concealing the teeth, yet allowing the tongue to be seen, and the space between the nostril and lip being full. There is a hollowness and convulsive motion of the cheeks, and a trem- bling of the lips and muscles on the sides of the neck. The lungs are kept distended; and the breathing is short and rapid. The surface is pale from the recession of blood; and the hair is lifted up by the creep- ing' of the skin. In fear, where the apprehended danger is more remote, but is approaching, the person trembles and looks pale; a cold sweat is on the face ; the scream of fear is heard; the eyes start forward; the lips are drawn wide; the hands are clenched, and the expression becomes more strictly animal, and indicative of such fear as is common to brutes. In terror or that kind of fear in which the mind participates more there is a more varying depression in the features, and an action of those muscles, which are peculiar to man, and seem to indicate his superior intelligence and mental feeling. The eye is bewildered ; the inner extremity of the eyebrows is turned up, and strongly knit by the action of the corrugator and orbicular muscles ; and distracting thoughts, anxiety and alarm are strongly indicated by this expression, which does not belong to animals. The cheek is slightly elevated, and all the muscles, that concentrate about the mouth, are in action. In admiration, the forehead is expanded and unruffled ; the eyebrow gently raised ; the eyelid lifted so as to expose the coloured circle of the eye, whilst the lower part of the face is relaxed into a gentle smile. The mouth is open ; the jaw is a little fallen ; and, by the relaxation of the lower lip, we just perceive the edge of the lower teeth and the tongue. In joy, the eyebrow is raised moderately, but without any angularity; the forehead is smooth; the eye full, lively and sparkling ; the nostril moderately inflated, and a smile is on the lips. This subject is, however, interminable. Enough has been stated to exhibit the anatomy of the varying characters of facial expression. It will be found beautifully treated and illustrated in the work of Sir Charles Bell, to which reference has been made. From all that has been said, it is evident, that the countenance is a good general index of the existing state of the feelings; but farther 504 MUSCULAR MOTION. than this it cannot be depended upon. Yet, in all ages, it has been regarded as the index of individual character. Allusion has been made to the estimate of personal character from the shape of the head, as described by the older poets. Similar indications were conceived to be deducible from the form of the face, expression of the eyes, &c. Thus Shakspeare:— Cleopat. " Bear'st thou her face in mind ? is't long or round 1 Messeng. Round, even to faultiness. Cleopat. For the most part, too, They are foolish that are so. Her hair, what colour'? Messeng. Brown, madam, and her forehead As low as she would wish it." Antony add Cleopatra, iii. 3. And again:— " Which is the villain ? Let me see his eyes, That when I note another man like him, I may avoid him." Much Ado About Nothing. John Baptist Porta1 and Lavater2 have endeavoured to establish a " science," by which we can be instructed, how to discover the secret dispositions of the head and heart from the examination of particular features. The latter enthusiast, in particular, appears to have carried his notions to the most chimerical extent. "No study," he remarks, " excepting mathematics, more justly deserves to be termed a science than physiognomy. It is a department of physics including theology and belles lettres, and in the same manner with these sciences may be reduced to rule. It may acquire a fixed and appropriate character. It may be communicated and taught." In another place, he remarks, that no person can make a good physiognomist unless he is a well-pro- portioned and handsome man ;3 yet he himself was by no means highly favoured in these respects; and it is difficult to say, according to his own theory, how he obtained such progress in the " science !" There is one case, and perhaps, one only, in which physiognomy can aid us in the appreciation of character. It has been remarked, that the facial expression may accurately depict the existing emotion. If, therefore, any passion be frequently experienced, or become habitual, its character may remain impressed upon the countenance, and admit of an opinion being formed of the individual. No one, who has seen the melancholy mad, can mistake the piteous expression produced by brooding over the corroding idea that engrosses him. In the sketch (Fig. 207), from Sir Charles Bell,4 we have the testy, peevish counte- nance, bred of melancholy; of one who is incapable of receiving satis- faction from whatever source it may be offered, and who "cannot endure any man to look steadily upon him, even to speak to him, or laugh, or jest, or be familiar, or hem, or point,.without thinking himself contemned, insulted, or neglected." Such a countenance no one can misapprehend. 1 La Physiognomie Humaine de JeanBaptiste Porta, Rouen, 1655. 2 Works, from the French, by G.Grenville,Esq.,Lond.; or Precis Analytique et RaisonnS du Systeme de Lavater, par N.J. Ottin, Bruxelles, 1834. » Good's Book of Nature, iii. 309, Lond., 1834. 4 Anat. of Expression, edit. cit. GESTURES. 505 In lesser degrees, Fig- 207. particular features are found bearing, or seeming to bear, the impress of par- ticular emotions; and, accordingly, we are in the daily habit of forming opinions at first sight, both of the intellectual and moral characteris- tics of individuals, by the expression of the countenance. Of course, we are fre- quently led into er- ror ; inasmuch as habitual feelings alone are indicated by the physiognomy, whilst the natural disposition may be of an opposite cha- racter. The falla- ciousness of this mode of judging of mankind has been proverbial in all times. Whenever we attempt to decide upon a man's intellectual powers by the rules laid down by Lavater we are constantly deceived; and, in this respect, he has himself evidently fallen into gross errors. What may be, not inappropriately, styled "medical physiognomy," or the changes of features indicative of, and peculiar to, different dis- eases and stages of disease, is a subject of moment, and has not met with sufficient attention. In diseases of infancy in particular, the ap- pearance of the countenance often materially aids us in discriminating their seat. There is a marked difference between the facial expression of one labouring under violent pain in the head, and of one suffering from excruciating pain in the abdomen, even in the adult. Less degrees of pain are, of course, disregarded; and it is only in severe cases, that physiognomy can be inservient to diagnosis; but in the infant, which readily gives expression to pain or uneasiness, the countenance is an excellent medium of discrimination, and frequently indicates, at the first glance, the seat of the derangement. The character, too, of the coun- tenance, in serious disease, as to anxiety, convulsion, &c, is often a subject of watchful interest with the physician.1 Mute expression is * See, on special medical physiognomy, M. Jadelot, cited by M. de Salle, in Traite des Maladies des Enfans de Michael Underwood, &c, p. 36 et seq.; and in the author's Com- mentaries on Diseases of the Stomach and Bowels, p. vii., Lond., 1824. Physiognomy of Melancholy. (Sir Charles Bell.) 506 MUSCULAR MOTION. not, however, restricted to the face, although, as already remarked, in civilized man, whose nakedness is covered, we are shut out from the observation of many acts of this nature. During emotion, the skin covering the body may participate with that of the face in its changes from pale to red; and it may be warm or cold; dry or bathed in perspi- ration; or, during particular depressing passions, may creep and exhibit the rough character of the cutis anserina or goose skin. Under special emotions, the erectile tissues of the organs of generation, and of the nipple in the female, experience turgescence. All these changes are more or less concealed from view. We are, therefore, more familiar with the sight of phenomena of expression, that affect the whole body, as regards its different attitudes and modes of progression. How tre- mulous and vacillating is the attitude of one labouring under fear; and how different the port of the meek and lowly from that of the proud and haughty! In walking, we observe a similar difference; and can frequently surmise the passion, whether exhilarating or depressing, under which a person, at a distance, may be labouring, from the cha- racter of his progression. " You may sometimes trace A feeling in each footstep, as disclosed By Sallust, in his Catiline, who, chased • By all the demons of alj passions, showed Their work even by the way in which he trode."—Byron's "Don Juan." Again, on the communication of sudden tidings of joy, we feel a desire to leap up, and give way to the most wild and irregular motions; whilst the shrinking within ourselves, as it were, and the involuntary shudder, sufficiently mark the reception of a tale of horror. Properly speaking, the subject of cranioscopy belongs to the func- tion of expression, but it has already been considered under another head. Many of the partial movements constitute an important part of the language of expression, especially with the savage, and with those unfortunates who are debarred the advantages of spoken language. In almost all nations, the motions of the head on the vertebral column are used as signs of affirmation or negation;—the former being indi- cated by a sudden and short forward flexion of the head on the column; the latter, by a rapid and short rotation on the axis or vertebra den- tata. The shoulders are shrugged in testimony of impatience, con- tempt, &c. The upper extremities are extensively employed as a part of conventional language, and were probably used for this pur- pose before speech was invented. The open and the closed hands communicate different impressions to the observer; the pointed finger directs attention to the object we desire to indicate, &c. When per- sons are at such a distance from each other, that the voice cannot be heard, this is the only language they can have recourse to; and the various important inventions, by which we communicate our feelings to a distance, such as writing and telegraphing, belong to this variety of language. For the deaf and dumb, our ordinary spoken language is translated into gestures, by which a conversation can be held, sufficient for all useful purposes; whilst the deaf, dumb, and blind are mainly GESTURES—NATURAL SIGNS OF THE PASSIONS. 507 restricted to those gestures that are conveyed through their sense of touch. Each acquired gesture is, like each acquired movement of the glottis, an evidence of the possession of intellect. The infant and the idiot have them not, because unable to appreciate their utility. The ges- tures resemble the spoken language in this and many other respects. The eye sees the gesture, to which the intellect attaches an idea as it does to the sound conveyed by the organ of hearing; and the will reproduces the gesture, in the same manner as it reproduces the sound heard. The lower extremities are, also, slightly concerned in the func- tion of expression. They are agitated when impatient, and incessantly changing their position. The foot is stamped' upon the ground in anger; and, like the upper extremity, is employed to convey to the object that has aroused the emotion the most unequivocal evidences of expression. Occasionally, the lower extremity is used as a part of conventional language, as when we tread upon the toes to arouse atten- tion, or to convey insult. Nor are the internal organs foreign to the function of expression. The respiratory movements are affected,—the number of respirations being accelerated or retarded, or manifesting themselves under the different modifications of sighing, yawning, laughing, and sobbing. The heart, too, throbs at times to such an extent, that its action is perceptible externally; or, it may be retarded or hurried in its pulsations,—from a state of syncope or fainting to that of the most violent palpitation. Lastly: the excretions, certain of them especially, are greatly impli- cated in many of these moral changes. That of the tears is a well- known and characteristic expression—of grief more especially, but occasionally of joy. The mind, 'however, may be so possessed by the emotion, that the ordinary power over the sphincter muscles may be more or less destroyed, and the contents of the rectum be spontane- ously evacuated. The action of the stomach is, at times, inverted; and, at others, the peristaltic action is augmented. Who has not felt, whilst labouring under anxiety or dread, the constant desire not only to evacuate the faeces, but also the urinary secretion ! It is obvious, from this detail, that there is scarcely a function, which does not express some participation, when the mind is engaged in deep emotion; and that it would be vain to attempt to depict the various forms under which these manifestations may occur. What has been said will suffice to attract attention to the subject, which is not devoid of interest to the anthropologist. In conclusion, we may refer to the question that has often been agi- tated, whether these rapid and violent movements, that characterize the expression of emotions, be instinctive or natural signs of the pas- sion existing in the mind; or whether they be not voluntary muscular exertions, called for by the stress of the case, and constituting the means of resistance, or belonging simply to the outward manifestation of the inward emotion. The supporters of the latter view contend, that the various changes of facial expression or of gesture, which accompany the different mental emotions and indicate their character. 508 MUSCULAR MOTION. are, in all cases, the effect of habit, or are suddenly excited to accom- plish some beneficial purpose. It is difficult, however, to regard the different concomitants of the passion as separate from it. Without them, the expression is incomplete; and, moreover, we observe the dif- ferent gestures similarly developed in all the various races of mankind, when affected with the same mental contention. We must, conse- quently, regard the expressions as constituting a natural language, in which each has its appropriate sign; and this view is confirmed by the fact, that there are certain muscles of the face, which seem, in our existing state of knowledge, to be exclusively destined for expression; —those about the eyebrows and angles of the mouth for example. When the triangularis muscle and levator menti combine action, an expres- sion is produced, which is peculiar to man; the angle of the mouth is drawn down, and the lip arched and elevated; hence the most con- temptuous and proud expression. A question of a different character has, however, been mixed up with this:—whether the infant be capable instinctively or naturally of com- prehending the difference between the facial expressions of kindness or of frowns; some believing, that smiles are merely considered by it to be expressions of kindness, because accompanied by endearments,— and frowns to be proofs of displeasure, because followed by punishment. It is certain, however, that the infant interprets the countenance long before it can trace such sequences in its mind; but this does not remove the difficulty. The face of one, whom it has not been accustomed to see, will, at a very early period, impress it unfavourably, although the countenance may be unusually prepossessing; and the alteration of the ordinary expression of the material countenance may be attended with similar results. It is difficult, indeed, to comprehend how the child should be capable of discriminating between the smile And frown, when first presented to it. That organs may be associated in the expression of any encephalic act is intelligible; but that an act of judgment can be executed naturally or instinctively appears inexplicable. Sir Charles Bell,1 who maintains the doctrine of the instinctive character of the expression of human passions, rejects the notion of instinctive expres- sion in the face of the quadruped, contending that, even in the passion of rage, which is the most strongly marked of all the changes that occur in the features, are merely motions accessory to the great objects of opposition, resistance, and defence. "In carnivorous animals," he remarks, "the eyeball is terrible, and the retraction of the flesh ofthe lips indicates the most savage fury. But the first is merely the excited attention of the animal, and the other a preparatory exposure of the canine teeth." It appears to be a sufficient answer to this view, that no such expression is ever witnessed in other cases of excited attention, or in the simple exposure of the canine teeth, when the animal is de- vouring its food; unless, indeed, the repast be made during the exist- ence of the passion. On a former occasion, it was remarked, that the encephalon is ex- clusively concerned in the production of the different passions, and that * Anat. of Expression, edit. cit. GESTURES—NATURAL SIGNS OF THE PASSIONS. 509 the parts to which they are usually referred, attract our attention to them principally, in consequence of the sensation which accompanies them being there chiefly experienced. The same may be said of the different gestures that accompany the various emotions. They are dependent upon the influence exerted by the function of sensibility on the other functions. Gall,1 in his system, has feebly attempted to show, that each gesture has a reference to the encephalic situation of the organ concerned in the production of the emotion of which it is a con- comitant. The idea was suggested to him, he asserts, by the fact, observed by him a thousand times, that in fractures of the skull, the hand, (naturally we should think,) was carried mechanically to the seat of the' fracture. He farther remarks, that the organs of the memory of words and of meditation are seated in the forehead; and that the hand is carried thither, whenever we are engaged in deep study;—that the organ of religious instinct corresponds to the vertex; and hence, in the act of prayer, all the gestures are directed towards that part of the body. Like every professed systematist, Gall is here pushing his prin- ciples ad absurdum. They are, indeed, controverted by facts. The hand is usually carried, not to the part of the encephalon in which any passion is effected, but to the part of the body in which its more pro- minent effects are perceptible,—as to the region of the stomach or heart; and frequently the gesture is referable to the determinate action, which must be regarded as a necessary effect of the passion. Finally, poetry and painting belong properly to the varieties of ex- pression ; but they are topics that do not admit of elucidation by phy- siology. Here terminates the history of the animal functions, which have the common character of being periodically suspended by sleep. By many physiologists, this function has, therefore, been examined in this place; Wt as the nutritive and generative functions are, likewise, greatly in- fluenced by sleep, we shall follow the example of M. Magendie,2 and defer its study until those functions have been inquired into. CILIARY MOTION. Although not an animal function, it may be convenient to allude, in this place, to the phenomena of vibratory or ciliary motion, which, in recent times, have received the attention of observers. These terms have been employed to express the appearance produced by cilia,—a peculiar sort of moving bodies resembling small hairs, which are visible by the aid of the microscope, on parts that are covered with ciliary or vibratory epithelium.3 1 Sur les Fonctions du Cerveau, v. 436, Paris, 1825. * Precis Elementaire, i. 366. » See page 132; and, also, Sharpey, art. Cilia, Cyclop, of Anat. and Physiol., P. vi., p. 606, Lond., 1836; and Henle, Allgem. Anat., or Jourdan's French Translation, p. 251, Paris, 1843 ; and the excellent article Flimmerbewegung, by Valentin, in Wagner's Handworterbuch der Physiologie, 3te Lieferung,s. 484, Braunschweig, 1842. 510 CILIARY MOTION. Cilia. This ciliary motion has been seen in different animals, on the external surface, in the aliment- ary canal, the respiratory sys- tem, the female generative or- gans ; and in the cavities of the nervous system. It has not been observed, however, in the vagina; but may be traced from the lips of the os uteri through its cavity, and through the Fallopian tubes to their fimbriated extremities. In the upper classes of animals, it is not witnessed on the external 1. Portion of a bar of the gill of the Mytilis f.du- cllrfopp PYnpnt in tVip pmhvvn Tn *is, showing cilia at rest and in motion. 2. ciliated suriace except in tne emoryo. in epithelium particles from frog's mouth. 3. Ciliated mOSt animals, a high magnifying epithelium particle from inner surface of human . ° . */ . ° membrana tympani. 4. Ditto, ditto : from the human power IS neCeSSary tO perceive it. bronchial mucous membrane. 5. Leucophrys patula, » email tUpcc- nf mnemm mem a polygastric infusory animalcule; to show its sur- -«- eiildll piece Ol LUUCUUS in em- face covwed with cilia, and the mouth surrounded by Drane on which it exists, should them. (Todd and Bowman.) ' . . . ' be moistened with water, and Fig. 209. covered with a plate of glass, by which the. membrane is spread out, and its border rendered clear- ly visible. With the aid of a pow- erful microscope, an appearance of undulation is perceptible, and small bodies floating in the water may be, seen, near the border of the membrane, to be driven along in a determinate direction. With a still higher magnifying power, the cilia themselves may sometimes be recognized, although seldom very distinctly, owing to the great rapidity of their motion. The influence of the motion on the fluids and small bodies in contact with the membrane may be well exhibited by strewing a fine powder on the surface; as the motion of the cilia has a uniform direction, it gives rise to currents over the surface of the membrane. An easy mode of observing the phenomenon is to scrape with a knife a few scales of epithelium from the back of the throat of a living frog. If these be moistened with water or serum, they will continue to exhibit the motion of the adherent cilia for a very considerable time, if the epithelium be only kept moistened. On one occasion, Messrs. Todd and Bowman observed a piece of epithelium prepared in this manner exhibit motion for seventeen hours; and they thought it would probably have done so for a longer time had not the moisture around it evaporated. In the turtle, after death by decapitation, MM. Purkinje and Valentin found it lasted in the mouth nine days; in the trachea and lung, thirteen days; and in the oesophagus, nineteen days.1 1 Physiological Anatomy and Physiology of Man, by Messrs. Todd and Bowman, p. 62, Lond., 1843. Vibratile or Ciliated Epithelium. a. Nucleated cells, resting on their smaller extre- mities, b. Cilia. CILIARY MOTION. 511 According to M. Donne,1 cilia are seen only on the "true mucous membranes" of his division,2 or those that secrete an alkaline mucus. They are never met with on the acid membranes, which are analogous to the skin, and simple reflections of the cutaneous envelope. Hence, they are not found in the mouth or vagina, but in the nasal and bron- chial mucous membrane. The organs of ciliary motion are delicate transparent filaments, varying in length, according to Purkinje and Valentin, from j^ini to y^'jg of an inch, and are generally thicker at the base than at the free extremity. Their motion continues after death as long as the tissues retain their contractility, and often much longer. Miiller3 thus sums up the present state of our knowledge in regard to the phenomenon: That the ciliary motion of the mucous membranes is due to the action of some unknown contractile tissue, which lies either in the substance of the cilia or at their base,—that this tissue resembles in contractility the muscular and other contractile tissues of animals;—that its pro- perties so far agree with those of the muscular tissues—at all events with those of the involuntary muscles of the heart, and the vibratory laminae of the lower Crustacea;—that the motions, which it produces, continue without ceasing with an equable rhythm ;—that its properties agree also with those of the muscular tissue of the heart in its motions, continuing long after the separation of the part from the rest of the animal body;—that this tissue differs essentially, however, from muscle, in the circumstance of its motions not being arrested by the local ap- plication of narcotics; and lastly, that the ciliary motion presents itself under conditions where it is not probable that a complicated organization exists,—namely, in the undeveloped embryos of polypiferous animals. M. Donne'4 regards the cilia as animalcules; resembling in many respects the spermatozoids. They certainly resemble each other; but there is no sufficient reason to believe either of them animalcular. The production of currents by the ciliary motion is not easy of ex- planation. Purkinje and Valentin ascribe them to the return of the cilia from the bent to the erect state, which gives an impulse to the fluid. The direction in which the cilia act is most commonly towards the outlet of the canal on which they are placed; but, as Mr. Paget5 has remarked, their special purpose is in many instances—for example, in the ventricles of the brain—as uncertain as the power by which they act. We shall have to refer to ciliary motion under other heads. V Coursde Microscopie, p. 170, Paris, 1844. 1 See Secretion of Mucus in vol. ii. of this work. 3 Elements of Physiology, by Baly, P. iv. p. 866, Lond., 1838. 4 Op. cit., p. 176. 6 Brit, and For. Med. Review, July, 1842, p. 264. 512 DIGESTION. BOOK II. NUTRITIVE FUNCTIONS. The human body, from the moment of its formation to the cessation of existence, is undergoing constant decay and renovation—decomposi- tion and composition:—so that at no two periods can it be said to have exactly the same constituents. The class of functions about to engage attention, embraces those that are concerned in effecting such changes. They are seven in number ;—digestion, by which . the food, received into the stomach, undergoes such conversion as fits it for the separa- tion of its nutritious and excrementitious portions; absorption, by which this nutritious portion, as well as other matters, is conveyed into the mass of blood; respiration, by which the products of absorption and venous blood are converted into arterial blood; circulation, by which the vital fluid is distributed to every part of the system; nutri- tion, by which the intimate changes of composition and decomposition are accomplished; calorification, by which the system is enabled to resist the effects of greatly elevated or depressed atmospheric tempera- ture, and to exist in the burning regions within the tropics, or amidst the arctic snows; and secretion, by which various fluids and solids are separated from the blood;—some to serve useful purposes in the ani- mal economy; others to be rejected from the body. CHAPTER I. OF DIGESTION. The food, necessary for animal nutrition, is rarely found in such a condition as to be adapted for absorption. It has, therefore, to be subjected to various actions in the digestive organs; the object of which is to enable the nutritive matter to be separated from it. These actions constitute the function of digestion; in the investigation of which we shall commence with a brief description of the organs con- cerned in it. These are numerous, and of a somewhat complicated nature. 1. ANATOMY OF THE DIGESTIVE ORGANS. The human digestive organs consist of a long canal, varying con- siderably in its dimensions in different parts, and communicating ex- ternally by two outlets,—the mouth and anus. It is usually divided into four chief portions—the mouth, pharynx, oesophagus, stomach, and intestines. These we shall describe in succession. DIGESTIVE ORGANS. 513 1. The mouth is the first cavity Fig. 210. of the digestive tube, and that into which the food is immediately re- ceived, and subjected to the action of the organs of mastication and in- salivation. Above and below, it is circumscribed by the jaws, and la- terally by the cheeks;—anteriorly by the lips and their aperture, con- stituting the mouth proper; and, posteriorly, it communicates with the next portion of the tube,—the pharynx. It is invested by a mu- cous exhalant membrane, which is largely supplied with follicles; and into it the ducts from the different salivary glands pour their secre- tion. In all animals furnished with distinct digestive organs, means exist for comminuting the food, and enabling the stomach to act with greater facility upon it. These consist, for the most part, as in man, of the jaws, the teeth fixed into the jaws, and muscles by which the jaws are moved. The jaws chiefly determine the shape and dimensions of the mouth; the upper forming an es- sential part of the face, and mov- ing only with the head; the lower, on the contrary, possessing great mobility. Each of the jaws has a prominent edge, forming a semi- circle, in which the teeth are im- planted. This edge is called the alveolar arch. The teeth are small organs, of a density superior to bone; and covered externally by a hard substance called enamel. By many, they have been regarded as bone; but they differ from it in many essential respects, although they resemble it in ' hardness and chemical composition. At another opportunity we shall inquire into their origin, structure, and developement. We may merely remark, at present, that by many they are looked upon as analogous to the corneous substances, which develope themselves in the tissue of the skin. De Blainville assimilates them to the hair; and believes, that they are primarily developed in the substance of the membrane lining the mouth; and that their enclosure in the substance of the alveolar arches of the jaws occurs subsequently. vol. 1.—33 Diagram of the Stomach and Intestines to show their course. 1. Stomach. 2. CEsophagus. 3. Left, and 4. Right end of stomach. 5, 6. Duodenum. 7. Convolu- tions of jejunum. 8. Those of ileum. 9. Caecum. 10. Vermiform appendix. 11. Ascending; 12. Trans- verse; and 13. Descending colon. 14. Commence- ment of sigmoid flexure. 15. Rectum. 514 DIGESTION. The number of the teeth is sixteen in each jaw. These are divided into classes, according to their shape and use. There are, in each jaw, four incisores; two cuspidati or canine teeth; four bicuspidati; and six molares ox grinders. Each tooth has three parts:—the crown, neck, and fang or root;—the first being the part above the gum; the second that embraced by the gum; and the third, the part contained in the alveolus or socket. The crown varies in the different classes. In the incisors, it is wedge-shaped; in the canine, conical; and in the molar, cubical. In all, it is of extreme hardness, but in time wears away by the constant friction to which it is exposed. The incisor and canine teeth have only one root; the molares of the lower jaw, two; and the upper, three. In all cases, they are of a conical shape, the base of the cone corresponding to the corona, and the apex to the bot- tom of the alveolus. The alveolar margin of the jaws is covered by a thick, fibrous, resisting substance, called gum. It surrounds accurately the inferior part of the crown of the tooth, adheres to it strongly, and thus adds to the solidity of the junction of the teeth with the jaws. It is capable of sustaining considerable pressure without inconvenience.— But we shall have to return to the subject of the teeth hereafter. The articulation of the lower jaw is of such a nature as to admit of depression and elevation; of horizontal motion forwards, backwards, and laterally; and of a semi-rotation upon one of its condyles. The muscles that move it may be thro,wn into two classes:—elevators and depressors. These, by a combination of their contraction, can produce every intermediate movement between elevation and depression. The raisers or levator muscles of the jaw extend from the cranium and upper jaw to the lower. They are four in number on each side,—the temporal, and masseter, which Fig. 211 are entirely concerned in the function; the external pterygoid, which, whilst it raises the jaw, carries it at the same time forward, and to one side; and the internal pterygoid, which, according as it unites its action with ^.^-.m^^ywro^.—•ssssss,- the temporal or with Skull of the Polar Bear. the external pterygoid, is an elevator of the jaw or a lateral motor. The depressors may be divided into imme- diate and mediate, according as they are, or are not, attached to the lower jaw itself. There are only three of the former class: 1, the digastricus, the anterior fasciculus of which, or that which passes from the os hyoides to the lower jaw, depresses the latter; 2, the genio- hyoideus; and 3, the mylo-hyoideus, all of which concur in the forma- tion of the floor of the mouth. The indirect or mediate depressors are all those, that are situate between the trunk and the lower jaw, without being directly attached to the latter;—as the thyro-hyoideus, DIGESTIVE ORGANS. 515 Fig. 212. the sterno-thyroideus, and the omo-hyoideus; the names of which indi- cate their origin and insertion. These, in the aggregate, form a mus- cular chain, which, when it makes the trunk its fixed point, depresses the lower jaw. The arrangement of the elevators and depressors is such, that the former predominate over the latter; and hence during sleep the jaws continue applied to each other, and the mouth is conse- quently closed. The human organs of mastication hold an intermediate place between those of the carnivorous and herbivorous animal. In the carnivorous animal, which has to seize hold of, and retain its prey between its teeth, the jaws have considerable strength; and the movement of elevation is all that is practicable; or, at least, that can be effected to any extent. This is dependent upon organization. The condyle is broader from side to side, which prevents motion in that direction: the glenoid cavity is very deep, so that the head of the jaw-bone cannot pass out of it; and it is, moreover, fixed in its place by two eminences before and behind. The muscular apparatus is also so arranged as to admit of energetic action on the part of the muscles that raise the jaw; but of scarcely any in a horizontal direction. The deep impressions in the regions of the temporal and masseter muscles indicate the large size of these mus- cles in the purely carnivorous animal; whilst the pterygoid muscles are extremely small. The teeth, too, are characteristic; the molars being comparatively small, at the same time that they are much more pointed. On the other hand, the cuspidati are remarkably large, and the incisors, in general, acuminated. The herbivorous animal has an ar- rangement the reverse of this. The condyle or head of the lower jaw is rounded; and can, therefore, be moved in all directions; and as easily hori- zontally as up and down. The glenoid cavity is shallow, and yields the same facilities. The articulation, which is very close in the carnivorous animal, is here quite loose. The levator muscles are much more feeble; the temporal fossa is less deep; the zygomatic arch less convex; and the zygomatic fossa less extensive. On the other hand, the pterygoid fossa is ample and the muscles of the same name are largely developed. The molares are large and broad; and their magnitude is so great as to require, that the jaw should be much elongated in order to make room for them. . The joint of the lower jaw has, in man, solidity enough for the jaws to exert considerable pressure with impunity, and laxity enough that the lower jaw may execute horizontal movements. The action of the leva- Skull of the Cow. 516 DIGESTION. tor muscles is the most extensive; but the lateral or grinding motion is practicable to the necessary extent; and the muscles of both kinds have a medium degree of developement. The teeth, likewise, partake of the characteristics of those of the carnivorous and herbivorous animals ;—twelve—the canine teeth and lesser molares—corresponding to those of the carnivorous; and twenty—the incisors and larger mo- lares—to those of the herbivorous. The tongue must be regarded as an organ of mastication. It rests horizontally on the floor of the mouth; is free above, anteriorly; and, to a certain extent, beneath and at the sides. Behind, it is united to the epiglottis by three folds of the mucous membrane of the mouth; and is supported at its base by the os hyoides, with which it partici- pates in its movements. The tongue, as the organ of taste and articu- lation, has been described already (p. 145). We have only, therefore, to describe the os hyoides and its attachment to that bone. The hyoid bone has, as its name imports, the shape of the Greek letter v, the convex part being before. (Fig. 194.) It is situate between the tongue and larynx : and is divided into body or central part; and into branches, one extremity of which is united to the body by an inter- mediate cartilage, that admits of slight motion; whilst the other is free, and is called greater cornu. Above the point, at which the branch is articulated with the body, is an apophysis or process, called lesser cornu. The os hyoides is united to the neighbouring parts by fibrous organs, and muscles. The former are;—above, the stylo-hyoid ligament, which extends from the lesser cornu of the bone to the styloid process of the temporal bone; below, a fibrous membrane, called thyro-hyoid, passing between the body of the bone and the thyroid cartilage; and two liga- ments, extending from the greater cornu of the hyoid bone to the thyroid cartilage, called thyro-hyoid. Of the muscles; some are above the hyoid bone, and raise it;—viz., the genio- and mylo-hyoideus, already referred to; the stylo-hyoid, and some fibres of the middle constrictor of the pharynx. Others are below, and depress it. They are the sterno-thyro- hyoideus, omo-hyoideus and sterno-thyroideus. The base of the tongue is attached to the body of the bone by a ligamentous tissue, and by the fibres of the hyoglossus muscle. Among the collateral organs of mastication are those which secrete the saliva, and the various fluids which are poured out into the mouth, —constituting together what has been termed the apparatus of insali- vation. These fluids proceed from different sources. The mucous membrane of the mouth, like other mucous membranes, exhales a serous or albuminous fluid, besides a mucous fluid secreted by the nu- merous follicles contained in its substance. Four glands likewise exist on each side, destined to secrete the saliva, which is poured into the mouth by distinct excretory ducts. They are the parotid, submaxil- lary, sublingual, and intra-lingual or lingual. The first is situate be- tween the ear and the jaw; and its excretory duct opens into the mouth opposite the second small molaris of the upper jaw. By pressing upon this part of the cheek, the saliva can be made to issue into the mouth, in perceptibly increased quantity. The submaxillary gland is situate beneath the base of the jaw; and its excretory duct opens into DIGESTIVE ORGANS—SALIVARY GLANDS. 517 the mouth at the side Fig. 213. of thefrsenum linguae. The sublingual gland is situate under the tongue, and its excre- tory ducts open at the sides of that organ, and the intra-lingual or lingual is seated at the inferior surface of the tongue, where the mucous membrane forms a fringed fold. Theseglands are con- stantly pouring saliva into the mouth ; and it has been presumed, that the fluids Se- Salivary Glands in situ. Cretetl by tnem may 1. Parotid gland in situ, extending from the zygoma above, to the differ from each Other ?ngrle^f ^ laZhf}™' ,2-1D"ctof Sten0- 3- Submaxillary gland. . 4. Its duct. 5. Sublingual gland. in physical and che- mical characters. Such, at least, has been the view of some as re- gards the sublingual, the texture of which more nearly resembles that of the compound follioles than of glands; but the circumstance has not been proved by any direct experiment. The saliva, as met with, is a compound of every secretion poured into the mouth: and it is this fluid which has been chiefly subjected to analysis. The secretion of the saliva, and its various properties, will be considered, however, hereafter. The two apertures of the mouth are the labial and pharyngeal. The former, as its name imports, is formed by the lips, which consist ex- ternally of a layer of skin ; are lined internally by a mucous membrane; and, in their substance, contain numerous muscles, already described under the head of Gestures. These muscles may be separated into constrictors and dilators; the orbicularis oris being the only one of the first class, and the antagonist to the others, which are eight in number, on each side—levator labii superioris alaeque nasi, levator labii superioris proprius, levator anguli oris, zygomaticus major, zygomati- cs minor, buccinator, triangularis, and quadratus menti. (Fig, 201.) To the last two muscles are added some fibres of the platysma myoides. The pharyngeal opening is smaller than the labial, and of a quadri- lateral shape. It is bounded above by the velum palati or pendulous veil of the palate; below, by the base of the tongue; and laterally, by two muscles, which form the pillars of the fauces. The pendulous veil is a musculo-membranous extension, constituting a kind of valve, at- tached to the posterior margin of the bony palate, by which all com- munication between the mouth and pharynx, or between the pharynx and nose can be prevented. (Fig. 214.) To produce the first of these effects, it becomes vertical; to produce the latter, horizontal. At its inferior and free margin, it has a nipple-like shape, and bears the name 518 DIGESTION. Fig. 214. of uvula. It is composed of two mucous membranes, and of muscles. One of the mem- branes,—that forming its ante- rior surface—is a prolongation of the membrane lining the mouth, and contains numerous follicles; the other, forming its posterior surface, is an extension of the mucous membrane lining the nose, and is redder, and less provided with follicles than the -, other. The muscles that con- stitute the body of the velum - palati are —the circumflexus Cavity of the Mouth, as shown by dividing the An- palati or Spheno-Salpingo-sta- gies and turning off the Lips. phylinus of Chaussier; the leva- 1. Upper lip, turned up. 2. Its fraenum. 3.Lower tor palati OT petrOSalpingo-Sta- lip, turned down. 4. Its framum. 5. Internal surface v.J.,,.]l;v. i~l.t. nnA \*f+ Jfio/. .Ajvi.-inc 11 View ofExternal Parietes of Abdomen, with the po- sition of the Lines drawn to mark off its Regions. 5. le. The the principal digestive Organs gastric region. 10,10. Right and left iliac regions. "11. r. r n a . P , The lower part of the hypogastric, sometimes called are situate, and whose parietes pUbic. » Lecons d'Anatomie Comparee, Paris, 1799. 941 538 DIGESTION. exert considerable influence on the digestive function, requires a brief description. It is the division of the body, which is betwixt the thorax and pelvis; is bounded, above, by the arch of the diaphragm; behind, by the vertebral column; laterally, and anteriorly, by the abdominal muscles; and, below, by the ossa ilii, os pubis, and the cavity of the pelvis. To connect the knowledge of the internal parts of the abdomen with the external, it is customary to mark certain arbitrary divisions on the sur- face, called regions. (Fig. 245.) The epigastric region is at the upper portion of the abdomen, under the point of the sternum, and in the angle formed by the cartilages of the ribs. The hypochondriac regions are covered by the cartilages of the ribs. These three regions—the epigas- tric, and right and left hypochondre—constitute the upper division of the abdomen, in which are seated the stomach, liver, spleen, pancreas, duo- denum, and part of the arch of the colon. The space surrounding the umbilicus, between the epigastric region and a line drawn from the crest of one os ilii to the other, is the umbilical region. Here the small intes- tines are chiefly situate. This region is bounded by lines, raised per- pendicularly to the spine of the ilium; and the lateral portions on the outside of these lines, form the iliac regions, behind which, again, are the lumbar regions or loins. In these, the colon and kidneys are chiefly situate. The hypogastric is, likewise, divided into three regions,—the pubic in the middle, in which is the bladder; and an inguinal on each side. The muscles that constitute the abdominal parietes, are,—first of all, above, the diaphragm, which is the boundary between the thorax and abdomen, convex towards the chest, and considerably concave towards the abdominal cavity. Below, if we add the pelvic cavity,—which, as it contains the rectum, and muscles concerned in the evacuation of the faeces, it may be proper to do,—the cavity is bounded by the perineum, formed chiefly of the levatores ani and coccygei muscles. Behind, la- terally, and anteriorly, from the lumbar vertebrae round to the umbilicus, the parietes consist of planes of muscles, and aponeuroses in super- position, united at the median line, by a solid, aponeurotic band, extend- ing from the cartilago-ensiformis of the sternum to the pubes, called linea alba. The abdominal muscles, properly so called, are,—reckoning the planes from within to without,—the greater oblique muscle, lesser oblique, and transversalis, which are situate chiefly at -the sides of the abdomen;—and the rectus and pyramidalis, which occupy the anterior part. The greater oblique, obliquus externus, costo-abdominalis; lesser oblique, obliquus internus, ilio-abdominalis, and transversalis, transver- sus abdominis, lumbo-abdominalis, support and compress the abdominal viscera; assist in the evacuation of the faeces and urine, and in the expulsion of the foetus; besides other uses, connected with respiration and the attitudes. The rectus, pubio-sternalis or sterno-pubialis; and the pyramidalis or pubio-subumbilicalis, are more limited in their action, and compress the forepart of the abdomen; besides having other functions. Lastly, a serous membrane—the peritoneum—-lines the abdomen, and gives ,a coat to most of the viscera. The mode, in which its various DIGESTIVE ORGANS—PERITONEUM. 539 reflections are made, is singular, but easily intelligible from the accom- panying figure (Fig. 246). It has neither beginning nor end, constitut- Fig. 246. 1. Section of the spinal column and canal. 2. Section of the sacrum. 3. Section of the sternum, &c. 4. Umbilicus. 5. A section of the linea alba and abdominal muscles. 6. Mons veneris. 7. Section of the pubis. 8. Penis divided at the corpora cavernosa, 9. Section of the scrotum. 10. Superior right half of the diaphragm. 11. Section ofthe liver. 12. Section of the stomach, showing its cavity. 13. Section of the transverse colon. 14. Section of the pan- creas, 15. Section of the bladder, deprived of the peritoneum. 16. Rectum cut off, tied and turned back on the promontory of the sacrum. 17. Peritoneum covering the an- terior parietes of the abdomen. 18. Peri- toneum on the inferior under side of the diaphragm. 19. Peritoneum on the convex side of the diaphragm. 20. Refleetion of peritoneum' from diaphragm to liver. 21. Peritoneum on front of liver. 22. The same,, on its under surface. 23. Hepato- gastric omentum. 24. A large pin passed, through the foramen of Winslow into the cavity behind the omentum. 25. Anterior face of the hepatb-gastric omentum, pass- ing in front of the stomach. 26. THe -same membrane leaving the stomach to make the anterior of the four layers of the. great omentum. 27, 28. Junction of the peri-' toneum from the front and back" part of the stomach, as they turn to go up to the colon. 29. Gastro-colic, or greater omentum. 3d. Separation of its layers, so as to cover the colon. 31. Posterior layer passing over the jejunum. 32. Peritoneum in front of the right kidney. 33. Jejunum cut off and tied. 34, 34. Mesentery cut off from the small intestines. 35. Peritoneum reflected from the posterior paries of the bladder to the anterior of the rectum. 36. Cul-de-sac be- tween the bladder and the rectu-m. > - Reflections of the Peritoneum, as shown in a Verti cal Section of the Body. ing, like all serous membranes, a shut sac; and, in reality, having no viscus within it. If we assume the diaphragm as the part at which it commences, we find it continued from the surface of that muscle over the'abdominal muscles, 5; then reflected, as exhibited by the curved line, over the bladder, 15; and, in the female, over the uterus ; thence over the rectum, 16; the kidney, enveloping the intestine, 13, and constituting, by its two laminae, the mesentery, 34; giving a coat to the liver, 11 ;' and receiving the stomach, 12, between its duplicatures. The use of this membrane is to fix and support the different viscera; to constitute, for each, a pedicle, along which the vessels and nerves may reach the intestine ; and to secrete a fluid, which enables them to move readily upon each other. When we speak of the cavity of the perito- neum, we mean the inside of the sac ; and when it is distended with fluid, as in ascites, the fluid is contained between the peritoneum lining the abdominal muscles, and that which forms the outer coat of the intes- tines. The omenta or epiploa are fatty membranes, which hang over the face of the bowels; and are reflections, formed by the peritoneum after it has covered the stomach and intestines. Their names sufficiently indicate their position :—the lesser epiploon or omentum,—the omentum 540 DIGESTION. hepato-gastricum; the greater or gastro-colic; and the appendices or appendiculae epiploicae; which last have already been referred to, and may be regarded as so many small epiploons. The abdomen is entirely filled by the contained viscera. There are several apertures in it; three, above, in the diaphragm, for the passage of the oesophagus, vena cava inferior, and aorta; one anteriorly in the course of the linea alba, which is closed after birth,—the umbilicus; and two anteriorly and inferiorly ; the one—the abdominal, inguinal; or supra-pubian ring—which gives passage to the vessels, nerves, &c, of the testicle; and the other—the crural arch—through which the vessels and nerves pass to the lower extremity. Lastly, two others exist in the inferior paries, for the passage of the obturator vessels and nerves, and sciatic vessels and nerves, respectively. Such is a brief view of the various organs concerned in digestion. To this might have been added the general anatomy of the liver and pancreas,—each of which furnishes a fluid, that is a material agent in the digestive process,—and of the spleen, which has been looked upon by many as inservient, in some manner, to the same function. As, how- ever, the physiology of these organs will be considered in another place, we defer their anatomy for the present. > 2. FOOD OF MAN". The articles, inservient to the nourishment of man, have usually been considered to belong entirely to the animal and vegetable kingdoms;' but there seems to be no sufficient reason for excluding those articles of the mineral kingdom that are necessary for the due constitution of the different parts of the body. Generally, the term food or aliment is applied to substances, which, when received into the digestive organs, are capable of being converted into chj\e; but, from this class again, the products ofthe mineral kingdom—chloride of sodium, phosphorus, sulphur, and lime, either in combination or separately—cannot, with entire propriety, be excluded. There are numerous tribes who feed at particular seasons more especially on mineral substances. Kessler affirms, that the quarriers on the Kyffhaiuser, in northern Thuringia, spread a Steinbutter—"rock butter," on bread, which they eat with appetite; and Humboldt relates, among many other instances, that of the Ottomacs, who, during the periodical rise of the Orinoco and Meta, when the taking of fish ceases—a period of two or three months' dura- tion—swallow great quantities of earth. They* found piles of clayballs in pyramidal heaps in the huts, and Humboldt was informed, that an Ottomac would eat from three-quarters of a pound to a pound and a quarter in a day. Some of, this earth was analyzed by M. Vauquelin, and found to contain no organic matter. It would appear, that the practice of eating earth exists in many parts of the torrid zone, among indolent nations, who inhabit the finest and most fertile regions of the globe. But it is not confined to them; for the same writer affirms, that in the north, by information communicated by Berzelius and Retzius, hundreds of cartloads of earth containing infusoria are annually consumed by the country people in the most remote parts of FOOD OF MAN. 541 Sweden as bread meal, and even more as a luxury—like tobacco—than as a necessary. In Finland, the earth is occasionally mixed with the bread. It consists of empty shells of animalcules, so small and soft as not to cranch perceptibly between the teeth, filling the stomach, but affording no real nutriment. Many similar cases are recorded by Hum- boldt.1 Animals are often characterized by the kind of food on which they subsist. The carnivorous feed on flesh; the piscivorous on fish ; the insectivorous on insects ; the phytivorous on vegetables; the granivorous on seeds ; the frugivorous on fruits ; the graminivorous and herbivorous on grasses ; and the omnivorous on the products of both the animal and vegetable kingdoms. In antiquity, we find whole tribes designated according to the aliment they chiefly used. Thus, there were the Ethio- pian and Asiatic ichthyophagi or fish-eaters ; the hylophagi, who fed on the young shoots of trees; the elephantophagi, and struthiophagi, ele- phant and ostrich-eaters, &c. &c. We have already shown, that the digestive apparatus of man is inter- mediate between that of the carnivorous and the herbivorous animal; that it partakes of both, and that man may, consequently, be regarded omnivorous ; that is, capable of subsisting on both the products of the animal and the vegetable kingdom;—an important capability, seeing, that he is destined to live in arctic regions, in which vegetable food is not to be met with, as well as in the torrid zone, which is more favorable for vegetable than animal life. The nature of the country must, to a great extent, regulate the food of its inhabitants ; for although commerce can furnish articles of luxury, and many, which are' looked upon as necessaries, no nation is entirely indebted to it for its Supplies. Besides, numerous extensive tribes of the human family are denied the advantages of commerce, and com- pelled to subsist on their own resources. This is the main cause why the Esquimaux, Samoiedes, &c, live wholly on animal food; and why the cocoa-nut, plantain, banana, sag6, yam, cassava, maize and millet, form chief artioles of diet with the natives of torrid regions. In certain countries, the scanty supply of the useful and edible ani- mals has given occasion to certain prohibitory dietetic rules and regula- tions, which have been made to form part of the religious creed, and, of course, are most scrupulously observed. Thus, in Hindoostan, animal food is not permitted to be eaten; but the milk of the cow is excepted. Accordingly, to insure the necessary supply of this fluid, the cow is made sacred; and its destruction a crime against religion. Amongst the laws of the Egyptians are similar edicts, but they seem to have been chiefly enacted for political purposes, and not in consequence of the unwholesome character of the interdicted articles. The same remark applies to many of the dietetic rules of Moses, for the regula- tion of the tables of the Hebrews. Blood was forbidden, in consequence, probably, of the fear entertained, that it might render the people too familiar with that fluid, and diminish the horror inculcated against 1 Ansichten der Natur; translated under the title of Aspects of Nature, by Mrs. Sabine, Amer. edit., p. 159, Philad., 1849. 542 DIGESTION. shedding it: the parts of generation were excluded from the table, because the taste, if indulged, might interfere with the reproduction of the species, &c. &c. We have said, that, in his arrangement.of the digestive organs, man is intermediate between the carnivorous and the herbivorous animal. Not the slightest ground is afforded by anatomy for the opinion of Rousseau, that man was originally herbivorous; or for that of Helvetius,1 that he was exclusively carnivorous. Broussonet affirms, that he is more herb- ivorous than carnivorous, since, of his thirty-two teeth, twenty resem- ble those of the herbivorous, whilst twelve only resemble those of the carnivorous animal. Accordingly, he infers, that, in the origin of society, the diet of man must have been exclusively vegetable. Mr. Lawrence,2 too, concludes, that, whether, we consider the teeth and jaws, or the immediate instruments of digestion, the human structure closely resembles that ofthe simiae—the great archetypes, according to Lord Monboddo3 and Rousseau, of the human race,—all of which are, in their natural state, herbivorous. Again:—a wide discrepancy between man and animals is observed in the variety of their aliments. Whilst the latter are generally restricted to either the animal or vegetable kingdom, and to but a small part of either, man embraces an extensive range, and by means of his culinary inventions can convert a variety of articles from both kingdoms into materials of sustenance. But it has been argued by those, who are sticklers for the natural, that man probably confined himself, primi- tively, like animals, to one kind of food; that he adhered'to this whilst he remained in his natural state, and that his omnivorous practices are a proof of his degeneracy. Independently, however, of all arguments deduced from organization, experience sufficiently shows the inaccuracy of such assertions. If we trace back nations to their,state of infancy, we find, that then, as in their more advanced condition, their diet was animal, or vegetable, or both, according to circumstances. Of this fact we have some signal examples in a part of the globe where the lights of civilization have penetrated to a less extent than in most others; and where the influence of circumstances that. prevailed in ancient periods has continued, almost unmodified, until the present time. Aga- tharchides4 describes the rude tribes, who lived on the coast of the Red Sea, and subsisted on fish, under the name ichthyophagi. Along both banks of the Astaboras, which flows on one side of Meroe, dwelt another nation, who lived on roots of reeds growing in the neighbour- ing swamps. These roots they cut to pieces with stones, formed them into a tenacious mass, and dried them in the sun. Close to them were the hylophagi, who lived on the fruits of trees, vegetables growing in the valleys, &c. To the west of these were hunting nations, who fed on wild animals, which they killed with the arrow. There were, also, other tribes, who lived on the flesh of the elephant and ostrich,—elephanto- 1 De PHonime, ii. 23, Londres, 1775. 3 Lectures on Physiology, Zoology, &c, p. 221, Lond., 1819. 3 On the Origin and Progress of Language, Pt. i. Book 2, Chap. 2, Edinb., 1773. 4 De Rubro Mare, in Hudson's Geograph. Minor., i. 37. FOOD OF MAN. 543 phagi and struthiophagi. Besides these, he mentions another and less populous tribe,' who fed on locusts, which came in swarms from the southern and unknown districts. The mode of life, with the tribes described by Agatharchides, dbes not seem to have varied'for the last two thousand years. Although cultivated nations are situated around them, they have made no progress themselves. Hylophagi are still to be met with. The Dobenahs, the most powerful tribe amongst the Shangallas, still live on the elephant; and, farther to the west, dwells a tribe, which subsists in the summer on the locust; and, at other seasons, on the crocodile, hippopotamus, and fish.1 In the infancy of society, as in his own infancy, man was perhaps almost wholly carnivorous; as the tribes least advanced in civilization are at the present day. For a time, he may, in most situations, have confined himself to'the vegetable banquet prepared for him by his boun- teous Maker; but, as population increased, the means of subsistence would become too scattered fo,r him, and it would be necessary to crowd together a number of nutritious vegetables into a small space, and to cultivate the earth, so as to multiply its produce ; but this would imply the existence of settled, habits and institutions which could only arise after society had made progress. Probably, much before this period, it would have been discovered, that certain of the beasts of the forest, and of the birds of the air, and some of the insect tribes, could minister to his wants, and form agreeable and nutritious articles of diet; and thus would arise their adoption as food. On the coasts of the ocean, animal food was perhaps employed from the period of their first settle- ment; as well as on the banks of the large streams which are so com- mon in Asia,—the cradle of mankind. The fish, left upon the land after the periodical inundations of the river's, or thrown on the sea- coast, would minister to their necessities, without the slightest effort on their /part; and, hence, they would have but little incentive to mental or corporeal exertion. This is the cause of the abject condition of the ichthyophagous tribes of old; and of .their comparatively low state of civilization at the present day.2 Again:—savages, in various parts of the globe, live by the chase or the fishery; and must, consequently, be regarded as essentially carnivorous. It would not,' however, be justifi- able, to regard barbarism as the natural state of man; nor is it clear what the different writers on this point of anthropology have meant by the term. The Author of nature has invested him with certain prero- gatives, one of which is. the capability of rendering the organized king- dom subservient to his wishes and necessities; and, by the invention of the culinary art, of converting various organized bodies into wholesome and agreeable articles of diet, which thus become as natural to him as the restriction to one species of aliment is to the animal. It has been remarked, that the exclusive or predominant use of ani- mal or of vegetable food has a manifest effect upon the physical and moral powers. Buffon affirms, that if man were obliged to abstain from flesh in our climates, he could not exist, nor propagate his kind. 1 Bruce, Travels, 3d edit., v. 83. J The Author, in Amer. Med. Intelligencer, i. 99, Philad., 1838. 544 DIGESTION. Others, again, have depicted a state of ideal innocence, in the infancy of society, when he lived, as they conceive, entirely on vegetables; " His food the fruits; his drink the crystal well;" unsolicitous for the future in consequence of the abundant subsistence spread before him; independent; and always at peace with his fellows, and with animals; but he gradually sacrificed his liberty to the bonds of society; and cruelty, with an insatiable appetite for flesh and blood, were the first fruits of a depraved nature. Either immediately or remotely, all the physical and moral evil, by Avhich mankind are afflicted, arose from these carnivorous practices. "The principal patrons of this twaddle, in modern times"—says Dr. Fletcher—"to say nothing of Pythagoras and the ancients—have been Gassendi, Rousseau, Wallis, Lamb, and Newton; the last of whom, in the plenitude of his infatuation, asserts that real men have never yet been seen, nor ever will be, till they shall be content to subsist entirely on herbs and fruits and distilled water.'-1 In point of fact, we find, that the inhabitants of countries, in which^ mankind are accustomed to be omnivorous, or to unite animal with vegetable,diet, are those most dis- tinguished for both mental and corporeal endowments. The tribes, which feed altogether on animal food,—as the Laplanders, Samoiedes, Esquimaux, &c,—are far inferior, in both these respects, to the European, or Europeo-American; and the same may be said, although not to the like extent, of the various tribes in whose diet animal food predominates,—as the Indian inhabitants of our own continent. A similar remark is applicable to those, who live almost exclusively on vegetables, as the Hindoos, millions of whom are kept in subjection by a few Europeans.2 Attempts have-frequently been made to refer the nutrient properties of all articles of diet to a particular principle of a constant character, which, alone, of all the elements, is entirely capable of assimilation. Haller3 conceived this to be jelly;—Dr. Cullen4 thought it to be oily, or saccharine, or what seemed to be a combination of the two;—Becker, Stahl, Fordyce,5 &c, to be mucilage; M. Dumas,6 mucus; and M. Halle, a hydro-carbonous oxide very analogous to gummi-saccharine matter !7 It is probable, that there is no such special principle as the one contended for; and that, in all cases, in the formation of the chyle or reparative fluid, which is separated from it, the food is resolved into its elements. To this conclusion we are necessarily impelled, when we reflect, that chyle can be formed from both animal and vegetable sub- stances. In an early part of this work, occasion was taken to mention, that all organized tissues, animal and vegetable are reducible into nearly the same ultimate elements,—oxygen, hydrogen, carbon, and 1 Rudiments of Physiology, Part ii., a. p. 121, Edinb., 1836. 3 Lawrence's Lectures, edit, cit., p. 216. 3 Elementa Physiologiae, Lib. xix., Sect. 3, Bernge, 1764. * Institutions of Medicine, Part i., Physiology, § 211, Edinb., 1785. 6 Treatise on the Digestion of Food, p. 84, 2d edit., Lond., 1791. 6 Principes de Physiologie, i. 187, Paris, 1806. 7 Tiedemann, Physiologie des Menschen, iii. 95, Darmstadt, 1836. FOOD OF MAN. 545 nitrogen. Great light has been thrown on this subject, in recent pe- riods, by the labours of the organic chemist. These have shown, that the chief proximate principles of animal tissues, and those that have been regarded as highly nutritious amongst vegetables, have almost identically the same composition; and are modifications of protein.1 The following tables from Liebig2 exhibit the striking similarity in con- stitution, and in the proportion of constituents, of different animal and vegetable compounds of organization. Carbon, . Hydrogen, Nitrogen, Oxygen, . Sulphur, . . Phosphorus, Carbon, . Hydrogen, Nitrogen, Oxygen, Sulphur, Phosphorus, Animal proximate principles, according to Mulder Albumen. Fibrin. 54-84 . . 54-56 7-09 15-83 21-23 0-68 033 6-90 15-72 22-13 0-33 0-36 Casein. 54-96 7-15 15-80 21-73 0-36 100-00 100-00 100-00 dmate principles, according to Scherer and Jones. Albumen, from wheat. Fibrin. Casein or Legumin 55-01 . 54603 54-138 7-23 7-302 . 7-156 15-92 15-809 15-672 21-84 22-286 23034 100-00 100-000 100-000 As the different parts of organized bodies contain a considerable portion of nitrogen, a question has arisen regarding its source; some believing, that it is obtained from the food, others by respiration. M. Magendie3 instituted experiments wijih. the view of determining the nutritive qualities of ndn-nitrogenized substances. They consisted in feeding animals, fbr the necessary time, on a diet whose chemical composition was rigidly determined. He fed a dog, three years old and in good condition, on pure white sugar and distilled water. For seven or eight days, the animal appeared to thrive well, was lively, and ate and drank- with avidity. In the second week^ it began to fall off, although its appetite continued good, and it ate six or eight ounces of sugar in the twenty-four hours. " In the third week, it became ema- ciated, its strength diminished, its gaiety was gone, and its appetite impaired. An ulcer formed on each eye, at the centre of the cornea, which subsequently perforated it, and allowed the humours to escape. The emaciation, as well as loss of strength, went on progressively in- creasing; and, although the animal ate daily three or four ounces of sugar, the debility became so great, that it could neither chew, swallow, nor execute the slightest movement. It died on the thirty-second day ofthe experiment. On dissection, the fat was found to have entirely OGG DH£T6 47 'Animal Chemistry, Gregory's and Webster's edit., pp. 100, 283, and 301,. Cambridge, Mass., 1842. » Precis Elementaire, 2de edit. ii. 488, Paris, 1825. vol. I.—35 546 DIGESTION. disappeared; the muscles were reduced to less than five-sixths of their ordinary size; the stomach and intestines were much diminished, and powerfully contracted; and the gall and urinary bladders filled with fluids not proper to them. These were examined by M. Chevreul, who found them to possess almost all the characters of the bile and urine of herbivorous animals. The urine, in place of being acid, as it is in the carnivora, was sensibly alkaline, and presented no trace of uric acid or phosphates. The bile contained a considerable proportion of picromel, like that of the ox and herbivora in general. The excrements con- tained very little nitrogen, which they usually do in abundance. A second dog was subjected to the like regimen, and with similar results. He died on the thirty-fourth day of the experiment. A third experiment, having eventuated in the same manner, M. Magendie con- cluded that sugar alone is incapable of nourishing the dog. In all these cases, ulceration of the cornea occurred, but not exactly at the same period of the experiment. He next endeavoured to discover, whether these effects might not be peculiar to sugar; or whether non- nitrogenized substances, generally considered nutritious, might not act in the same manner. He took two young and vigorous dogs, and fed them on olive oil and distilled water. For fifteen days they were ap- parently well; but, after this, the same train of,phenomena supervened as in the other cases, except that there was no ulceration of the cornea. They died about the thirty-sixth day of the experiment. Similar ex- periments were made with gum Arabic, and with butter—one of the animal substances that do not contain nitrogen. The results were identical. Although the character of the excrements passed by the different animals indicated that the substances were well digested, M. Magendie was desirous of establishing this in a positive manner. Accordingly, after having fed animals for several days on oil, gum, or sugar, he opened them, and found that each of these substances was reduced to a particular kind of chyme in the stomach; and that all afforded an abundant supply of chyle;—that from oil being of a manifest milky appearance, and that from gum or sugar transparent, opaline, and more aqueous than the chyle from oil; facts which prove, that if the various substances did not nourish the animals, the circumstance could not be attributed to their not having been digested. These results, M. Magendie thought, render it likely, that the nitrogen,, found in different parts of the animal economy, is originally obtained from the food. This, however, is doubtful. We have no proof, that the animals died simply from privation of nitrogen. It is, indeed, probable, that it had little or no agency in the matter, for there seems to be no sufficient reason why it should not have been procured from the air in respiration, as well as from that contained between the particles of the sugar, where this substance was administered. It must be recollected, moreover, that the subjects of these experiments were dogs;—animals which, in their natural state, are carnivorous, and, in a domestic state, omni- vorous ; and that they were restricted to a diet foreign to their nature, and one to which they had not been accustomed. Ought we, under such circumstances, to be surprised, that they should sicken, and fall off? FOOD OF MAN. 547 In the period that elapsed between the publication of the first and second editions of his Precis Elementaire de Physiologie, M. Magendie found that his deductions were not, perhaps, as absolute or demonstra- tive as he had at first imagined; and additional experiments induced him to conclude,—as Dr. Bostock1 afterwards did, without being aware, apparently, of his observation,—"that variety and multiplicity of articles of food constitute an important hygienic rule." " This," M. Magendie2 adds, "is indicated to us by our instinct, as well as by the changes that wait upon the seasons, as regards the nature and kind of alimentary substances." The additional facts, detailed by M. Magendie, are the following :—A dog, fed at discretion on pure wheaten bread, and drinking common water, does not live beyond fifty days; whilst another, fed exclusively on military bread—pain de munition—seems to suffer in no respect. Rabbits or Guinea-pigs, fed on a single sub- stance, as wheat, oats, barley, cabbage, carrots, &c, commonly die, with every mark of inanition, in a. fortnight; and, at times, much earlier. When the same substances are given together, or in succes- sion, at short intervals, the animals continue in good keeping. An ass, fed on rice, lived only fifteen days, refusing his food for the last few days; whilst a cock was- fed upon boiled rice for several months without his health suffering. Dogs, fed exclusively on cheese, and others on hard eggs, lived for a long time; but they were feeble and lean, losing their hair, and their whole appearance indicated imperfect nutrition. The substance, which, when given alone, appeared to sup- port the rodentia3 for the greatest length of time, was muscular flesh. Lastly, M. Magendie found, that if an animal had subsisted for a cer- tain time on a substance, which, taken alone, is incapable of nourishing it,—on white bread, for instance,( for forty days,—it is useless, at the end of that time, to vary his nourishment, and restore him to his ac- customed regimen. He wilLfeed greedily on the new food presented to him; but continues to fall off; and dies-at the same period as he would probably have done, if maintained on his exclusive regimen. That these effects are not owing to privation of nitrogen, the same ob- server4 has since' been amply satisfied. As chairman of a committee appointed to inquire into the nutritive properties of gelatin, he reported that gelatin, albumen, and fibrin—all of which are highly nitrogenized —when taken separately, nourish animals for a limited period only, and imperfectly. They generally soon excite so insurmountable a dis- gust that the animals would rather die than partake of them. These experiments led to the too hasty conclusion, that the gelatinous tissues are incapable of conversion into blood. "The gelatinous substance," says Liebig,5 "is. not a compound of protein; it has no sulphur, no 1 Physiology, 3d edit., p. 561, Lond., 1836. 2 Op. citat., ii. 494. 3 The rodentia are gnawing animals, having large incisors in each jaw, with which they divide hard substances. They are the rongeurs of the French naturalists. The squirrel, mouse, rat, Guinea-pig, hare, rabbit, beaver, kangaroo, porcupine, &c, belong to this division. 4 Comptes Rendus, Aout, 1841. Similar results were obtained by the Amsterdam Com- mission, in Het Instituut, No. ii. 1843, pp. 97-114, cited by Mr. Paget, Brit., and For. Med. Rev., April, 1845, p. 563. 5 Animal Chemistry, Amer. edit., by Webster, p. 124, Cambridge, Mass., 1842. 548^ DIGESTION. phosphorus, and contains more nitrogen or less carbon than protein. The compounds of protein, under the influence of the vital energy of the organs that form the blood, assume a new form, but are not altered in composition; whilst these organs, as far as our experience reaches, do not possess the power of producing compounds of protein, by virtue of any influence, from substances that contain no protein. Animals, which were fed exclusively on gelatin, the most highly nitrogenized ele- ment of the food of carnivora, died with symptoms of starvation." "In short," he adds, "gelatinous tissues are incapable of conversion into blood." Such too, seems to be the opinion of Professor Bdrard.1 Yet it has been shown above, that fibrin and albumen—both compounds of protein—when exhibited singly to animals, nourished them as imper- fectly as gelatin; and there is some reason to believe, that it is mainly on chemical considerations that the value of gelatin as a nutriment has been much underrated. " Such persons only," says Professor Mulder,2 "as are under the influence of prejudice (making their experi- ments with dogs—animals which, according to the account of the gela- tin committee, prefer to starve in the midst of gelatin, rather than touch it), such persons only as deny the results of innumerable ob- servations, will refuse to gelatin its place among useful nutritive sub- stances." And he adds: "I have thought it necessary, before closing this short account of gelatin, to express my opinion of the experiments by which pure gelatin is rejected as food:—namely, that these experi- ments have taught me nothing but how experiments ought not to be made." It is somewhat singular, too, that-most of those who deny much nutrient property to gelatin are of opinion, that the nutritious properties of different articles of vegetable food may be generally esti- mated by the proportion of nitrogen they contain, and on this principle tables have been formed by several experienced chemists,—by Boussin- gault, Schlossberger, Kemp,3 and Professor Horsford,4 of Cambridge, Massachusetts. The latter gentleman, especially, has furnished us with the results of elaborate investigations into the nature of different kinds of vegetable food, based upon the amount of nitrogen. The tables of Boussingault and Horsford are considered by Professor Fre- richs,5 of value; whilst those of Schlossberger and Kemp are declared to be practically useless, because no regard was paid to the quantity of water in the fresh condition; and for the strange reason, "that the nitrogen found in most of the substances analyzed that contain gelatin is no measure of the quantity of the haematogenetics or blood-forming constituents!" Independently of showing the necessity of variety of food for animal sustenance, the experiments of M. Magendie exhibit some singular anomalies; and sufficiently demonstrate, that we have yet much to learn 1 Archives Generates de Medecine, Fevrier, 1850, p. 247. 2 The Chemistry of Vegetable and Animal Physiology, by G. J. Mulder, &c., p. 328, Edinb. and Lond., 1849. 3 Annal. der Chemie und Pharmacie, B. lvi. s. 78-94 j see also, Philosophical Magazine for Nov., 1845. * Philosophical Magazine, for Nov., 1846, p. 365. 5 Art. Verdauung, in Wagner's Handworterbuch der Physiologie, 19te Lieferung, s. 732, Braunschweig, 1848. FOOD OF MAN. 549 on the subject. A great deal, doubtless, depends on the habits of the particular animal or individual; and on the morbid effects excited by completely changing the function of assimilation. It has been long known, that if a man, previously habituated to both animal and vege- table diet, be restricted exclusively to one or the other, he will fall off, and become scorbutic; and yet, that he is capable of subsisting on either one or the other exclusively, provided the restriction has been enforced from early, infancy, has been sufficiently shown by the refer- ence made to carnivorous and herbivorous tribes existing in different regions of our globe. The importance of variety of diet is illustrated by the experiments made by Dr. Stark,1 upon his own digestive powers, and to which he ultimately became a martyr. His object was to dis- cover the relative effect of various simple substances, when used exclu- sively for a long spaee of time as. articles of food. The system, he found, was in all cases reduced to a state of extreme debility, and there was not a single aliment, that was capable, of itself,'of sustaining the vigour of the body for any considerable period. By this kind of regi- men Dr. Stark is said to have so completely ruined his own health, as to bring on premature death. In accordance with his views, that nitrogenized food is alone capable of forming organized tissue; and that the non-nitrogenized food is in- servient to respiration only, Liebig thus classifies aliments:— itrogenized Food or Plastic Elements of Nutrition. Non-nitrogenized Food or Elements of Respi-ration. Vegetable Fibrin, " Albumen, " Casein, Flesh, . ; " . Blood. Fat, Pectin, Starchf Bassorin, Gum, Wine, Cane Sugar, Beer, Grape Sugar, Spirits. Sugar of Milk, These views, however,- demand further proof. They are not confirmed by what.is observed in chylification. In the small chyliferous vessels, more fat, which is a non-nitrogenized substance, is found than can be accounted for by the adipose matter in the food; and of the conver- sion of the amylaceous and saccharine matters in the food to oil during the digestive function a striking example has been published by M. Kb'ss.2 A workman was killed on a railroad after having eaten a full meal of bread and grapes only. On examining his body, the pro- cess of chymification was found to have been in full activity; and in those portions of the small intestine, which the chyme had reached, the mucous membrane was dotted with white points, which, on closer examination, were found to be owing to drops of oil in the epithelial cells surrounding the extremities of the villi. As the chyle proceeds along the lacteals, the proportion of fat becomes less and less, whilst that of the nitrogenized matters increases; hence nitrogen must have been obtained, and a conversion have taken place of non-nitro- genized into nitrogenized matters. (See Physiology of Chylosis.) On the other hand it has been shown, that the followers of Liebig maintain, 1 The-Worksof the late Wm. Stark, M. D., &c, by Dr. J. C. Smyth., Lond., 1787. 1 Cited in London Med. Gazette, Oct., 1846. 550 DIGESTION. that gelatin is not convertible into a proteinaceous substance; and hence it is not classed by them amongst the elements of nutrition; yet it con- tains an unusual amount of nitrogen. It has been affirmed, that all nitrogenized food, according to the above classification of Liebig, is reduced in the stomach to the form of albumen; which is said to resemble the gum of plants in being the raw material, as it were, out of which the various fabrics of the body are constructed. Yet this is not demon- strated; and it is probable that the conversion into albumen takes place more especially in the chyliferous vessels. The alimentary substances, employed by man, have generally been classed either according to the ultimate chemical elements entering into their composition; or to the chief proximate principle or compound of organization. In the former case, they have been grouped into:—1, those that contain nitrogen, carbon, hydrogen, and oxygen;—2, those that contain carbon, hydrogen, and oxygen; and 3, those that contain neither nitrogen nor carbon. The first class will comprise most animal and many vegetable substances; the second, vegetable substances chiefly; whilst water is perhaps the only alimentary matter that belongs to the third. : The division proposed by M. Magendie,1 and adopted by Dr. Paris,2 is according to the proximate principles, which predominate in the ali- ment. 1. Amylaceous aliments; wheat, barley, oats, rice, rye, Indian corn, potato, sago,, salep, peas, haricots, lentils, &c. 2. Mucilaginous aliments; carrot, salsify, beet, turnip, asparagus, cabbage, lettuce, artichoke, melon, &c. 3. Saccharine aliments ; the different kinds of sugar, figs, dates, raisins, &e. 4. Acidulous aliments ;his is asserted, by many rural econo- mists, to be the most effectual plan for fattening poultry speedily; the coarse shell, in passing along the mucous membrane of the intestines; seems to stimulate it to augmented action, and a more bountiful separa- tion of nutritious matter is the consequence. The aromatic condiments act in a similar manner. In regard to the quantity of food required for human sustenance, nothing definite can be laid down. It must differ according to habit, constitution, way of life, a-ge, sex, &c. The diet scale of the British navy affords a good average for the adult male in busy life, who requires 1 See an article by the author in the American Quarterly Review, ii. 422, Philad.. 1827; and Fletcher, op. citat., p. 121. 2 Kitchener, Invalid's Oracle, Amer. edit, p. 136, New York, 1831. PHYSIOLOGY OF DIGESTION. 553 more aliment than those in less active employment. It consists of from. 31 to 35J ounces of dry nutritious matter daily; of which 26 ounces are vegetable and the rest animal,;—91 ounces of salt meat, or 41 ounces of fresh, being the proportion of the latter. This is found to be an ample allowance. In prisons a reduction must be made. In a convict Bhip, which took out 433 prisoners to New Holland, in 1802, the mor- tality was trifling, and the general health good, although the prisoners were allowed only 16 ounces of vegetable food, and 71 ounces of animal food per day. Whenever the allowance is more restricted, or a due ad- mixture of animal and vegetable food is not permitted, the health suffers, and signs of scorbutus appear;—a result occasionally witnessed in our public eleemosynary institutions, when under the care of ignorant and too economical superintendents.. It would seem, from the experiments of M. Chossat,1 that under such circumstances an incapability is induced of digesting even the inadequate amount supplied. The smallest quantity of food upon which life is known to have been actively supported was in the case of Cornaro, who affirms that he took no more than 12 ounces a day, and that chiefly vegetable, for a period of sixty-eight years. Of the amount that can be eaten by the glutton, we have surprising instances on record,—the stomach acquiring, at times, an enormous capacity. Captain Parry relates the case of a young Esquimaux, who was permitted to devour as much as he chose. It amounted, in the twenty-four hours, to thirty-five pounds of various kinds of aliment, including tallow candles; and a case has been pub- lished of a Hindoo, who could eat a whole sheep at,a time. These few remarks on the food of man will serve as an introduction to the mode in which the various digestive processes are accomplished. The more intimate consideration of alimentary substances, with their comparative digestibility, &c, will be found in another work of the author, to which the reader is referred.2 3. PHYSIOLOGY "OF DIGESTION. The detail entered into regarding the various organs concerned in digestion will have led to the anticipation, that the history of the func- tion must be multiple and complex. The food is not, in the case of the animal—as it is in that of the vegetable—placed in immediate contact with the being to be nourished; an act of volition is, consequently, neces- sary to procure and to convey it to the upper orifice of the digestive tube. This act of volition is excited by an internal sensation—that of hunger—which indicates the necessity for taking fresh nourishment into the system. The appetite and hunger, with the prehension or reception of food, must therefore be regarded part of the digestive operations. These may be enumerated and investigated in the following order:— 1st. Hunger, or the sensation that excites us.to take food. 2dly. Pre- hension of food, the voluntary muscular action, that introduces it into the mouth. 3dly. Oral or buccal digestion, comprising the changes 1 Referred to at page 558. 2 Human Health, p. 179, Philad, 1844. For different dietaries, &c, see Pereira, Treatise on Food and. Diet, Amer. edit, by Dr. C. A. Lee, p. 222, New York, 1843; and Art.. Diet Scale, in the author's Med. Dictionary, 7 th edit, Philad, 1848. 554 DIGESTION. wrought on the food in the mouth. 4thly. Deglutition, or the part taken by the pharynx and oesophagus in digestion. 5thly. Chymifica- tion, or the action of the stomach on the food. 6thly. The action of the small intestine. 7thly. The action of the large intestine. And, 8thly. Defecation or the expulsion of the faeces. All these processes are not equally concerned in the formation of chyle. It is separated in the small intestine: the first six, therefore, belong to it;—the remainder relate only to the excrementitious part of the food. The digestion of solid food requires all the eight processes: that of liquids is more simple; comprising only thirst, prehension, deglutition, the action of the stomach, and that of the small intestine. Fluid rarely reaches the large intestine. In inquiring into this important and interesting function, we shall first attend to the digestion of solids, and afterwards to that of liquids. 4. DIGESTION OF SOLID-FOOD. a. Hunger. Hunger is an internal sensation, the seat of which is invariably refer- red to the stomach. Like every internal sensation, it proceeds from changes in the very texture of the organ. It is not produced by any external cause; and to it are applicable all those observations, that were made on internal sensations in general. In its slightest coriditioh, it is merely an appetite, (opsfij; Germ. E s s 1 u s t;) but if this be not heeded, the painful sensation of hunger (Fames, %tpos), supervenes, which becomes more and more acute and lacerating unless' food is taken. If this be the case, however, the uneasiness gradually abates; and if suffi- cient be eaten, a feeling of satiety is produced. The sensation usually occurs, in the healthy state, after the stomach has been for some time empty, having finished the digestion of substances taken in at the previous meal. Habit has a great effect in regulating this recurrence ; the appe- tite always appearing about' the time at which the stomach has been accustomed to receive food. This artificial desire may be checked by various causes;—by the exciting or depressing passions, the sight of a disgusting object, or anything that occasions intense mental emotion; or it may be appeased by filling the stomach with substances that con- tain no nutritious properties. As, however, the feeling of true hunger arises from the wants of the system, the natural and instinctive sensa- tion soon appears, and cannot be long postponed by any of these means. Hence, it has been proposed to make a distinction between appetite and hunger; applying the former term to the artificial, the latter to the natural, desire. In these respects, there is certainly a wide distinction between them, as well as in the capriciousness, which occasionally cha- racterizes the former, and gives rise to singular and fantastic preferences. The sensation of hunger varies in intensity according to different circumstances. It is more powerful in the child and youth than in one who has attained his full height. In the period of second childhood, it is urgent,—probably owing to the diminished power of assimilation requiring that more aliment should be received into the stomach. In disease, the sensation is generally suppressed, and its place often sup- plied by loathing or disgust for food: at times, again, its intensity makes HUNGER. 555 it a true disease, as in bulimia, and pica; in the latter of which, the appetite is, at times, irresistibly directed to substances, which the'per- son never before relished, or are not edible,—as chalk, earth, slate- pencil, &c. The appetite is also modified by exercise or inactivity, and other circumstances extrinsic and intrinsic,—regular exercise, and the exhilarating passions; a cold and dry atmosphere, &c, augmenting it, whilst it is blunted by opposite circumstances. Long continued exer- tion, with a scanty supply of nourishment, if not continued so long as to injure the tone of the stomach, produces, occasionally, in adults, a voracious appetite and rapid digestion. Mr. Hunter has quoted, in illustration of this point, the following extract from Admiral Byron's narrative. After describing the privations he had suffered when ship- wrecked on the coast of South America, the Admiral incidentally refers to their effect upon his appetite. "The governor ordered a table to be spread for us with cold ham and fowls, which only we three sat down to, and in a short time despatched more than ten men with common appetites would have done. It is amazing, that our eating to that excess we had done from the time we first came.among these kind Indians had not killed us, as we were never satisfied, and used to take all opportu- nities for some months -after, of filling our pockets, when we were not seen, that we might get up two or three times in the night to cram ourselves."1 Authors have distinguished the local from the general phenomena of hunger; but many of their assertions on these points appear ima- ginative. We are told by M. Adelon2 and others,3 that the stomach becomes contracted, and that this change is effected by the action of its muscular coat alone ;^-the mucous or lining membrane becoming Wrinkled, and the peritoneal coat, externally, permitting the organ to retire between its laminae. Such, MM. Tiedemann and Gmelin4 assert, is the result of' their observations. M. Magendie,5 however, affirms, that after twenty-four, forty-eight, and even sixty hours complete absti- nence, he has never witnessed this contraction of the organ. It had always considerable dimension, especially in its splenic portion; and not until after the fourth or fifth day did it appear to him to close upon itself, diminish greatly in capacity, and slightly change its posi- tion; and these effects were not observed unless- the fasting was rigor- ously maintained. At the time that the stomach changes its shape and situation, the duodenum is said to be drawn slightly towards it; its parietes appear thicker,—and the mucous follicles and nervous papillae project more into the interior. Its cavity is void of food, and contains only a little saliva, mixed with bubbles of air; a small quantity of mucus; and, according to some, a little bile and pancreatic juice, which the traction of the duodenum has caused to flow into it. Much dispute has arisen as to whether the circulation of the blood in ' Byron's Voyage, p. 181; and Hunter on the Animal Economy, p. 196. ' Physiologie de l'Homme, ii. 396. 3 Rullier, Art.^Faim, in Diet, de Medecine, torn, viii, Paris, 1823. 4 Die Verdauung nach Versuchen, u. s. w.; or French translation, by A. J. L. Jourdan, Paris, 1827. 6 Op. citat, ii. 25. 556 DIGESTION. the stomach experiences any mutation. M. Dumas1 was of opinion, that when the organ is empty, it receives less blood than when full; either on account of the great flexion of the vessels in the former case, or on account of the compression experienced by the nerves in consequence of the contracted state of the organ. He thinks that, under such cir- cumstances, a part of the blood sent to it reflows into the liver, spleen, and omentum; and he regards these organs as diverticula for the blood of the stomach, especially as the liver and spleen are then less com- pressed, and the omentum more extensive, owing to the retraction of the stomach. Bichat, however, denies both the fact and its explanation. He affirms, that on opening animals suffering under hunger, he never observed the vessels of the stomach less full of blood, the mucous mem- brane less florid, or the vessels of the omentum more turgid. Is it not true, he adds, that the vessels of the stomach are more flexuous when the organ is empty? being, as well as the nerves, connected with the serous coat, they are unaffected by changes of size in the organ; and besides, the retraction of the stomach could never be great enough to compress the nerves. He denies, moreover, that the liver and spleen are more free, and the omentum larger, whilst the' stomach is empty, as the abdominal parietes contract in the same proportion as the stomach. Magendie,2 however, contests this last assertion of .Bichat; a,nd affirms, on the faith of positive experiments, that the pressure sustained by the abdominal viscera is in a ratio with the distension of the stomach. If the stomach be full, the finger, introduced into the cavity of the abdo- men through an incision in its parietes, will be strongly pressed upon, and the viscera forced towards the opening; whilst, if it be empty, the pressure as well as the tendency of the viscera to escape through the opening is considerable. 'During the state of vacuity of the organ, he remarked that the.different reservoirs in the cavity of the abdomen,— the bladder and gall bladder,—were .more easily filled by their proper fluids. With regard to the quantity of blood circulating through the stomach in the empty and full state,—he is disposed to believe, that the organ receives less in the former condition; but that in this respect it does not differ from other abdominal viscera. , The general effects, said to be produced by hunger, in contradistinc- tion to the local, are;—debility and diminished action of every organ; the circulation and respiration are less frequent; the heat of the body sinks; the secretions diminish, and all the functions are exerted with more difficulty, if we except absorption, which it is affirmed, and with much probability, is augmented. If the abstinence be so long protracted as to cause death, the debility of the functions becomes real, and not sympathetic. Respiration and circulation languish; all the animal functions totter; whilst absorption continues, and the blood is supplied by the decomposition of the different organs,—the fat, the various liquid matters and the tissues of the organs being successively sub- jected to its action. It is obvious, however, that, with the drain per- petually taking place, this state of affairs cannot exist long.; the blood becomes diminished in quantity, and insufficient in every respect to vivify the organs; the functions of the brain are perverted, and, in ' Principes de Physiologie, Paris, 1806. 3 Precis, &c, edit, cit, ii. 26. HUNGER. 557 many instances, furious delirium has closed the scene; whilst, at others the miserable sufferer has sunk passively into the sleep of death. Oc- casionally, again, so dreadfully painful are the sensations caused by pro- tracted privation of food, that the most violent antipathies and dearest affections have been overcome; and numerous instances have occurred in which the sufferer has attacked his own species, friends, children, and even his own person. The horrible picture of the shipwreck, by Byron,1 is not a mere romance. It is a narrative of facts that have actually occurred, expanded somewhat by the imagination of the poet. Dr. James Currie2 has related the case of a person, who died of inanition from stricture of the oesophagus, the particulars of which may exemplify the phenomena presented by some of those who perish from abstinence. The records of such cases are rare. From the 17th of October to the 6th of December, the patient was supported, without the aid of the stomach, by means of broth clysters; and was immersed in a bath of milk and water. At one period he had a parched mouth: a blister discharged only a thin, coagulable lymph; and the urine was scanty, extremely high-coloured, and intolerably pungent. The heat of the body was natural and nearly uniform from first to last; and the pulse was perfectly natural until the last days. His sleep was sound and refreshing; spirits even; and intellect unimpaired, until the four last days of existence, when clysters, were no longer retained. Vision was deranged on the first of December, and delirium followed on the suc- ceeding day; yet the eye was unusually sensible, and the sense of touch remarkably acute. The surface and extremities were at times of a burning heat; at others, clammy and cold. On the fourth, the pulse became feeble and irregular, and respiration laborious; and, in ninety- six hours after all means of nutrition as well as medicine had been abandoned, he ceased to breathe. He was never much troubled by hunger. Thirst was, at first, troublesome, but it was relieved by the tepid bath. This was a case in which the patient sank tranquilly to death. In others, the distressing accompaniments above described, are met with; and the death is.that of a furious maniac. The period at which the fatal event may occur from protracted absti- nence is dependent on many circumstances. As a general rule the young and robust will expire sooner than the older; and this will have to be our guidance in questions of survivorship, where several individuals have perished together from this cause. The picture, drawn by Dante ofthe sufferings and death of Count Ugolino della Gherardescha, who saw his sons successively expire before him from hunger, is in this re- spect true to nature. " Now when our fourth sad morning was renew'd, Gaddo fell at my feet, outstretch'd and cold, Crying:—' Wilt thou not, father! give me food V There did he die; and as thine eyes behold Me now, so saw I.three fall, one by one, On the fifth day an^ sixth; whence in that hold, I, now grown blind, overeach lifeless son Stretch"d forth mine arms. Three days I called their names, Then Fast achieved what Grief not yet had done." " Inferno," canto xxxiii. 1 Don Juan, canto ii, 58. » Medical Reports, &c, Amer. edit, Philad, 1808. 558 DIGESTION. In some experiments on inanition undertaken by M. Chossat,1 on pigeons and turtle doves, the following general phenomena were ob- served. Commonly, the animal remained calm during the first half or two-thirds of the period. It then became more or less agitated, and this state continued as long as the temperature remained elevated. On the last day of life, however, the restlessness ceased, and gave place to stupor. When set at liberty, it sometimes looked round with astonish- ment, without attempting to fly, and at times closed its eyes, as if in a state of sleep. Gradually, the extremities became cold,' and the limbs so weak as to be no longer able to sustain it in the standing posture. It fell over on one side, and remained in any position in which it might be placed^ without attempting to move. Respiration became slower and slower; the general weakness increased, and the insensibility became more profound; the pupils dilated; and life became extinct,—at times in a calm and tranquil manner; at others, after convulsive actions, pro- ducing opisthotonic rigidity of the body. He endeavoured to discover the effect of age in modifying the con- tinuance of life during inanition, but was unable to ascertain the rela- tive ages of the turtle doves, the subjects of his experiments; he endeavoured, however, to form some estimate—although, obviously, a fallacious one—from their relative weights, classing them as "young," "middle-aged," or "adult," according as their weights were beneath 120 grammes, from 120 to 160, or above 160. The following table is interesting, however, by showing the duration of life, and the loss of substance during inanition, in animals of different weights. Weight of the Body. ' | - Loss of the Body. Duration of life. Weight at commence-ment. ' Weight at death. Entire abso-lute loss. Proportional loss in 1000 "" pa,rts. Daily propor-tional loss. a. Young . . b. Middle-aged c. Old . . . Gram. 110 42 143-62 189-36 Gram. 82-84 9160 101-61 Gram. 27-58 52-02 1 «7-75 0'250 0-362 0-463 0-081 0-059 0-035 307 6-12 13-36 The entire absolute loss, and the proportionate loss, were much greater in the heavier animals; the daily loss was by much the most rapid in the lightest; and it is probable, that this was owing to the more rapid waste which takes place in the young. The sensation of hunger resembles every other sensation in the mode in which it is accomplished. There must be impression, conduction, and perception. That the encephalon is the organ of the last part of the process is proved by all the arguments used in the case of the internal sensations in general. Without its intervention in this, as in every other case, no sensation can be accomplished. The stomach is the organ in which the impression is effected; and by means of the nerves this impression is conveyed to the spinal marrow and encepha- lon. The eighth pair or pneumogastric nerves have generally been 1 Recherches Experimentales sur l'lnanition, Paris, 1843; noticed in Brit, and For. Med. Rev, April, 1844, p. 347. HUNGER. 559 regarded as the agents of this transmission; and it has been affirmed by Baghvi, Valsalva, Haller, Dumas, Legallois, Chaussier, and others that if they be divided in the neck, although the stomach may be favourably circumstanced, in other respects, for the developement of the impression of hunger, and the encephalon for its reception, there is no sensation; but MM. Leuret and Lassaigne,1 Dr. John Reid,2 Nasse,3 and Longet,4 deny, that such effect follows the division of these nerves; and the first gentlemen affirm, that horses have eaten as usual, and apparently with the same appetite, after they had removed several inches of the pneumogastric nerves; and even continued to eat after the stomach was filled. To these experiments we shall have occasion to refer hereafter. They by no means, however, exhibit that this in- ternal sensation differs in its essence from others. A difficulty, which the physiologist has always felt, concerns the precise nature of the action of impression. Its seat is clearly in the stomach. This was shown incontestably by a case of fistulous opening into the organ, which fell under the care of Dr. Beaumont, and to which there will be frequent occasion to refer. When the subject of this case was made to fast until his appetite was urgent, it was imme- diately assuaged by feeding him through the aperture. To the stomach, indeed, all eur feelings refer the sensation. It is dependent upon some modification occurring in the very tissue of the viscus; and in the nerves, which, as has been shown, are the sole agents in all phenomena of sensibility. These nerves are spread over the stomach, so that the precise seat of the impression cannot be as accurately defined as in the case of the organs of external sense. Moreover, the nerves of the stomach proceed from two essentially different sources,—the eighth pair, and great.sympathetic. The question consequently arises:—on which of these is the impression made ? The results of the experiment of cutting the eighth pair in the neck would appear to decide in favour of the former. As to the proximate or efficient cause of hunger, we cannot expect to arrive at any satisfactory conclusion. It is a sensation; and, like all sensations; inscrutable. Theories, however, as on all obscure topics, have been numerous, and these have generally been of a mechanical or a chemical nature. Some have attributed it to the mechanical friction of the parietes of the stomach against each other, in consequence of its contraction; in which state, they, affirm, the mucous coat is rugous, and its papillae and follicles prominent. It is manifest, however, from the structure of the orgah, that no such friction-can take place. Yet this view was embraced by Haller.5 Dr. Fletcher6 ascribes it to a kind of permanent though partial contraction of the muscular fibres of the stomach;—"not that alternate general contraction and relaxation, 1 Recherches Physiologiques et Chimiques pour servir a I'Histoire de la Digestion, Paris, 1825. "Edinb. Med. and Surg. Journal, April, 1839, and art. Par Vagum, in Cyclop, of .Anat. and Physiol, Pt. xxviii, p. 899, Lond, April, 1847. 3 Untersuchungen zur Physiologie und Pathologie, Bonn, 1835-6. 4 Traite de Physiologie, ii. 342, Paris, 1850. 5 Element. Physiol., lib.' xix, sect. 2, § 12, Bern, 1764. 6 Rudiments of Physiology, Part iii, by Dr. Lewins, p. 73, Edinb, 1837. 560 DIGESTION. which produces a sensible motion of this organ, nor that permanent general contraction, which would serve to diminish its cavity, but that kind of permanent contraction, which takes place in certain fibres alone, and perhaps through a part of their length only, and by which these fibres are, as it were, drawn away from the others, or, in other words, a minor degree of cramp." Others, again, have accounted for the sensation by the action of the gastric juice, which is supposed to have a tendency to irritate the internal membrane. In proof of this, they refer to a case, mentioned by Mr. Hunter, in which the mucous membrane, in a man who died of fasting, was found corroded. The gastric juice is, however, incapable of eroding living animal matter; and the nume- rous cases, which have occurred since that of Hunter, have shown, that the corrosion and perforation, which we meet with on dissection, are to be referred to an action after death, and must, consequently, be totally unconnected with the sensation felt during life. We have, indeed, no reason for believing that the gastric juice can ever attain a state of acridity, and affect physically the surface by which it is secreted. It has been remarked, that,it is a law of the animal economy, that no secretion acts upon the part over which it is destined to pass, provided such part be in a healthy condition. Yet Sommering1 ascribes the pain from long-continued fasting to the action of the gastric juice; and Dr. Wilson Philip2 is manifestly induced to believe that its influence on the stomach is, in some mode or other, productive of the sensation: his remarks, however, tend simply to show,—what we have so many oppor- tunities for observing, that the sensation can be postponed by exciting vomiting, or inducing, for the time, a morbid condition of the stomach. The unanswerable objection, however, to all these views is the fact— repeatedly proved by Dr. Beaumont,3 and which the author had an opportunity of observing—that, in the fasting state there is little or no gastric juice in the cavity of the stomach. Dr. Beaumont thinks, that the sensation of hunger, is produced by distension of the vessels, that secrete the solvent; but such distension, if it exist—which is by no means proved—must itself be consecutive on the nervous condition that engenders the sensation: the efficient cause of such condition has still to be explained. Bichat, again, attributed it to the lassitude or fatigue of the stomach, occasioned by the contraction of its muscular coat when continued beyond a certain time. In answer to this, it naay be remarked, that if any thing impedes the nutrition of the body, hunger continues, although the stomach may be distended. This happens in cases of scirrhous pylorus, where the nutritive mass cannot pass into the small intestine, to be subjected to the action of the chyliferous vessels, and the losses of the body cannot, therefore, be repaired;— facts which would seem to show, that hunger is a sensation excited in the stomach by sympathy with the wants of the constitution; and that it is immediately produced by some inappreciable alteration in the condition of the nerves of the organ. It appears, from the experiments 1 De Corp. Human. Fabric, torn. vi,Traject. ad Moenum, 1794-1801. a Experimental Inquiry into the Laws ofthe Vital Functions, 2d edit, Lond, 1818. 3 Experiments and Observations on the Gastric Juice, and the Physiology of Digestion, p. 57, Plattsburg, 1833. PREHENSION OF FOOD. 561 of M. Magendie,1 that when the cerebrum and a great part of the cere- bellum were removed in ducks, the instinct of seeking food was lost in every instance, and the instinct of deglutition in many: food, however, introduced into the stomach, was found to be digested. b. Prehension of Food. The arms and mouth have been described as organs of prehension. It is scarcely necessary to say, that the hands seize the food and convey it to the mouth under ordinary circumstances; but there are cases in which the mouth is the sole or chief organ of prehension. Most animals are compelled to use the mouth only. When the food is conveyed to it by the hands, it must open to- receive it. The mode in which this is effected has given rise to controversy; and, strange to say, is not yet considered determined. Whilst some physiologists have asserted, that the lower jaw alone acts in opening the mouth moderately; others have affirmed, that both the jaws separate a little;—the lower, however, moving five or six time's as much as the upper. That the latter is the correct view can be proved by positive experiment. If, when the mouth is closed, we place the flat side of the blade of a knife against the teeth of both jaws; and, holding the knife immovably, separate the jaws; we find, that both jaws move on the blade; but the lower to a much greater extent than the upper. Now, as the upper jaw is fixed immovably to the head, the whole head must, of necessity, participate in this move- ment; and the question arises, what are the agents that produce it? Some attribute it to a slight action of the extensor muscles of the head; and affirm, that whilst the depressors of the lower jaw carry it down- wards, the extensors of the head draw the head slightly backwards, and thus raise the upper jaw. MM. Magendie2 and Adelon3 assert, that when the mouth is opened moderately, the upper jaw does not participate; but, that if the motion be "forced" or extensive, it participates slightly. The experiment, however, with the knife, which is adduced by M. Adelon himself, com- pletely overthrows this notion; and shows, that both jaws act, whenever the mouth is slightly opened. M. Magendie agrees writh those who con- sider, that, whenever the upper jaw is raised, it must be by the head being thrown back on the vertebral column; and he properly remarks, that where there is a physical impediment to the depression of the lower jaw, the mouth must be opened solely by the retroversion of the head on the spine. M. Ferrein4 conceived, that the motion of the upper jaw is occasioned by the action of the stylo-hyoideus muscle, and the posterior belly of the digastricus; and he affirms, that whilst the anterior fasci- culus or belly of the digastricus depresses the lower jaw; the posterior belly with the stylo-hyoideus carries the head backwards, and, with it, the upper jaw. The attachments, however, of these muscles sufficiently show, that they cannot be the agents: the mastoid process, to which the posterior belly of the digastric muscle is attached, is near the arti- culation of the head with the atlas; whilst the styloid process, to which 1 Precis, &c, ii. 168. 2 Op. citat, ii. 43. 3 Op. citat, ii. 408. 4 Memoir, de l'Acad. des Sciences pour 1744. vol. i.—36 562 digestion. the stylo-hyoideus is attached, is anterior to the articulation; and its effect ought to be to depress the upper jaw. The view of Professor Chaussier is the most probable. He ascribes the slight elevation of the upper jaw to the mechanical arrangement of the joint of the lower. The temporo-maxillary articulation is not formed by a single condyle, but by two, which are s"o disposed, that the lower cannot roll downwards during the depression of the lower jaw without causing the upper con- dyle to roll upwards, and, consequently, to elevate slightly the upper jaw. Under ordinary circumstances, then, the jaws cannot be at all separated without both participating; but if we determine to fix the upper jaw we can make the lower the sole agent in the movement. As soon as the food is introduced into the mouth, the jaws are closed to retain it, and subject it to mastication. Frequently, however, they assist in the act of prehension, as when we bite a fruit, to separate a portion from it;—the incisor teeth acting, in such case, like scissors. This is chiefly produced by the contraction of the muscles that raise the lower jaw; and it is probable, that the action of the stylo-hyoideus -Fig. 247, . Action of the Lower Jaw in Prehension. A. Frontal bone. B. Temporal. C. Parietal. D. Occipital. E. Coronoid process of the lower jaw, to which the temporal muscle is attached. F. Condyloid process or head of the lower jaw. G. Lower jaw. H. Mastoid process.- I. Upper jaw. J. Cheekbone. K. Orbit. L. Meatus auditorius externus. L*. Coronal suture. M. Squamous suture. N. Lambdoidal suture, g. Lower jaw de- pressed. is concerned in the movement; drawing the head and upper jaw with it downwards and forwards. The levator muscles of the jaw act here with ORAL DIGESTION. 563 great disadvantage;—the lower jaw representing a lever of the third kind; the fulcrum being in the joint; the power at the insertion ofthe levator muscles; and the resistance in the substance between the teeth. The arm of the resistance is, consequently, the whole length of the lever; and we can understand why we are capable of developing so much more force, when the resistance is placed between the molares; and why old people,—who have become toothless, and are, consequently, constrained to bite with the anterior part of the jaws,—the only portion that admits of contact,—cannot bite with any degree of strength. The size of the body, put between the incisor teeth,' influences the degree of force that can be brought to bear upon it. When small the force can be much greater, as the levator muscles are inserted perpen- dicularly to the lever to be moved, and the whole of their power is advantageously exerted; but if the body be so large, that it can scarcely be received into the mouth, and be resisting withal, the incisors can scarcely penetrate it;—the insertion of the levator muscles into, the jaw being rendered very oblique; and the greater part of the force they develope consequently lost. This will be readily seen by Figure 247. When the mouth is closed,,or nearly so, the masseter, and temporal muscles represented respectively by the lines B E and J j, are inserted nearer the perpendicular ; but when the lower jaw is depressed, so that the situation of these muscles is represented by the dotted lines B e and J k, the direction in which the muscles act will be more oblique, and, there- fore, more disadvantageous: When the muscles of the jaws are incapa- ble, of themselves, of separating' the substance, as in the case of the apple, the assistance of the muscles of the hand is invoked; whilst the muscles on the posterior part of the neck, which are inserted into the head, draw it backwards; and, by these combined efforts, the substance is forcibly divided. C; Oral or Buccal Digestion. The changes, effected upon the food in the mouth, are important preliminaries to the function that has to be executed in the stomach and duodenum. . As soon as it enters the cavity, it is subjected to the action of the organ of taste; and its sapid qualities are appreciated. By its stay there, it also acquires nearly the temperature of the cavity. This is, however, a change of little moment, unless the food is so hot, that it would injure the stomach, if passed rapidly into it. Under such circumstances, it is tossed about in the mouth, until it has parted with its caloric to various portions of the parietes of the cavity; and then, if in a fit state for the action of deglutition, it is transmitted along the oesophagus; but the most important parts of oral digestion are the movements of mastication and insalivation by which solid food is com- minuted, and imbued with the secretions poured into the interior of the mouth, and which we have shown to be of a very compound character. Under the sense of taste, the influence of the agreeable or disagreea- ble character of the food upon the digestive function was expatiated upon. It is unnecessary, therefore, to do more than allude to the sub- ject here. We find that whilst a luscious aliment excites to prolonged mastication, and the salivary glands to augmented secretion, the mas- 564 DIGESTION. ticatory and salivary organs, by dividing and moistening the food, per- mit the organs of gustation to enjoy the savour by successive applica- tions. When the food is received into the mouth, if it be sufficiently soft, it is commonly swallowed immediately; unless the flavour is delicious, when it is detained. If solid, and, especially, if of any size or density, it is divided into separate portions, or chewed,—the action constituting mastication. If the consistence of the substance be moderate, the tongue, by being pressed strongly against the bony palate, is sufficient to effect this division; bruising it, and at the same time, expressing its fluid portions. If the consistence be greater, the action of the jaws and teeth is required. For this purpose, the lower jaw is successively depressed and elevated by the action of its depressors and levators; and the horizontal or grinding motion is produced at pleasure by the action of the pterygoids. Whilst these muscles are acting, the tongue and cheeks are incessantly moving, so as to convey the food between the teeth, and insure its comminution. Mastication is chiefly effected by the molares. There is advantage in using them, independently of their form, in consequence of the arm of the resistance being much shortened, as has already been shown. The teeth are well adapted for the service they have to perform. The incisors, as their name imports, are used for cutting; hence their coronae come to an edge; the canine teeth penetrate and lacerate, and their coronae are acuminated; whilst the molares bruise and grind, and their touching surfaces are tuberous. The first, having usually no great effort to sustain, are placed at the extremity of the lever; the latter, for opposite reasons, are nearest the fulcrum. To preclude displacement by the efforts they have occasionally to sustain, they are firmly fixed in the alveoli or sockets; and,, as the roots, are conical, and the alveoli accurately embrace them, the force, as in the case of the wedge, is transmitted in all directions, instead of bearing altogether upon the jaw, which it would do, were the fangs cylindrical. The molar teeth, having the greatest efforts to sustain, are furnished with several roots; or with one that is extremely large. The gums add materially to the solidity of the junction of the teeth with the jaws. They are themselves formed of highly resisting mate- rials, so as to withstand the pressure of hard and irregular substances. Whenever they become spongy, and fall away from the teeth, the latter become loose; and are frequently obliged to be extracted, in conse- quence of the loose tooth acting as an extraneous body, and inflaming the lining membrane of the alveolus. The arrangement of the jaw is well adapted to the function; the lower jaw passing behind the upper at its anterior part; but coming in close contact at the sides, where mastication is chiefly effected. During the whole time that mastication is going on, the mouth is closed;—anteriorly, by the lips and teeth, which prevent the food from falling out of the cavity; and posteriorly by the velum palati, the anterior surface of which is applied to the base of the tongue. At the same time, the food is undergoing insalivation or admixture with the various fluids poured into the mouth, and particularly with the saliva, ORAL DIGESTION. 565 the secretion of which is augmented, not only by the presence of food, but even by the sight of it, especially if the food be desirable;—giving rise to what is called " mouth-watering." It is probable, that, inde- pendently of mental association, the action of the secretory organs is increased by the agitation of the organs themselves during the masti- catory movements. It has, indeed, been asserted, that the parotid glands are so situate, as regards the jaws, that the movement of the lower jaw presses upon them, and forces out the saliva; but MM. Bordeu and J. Cloquet have demonstrated, anatomically and by ex- periment, that ^his is not the case.1 It has been supposed by,some, that admixture with saliva communi- cates to the food its first degree of animalization; or in other words, its first approximation to the substance ofthe animal it has to nourish. Such are the opinions of Professor S. Jackson2 and M. Voisin.3 The former asserts, that he has ascertained positively, that the saliva exerts a very energetic operation on .the food, separating, by its solvent pro- perties, some of its constituent principles, and performing a species of digestion. MM. Tiedemann and Gmelin, too, think that the water, and the carbonates and acetates of potassa.*and soda, and the chlorides of potassium and sodium, of the saliva, contribute to soften and dissolve the food; whilst the nitrogenized materials, the salivary and albuminous matters, communicate io it a first degree of animalization. It is more probable, however, that the great use of mastication and insalivation is to give the food the necessary consistence, in order that the stomach and small intestine may exert their action upon it in the most favourable manner; and that, consequently, the changes effected upon it in the mouth, are chiefly of a mechanical character. In the case of many substances—as sugar, salt, &c.—a true solution takes place in the saliva; and this probably happens to sapid bodies in general;—the par- ticles being separated by imbibing, the fluid. Krimer,4 of Leipzig, held in his mouth a piece of ham, weighing a drachm, for three hours. At the expiration of this time, the ham was white on its surface, and had increased in weight twelve grains. Krimer, it may be remarked, be- lieves, that the tears assist in digestion, and that they flow constantly by the posterior nares into the stomach. It would seem, too, that an important action of the saliva is the conversion of starch into dextrin or grape sugar. From one drachm of starch, Dr. Wright5 obtained in twelve hours, at a temperature of 98°, by admixture with saliva, thirty- one grains of sugar. This probably takes place by the action of some nitrogenized secretion, like pepsin in stomachal digestion. It has been affirmed, indeed, on the strength of numerous and varied experiments detailed before the French Academy of Sciences,6 by MM. Bernard de Villefranche and Barreswil, that in the gastric juice, pancreatic fluid, and saliva, an organic principle exists, which is common to them all; and that it is the nature of the chemical reaction associated with it, which alone determines their power of digesting the different aliment- ' Adelon, op. cit, ii. 4*18. ^Principles of Medicine, p. 354, Philad, 1832. 3 Nouvel Apercu sur la Physiologie du Foie, &c, Paris, 1833. 4 Versuch einer Physiologie des Blutes, Leipz, 1820. 6 Lond. Lancet, 1841-2. « Comptes Rendus, 7 Juillet, 1845. 566 DIGESTION. ary principles. In an alkaline fluid, all three have the power of trans- forming starch, and do not digest meat; whilst in an acid fluid they dissolve meat, but do not act on starch. Hence, they think, it appears easy to transform these fluids into each other, and to make for example an artificial gastric juice from pancreatic fluid. The action of saliva, however, is said to be less energetic, both on meat and starch, than the pancreatic fluid. For the organic compound in the saliva, M. Mialhe1 proposes for it the name animal diastase salivaire. It would seem, how- ever, from the experiments of MM. Magendie2 and Bernard,3 that many substances besides saliva,—as pieces of the mucous 'membrane of the mouth, bladder, rectum and other parts, various animal and vegetable tissues, and even morbid products effect the transformation of starch into sugar; but that the gastric fluid does not. The part of the saliva, according to M. Bernard, which appears to be most active is that secreted by the small glands and the mucous membrane of the mouth; but it has been properly observed, by Messrs. Kirkes and Paget,4 that if the influence of saliva in aiding the digestion of farinaceous food be admitted, we have yet to seek for the corresponding purpose served by the saliva of the carnivora, which consume no such food; and on this point we possess at present no information. It is probable, however, that the main action of saliva is to soften the food; for when substances are well mixed with water, they are retained in the mouth for a short time only; and, consequently, in an amylaceous solution there is no opportunity for change to be effected. Experiments, instituted by M. Lassaigne,5 by a committee of the Institute, and by M. Bernard6 show, that when the food is dry a con- siderable admixture of saliva takes place, whilst if it be so softened, that mastication is not needed, it absorbs scarcely any. In executing these experiments, the aliment was weighed before giving it to the animal; the oesophagus was cut across; and the aliment, after having been chewed and insalivated, was inserted through the wound in the neck. The difference in weight indicated the quantity of saliva that had been added to it. According to Professor Berard,7 these experiments teach us: First. That dry forage absorbs about four or five times its weight of saliva and mucus. Secondly. That dry feculaeeous articles (oats, starch and bar- ley meal) absorb a little more than their weight. Thirdly. That green forage (green leaves and stalks of barley) absorb a little less than half their weight; and fourthly; that moist feculaeeous articles (starch and bran) to which sufficient water has been added for the food to be swal- lowed without previous mastication, do not sensibly absorb any. Both mastication and insalivation are of moment, in order that diges- tion shall be accomplished in perfection; and, accordingly, they who 1 Lancette Francaise, Avril, 1845; and Ranking's Abstract, vol. i. Part, ii, Amer. edit, p. 270, New York, 1846. 2 Comptes Rendus, 1847, p. 117. 3 Canstatt und Eisenmann, Jahresbericht uber die Fortschritte in der Biologie, im Jahre, 1847, s. 117. 4 Manual of Physiology, Amer. edit, p. 162, Philad, 1849. 5 Journal de Chimie Medicale, p. 472, Paris, 1845. 6 Archives Generales de Medecine, 4e serie, torn. xiii. p. 1. 7 Cours de Physiologie, p. 721, Paris, 1848. ORAL DIGESTION. 567 swallow food without due mastication, or waste the saliva by constant and profuse spitting, are more liable to attacks of dyspepsia, or imper- fect digestion. It is proper, however, to add, that Dr. Budge,1 on extirpating the salivary glands in animals, did not find that they sus- tained the smallest apparent injury; whence he conjectures, that certain glands can act as succedanea to others, and that in the removal of the salivary glands the pancreas supplies perhaps the fluid usually secreted by the other. A table given by Dr. Robert Dundas Thomson2 as the results of ex- periments on two cows, signally exhibits the beneficial effects of a proper grinding of the food. The cows were fed on entire barley and malt steeped in hot water. They were then fed on crushed barley and malt prepared in the same manner. The influence of the finer division of the grain in increasing the quantity of milk is strikingly shown. Brown Cow. White Cow. Milk in periods of five days. Milk in periods of five days _ . , . , - ( 111A lbs. Entire barley and grass, . < Q7^ u r, • ,i < 96" Entire malt and grass, . ? 95 " 106 lbs. 94 " 98 " 104 " C 115* « 109* « Crushed barley, grass and hay, < 105 " ( 110 " 109§ " 110 " } 97 * 106J " Crushed malt and hay, •. < 96 " ( 98 " 107i«" The table exhibits, that with the entire barley, the milk diminished during the second five days of the experiment, whilst with the crushed barley it had a tendency to increase during each succeeding period. The degree of resistance, and sapidity of the food, apprise us when mastication and insalivation have been sufficiently exerted. When this is the case it is subjected to the next of the digestive processes. Some physiologists have affirmed, that the uvula is the organ whicli judges when the food is adapted for deglutition. M. Adelon, whose views are generally worthy of great favour and attention, asserts, "that it judges by its mode of sensibility, of the degree in Avhich the aliment has been prepared in the mouth; of the extent to which.it has been chewed, im- pregnated with saliva, and reduced to paste; and, according to the impression it receives, it excites, sympathetically, the action of all those parts; directs the convulsive contraction of the muscles that raise the pharynx, even keeps the stomach on the alert, and disposes it to receive favourably or to reject the food passing to it." Such a func- tion would be anomalous. It is, indeed, impossible for us to conceive, how so insignificant an organ could be possessed of those elevated attributes. Observation, also, proves, that the notion is the offspring of fancy. M. Magendie3 asserts, that he has known several persons who had entirely lost the uvula, either by venereal ulceration or by ex- 1 Medicinische Zeitung, May 4, 1842; cited in British and For. Med. Rev, July, 1842, p 221 "2 Experimental Researches on the Food of Animals, Amer. edit. New York, 1846. 3 Op. cit, ii. 58. 568 DIGESTION. cision, and yet he never remarked that their mastication experienced the slightest modification, or that they swallowed inopportunely. Our experience corresponds with that of M. Magendie. We know of more than one individual in whom there is not the slightest vestige of uvula, yet they taste, chew, and swallow like other persons. d. Deglutition. The act of swallowing, although executed with extreme rapidity, and apparently simple, is the most complicated of the digestive opera- tions, and requires the action of mouth, pharynx and oesophagus. It has been well analyzed by M. Magendie,—first of all in a thesis, main- tained at the Ecole de Medecine of Paris, in 1808, and subsequently, in his Precis Elementaire de Physiologie.1 To facilitate its study, he divides it into three stages. In the first, the food passes from the mouth into the pharynx; in the second, it clears the apertures of the glottis and nasal fossae, and attains the oesophagus; and-, in the third, it clears the oesophagus and enters the stomach. 1. When the food has been sufficiently masticated and imbued with saliva, it is collected by the action of the cheeks and tongue upon the upper surface of the last organ;—the mass being more or less rounded, and hence usually termed alimentary bolus. Mastication now stops; the tongue is raised and applied against the bony palate in succession from the tip to the root, and the alimentary bolus, having no other way of escaping from the force pressing it, is directed towards the pharynx. Previous to this, the pendulous veil of the palate had been applied to the base of the tongue. The bolus now raises it to the hori- zontal position: the circumflexus palati muscles render the velum tense, so that the food cannot pass into the nasal fossa?; and the muscles that constitute the pillars of the fauces—palato-pharyngei and glosso-sta- phylini—contribute to this effect. By this combination of results, the food is impelled into the pharynx. The muscles, which, by their action, apply the tongue to the roof of the mouth arid to the velum palati, are the proper muscles of the organ, aided by the mylo-hyoidei. In this first stage of deglutition, the motions are voluntary, except those of the velum palati. The process is. not executed with rapidity, and is easily intelligible. Such is not the case with the second stage. The actions in it are complicated, and executed with so much celerity, that they have been regarded as a kind of convulsion. 2. The distance, over which the bolus has to travel, in the second stage, is trivial; the rapidity of its course is owing to the larynx or superior aperture of the windpipe, which opens into the pharynx, having to be cleared instantaneously, otherwise respiration might be arrested, and serious effects ensue. The mode, in which the second stage is accomplished, is as follows. As soon as the alimentary bolus comes in contact with the pharynx all is activity; the pharynx con- tracts, embraces, and presses the bolus; and the velum pendulum, drawn down by the palato-pharyngei and glosso-staphylini muscles, fulfils a similar office. At the 'same time, the genio-glossus, by applying the 1 Edit, cit, ii. 63. DEGLUTITION. 569 tongue to the palate, from the tip to the root, raises the os hyoides, the larynx^ and, with it, the anterior paries of the pharynx. The same effect is directly induced by the contraction of the mylo-hyoidei, and genio-hyoidei muscles; which, instead of acting as depressors of the lower jaw, as they do during mastication, take the jaw as their fixed point, and are levators of the os* hyoides. The larynx is thus elevated, carried forwards, and meets the bolus to render its passage over the aperture of the larynx shorter, and, therefore, more speedy. To aid this effect,—when we make great efforts to swallow, the head is inclined forwards on the thorax. Whilst the os hyoides and the larynx are raised, they approach each other,—the upper margin of the thyroid cartilage passing behind the body of the' hyoid bone: the epiglottic gland is pushed backward, and the epiglottis is depressed, and inclined backwards and downwards, so as to cover the entrance to the larynx. The cricoid cartilage executes a rotatory motion on' the inferior cornua of the thyroid cartilage, which occasions the entrance of the larynx to become oblique from above to below, and, of course, from before to behind. The bolus thus glides over its surface ; and, forced on by the veil of the palate, and by the constrictors of the pharynx, reaches the oesophagus. At one time, it was universally believed, that the epiglottis is the sole agent in preventing substances from passing into■ the larynx. The experiments of M. Magendie1 have, however, demonstrated, that this is the combined effect of the motions of the larynx just described, and of the muscles, whose office it is to close the glottis; so that, if the laryngeal and recurrent nerves be divided in an animal, and the epi- glottis be left in a state of integrity, deglutition is rendered extremely difficult;—the principal cause, that prevented the introduction of ali- ments into the glottis, having been removed by the section. M. Magen- die, and MM. Trousseau and Belloc2- refer to cases of individuals, who were totally devoid of epiglottis, and yet swallowed without any diffi- culty,3 and Magendie remarks, that if, in laryngeal phthisis with destruc- tion of the epiglottis, deglutition be laboriously and imperfectly accom- plished, it is owing *to the carious condition of the arytenoid cartilages, and to the lips of the glottis being so much ulcerated as not to be able to close the glottis accurately. Whilst the bolus, then, is passing over the top of the larynx, respiration v must be momentarily suspended, owing to closure of the glottis1; and if, from distraction of any kind, we attempt to speak, laugh; or, breathe, at the moment of deglutition, the glottis opens, the food enters, and cough is excited, which is not appeased, until the cause is removed. This is what is called, in com- mon language, "the food going the wrong way." As soon as the bolus has cleared the glottis, the larynx descends, the epiglottis rises, and the glottis opens to give passage to the air. This is owing to the relaxation of the muscles that had previously raised the larynx and 1 Memoire sur l'TJsage de l'Epiglotte dans la Deglutition, Paris* 1813 ; and Preois,&c, i. 67. 2 A Practical Treatise oh Laryngeal Phthisis, &c. &c; Dr. Warder's translation, p. 84, in Dunglison's American Medical Library, Philad, 1839. 3 A similar case is given by Targioni, in which neither deglutition nor speech was im- paired; Morgagni, xxviii. 13. 570 DIGESTION. closed the glottis. M. Chaussier thinks, that the sterno-hyoidei muscles now act, and aid in producing the descent of the parts.1 The author had an excellent opportunity for noticing the laryngeal phenomena of deglutition in a man, who had cut his throat, and in whom a fistulous opening remained, which permitted the inferior ligaments of the larynx to be seen distinctly. The glottis was observed to be firmly closed.2 M. Longet,3 who has made experiments connected with this subject on animals, is disposed-to think, that the displacements of the base of the tongue and epiglottis are the two most important conditions, and that the closed glottis is only the last obstacle set up against the passage of food into the larynx; but he evidently assigns too much importance to the epiglottis. The velum pendulum, then, protects the posterior nares and the orifices ofthe Eustachian tube from the entrance of the food; and the epiglottis, the elevation of the larynx, with the contraction of the mus- cles that close the glottis, are the great agents in preventing it from passing into the larynx. The whole of this second stage consists of rapid movements, of an entirely involuntary character, which, accord- ing to Bellingeri,4 are under the presidency of the palatine filaments of the fifth pair; but these filaments are sensory; the motor filaments being probably derived from the pneumogastric; or, according to M. Longet, from the spinal.5 3. In the third stage, the pharynx, by its contraction, forces the ali- mentary bolus into the oesophagus, so as to somewhat dilate the upper part of the organ. The upper circular fibres are thus excited to action, and force the food onward. In this way, by the successive contraction of the circular fibres, it reaches the stomach. In the upper part of the oesophagus, the relaxation of the circular fibres speedily follows their contraction; but this is not the case in the lowest third, the circular fibres remaining contracted, for some time after the entrance of the bolus into the stomach,—probably to prevent its return into the oeso- phagus. The passage of the bolus along the oesophagus is by no means rapid. M. Magendie6 affirms, that he was struck, in the prosecution of his experiments, with the slowness of its progression. At times, it was two or three minutes before reaching the stomach; at others, it stopped repeatedly, and for some time. Occasionally, it even ascended from the inferior extremity of the oesophagus towards the neck, and subse- quently descended again. When any obstacle existed to its entrance into the stomach, this movement was repeated a number of times, before the food was rejected. Every one must have felt the slowness of the progression of the food through the oesophagus when a rather larger morsel than usual has been swallowed. If it stops, we are in the habit of aiding its progress by drinking some fluid, or by swallowing a piece of bread. Occasionally, however, the probang is necessary to propel it. The pain produced in these cases, according to M. Magendie, is owing 1 Adelon, op. citat, ii. 424. 2 Dunglison's American Medical Intelligencer, Oct, 1841, p. 73. 3 L'Examinateur Medical, 17 Oct, 1841; and Brit, and For. Med. Rev, Jan, 1842, p. 228. * Dissert. Inaugural. Turin, 1823 ; noticed in Edinb. Med. and Surg. Journ. for July, 1834. 5 Traiti de Physiologie, ii. 337, Paris, 1850. 6 Op. citat, ii. 69. DEGLUTITION. 571 to the distension of the nervous filaments, that surround the pectoral portion of the canal. In the case of a female, labouring under a disease which permitted the interior of the stomach to be seen, M. Halle noticed, that whenever a portion of food passed into the stomach, a sort of ring or bourrelet was formed at the cardiac orifice, owing to the mucous membrane of the oesophagus being forced into the stomach by the con- traction of its circular fibres.1 The mucous fluid pressed out from the different follicles, by the passage of the bolus, materially facilitates its progress. Notwithstanding the facility with which deglutition is accomplished, almost every part of it is uninfluenced by volition, being dependent upon organization, and exerted instinctively. If the alimentary mat- ter contained in the mouth be not sufficiently masticated; or if it has not the shape, consistence, and dimensions^ it ought to possess; or if the ordinary movements, that precede mastication, have not been executed,—whatever effort we may make, deglutition is impractica- ble. We constantly meet -with persons who are unable to swallow the smallest pill; and yet can swallow a much larger mass, if cer- tain preliminary motions be executed, which, in the case of the pill, are inadmissible, in consequence of its being usually of a nauseous character. It appears, that the involuntary parts of the function are excited by the stimulation of the aliment; ,for, if we attempt to swal- low the saliva several times in succession, we find after a time, that the act is impracticable, owing to the deficiency of saliva. Every one must have experienced the difficulty of deglutition, when the mouth and fauces were not duly moistened by their secretions. The involuntary part of deglutition is under the control of the reflex system of nerves. An impression is made by the alimentary matters upon the excitor or afferent nerves, which impression is conveyed to the gray matter of the spinal cord, and in the invertebrata to ganglia corre- sponding to it; whence it is reflected to the muscular fibres that have to be thrown into contraction. The portion of the spinal cord, which serves as a centre for the reception of the impression, and the point of departure for the motor influence, is the medulla oblongata; and the experiments of Dr. John Reid2 lead to the inference, that the glosso- pharyngeal, which is chiefly distributed to the mucous surface of the tongue and fauces, is the excitor nerve; the pharyngeal branches of the pneumogastric, the motors. It would seem, however, that these nerves do not alone possess the function ; for after they have been divided, the animal is still capable of imperfect deglutition. The associate excitor or afferent nerves, Dr. Reid concludes to be—the branches of the fifth pair, that are distributed to the fauces, and probably also those of the superior laryngeal distributed to the pharynx:—the associate motor or efferent nerves being branches of the hypoglossal, that are distributed to the muscles of the tongue, and to the sterno-hyoid, sterno-thyroid, and thyro-hyoid muscles; filaments of the inferior laryngeal that ramify on the larynx; some of the branches of the fifth pair that supply the levator jnuscles of the lower jaw; the branches of the portio dura that i Op. cit, ii. 70. 2 Edinb. Med. and Surg. Journ, vol. xlix. 572 DIGESTION. ramify upon the digastric and stylo-hyoid muscles, and upon the muscles of the lower part of the face; and probably some' of the branches of the cervical plexus, which unite themselves to the descendens noni. It mus£ be admitted, however, that this part of the physiology of deglu- tition is obscure.1 Some individuals are capable of swallowing air; and, according to M. Magendie,2 it is an art that can be attained by a little practice. In the stomach, the air'acquires the temperature of the viscus, becomes rarefied, and distends the organ; exciting, in some, a feeling of burning heat; in others, an inclination to vomit, or acute pain. He thinks it pro- bable, that its chemical composition undergoes change; but, on this point, nothing certain is known. The time of its stay in the stomach is variable. Commonly, it ascends into the oesophagus, and makes its exit through the mouth or nostrils. At other times, it passes through the pylorus, and diffuses itself through the whole of the intestinal canal, as far as the anus,—distending the' abdominal cavity, and simulating tympanites. M. Magendie refers to the case of a young conscript, who feigned the disease in this manner. e. Chymification. When the food has experienced changes impressed upon it by the preceding process, it reaches the cavity of the stomach, where it is re- tained for several hours, and undergoes another portion of the digestive action, being converted into a pultaceous mass, to which the term chyme has been applied; whilst the process has been called chymification. It does not seem, that all physiologists have employed these terms in this signification; some have confounded chyle with chyme; and chylification with chymification. The former of these processes is distinctly an in- testinal act: the latter is exclusively gastric. The aliment, as it is sent down by repeated efforts of deglutition, descends into the splenic portion of the stomach without difficulty, as regards the first mouthfuls. The stomach is but little compressed by the surrounding viscera, and its parietes readily separate to receive the food; but when it is taken in considerable quantity, the distension gradu- ally becomes more difficult, owing to the compression of the viscera and the distension of the abdominal parietes. The accumulation takes place chiefly in the splenic and middle portions. Dr. Beaumont3 ob- served, that when a piece of food was received into the stomach, the rugse of the latter gently closed upon it; and if it were sufficiently fluid, gradually diffused it through the cavity of the organ, but entirely ex- cluded more whilst the action continued. The contraction ceasing, another quantity of food was received in the same manner. It was found, in the subject of his experiments, that when the valvular portion of the stomach, situate at the fistulous aperture, was depressed, and solid food introduced, either in large pieces or finely divided, the same gentle contraction or grasping motion took place, and continued for fifty or eighty seconds, and it would not allow of another quantity, until ' Longet, Traite de Physiologie, ii. 334, 337, Paris, 1850. * Carpenter, Human Physiology, ii. 146. 3 Experiments, &c, on the Gastric Juice, p. 110. CHYMIFICATION. 573 that period had elapsed: the valve 'could then be depressed, and more food put in. When the man was so placed, that the cardia could be seen, and was permitted to swallow a mouthful of food, the same con- traction of the stomach and grasping of the bolus were invariably ob- served to commence at the oesophageal ring. Hence, when food is swallowed too rapidly, irregular contractions of the muscular fibres of the oesophagus and stomach are produced; the vermicular motions of the rugse are disturbed, and the regular process of digestion is inter- rupted. Whilst the stomach is undergoing distension by food, it experiences changes in its size, situation, and connexion with the neighbouring organs. The dilatation does not affect its three coats equally. The two laminae of the peritoneal coat separate, and permit the stomach to pass farther between them. The muscular coat experiences a true distension;. its fibres lengthen, but still so as to preserve the particu- lar shape of the organ; whilst the mucous coat yields, in those parts especially where the rugse are numerous; that is, along the great curva- ture and splenic portion. In place, too, of being flattened at its anterior and posterior surfaces, and occupying only the epigastrium, and a part ofthe left hypochondrium, it assumes a rounded figure. Its great cul-de- sac descends into the left hypochondre and almost fills it, and the greater curvature descends towards the umbilicus, especially on the left side. The pylorus preserves its position and connexion with the surrounding parts;—being fixed down by a fold of the peritoneum. It is chiefly forwards, upwards, and to the left side, that the dilatation occurs. The posterior surface cannot dilate on account of the resistance of the verte- bral column, and of, a ligamentous formation which prevents the stomach from pressing on the great vessels behind it. Its cardiac and pyloric portions are also fixed; so that when it is undergoing distension, a movement of- rotation takes place, by which the great curvature is directed slightly forwards; the posterior surface inclined downwards, and the superior upwards. 'A wound received in the epigastric region, will, consequently, penetrate the stomach in a very different part, ac- cording as the viscus may be, at the time, full or empty. The dilatation of the organ producers changes in the condition of the abdomen and its viscera. The total size of the abdominal cavity is augmented; the belly becomes prominent; and the abdominal viscera are compressed,—sometimes so much as to excite a desire to evacuate the contents of the bladder or rectum. The diaphragm is crowded to- wards the thorax, and is depressed with difficulty; so that, not only is ordinary respiration cramped; but speaking and singing become labo- rious. When the distension of the organ is pushed to an enormous extent, the parietes of the abdomen may be painfully distended, and the respiration really difficult. It is in these cases of over-distension, that an energetic contraction of the oesophagus is necessary; hence the advantage of the strong muscular arrangement at its lower part. In proportion as the food accumulates in the stomach, the sensation of hunger diminishes; and, if we go on swallowing additional portions, it entirely disappears, or is succeeded by nausea and loathing. The quan- tity, necessary to produce this effect, varies according to the individual, 574 DIGESTION. as well as to the character of the food; a very luscious article sooner cloying than one that is less so. A due supply of liquid with solid ali- ment also enables us to prolong the repast with satisfaction. As the stomach, when distended, presses upon the different viscera and upon the abdominal parietes, it is obvious, that it must experience a proportionate reaction. An interesting question consequently arises;— to determine the causes, which oppose the passage of the food back along the oesophagus, as well as through the pylorus. M. Magendie1 found, in his vivisections, that the lower portion of the oesophagus experiences, continuously, an alternate motion of contraction and relaxation. The contraction begins at the junction of the two upper thirds with the lowest third; and is propagated, with some rapidity, to the termination of the oesophagus in the stomach. Its duration, when once excited, is variable; the average being, at least, half a.minute. When thus con- tracted, it is hard and elastic, like a cord strongly stretched. The relaxa- tion, that succeeds the contraction, occurs suddenly and simultaneously in all the contracted fibres; at times, however, it appears to take place from the upper fibres towards the lower. ' In the state of relaxation, the oesophagus is remarkably flaccid;—forming a singular contrast with that of contraction. This movement of the oesophagus is, according to M. Magendie,2 under the dependence of the eighth pair of nerves. When these nerves were divided in an animal, the oesophagus was no longer contracted. Still it was not relaxed. Its fibres, deprived of nervous influence; were shortened with a certain degree of force; and the canal remained in a state intermediate between contraction and' relaxation. The lower part of the oesophagus of the horse, for ,an extent of eight or ten inches, is not contractile tin the manner, of muscles. M. Ma- gendie3 found, when the eighth pair of nerves was irritated, or the parts were exposed to the galvanic stimulus, that no contraction was produced. The oesophagus of that animal is, however, highly elastic; and its lower extremity is kept so strongly closed, that for a long time after death, it is difficult to introduce the finger; and considerable pres- sure is required to force air into it. M. Magendie considers this arrange- ment to be the true reason, why horses vomit with such difficulty as to occasionally rupture the stomach by their efforts. The alternate mo- tions of the oesophagus, which we have described, oppose the return of the food from the stomach. The mO;re the organ is distended, the more intense and prolonged is the contraction, and the shorter the relaxation. The contraction commonly coincides with inspiration; the time at which the stomach is, of course, most strongly compressed. The relaxation is synchronous with expiration. The pylorus prevents the alimentary mass from passing into the duodenum. In living animals, whether the stomach be filled or empty, this aperture is constantly closed by the constriction of its fibrous ring, and the contraction, of its circular fibres; and, so accurately is it closed, that, if air be forced into the stomach from the oesophagus, the organ must be distended, and considerable exertion made to overcome the resistance of the pylorus. Yet, if air be forced from the small intes- 1 Pr6cis, &e, ii. 82. 2 Ibid, ii. 18. 3 Ibid, ii. 19. CHYMIFICATION. 575 tine in the direction of the stomach, the pylorus offers no resistance;— suffering it to enter the organ under the slightest pressure;—a circum- stance that accounts for the facility with which bile enters the stomach; especially when there exists inverted action of the duodenum. To the pylorus, however, a more active part has been assigned in the passage of the chyme from the stomach into the intestine. "Nothing in the animal economy," says Dr. Southwood Smith,1 "is more curious and wonderful than the action of that class of organs of which the pylorus affords a remarkable example. If a portion of undigested food present itself at this door of the stomach, it is not only not permitted to pass, but the door is closed against it with additional firmness; or, in other words, the muscular fibres of the pylorus, instead of relaxing, contract with more than ordinary force. In qertain cases, where the digestion is morbidly slow, or where very indigestible food has been taken, the mass is carried to the pylorus before it has been duly acted upon by the gastric juice: then, instead of inducing the pylorus to relax, in order to allow of its transmission to the duodenum, it causes it to con- tract with so much violence as to produce pain, while the food, thus re- tained in the stomach longer'than natural, disorders the organ: and if digestion cannot ultimately be performed, that disorder goes on increas- ing until vomiting is excited, by. which means the load that oppressed it is expelled. The pylorus is a guardian placed between the first and the second stomach, in order to prevent any substance from passing from the former until it is in a condition to be acted upon by the latter; and so faithfully does this guardian perform its office, that it often, as we have seen, forces the stomach to reject the offending matter by vomiting, rather than allow it to pass in an unfit state; whereas, when chyme,, duly prepared, presents itself, it readily opens a passage for it into the duodenum." This view of the functions of the pylorus has antiquity in its favour. It is, indeed, as old as the name, which was given to it in consequence of its being believed to be a faithful porter or janitor, (nvKupoc, ,"a porter;'')-but it is doubtless largely hypothetical. We constantly see substances traverse the whole extent of the intestinal canal, without having experienced the slightest change in the stomach. Buttons, half-pence, &c, have made their way through, without diffi- culty ; as well as the tubes and globes, employed in the experiments of Spallanzani, Stevens, and others. There are certain parts of fruits, which are never digested, yet the "janitor" is always accommodating. Castor oil is capable of being wholly converted into chyle; and would be so, if it could be retained in the stomach and small intestines; yet there is no agent, which arrests its onward progress. Still, from these, and other circumstances, M. Broussais2 has inferred, that there is an internal gastric sense, which exerts an elective agency; detaining, as a general rule, substances that are nutritive; but suffering others to pass. The presence of food in the stomach after a meal soon excites the organ to action, although no change in the food is perceptible for some time. The mucous membrane becomes more florid, in consequence of 1 Animal Physiology, Library of Useful Knowledge, p. 41. 2 Traite de Physiol. appliqueealaPathologie; translated by Drs. Bell and La Roche, p. 314, Philad, 1832. 576 DIGESTION. the larger afflux of blood; and the different secretions appear to take place in greater abundance; become mixed with the food, and exert an active and important part in the changes it experiences in the stomach. Direct experiment has proved that such augmented secretion actually occurs.' If an animal be kept fasting for some time, and then be made tO swallow dry food, or even stones, and be deprived of liquid aliment, the substances swallowed will be found,—on killing it some time after- wards,—surrounded by a considerable quantity of fluid. Such is not the case with animals killed after fasting. The stomach then contains no fluid matter. The augmented secretion in the former case must, therefore, be owing to the presence of dry foodin the stomach. That it is not simply the fluid passed down by deglutition,—the salivary and mucous secretions, for example,—is proved by the fact, that the same thing occurs when the oesophagus has been tied. Besides, if the sto- mach of a living animal be opened, and any stimulating substance be applied to its inner surface, a secretion is seen to issue in considerable quantity at the points of contact; and, again, if an animal be made to swallow small pieces of sponge, attached to a thread hanging out of the mouth, by means of which they can be withdrawn, they become filled with the fluids secreted by the stomach, and, on withdrawing them, a sufficient quantity can be obtained for analysis. Such experiments have been repeatedly performed by MM. Reaumur,1 Spallanzani,2 and others. In Dr. Beaumont's case3 the collection of gastric secretion was obtained by inserting an elastic gum tube through the opening: in a short time fluid enough was secreted to flow through the tube. This admixture with the fluids of the mucous membrane of-the. stomach, and the secretions continually.sent down from the mouth by the efforts of deglutition, is the only apparent change witnessed for some time after the reception of solid food. 'Sooner or later, according to circum- stances, the pyloric portion of the organ contracts sending into the splenic portion the food it contains: to the contraction dilatation suc- ceeds ; and this alternation of movements goes on during the whole of digestion. After this time chyme only is found in the pyloric portion mixed with a small quantity of unaltered food. This motion of con- traction and relaxation has been called peristole; and it appears, at first, to be limited to the pyloric portion, but gradually extends to the body and splenic portion, so that, ultimately, the whole stomach parti- cipates in it. It consists in an alternate contraction and relaxation of the circular fibres; and the gentle oscillation, thus produced, not only facilitates the admixture of the food with the gastric secretions, but continually exposes fresh portions to.their action. The experiments of Bichat satisfied him, that the peristole is more marked, the greater the fulness of the stomach. - He made dogs swallow forced-meat balls, in the centre of which he placed cartilage, and found, that when the sto- mach was greatly charged, the cartilages were pressed out of the balls. This did not happen, when the organ contained a smaller quantity of food. 1 Memoir, de l'Acad. pour 1752. 2 Exp£r. sur la Digestion, Geneve, 1783. 3 Experiments, &c, on the Gastric Juice, p. 106. CHYMIFICATION. 577 The ordinary course and direction of the revolutions of the food, according to Dr. Beaumont,1 are as follows:—The bolus, as it enters the cardia, turns to the left; passes the aperture; descends into the splenic extremity, and follows the great curvature towards the pyloric end. It then returns in the course of the lesser curvature, and makes its appearance again at the aperture, in its descent into the great cur- vature to perform similar revolutions. That these are the revolutions of the contents of the stomach, he ascertained by identifying particular portions of food; and by the fact, that when the bulb of the thermome- ter was introduced during chymification, the stem invariably indicated the same movements. Each revolution is completed in from one to three minutes, and the motions are slower at first than when chymifi- cation has made considerable progress. In addition to these move- ments, the stomach is subjected to more or less succussion from the neighbouring organs. At each inspiration it is pressed upon by the diaphragm; and the large arterial trunks in its vicinity, as well as the arteries distributed over it, subject it to constant agitation. It has been already remarked, that the peristaltic action of the sto- mach,—and the action extends likewise to the intestines,—is effected by the muscular coat of the organ. It is, however, an involuntary con- traction, and appears to be little influenced by the nervous system; continuing, for instance, after the division of the eighth pair of nerves; becoming more active, according to M. Magendie,2 as animals are more debilitated, and even at death ; and persisting after the alimentary canal has been removed from the body. MM. Tiedemann and Gmelin,3 however, affirm, that by irritating the plexus -of the eighth pair of nerves situate around the oesophagus with the point of a scalpel, or touching it with alcohol, the peristole of both stomach and intestines can be constantly excited; and Valentin and Dr. John Reid' state, that distinct movements may be excited in the stomach by irritating the pneumogastric. This involuntary function, as well as that exerted by the heart and other involuntary organs, affords us a striking instance of the little nervous influence, which seems to be requisite for carry- ing on many of those functions that have to be executed independently of volition through the whole course of existence ; and which appear to be excited at times, in a reflex manner, by the presence of appropriate excitants ;—of food, in the case of the peristaltic action of the stomach; of blood, in that of the heart, &c.; and yet may be carried on in the absence of all nervous influence, as in the cases of the intestinal canal, and the heart, which may contract for a long time after they have been removed from the body. In the intestinal canal, the movements are doubtless influenced by the spinal cord, probably through the sympa- thetic by means of the fibres which the canal derives from it; but although influenced by the spinal cord, they are not dependent upon it for contractility. As Dr. Carpenter has remarked, the canal is ena- bled to propel its contents by its inherent powers; but—as in other instances—the nervous centres exert a general control over even the 1 Op. citat, p. 110. 3 Precis Elementaire, ii. 20. 3 Die Verd'auung, u. s. w. or French edit, Recherches sur la Digestion, Paris, 1827. vol. i.—37 578 DIGESTION, organic functions, " doubtless for the purpose of harmonizing them with each other, and with the conditions of the organs of animal life."1 The gentle, oscillatory or vermicular motion of the stomach, and the admixture with the fluids, secreted by its internal membrane, as well as by the different follicles, &c, in the supra-diaphragmatic portion of the alimentary canal, are probably the main agents in the digestion ope- rated in the stomach. Much contrariety of sentiment has existed regarding the precise organs that secrete the fluid which oozes out as soon as-food is placed in contact with the mucous coat of the stomach.- Whilst some believe it to be exhaled from that membrane ; others conceive it to be secreted by the numerous follicles, seated in the membrane as well as in that of the lower portion of the oesophagus; or by what have been termed gas- tric glands. The analogy of many animals, especially of birds, would render the last opinion the most probable. Jn them we find, in the second stomach, the-cardiac or gastric glands largely developed ; and it is probable, that they are the great agents of the secretion of the digest- ive fluid, (See Figs. 228 and 229.) MM. Tiedemann and Gmelin2 affirm, that the more liquid portion of the gastric fluid is exhaled, and that the thicker, more ropy and mucous portion is secreted by the follicles. Rudolphi3 assigns it a double origin ;—from exhalants, and gastric glands; whilst MM. Leuret and Lassaigne4 ascribe its formation exclu- sively to the villi. Dr. Beaumont,5 who had an excellent opportunity for experimenting on this matter, remarks, that -on applying aliment, or any irritant, to the internal coat of the stomach, and observing the effect through a magnifying-glass, innumerable minute, lucid points, and very fine papillae, could be seen protruding, from which a pure, limpid, colourless, slightly viscid fluid distilled, which was invariably and dis- tinctly acid. On applying the tongue to the mucous coat in its empty, unirritated state, no acid taste could'be perceived. Although no aper- tures were perceptible in the papillae,'even with the assistance of the best microscope that could be obtained, the points, whence the fluid issued, were clearly indicated by the gradual appearance of innumera- ble very fine, lucid specks, rising through the transparent mucous coat, and seeming to burst, and discharge themselves upon the very points of the papillae, diffusing a limpid, thin fluid .over the. whole interior gas- tric surface. A like difference of opinion has prevailed regarding the chemical character of the fluids ; and this has partly arisen from the difficulty of obtaining them identical. The true fluid secreted by the gastric fol- licles or mucous membrane can never, of course, be obtained for examina- tion in a state of purity. It must always be mixed not only with the other secretions of tbe stomach, but with all those transmitted to - the organ, by the constant efforts of deglutition. It is, consequently, to this mixed fluid, that the term gastric juice has really been applied; although it is more especially appropriated to the particular fluid, pre- sumed tp be secreted by the stomach, and to be the great agent in diges- 1 Human Physiology, p. 151, Lond, 1842. 2 Op. citat. 3 Grundriss der Physiologie, 2er Band, 2te Abtheilung, s. iii, Berlin, 1828. 4 Recherches sur la Digestion, Paris, 1825. 5 Op. citat, p. 103. CHYMIFICATION. 579 tion. To the nature of the gastric juice and its effects in the process of digestion, we shall have occasion to recur presently. It is probably owing to the quantity of fluid secreted by the stomach, that it is so largely supplied with bloodvessels; and that the mucous membrane is more injected, during the presence of food in'the organ. Experiments, by Sir Benjamin Brodie1 and others, would seem to show, that the secretion is under the influence of the eighth pair of nerves. Having administered arsenic to different animals—on some of which he had divided these nerves,—he found, that; whilst the stomachs of those, in which the nerves were entire, contained a large quantity of a thin, mucous fluid; in those, whose nerves were divided, the organ was in- flamed and dry. Leuret and Lassaigne,2 however, affirm, that divi- sion of the nerves had no influence on the secretion. But more of this presently. Before entering into the views of different physiologists on chymifi- cation,—in other words, into the theories of digestion,—it will be well to refer to the physical and chemical properties of the chyme. Whether the changes in the'food be simply physical or chemical, or whether the first stage of animalization be effected within the stomach, will be a topic for future inquiry. Chyme is a soft, homogeneous' substance, of grayish colour and acid taste. Such are its most common characters: it varies, however, according to the food taken, as may be observed, by feeding animals on different simple alimentary substances, and killing them during digestion. This difference in its properties accounts for the discrepancy observable in the accounts of writers. The change wrought on the aliments is, doubtless, of a chemical nature; but the new play of affinities is controlled by circumstances inappreciable to us. In the case of a female patient at the hospital La Charite, of Paris, who had been gored by a bull, and had a fistulous opening in the stomach, the food, during its conversion into chyme, appeared to have acquired an increase of its gelatin; a greater proportion of chlo- ride of sodium ; phosphate of soda and phosphate of lime; and a sub- stance, in appearance, fibrinous.3 It has been said, again, that the food becomes decarbonized and more nitrogenized; that the carbon which disappears is removed by the oxygen of the air swallowed with the food, or by that contained in the food itself; and that the nitrogen proceeds from the secretions of the stomach, or predominates simply because the food is decarbonized. M. Adelon4 has properly remarked, that the fact and the explana- tion are here equally hypothetical. Generally, the chyme possesses acid properties. MM.de Montegre,5 Magendie,6 and Tiedemann and Gmelin,7 always observed it to be so. Haller8 and Marcet found it to be neither acid nor alkaline. In the chyme examined by the latter gentleman, he detected albumen, an animal matter, and some salts, 1 Philos. Trans, for 1814, ■ 2 Op. citat _ 3 Richerand's Nouveaux Elemens de Physiologie, edit. 13eme, par Berard, aine, p. 72, Bruxelles, 1837. 4 Physiol, de l'Homme, &c, edit, cit, torn. u. * Experiences sur la Digestion, Paris, 1824. 6 Op citat, up. 87. 1 Od c't Element. Physiol, xiX. 1. 580 DIGESTION. differing, however, slightly, according as it proceeded from animal or vegetable food. In the latter case, it afforded four times as much carbon as in the former, but less saline matter; and this consisted of lime and an alkaline chloride. MM. Leuret and Lassaigne1 analyzed the chyme from the stomach of an epileptic, who died suddenly in a fit, five or six hours after having eaten. It was of a white, slightly- yellowish colour; and strong, disagreeable taste'. On analysis, it afforded a free acid,—the lactic; a white, crystalline, slightly saccha- rine matter, analogous to the sugar of milk; albumen, soluble in water; a yellowish, fatty, acid matter, analogous to rancid butter; an animal matter, soluble in water, having all the properties of casein; and a little chloride of sodium, phosphate of soda, and much phosphate of lime. Dr. Prout2 affirms, that a quantity of chlorohydric acid is present in the stomach during the process of digestion. ' He detected it in that of the rabbit, hare, horse, calf, and dog, and in the sour matter ejected by persons labouring under indigestion:—a fact which has been confirmed by Mr. Children. MM. Tiedemann and Gmelin, and Dr. Beaumont,3 affirm, that the secretion of acid commences, as soon as the stomach receives the stimulus of a foreign body, and that it consists of chlorohydric and acetic acids. The experiments of these gentlemen were not confined to the chymous mass obtained from digesti- ble food. They examined the fluids, secreted by ihe mucous membrane when indigestible substances were sent into the stomach, and the acid character was equally manifested. These experiments, consequently, remove an objection, made by Dr. Bostock,4 regarding the detection of the chlorohydric acid by Dr. Prout;—that, as there did not appear to be any evidence of the existence of this acid before the introduction of food into the stomach, it might rather be inferred, that it is, in some way or other, developed during the process of digestion. In all Dr. Beaumont's experiments, the chyme was invariably, and distinctly acid. The principal theories on chymification have been the following:— 1. Coction, or elixation.—This originated with Hippocrates, ,and was vaguely used by him to signify the maceration, and maturation expe- rienced by the food in the stomach. The doctrine was embraced by Galen and others, who ascribed to the organ, an attracting, retaining, concocting, and expelling quality effected by heat.5 In proof of this, they affirmed that the heat of the stomach is increased charing chymi- fication; that the process is more rapid in.the warm, than cold-blooded animal;. that it is aided by artificial heat, and continues even after death, if care be taken to keep up the heat of the body; that in the ex- periments on artificial digestion made by Spallanzani, heat was always necessary, and the greater the degree of heat the more easy and com- plete the digestion. It is hardly necessary to say that the heat of the stomach is totally insufficient to excite any coction or ebullition in the physical sense of 1 Recherches, &c, p. 114. 2 Philos. Trans, for 1824; and Bridgewater Treatise, on Chemistry, &c, Amer. edit, p. 268, Philad, 1834. 3 On the Gastric Juice, &c, p. 105. 4 Physiology, 3d edit, p. 569,'Lond, 1S36. 5 Boerhaav. Prtelectiones Academ. Not. Adv, § 86, torn, i, Gotting, 1740-1743. CHYMIFICATION. 581 the term, and this applies particularly to the cold-blooded animal, which must digest, if not with the same, with due, rapidity. _ 2. Putrefaction.—The next great hypothesis was that of putrefac- tion, which, we are informed by Celsus,1 was embraced by Plistonicus, a disciple of Praxagoras of Cos, who flourished upwards of three hun- dred years before the birth of Christ. Of late, it has had no advocates, but appears to have been the view embraced by Cheselden.2 The rea- sons, urged in favour.of it, have been;—the putrescible character of the materials employed as food; the favourable circumstances of a heat of 98° or 100°, and of moisture; and, by some, the foetor of the ex- crements. The objections are, 1. That when the contents of the sto- mach are rejected, during chymification, they exhibit no evidence of putridity. 2. That in all the experiments, which have been made on the comparative digestibility of different substances, when it has been necessary to kill the animals at different stages of the digestive pro- cess, there has not'been the slightest sign-of putrefaction. 3. That opportunities frequently occur, for witnessing ravenous fishes and rep- tiles with an animal or portion of an animal,—too large to be entirely swallowed,—partly in the stomachvand the remainder in the gullet and mouth. In these cases, where the food, has remained in this situation some days, the part contained in the throat has been found putrid, whilst that in the stomach has been entirely sweet; and lastly, in Spal- lanzani's and other experiments, to be detailed presently, it was found, when food, in a state of putridity, was taken into the stomach, or mixed with the gastric juice out of the stomach, that it recovered its sweet- ness. It has been already observed, that it is the custom, in some countries, to .eat the gibier or game in a state of incipient putrefaction; yet the breath is not tainted by it. 3. Trituration.—The mathematical physiologists,—Borelli,3 Hecquet,4 Megallotti,5'Pitcairne,6 and others—after the example of Erisistratus,7 attempted to refer the whole process of digestion to trituration, ima- gining, that the food is subjected in the stomach to an action similar to that of the pestle and mortar of the apothecary, or of the millstone; and that the chyle is formed like an emulsion. The most plausible arguments, in favour of this view of the subject, are drawn from the presumed analogy of the granivoroiis bird, whose stomach is capable of exerting an astonishing degree of pressure on substances submitted to it. There is no analogy, however, between the human stomach, and the gizzard of birds. The latter is a masticatory organ, and therefore possessed of the. surprising powers which we have elsewhere described; whilst mastication, in man, is accomplished by distinct organs. No comparison can be instituted between the gentle oscillatory motion of the stomach, and the forcible compression exerted by the digastric muscle of the gizzard. The simple introduction of the finger through 1 De Medicina, cura E. Milligan, edit. 2da, p.' 5, Edinb, 1831. 2- Anatomy of the Human Body, &c, 8th edit, p. 155, Lond, 1763. 3 De Motu Ariimalium; Addit. J. Bernouillii, M.D, Medit. Mathem. Muscul, Lugd. Bat, 1710. 4 Trait6 de la Digestion, Paris, 1710. s Haller, Elem. Physiol, xix. 5. 6 Works, &c, Lond, 1715. > 7 Cels, loc. citat. 582 DIGESTION. a wound ofthe abdomen has shown, that the compression exerted by it on its contents is totally insufficient to bruise any resisting substance. Moreover, we constantly see fruits,—as raisins and currants,—passing through the whole intestinal canal unchanged; whilst worms remain in the stomach—reside there—unhurt; and, we shall see presently, that the experiments of Rdaumur and Spallanzani proved most convincingly, that digestion is effected independently of all pressure. The futility, indeed, of this mode of viewing the subject is signally illustrated by the fact, that, whilst Pitcairne estimated the power of the muscular fibres of the stomach at 12,951 pounds, Hales1 thought that twenty pounds would come nearer the,truth; and Astruc2 valued its compressive force at five ounces ! 4. Fermentation.—The system of fermentation had many partisans; amongst whom may be mentioned Van Helmont,3 Sylvius/ Willis,5 Boyle,6 Grew,7 Charleton,8 Lower,9 Raspail,10 &c; Digestion, in this view, was ascribed to the chemical reaction of the elements of the food during their stay in the stomach;—the action being excited by food that had already undergone digestion, or by a leaden secreted for the purpose by the stomach itself. In favour of this view, it was attempted to show, that air is constantly generated in the organ, and that an acid is always produced as the result of fermentation,—the formation of chyme being referred by the greater number of physiologists to the food undergoing the vinous and acetous fermentations. The objections to this doctrine of fermentation are ;—that digestion ought to be totally independent of the stomach, except as regards temperature; and the food.ought to be converted into chyme, exactly in the same manner,— if it were reduced to the same consistence, and placed in the same tem- perature,—out of the body; which is not found to.be the case. Bones are speedily reduced to chyme in the stomach of the dog, although they would remain unchanged for weeks, in the same temperature,-out ofthe body. The facts of the voracious fishes before mentioned likewise prove the insufficiency of the hypothesis ; according to which, digestion ought to be accomplished as effectually in the oesophagus as in the stomach. Yet it is found that, whilst the portion in the stomach is digested, the other may be unaltered, or be putrid. ' The truth is;—in healthy diges- tion, fermentation, in the ordinary acceptation of the term, does not occur; and, whenever the elements of the food react upon each other, it is an evidence of imperfect digestion; hence, fermentation is one of the most common signs of dyspepsia. 5. Chemical solution.—The theory of chemical solution, proposed by Spallanzani,11 and subjected to modifications, has met with more favour 1 Statical Essays, ii. 174, 4th edit, Lond, 1769. 2 Traite de la Cause de la Digestion, &c, Toulouse, 1714; and Haller, loc. citat. 3 Ortus Medicine, &c, Ainstel, 1648. 4 Opera, Genev, 1781. 5 Diatribae duae Medico-Philosophicse. &c, Lond, 1659. 6 Works, vol. ii, Lond, 1772. 7 Comp. Anat. of the Stomach, &c, Lond, 1681. 8 CEcon. Anim.'Exerc. 2. 9 Tractatus de Corde, &c, Amstel, 1-671. 10 Chimie Organique, p. 356, Paris, 1833. 11 Dissertations relative to the Natural History of Animals and Vegetables : sect, i, Lond, 1789. CHYMIFICATION. 583 from physiologists than any of the others that have been mentioned, and may be regarded as established. According to that observer, chymifi- cation is owing to the solvent action of a fluid, secreted by the stomach, which accumulates in that viscus between meals and during hunger,1 and acts as a true menstruum on the substances exposed to it. This fluid,—to which he gave the name gastric juice,—he affirmed to be peculiar in each animal, according to its kind of alimentation,—corre- sponding, as regards its energy, with the rest of the digestive apparatus, and differing in its source in the series of animals; in some, proceed- ing from the follicles of the oesophagus; in others from those of the sto- maeh; but always identical in the same animal; generally transparent, yellowish; of a saline taste; bitter; slightly volatile; and stronger in animals with a membranous than in those with a muscular stomach, and than in ruminant animals. To obtain the juice, Spallanzani opened animals, after they had been made to fast for a time; and collected the juice that had accumulated in their stomachs; or he made them swallow tubes pierced with holes, and filled with small sponges. By withdraw- ing these tubes, by means of a thread attached to them and suffered to hang out of the mouth, and expressing the sponges,- he obtained the fluid in quantity sufficient for examination. To determine whether this fluid, obtained'from fasting animals, was destined to chymify the food, he tried the following experiments. He caused numerous animals to swallow tubes filled with food, but pierced, with holes, so that the juices of the stomaeh migjit be able to get into their interior; and found that ehymification was effected, when he had taken the precaution to chew the substances before they were put into the tubes, or to triturate them; and the process was always more readily accomplished, the more easy the access of the fluids. On repeating these experiments on animals of' various kinds, with a muscular or membranous, and musculo-mem- branous stomach; on pullets, turkeys, ducks, pigeons, rooks, frogs, sala- manders, eels, serpents, sheep, cats, &c, he obtained the same results; and hence he affirmed, that trituration cannot be the essence of chymi- fication. Reaumur,2—originally a believer in the doctrine of tritura- tion,—had previously arrived at the same conclusion, by experiments of a similar kind. Spallanzani next repeated those experiments upon himself. - Having well chewed different articles of food, he enclosed them in wooden tubes pierced with holes, and swallowed them; but, as the tubes caused pain in the bowels, he substituted small bags of linen. The substances contained in bags were digested without the bags being torn; a fact, which proved, that digestion must have been accomplished by means of a fluid, that penetrated them. In 1777, Dr. Stevens3 re- peated these experiments. He made a person swallow balls of metal, filled with masticated food, and pierced with holes: when the balls were voided,—thirty-six or forty-eight hours afterwards,—they were entirely empty. Lastly.—Spallanzani was desirous of seeing whether this solvent juice could effect digestion out of the body. He put some well-masti- cated food in small glass tubes, and mixed gastric juice with it. These 1 It has been already stated, that the experiments of Dr. Beaumont have satisfactorily proved that no such accumulation takes place during hunger. _ 2 Memoir, de l'Acad. pour 1752. 3 »e Ahmentorum Concoctione, § 24. 584 DIGESTION. tubes he placed in his axilla, in order that they might be exposed to the same degree of heat as in the stomach; and in the space of fifteen hours, or of two days,—more or less,—the substances appeared to be converted into chyme. In these experiments he found it important to employ gastric juice, that had not been previously used, and to have a sufficient quantity of it. From all these experiments, Spallanzani conceived it to be demon- strated, that chymification is a true chemical solution; and he endeavour- ed to deduce from them the degree of digestibility of different alimentary substances. Similar experiments were instituted by Dr. Beaumont.1 In all cases, solution occurred as perfectly in the artificial as in the real digestions, but they were longer in being accomplished, for reasons which appear sufficient to explain the difference. In the former, the gastric secretion is not continuous; the temperature cannot be as accurately maintained, and there is an absence of those gentle motions *of the stomach, which are manifestly so useful in accomplishing real diges- tion. With regard to the precise nature of the gastric juice of Spallanzani, we have already observed that great contrariety of sentiment has pre- vailed; and that, in ordinary cases, it is impracticable to procure it unmixed with the other secretions of the digestive mucous membrane: Spallanzani affirmed, that the only properties he detected in it, were,— a slightly salt, bitterish taste; it was neither acid nor alkaline. Gosse2 found it vary according to the nature of the animal,—whether herbivor- ous or carnivorous;—and to be always acid in the former. Dumas3 held the same sentiments, and maintained from experiments on dogs, that it was acid or alkaline, according as the v animal had fed on vege- table or animal diet. He declared it, moreover, to be mawkish, thick, and viscid. Viridet4 and others affirmed that it was always acid. Mr. Hunter5 was hot inclined to suppose, that there* is any acid in the gastric juice as a component or essential part of it, " although an acid is very commonly discovered even when no vegetable matter has been introduced into the stomach." Scopoli6 analyzed the-gastric juice of the rook, and found it to consist of water, gelatin, a saponaceous matter, muriate of ammonia, and phosphate of lime. . Carminati7 describes it as salt, bitter, and frequently acid; and MM. Macquart8 and Vauquelin,9in the gastric juice of the ruminant animal, found albumen and free phosphoric acid,10 All these analyses were made on the mixed fluid, to which the term gastric juice has been applied. That such a mixed fluid does exist in the stomach at the time of chymification, and is largely concerned in the process, is proved by the facts already mentioned, as well as by the following. M. Magendie11 asserts, that one of his pupils—M. Pinel— 1 Op. citat, p. 139. 2 Experiences sur la Digestion, § 81, Genev., 1783. 3 Principes de Physiologie, Paris, 1806; * Tractatus Novus de Prima Coctione, &c, Genev, 1691. 6 Observations on Certain Parts of the Animal Economy, with Note's by Prof. Owen, Amer. edit, p. 134, Philad, 1840. « In Spallanzani, § 244. 7 Ricerche sulla Natura, &c, del Sueco Gastrico, Milano, 1785; or Journal Phys, t. xxiv. s Mem. de la Societe de Med, Paris, 1786. . 9 Fourcroy, El6m. de Chim, torn. iv. 10 See Burdach, Die Physiologie als Erfahrungswissenschaft, v. 240 und 431, Leips, 1833. 11 Precis, &c, ii. 11. CHYMIFICATION. 585 could procure, in a short time after swallowing a little water or solid food, as much as half a pint. M. Pinel " possessed the faculty of vomit- ing at pleasure." In this way, he obtained from his stomach, in the morning, about three ounces of fluid, which was analyzed by M. Thenard, who found it composed of a considerable quantity of water, a little mucus, and salts with a base of soda and lime; but it was not sensibly acid, either to the tongue or to reagents. On another occasion, M. Pinel obtained two ounces of fluid in the same manner. This was ana- lyzed by M. Chevreul, and found to contain much water, a considerable quantity of mucus, lactic acid—united to an animal matter, soluble in water, and insoluble in alcohol,—a little muriate of ammonia, chloride of potassium, and some chloride of sodium. Messrs. Tiedemann and Gmelin1 procured the gastric fluid by making animals, that had fasted, swallow indigestible substances, as flints. It always appeared to them to be produced in greater quantity, and to have a more acid character, in proportion as the alimentary matter was less digestible and less soluble; and they assign it, as constituents,— chlorohydric aeid; acetic acid; mucus; no, or very little, albumen; salivary matter; osmazome; chloride of sodium, and sulphate of soda. In the ashes, remaining after incineration, were, carbonate, phosphate, and sulphate of lime, and chloride of calcium. MM. Leuret and Las- saigne2 assign its composition, in one hundred parts, to be,—water, ninety-eight; lactic acid; muriate of ammonia; chloride of sodium; ani- mal matter soluble in water; mucus; and phosphate of lime, two parts. M. Braconnot3 examined the gastric juice of a dog, and found it to contain—free chlorohydric acid in great abundance; muriate of ammo- nia; chloride of sodium in very great quantity; chloride of calcium; a trace of chloride of potassium; chloride of iron; chloride of magnesium; colourless oil of an acid taste; animal matter soluble in water and alco- hol, in very considerable quantity; animal matter soluble in weak acids; animal matter soluble in water, and insoluble in alcohol (salivary matter of Gmelin); mucus; and phosphate of lime. In the winter of 1832-3, the author was favoured by Dr. Beaumont,4 with a quantity of the gas- tric secretion obtained from the individual with the fistulous opening into the stomach, which was examined by himself, and his friend, the late Professor Emmet, of the University of Virginia, and found to con- tain free chlorohydric and acetic a'cids, phosphates, and chlorides, with bases of potassa, soda, magnesia, and lime, and an .animal matter— probably pepsin—soluble in cold water, but insoluble in hot. The quantity of free chlorohydric acid was surprising: on distilling the fluid, the acids passed over, the salts and animal matter remaining in the retort: the amount of chloride of silver thrown down on the addi- tion of the nitrate of silver to the distilled fluid, was astonishing. The author had many opportunities for examining the gastric secretion obtained from the case in question. At all times, when pure or un- 1 Op. cit. 2 Recherches, &c, Paris, 1825. 3 Journal de Chimie Medicale, torn, ii, ser. 2, 1836, and Records of General Science, Jan, 1836. 4 See a letter from the author to Dr. Beaumont, in Beaumont's Experiments, &c,on the Gastric Juice, p. 77; and the author's Elements of Hygiene, p. 216, Philad, 1S35. 586 DIGESTION. mixed except with a portion of the mucus of the lining membrane of the digestive tube, it was a transparent fluid, having a marked smell of chlorohydric acid; and of a slightly salt, and very perceptibly acid, taste. It matters not, therefore, that M. Blondlot,1 in his experiments on the gastric secretions of dogs and other animals, obtained by arti- ficial fistulous openings made into the stomach, did not find, when dis- tilled, that they exhibited any acid reaction, whilst the residue in the retort Avas always strongly acid. The results referred to by the author as regards the gastric juice of man were positive and uniform; and established, that it always contains a large quantity of chlorohydric acid. After this it seems unnecessary to examine into the statement of M. Blondlot, that the true and almost only source of the acidity of healthy gastric fluid is the presence' of acid phosphate salts. If, at least, we admit this to be the case in animals, it is assuredly not so in man. The remark applies equally to the experiments of Dr. R. D. Thompson on the gastric "secretions of the sheep and pig.2 By these observers, the results obtained from the .examination of the gastric secretions in man, seem to have been passed over, and they have de- duced their inferences from those of animals, which may, in part, account for the great discrepancy in their statements.3 The source of the chlorine or chlorohydric acid, as Dr. Prout4 sug- gests, must be the common salt existing in the blood, which, he con- ceives, is decomposed by galvanic action. The soda, set free, remain- ing in the blood, a portion being "requisite to preserve the weak alkaline condition essential to the fluidity of the blood.;" but the larger part being directed to the liver to unite with the bile. This is plausi- ble ; but, it need scarcely be added, not the less hypothetical. Drs. Purkinje and Pappenheim5 are of a similar opinion in regard to the source of the chlorohydric acid. From their galvanic experiments they think it follows, that the juices mixed with the food in the natural way, saliva, mucus, the portions of chloride of.sodium present therein, and still more the gastric mucous membrane itself, develope as much as is required; and that if the nervous action in the stomach be either iden- tical with, or analogous to, galvanism, it would be sufficient to account for the secretion of the quantity of chlorohydric acid requisite for digestion, without the assumption of a special organ of secretion. M. Blondlot6 denies—and Liebig7 formerly "did likewise—that in health lactic acid exists in the stomach. In certain diseases, accord- ing to the latter, both it and mucilage are formed from the starch, and sugar of the food; and he affirms, that the property possessed by these substances of passing, by contact with animal substances, in a 1 Traite Analytique de la Digestion, Paris, 1844. An abstract of his views is given by Mr. Paget, Brit, and For. Med. Rev, Jan, 1845, p. 270. 2 Ranking's Abstract, vol. i, Pt. 2, Amer. edit, p. 271, New York, 1846. 3 Carpenter, Principles of Physiology, 4th Amer. edit, p. 494, Phitad, 1850; and Kirkes and Paget, Manual of Physiology, Amer. edit, p. 170, Philadelphia, 1849. 4 Bridgewater Treatise, Amer. edit, p. 268, Philad., 1834. 5 Muller's Archiv. fur Anatomie, u. s. w. Heft 1,1838, noticed in Brit, and For. Med. Rev, Oct, 1838, p. 529. 6 Op. cit. 7 Animal Chemistry, Gregory's and Webster's edit, p. 107, Cambridge, 1S42. CHYMIFICATION. 587 state of decomposition,- into lactic acid, has induced physiologists with- out farther inquiry, to assume that lactic acid is produced during di- gestion. He now, however, admits its existence in health,1 and with Dr. II. D. Thompson and MM. Bernard and Barreswil considers it to be an important agent in the digestive process. With some other che- mists, he denies the existence of free chlorohydric acid in the stomach, and believes, that when it is obtained by the simple distillation of the gastric juice it,is formed by the reaction of the lactic and phosphoric acids, which are present in the fluid, on the chlorides; and recently, Lehmann found, when he experimented on the stomachs of dogs placed in vacuo in such a manner as to cause the vapours from the gastric juice to pass through a'tube containing a solution of nitrate of silver, that there was no indication of free chlorohydric acid until the fluid had become so concentrated as to permit the action of the lactic acid on the earthy-chlorides. His results would tend to confirm the later conclusions of Liebig, as well as those of MM. Bernard and Barreswil, as to the nature of the acid on the gastric juice of certain-animals at least.2 It is proper to. remark, however, that neither Prout nor Braconnot could detect the lactic acid in the gastric juice ;. and, moreover, it does not appear to be formed in artificial digestion.3 The diversity of results obtained by chemical analysis; the difficulty of comprehending how the same fluid can digest substances of such opposite character; and the uncertainty we are in, regarding the organs concerned in its production, have led some physiologists to doubt the existence of any such gastric juice or solvent as that described by Spallanzani. M. Montegre,4 for example, in the year 1812, pre- sented to the French Institute a series of experiments, from which he concluded, that the gastric juice of Spallanzani is nothing more than saliva, either in a pure state, or changed by the chymifying action of the stomach and become acid.' As M. Montegre was able to vomit at pleasure, he obtained the gastric juice, as it had been done by previous experimenters, in this manner, whilst fasting. He found it frothy, slightly viscid, and turbid; depositing, when at rest, .some mucous flakes; and commonly acid; so much so, indeed, as to irritate the throat, and render the teeth rough. - He was desirous of proving, whether this fluid was in any manner inservient to chymification. For this purpose, he began by ejecting as much as possible by vomiting; and, afterwards, swallowed magnesia to neutralize what remained. On eating afterwards, the food did not appear less chymified, nor was it less acid; whence he concluded, that, instead of the fluid being the agent of chymification, it was nothing more than saliva and the mucous secretions of the stomach, changed by the chymifying action of that viscus. To confirm himself in this view, he repeated, with it, Spallanzani's experiments on artificial digestion; making, at the same sime, similar experiments with saliva: 1 Chemistry of Food, London, 1847". 2 Archiv. der Pharmacie, c. p. 79, cited in the British and Foreign Medico-Chirurgical Review, p. 261, Jan, 1849. 3 A full account of the various views in regard to the gastric acid is given by Frerichs, Art. Verdauung, Wagner's Handworterbuch der Physiologie, 21ste Lieferung, s. 780, Braun- schweig, 1849; and Berard, Cours de Physiologie, lie Livraison, p. 97, Paris, 1849. 4 Exper. sur la Digestion, p. 20, Paris, 1824. 588 DIGESTION. the results were the same in both cases. When gastric juice, not acid, was put into a tube, and placed in the axilla,—as in Spallanzani's experiments,—in twelve hours it was in a complete state of putrefac- tion. The same occurred to saliva placed in the axilla. Gastric juice, in an acid state, placed there, did not become putrid, but this seemed to be owing to its acidity; for the same thing happenedto.saliva, when rendered acid by the addition of a little vinegar; and even to the gastric juice,—used in the experiment just referred to,—when mixed with a little vinegar. Again:—he attempted artificial digestions with the gas- tric juice, acid and not acid; fresh and old; but they were unsuccessful. The food always became putrid; but sooner when the juice employed was not acid; and, if it sometimes liquefied before becoming putrid, this was attributed to the acidity of the juice, as the same effect took place, when saliva, mixed with a little vinegar, was employed. M. Mon- tegre, moreover, observed, that the food rejected from the stomach was longer in becoming putrid, in proportion to the time it had been subjected to the chymifying action of the stomach; and he concluded, that the fluid, which is sometimes contained in the empty stomach, instead of being a menstruum kept in reserve for chymification, is nothing more than the saliva continually sent down into that viscus, and that its purity or acidity depends upon the chymifying action of the stomach.1 As regards the fluid met with in the stomach of fasting animals, M. Montegre's remarks may be true in the main; but we have too many evidences in favour of the, chemical action of some secretion from the stomach during digestion to permit us to doubt thexfact for a moment. Besides, some of Montegre's experiments have been repeated with opposite results. MM. Leuret and Lassaigne,2 and Dr. Beaumont3 per- formed those relating to digestion.after the manner of Spallanzani, and succeeded perfectly; whilst they failed altogether in producing chymifi- cation with saliva, either in its pure state, or when acidulated with vine- gar. By steeping the mucous membrane of an animal's stomach in an acid liquor, a solution is obtained, to which Eberle4 gave the name pepsin. This solution has the property of dissolving organic matter in a much higher degree than diluted acids. It dissolves coagulated albumen, muscular fibre, and animal matters in general. In an experiment, one grain of the digestive matter dissolved one hundred grains of coagulated white of egg. Eberle thought that all mucus has the property, when acidulated, of inducing decomposition: and subsequent solution of the food; but it would appear, that no other mucus than that of the gastric mucous membrane, when acidulated, possesses it,5 and, consequently, that there must be a peculiar substance, pepsin, which may be regarded as the true digestive principle.6 This principle w*as not obtained by Schwann in a pure state ; but M. Wasmann7 would appear to have suc- 1 Chaussier and Adejon, in Diet, des Sciences Medicales, xx. 422. 2 Recherches sur la Digestion, Paris, 1825. 3 Op. citat, p. 139. 4 Physiologie der Verdauung nach, Versuchen, u. s. w, Wurzburg, 1834; Miiller, Archiv. Heft 1, 1836, or London Lancet, p. 19, March, 31, 1838. 5 Miiller, Elements of Physiology, by Baly, pp. 518 and 542, London, 1838. 6 Miiller and Schwann, in Muller's Archiv. Heft 1, 1836; and Miiller, op. citat. • 7 Journ. de Pharmacie; and American Journal of Pharmacy, for Oct. 1840, p. 19$. CHYMIFICATION. 589 ceeded better. A solution, containing only ^^ part of pepsin and slightly acidulated, is said to^ dissolve the white of an egg in six or eight hours. Even were the evidence adduced less positive, the following pheno- mena would be overwhelming in favour of the existence of some gastric secretion concerned in the digestive changes in that organ. Besides the fact of the most various and firm substances being reduced to chyme in the stomach, we find the secretions from its lining membrane possess- ing the power of coagulating albuminous fluids. It is upon the coagu- lating property of these secretions, that the method of making cheese is dependent. Rennet, employed for this purpose, is an infusion of the digestive stomach of the calf, which, on being added to milk, converts the albuminous portion into curd; and it is surprising how small a quantity is necessary to produce this effect. Messrs. Fordyce2 and Young,3 of Edinburgh, found that six or seven grains of the inner coat of a calf's stomach, infused in water, afforded a liquid, which coagulated more than one hundred ounces of milk,—that is, more than six thousand eight hundred and fifty-seven times its own weight; and yet its weight was probably but little diminished. The substance that possesses this property does not appear to be very soluble in water; for the inside of a calf's stomach, after having been steeped in water for six hours, and well washed, still furnishes a liquor or infusion, which coagulates milk. Liebig4 has denied, that the fresh lining membrane of the stomach of the calf, digested in weak chlorohydric acid, gives to that fluid the power of dissolving boiled flesh or coagulated white of egg; but Dr. Pereira5 affirms, that he has found, by experiment, that a digestive liquor can be prepared from the fresh undried stomach of a calf. This has, indeed, been shown on the best authority long ago. Mr. Hunter, for example, made numerous experiments upon the coagu- lating power of the secretions of the stomach, which show, that it is found in the stomachs of animals of very different classes. The lining of the fourth stomach of the calf is in common use, in a dried state, for the purpose mentioned above; and it has been proved, that every part of the membrane possesses the same property. Mr. Hunter found, by experiment, that the mucus ofthe fourth cavity of a slink calf, made into a. solution with a small quantity of water, had the power of coagu- lating milk; but that found in the three first cavities possessed no such poAver. The former, even after it had been kept several days, and was beginning to be putrid, retained the property. The duodenum and jejunum, with their contents, likewise coagulated milk; but the process was so slow as to give rise to the suggestion, that it might have occurred independently of the intestines employed for the purpose. He found, that the inner membrane of the fourth cavity in the calf, when old enough to be killed for veal> had the same property. Portions of the 1 Graham's Elements of Chemistry, Amer. edit, p. 695, Philad, 1843, and Thomson's Animal Chemistry, p. 229, Edinb, 1843. 2 A Treatise on the Digestion of Food, p. 57, 2d edit, Lond, 1791. 3 Thomson's System of Chemistry, 6th edit, iv. 596. 4 Animal Chemistry, Webster's Amer. edit, Cambridge, 1842. 5 Treatise on Food and Diet, Amer. edit, p. 36, New York, 1843. 590 DIGESTION. cuticular, of the massy glandular part, and of the portion near the pylo- rus of the boar's stomach, being prepared as rennet, it was found, that no part had the effect of producing coagulation but that near the pylorus, where the gastric glands of the animal are especially conspicuous. The crop and gizzard of a cock were salted, dried, and afterwards steeped in water. The solution, thus obtained, was added to milk: the portion of the crop coagulated it in two hours ; that of the gizzard in half an hour. The contents of a shark's stomach and duodenum coagulated it instan- taneously. Pieces of the stomach were washed clean, and steeped in water for sixteen hours. The solution coagulated milk immediately. Pieces of the duodenum produced the same effect. When the milk was heated to 96°, the coagulation took place in half an hour; when cold, in an hour and a quarter. The stomachs of the salmon and thornback, made into rennet, coagulated milk in four or five hours. But those experiments of Mr. Hunter do not inform us of the par- ticular secretions that are productive of the effect. They would, indeed, rather seem to show, that it is a general property of the whole internal membrane. To discover the exact seat ofthe secretion, and especially whether it be not in the gastric glands, Sir Everard Home1 selected those of the turkey; which, from their size, are better adapted for such an experiment than those of any other bird, except the ostrich. A young turkey was kept a day without food, and then killed. The gastric glands were carefully dissected separately from the lining of the cardiac cavity; cutting off the duct of each before it pierced the membrane, so that no part but the glands themselves were removed. Forty grains, by weight, of these glands were added to two ounces of new milk; and similar ex- periments were made with rennet; with the lining of the cardiac cavity of the turkey; and with the inner membrane of the fourth cavity of the calf's stomach. Coagulation and separation into curds and whey were first effected by the rennet. Next to this, and simultaneously, came the gastric glands, and the fresh stomach of the calf; and lastly, the cardiac membrane of the turkey. From these experiments, Sir Everard concluded, that the power of coagulation is in the secretion of the gastric glands; and that the power is communicated to other parts, by their becoming more 'or less impregnated with it. The marginal figure, copied from an engraving of the microscopic observations of Mr. Bauer, exhibits the gastric glands of the human oesophagus magnified fifteen times. These glands are the lining of the lower part of the oesophagus ; and have the appearance of infundibular cells, whose depth does not exceed the thickness of the membrane. This structure, although different from that of the gastric glands of birds, is a nearer approach to it than is to be met with in any part of the inner surface of the stomach or duodenum. It also resembles them, in the secretion which it produces coagulating milk, whilst none of the inspissated juices, met with in these cavities, according to Sir Everard, affect milk in the same way. From these facts, he thinks, there can be no longer any doubt entertained, that the gastric glands have the same situation respecting the cavity of the stomach as in birds. Yet 1 Lectures on Comparative Anatomy, i. 299, Lond., 1814, and iii. 134, Lond, 1823. CHYMIFICATION. 591 Gastric,Glands ofthe Oesophagus magnified fifteen times. M. Montegre1 denies that Fig. 248. the gastric juice has any coagulating power ! In some experiments, undertaken by M. J. F. Simon2 with a view to de- termine, whether the sto- mach of the child possesses the same properties of coagulating milk as that of the calf, he found that cow's milk was not coagu- lated by it, but that, when a quantity of ..the colos- trum of the mother of .a child, which died when five days old, was obtained, and a piece of calf's stomach was intro- duced into it, the milk coagulated. Another property, manifestly possessed by the secretion in question, is that of preventing putrefaction, or of obviating it in substances ex- posed to its action. Montegre and Thackrah3 deny it this property, but there can be no doubt of its existence. Spallanzani, Fordyce, and others, have ascertained, that in those animals which frequently take their food in a half putrid state, the first operation of the stomach is to disinfect, or remove the foetor from the aliment received into it. We have already alluded to many facts elucidative of this power. Helm of Vienna,4 in the case of a female who had a fistulous opening in her stomach, observed, that substances which were swallowed in a state of acidity or.putridity, soon lost those qualities in the stomach; and the same power of resisting and obviating putrefaction has been exhibited in experiments made out of the body. Nothing could be more unequivocal, as regards the possession of this property by the gastric fluid, than the experiments of Dr. Beaumont and the author,5 with the secretion obtained from the subject of his varied investigations. In the presence of the author's friend, N. P. Trist, Esq.—then consul of the United States at Havana,—the odour of putrid food was as speedily removed by it as by chlorinated soda, employed at the same time on other portions. The explanation of this property, as well as that of coagulation, has been a stumbling-block to the chemical phy- siologist. " We can' only say concerning it," says Dr: Bostock,6 "that it is a chemical operation, the nature of which, and the successive steps by which it is produced, we find it difficult to explain; at the same time, that we have very little, in the way of analogy, which can assist us in referring it to any more general principle, or to any of the es- tablished laws of chemical affinity." 1 Experiences sur la Digestion, Paris, 1824. s 2 Muller's Archiv. Heft 1, 1839, cited in Brit, and For. Med. Rev, Oct, 1839, p. 549. 3 Lectures on Digestion and Diet,-p. 14, Lond, 1824. 4 Rudolphi, Grundriss der Physiologie, 2er Band, 2te Abtheil, s. 114, Berlin, 1828. s See the author's Elements of Hygiene, p. 216, Philad, 1835\ 6 Edit, citat, p. 571. 592 DIGESTION. The cases of what are termed digestion of the stomach after death afford us, likewise, remarkable examples of the presence of some power- ful agent in the stomach; as well as of the resistance to chemical action, offered by living organs. Powerful as the action of the gastric juice may be, in dissolving alimetitary substances, it does not exert it upon the coats of the stomach during life. Being endowed with vitality, they effectually resist it. But when that viscus has lost its vitality, its parietes yield to the chemical power of the contained juices, and become softened, and, in part, destroyed. M. Hunter1 found the lining membrane of the stomach destroyed, in several parts, in the body of a criminal, who, for some time before his execution, had been prevailed upon, in consideration of a sum of money, to- abstain from food. Since Hunter's time, numerous examples have occurred, and been recorded by Messrs. Baillie, Allan Burns, Haviland, Grimaud, Pascalis, Cheese- man, J. B. Beck, Chaussier, Yelloly, Gardner, Treviranus, Godecke, Jager, Carswell, and others.2 The fact is of importance in medical jurisprudence; and, until a better acquaintance with the subject, would, doubtless, have been set down as strong corroborative evidence in cases of suspected poisoning. It is now established that solution of the sto- mach may take place after death, without there being reason for sup- posing that any thing noxious had been swallowed. The experiments Of Drs. Wilson Philip3 and Carswell4 are corro- borative of this physiological action on the gastric juice. On open- ing the abdomen of rabbits, that had been killed immediately after having eaten, and allowed to lie undisturbed for some time before ex- amination, the former found the great end of the stomach soft, eaten through, and sometimes altogether consumed; the chyme being covered only by the peritoneal coat, or lying quite bare for the space of an inch and a half in diameter: and, in this last case^ a part of the con- tiguous intestines was also destroyed; whilst the cabbage, which the animal had just taken, lay in the centre of the stomach unchanged, if we except the alteration that had taken place, in the external parts of the mass it had formed, in consequence of imbibing gastric fluid from the half-digested food in contact with it. Why. the perforation takes place, without the food being digested, is thus explained by Dr. Philip. Soon after death, the motions of the stomach, which are constantly carrying on the most digested food towards the pylorus, cease. The food that lies next to the surface of the stomach, thus becomes fully saturated with gastric fluid; neutralizes no more; and no new food being presented to the fluid it acts on the stomach itself, now deprived of life, and equally subjected to its action with other dead animal matter. It is extremely remarkable, however, that the gastric fluid of the rab- 1 Phil. Transact, Ixii.; and Observations on certain parts of the Animal Economy, with notes by Prof. Owen, Amer. edit, p. 144, Philad, 1840. 2 Beck's Medical Jurisprudence, 6th edit, ii. 311, Albany, 1838; Cars well's Path. Anat., No. 5, Lond, 1833; and T. Wilkinson King, Guy's Hospital Reports, vii. 139, Lond, 1842; and a case communicated to the author by Dr. Thomas M. Flint, in which the stomach had separated from the oesophagus, recorded in Med. Examiner, p. 715, for December, 1848^ 3 Treatise on Indigestion, Lond, 1821. 4 Ibid, and Edinb. Med. and Surg. Journal, Oct, 1830; and art. Perforation of the Hollow Viscera, in Cyclopaedia of Practical Medicine, P. xvi. p. 272, Lond, 1833. CHYMIFICATION. 593 bit, which, in its natural state, refuses animal food, should so completely digest the stomach, as not to leave a trace of the parts acted upon. Dr. Philip remarks, that he has never seen the stomach eaten through except at the larger end; but, in other parts, the external membrane has been injured. Mr. A. Burns,1 however, affirms, that in several instances he found the forepart of the stomach perforated, about an inch from the pylorus, and midway between the smaller and larger curvatures. From all these facts, then, we are justified in concluding, that the food in the stomach is subjected to the action of a secretion, which alters its properties, and is the principal agent in converting it into chyme. But many physiologists, whilst they admit, that the change effected in the stomach is of a chemical character, contend, that the nature of the action is unlike what takes place in any other chemical process, and is, therefore, necessarily organic and vital, and appertaining to vital chemistry. Such are the sentiments of Messrs. Fordyce,2 Brous- sais,3 Chaussier, and Adelon,4 and others. Dr. Prout suggests, that the stomach must have, within certain limits, the power of organizing and vitalizing the different alimentary substances; so as to render them fit for -being brought into more intimate union with a living body, than the crude aliments can be supposed to be. It is impossible, he conceives, to imagine, that this organizing agency of the stomach can be chemical. It is vital, and its nature completely unknown. The physiologist should' not, however, have recourse to this explanation, until every other has failed him. It is, in truth, another method of expressing his ignorance, when he affirms, that any function is executed in an organic or vital manner ; nor is this mode of explaining the con- version of the aliment into chyme necessary ; the secretion of the mat- ters that are the great agents of chymification is doubtless vital; but when once secreted, the changes, effected upon the food, are probably unmodified by any vital interference, except what occurs from tempera- ture, agitation, &c, which can only be regarded as auxiliaries in the function. It is in this way, that digestion is influenced by the nervous system. The effect of the different emotions on the digestive function is often evinced, and has already been alluded to; but the importance of the nervous influence to it has been elucidated, in an interesting manner to the physiologist, of late years chiefly. • Baglivi,5 having tied the nerves of the eighth pair in dogs, found that they were affected with nausea and vomiting, and obstinately refused food. Since Baglivi's time, the same results have been obtained by many physiologists. M. De Blain- ville, having repeated the operation on.pigeons, found the vetch in their crops entirely unchanged, and chymification totally prevented. Messrs. Legallois,6 Brodie,7 Philip,8 Dupuy, Clarke Abel, Hastings,9 and others— 1 Edinb. Med. and Surg. Journal, vi. 132. 2 On the Digestion of Food, 2d edit, Lond, 1791. 3 Traite de Physiologie, &c, translated by Drs. Bell and La Roche', p. 323. 4 Diet, des Sciences Medicales, ix. 5 Opera Omnia, Lugd. Bat, 1745. 6 Sur le Principe de la Vie, p. 214, Paris, 1842. 7 Phil. Trans, for I 814. 8 Experimental Inquiry, &c, Lond, 1817. 9 Journal of Science and Arts, vii. ix. x. xi. and xii. VOL. I.—38 594 DIGESTION. on carefully repeating the experiments—announced, that, after this ope- ration, the digestive process was entirely suspended.1' The result of these experiments was, however, contested by several physiologists of eminence, who affirmed, that, after the division of the eighth pair, digestion continued nearly in the natural state, or, at most, was only slightly impeded. Mr. Broughton2 asserted, that he had made the section on eleven rabbits, one dog, and two horses; and that digestion was not destroyed. M. Magendie3 expresses his belief, that the arrest of chymification, where it was observed, was owing to the disturbance of respiration caused by the division of the nerves ; and he states that digestion continued when care was taken to cut the nerve within the thorax, lower down than the part which furnishes the pulmonary branch. MM. Leuret and Lassaigne assert,4 that they found chymification continue, notwith- standing the division of these nerves ; and Dr. G. C. Holland5 thinks he has proved, that the suspension of the digestive function is not pro- duced by the influence of the nerves being withdrawn from the stomach, but by the disturbance of the circulatory system ; for when the natural conditions of this system were maintained, after the division of the nerves, the function of digestion still continued to be properly per- formed ; showing that the nervous connexion between the brain and stomach is not essential.to the process of digestion, the secretion of the gastric solvent, or the possession of contractility by the muscular fibres of the stomach. In opposition to these experiments, those of M. Dupuytren may be adduced. He divided, separately, the portions of the eighth distri- buted to the pulmonary, circulatory, and digestive apparatuses, and always found, when the section was made below the pulmonary plexus, that chymification was suspended. But how are we to explain the dis- crepancy between these results, and those of Messrs. Broughton and Magendie ? M. Adelon6 has supposed, that as the eighth pair is not the only nerve distributed to the stomach,—the great sympathetic sending numerous filaments to it,—these filaments, in the experiments of Messrs. Broughton and Magendie, might have been sufficient to keep up for some time the chymifying action of the stomach; and, again, he sug- gests, whether the nervous influence may not have still persisted for a time after the section of the nerve, like other nervous influences, which, he conceives, continue for some time even after death; and lastly, he thinks it probable, that, in the cases in which chymification continued, the experiment was badly performed. Most of these reasons, however, would apply with as much force to the experiments on the other side of the question. Why were not the agency of the'great sympathetic, and the continuance of the nervous influence for some time after the section of the nerve, evidenced in the experiments of Dupuytren, Wilson Philip, Hastings, and others ? 1 Ley, in App. to Laryngismus Stridulus, p. 447, Lond, 1836. . 2 Ibid, x. 292. 3 Precis, &c, ii. 102. 4 Edinburgh Med. and Surg. Journal, xciii. 365; and Recherches sur la Digestion, Paris, 1825. 5 Inquiry into the Principles, &c, of Medicine, i. 444, Lond, 1834. 6 Physiologie de l'Homme, &c, 2de edit, vol. ii. Paris, 1829. CHYMIFICATION. 595 More recent experiments by Messrs. Wilson Philip,1 Breschet, Milne Edwards, and Vavasseur,2 have shown, that the mere division of the nerves, and even the retraction of the divided extremities for the space of one-fourth of an inch, does not prevent the influence from being transmitted along them to the stomach; but that if a portion of the nerve be actually removed, or the ends folded back, chymification is wholly or partly suspended.3 Most of the experimenters agree with Sir Benjamin Brodie in the opinion, that chymification is suspended owing to the secretion of the gastric juice having been arrested by the division of the nerves under whose presidency it is accomplished. MM. Breschet and Milne Edwards, however, conceive, that the effect is owing to paralysis of the muscular fibres of the stomach produced by the section of the nerves; in consequence of which the different por- tions of/the alimentary mass are not brought properly into contact with the coats of the stomach, so as to be exposed to the action of its secretions; and they affirm, that when the galvanic influence is made to pass along the part of the nerVe attached to the stomach, its effect is to restore the due action of the fibres; and, that a mechanical irri- tant, applied to the lower end of the divided nerves, produces a similar kind of change on the food in the organ; from which they conclude, that the use of the par vagum, as connected with the functions of the stomach, is to bring, the alimentary mass into necessary contact with the gastric secretions. These experiments were repeated in London by Mr. Cutler, under the inspection of Dr. Philip and Sir B. Brodie; but the effects of mechanical irritation of the lower part of the divided nerve did not correspond with those observed by MM. Breschet and Milne Edwards.4 The experiments of F. Arnold,5 and of MM. Bouchardat and San- dras6 lead them also to infer, that the nerves of the stomach appear to influence chymification in so far as the process depends upon the various motions of the organ. M. Longet7 has endeavoured to reconcile these discordant results. Having opened many dogs, he ascertained, that in the greater number, irritation of the pneumogastric nerves induced contraction of the stomach. Frequently, during his experiments, he saw the stomach assume the hour-glass form. In -a few dogs, the movements of the stomach, on the irritation of the nerve, were scarcely perceptible. After repeating his experiments on forty dogs, he recognised that the differ- ence in the results obtained depended on the condition of the stomach itself. Thus, if the animal was opened when it was full, irritation of the pneumogastric nerves caused manifest movement; but, when empty, scarcely any was excited: the movements, in fact, were feeble in pro- 1 Philos. Transact, for 1822. 2 Archives Generales de Med, Aout, 1823. 3 Ware, North American Medical and Surgical Journal, Philad, 184 S. 4 Bostock's Physiology, 3d edit, p. 523, London, 1836. 5 Lehrbuch der Physiologie des Menschen, Zurich, 1836-7 ; noticed in British and Foreign Medical Review for Oct, 1839, p. 478. • Annuaire de Therapeutique, pour 1848, p. 283, Paris, 1848. ' Comptes Rendus, Fevr, 1842. See, also, Bischoff, in Muller's Archiv, Berlin, 1843, and Prof. E. Weber, art. Muskelbewegurig, in Wagner's Handworterbuch der Physiologie, 15te Lieferung, s^ 41, Braunschweig, 1846. 596 DIGESTION. portion to the time that had elapsed from the period of chymification, or of filling the stomach. M. Longet thinks, that these facts account for the different results arrived at by experimentalists in regard to the influence of the pneumogastric nerves over the movements of the stomach; for,- if the same experiments were made when the stomach was in different states, they might readily lead to opposite conclusions. He was never able to excite any movement of the coats of the stomach, by irritating or galvanizing the filaments of the great sympathetic or the semilunar ganglia. ^ On the whole, the proposition of Dr. Philip,—that if the eighth pair be divided in such a manner as to effectually intercept the passage of the nervous influence, digestion is suspended,—is generally considered to be established; although it- must, we think, be admitted with Mr. Mayo,1 that the rationale of the subject remains involved in great un- certainty. Like other secretions, that of the gastric juice, although capable of being modified by the nervous influence, cannot be regarded as immediately dependent upon it. The secretion/of the true acid cha- racter and solvent powers, is not always checked by the section of the nerves, and the experiments of Dr. John Reid2 and others have suffi- ciently shown, that the integrity of those nerves is not a condition absolutely necessary for secretion in the stomach, whilst at the same time they prove, that the amount of secretions usually poured into the interior of that organ may be modified in an important manner by causes acting through those nerves.3 It is denied, however, by Professor J. Miiller, that galvanism has any influence in reestablishing the gastric secretion, when it has been checked by their division. Finally:—Dr. Philip found, that every diminution of the nervous influence,—the section of the medulla spinalis at the inferior part, for example,—deprives the stomach of its digestive faculty; and MM. Edwards and Vavasseur obtained the same result by the removal of a certain portion of the hemispheres of the brain, or by the injection of opium into the veins in sufficient quantity to throw the animal into deep coma. Much must, of course, be dependent on the deranging influence of the experiments. By means of .the fistulous openings into the stomachs of dogs, first instituted by M. Blondlot, (see page 586/) M. Bernard4 undertook fresh experiments on this unsettled topic. A dog's digestion was watched for eight days, and found to be well accomplished. On the ninth day, after twenty-four hours' fast, M. Bernard sponged out the stomach, which contracted on the contact of the sponge, and at once secreted a large quantity of gastric fluid. He then divided the pneumogastric nerves in the middle of the neck, and immediately the mucous membrane, which had been turgid,, became pale, as if exsanguious; the movements of the stomach ceased; the secretion of gastric fluid was instantaneously arrested, and a quantity of neutral ropy mucus was soon produced in its' place. After this, digestion was 1 Outlines of Human Physiology, 4th edit, p. 122, Lond, 1837. 2 Edinb. Med. and Surg.-Journal, April, 1S39; and art. Par Vagum, in Cyclop.'of Anat. and Physiol, pt. xxviii. p. 899, Lond, April, 1847. 3 Longet, Traite de Physiologie. ii. 339, Paris, 1850. . 4 Gazette Medicale de Paris, 1 Juin, 1844. CHYMIFICATION. 597 not duly performed; milk was no longer coagulated; raw meat remained unchanged; and the food, consisting of meat, milk, bread, and sugar, which the dog had before thoroughly digested, remained for a long time neutral, and at length acquired acidity only from its transforma- tion into lactic acid. In the stomachs of other dogs, after the division of the nerves, he traced the transformation of cane sugar into grape sugar in three or four hours; and in ten or twelve hours, the trans- formation into lactic acid was complete. In others, when th» food was not capable of an acid transformation, it remained neutral to the last. In no case did any paYt of the food pass through the peculiar changes of chymification. More recently, MM. Bouchardat and Sandras,1 from the results of a series of experiments instituted by them, believe they have established, that stomachal digestion and the movements of the organ are interrupted by the simultaneous section of both pneumogas- trics on a level with the larynx; and farther, that intestinal digestion, and the production and absorption of a, very laudable chyle persist not- withstanding such section; and M. Longet2 concludes, that the section of the pneumogastrics seriously affects chymification, chiefly by paralysing the proper movements of the stomach, but partly by diminishing the secretion of the gastric solvent; and lastly, Professor Berard,3 after examining the different experiments and inferences of preceding in- quirers, infers:—that "the mixed cords of the pneumogastrics and the branches furnished by the great sympathetic to the stomach beneath the diaphragm, contribute to the maintenance of the contractility of the stomach and the secretion of the gastric juice. A greater share, however, ought to be assigned to the cords of the pneumogastric than to the sub-diaphragmatic branches of the great sympathetic. Moreover, the motor influence of the pneumogastric appears to predominate over the secretory; in other words, the resection of the nerve paralyses the movements more than it diminishes the secretion." Of all these theories of chymification, that of chemical action, aided by the collateral circumstances to be mentioned presently, can alone be embraced; yet, how difficult is it to- comprehend, that any one secretion can act upon the immense variety of animal and vegetable substances employed as food! The discovery of the chlorohydric and acetic acids and of pepsin in the secretion, aids us in solving the mys- tery expressed by the well-known pithy and laconic observation of Dr. William Hunter in his lectures: "Some physiologists will have it, that the stomach is a mill; others, that it is a fermenting vat, others, again, that it is a stewpan;—but, in my view of the matter, it is neither a mill, a fermenting vat, nor a stewpan;—but a stomach, gentlemen, a stomach." Allusion has been already made to pepsin—an organic compound thrown off from the stomach—which is an active agent in digestion. It had been observed in the experiments of Eberle and Schwann, that ' Bouchardat, Annuaire de Therapeutique, de Matiere Medicale, &c, pour 1848, p. 306, Paris, 1848. 2 Op. cit, p. 340. 3 Cours de Physiologie, 12e livraison, p. 235, Pans, 1849. 598 DIGESTION. although acids alone have little power in digesting food, they act ener- getically, when combined with the mucus of the stomach. Eberle thought, that the acidulated mucus of any membrane would produce the effect, but J. Miiller and Schwann found it to be restricted to that of the stomach. The agency of pepsin is regarded by Liebig1 to be similar to that of diastase in the germination of seeds. Both are bodies in a state of transformation or decomposition; the latter effecting the solu- tion of sl^rch by its conversion into sugar; and the former the forma- tion of alimentary matter into chyme. The present belief amongst physiologists and chemists—from all these experiments, as well as those of Wasmann and others—is, that pepsin, by inducing a new arrangement of the elementary particles ov atoms of alimentary matter, disposes it to dissolve in the gastric acids. Chlorohydric acid, indeed, dissolves white of egg by ebullition, just as it does under the influence of pepsin; so that pepsin replaces the effect of a high temperature in the stomach.2 Liebig, consequently, does not believe, that the digestive process is a simple solution, but a species of fermentation, not identical, however, with any-of the known processes of fermentation occurring in organic matters out of the body. It differs from ordinary fermen- tation in being unattended with the formation of carbonic acid; in not requiring the presence of oxygen, .and in not being accompanied by the reproduction of the ferment.3 The conclusions of MM. Bernard de Villefranche and Barreswil,4 from numerous and varied experiments related to the AcadSmie Royale des Sciences, of- Paris, have been referred to already. From these, it would seem, that an organic, compound of like nature exists, in the saliva, gastric juice, and pancreatic fluid; and that its digestive powers vary according as it is associated witfh fluid having an acid or an alka- line reaction. Thus in the gastric juice, which is acid^ it readily dis- solves nitrogenized substances,—fibrin, gluten, albumen, &c, whilst it is altogether without action on starch. These gentlemen affirm, that if we destroy this acid reaction, and render the gastric juice alkaline by the addition of carbonate of soda, the active organic matter being in presence of an alkaline fluid changes dts physiological action, and becomes able to modify starch rapidly, .whilst it loses the power of digesting nitrogenized substances. As the saliva and pancreatic juice are alkaline, it was interesting to know whether a change in the chemi- cal reaction of these fluids would produce in them the same change of properties as in the case of the gastric juice. Experiment proved such to be the fact. By rendering the pancreatic fluid or saliva acid, their ordinary action was inverted: they acquired the power of dissolving meat and other nitrogenized substances, whilst they lost their influence on starch. M. Magendie examined the gases in the stomach and intestines of executed criminals, and obtained the following results: a, in the case of an individual who had taken food in moderation an hour previous to 1 Animal Chemistry, Gregory and Webster's edit, p. 106, Cambridge, Mass, 1842. 2 Graham's Elements of Chemistry, Amer. edit, by Dr. Bridges, p. 696, Philad, 1843. 3 Kirkes and Paget, Manual of Physiology, Amer. edit, p. 173, Philad, 1849. 4 Comptes Rendus, 9 Decemb, 1844, and 7 Juillet, 1845. CHYMIFICATION. 599 death; b, in the case of one-who had eaten two hours previously; and c, in the case of one who had done so four hours previous to execution. 100 volumes of the gas contained Oxygen. Azote. Carbonic Acid. Inflammable Gas. From the stomach, 11-00 71-45 14-00 3-55 -------small intestines, 0000 2003 2439 55-33 --------large do. 00-00 51-03 43-50 . 5'47 From the stomach, 00-00 00-00 00-00 00-00 -------small intestines, 00-00 8-85 40-00 51-15 -------large do. 00-00 18-40 70-00 11-60 From the stomach, 00-00 00-00 00-00 00 00 -------small intestines, 0000 6660 25-00 8*40 --------Jarge do. 00 00 45-96 42-86 11181 From these results it appears, that when the execution occurred not longer than an hour after a meal, oxygen was found in the stomach ; and when not until two hours, it had entirely disappeared, and a large quan- tity of nitrogen was found in the intestines, with an entire absence of oxygen; whence it is inferred, that the oxygen g-f the air is separated from the nitrogen in the stomach; and the former is employed in diges- tion. The view of Liebig is, that the oxygen occasions a molecular action in the pepsin or animal matter in the stomach, and that this in- testine motion is communicated'to the molecules of the albumen or pro- tein of the food, so that the latter is rendered soluble in the gastric acid.2 The oxygen he refers to atmospheric air enclosed in the saliva during mastication, and in that way introduced into the stomach. Researches into the phenomena [of digestion, made some years ago by MM. Bouchardat and Sandras,3 led them to the following conclu- sions. First. The functionsof the stomach in digestion consist in dis- solving, with the aid of chlbrohydric acid, all albuminous matters, as fibrin, albumen, casein^ and gluten. Secondly. This acid, if diluted with 5000 parts of water, dissolves the same matters out of the body, provided they are not cooked; but if boiled, the solution has no action upon them. As they are found, however, dissolved in the stomach, it is probable that some other agency is at work than simple solution by means of chlorohydric acid; but the presence of that acid appears to be indispensable. Thirdly. As far as albuminous matters are concerned, digestion and absorption take place exclusively in the stomach through the veins; the intestines present scarcely any traces of those matters although they exist in such abundance in the stomach. Fourthly. Solu- tion of fecula occurs in the stomach. This principle does not appear to pass into the state of sugar; and the experiments did not even war- rant the statement, that it passes into that of soluble starch; but they regard its transformation into lactic acid as proved. Fifthly. The absorption of this form of aliment appears to take place less exclusively from the stomach than that of albuminous matters,—a circumstance which accords with the special arrangement and length of the intestines of animals not carnivorous. Sixthly. Fatty matters are not acted on 1 Liebig, op. cit, p. 289. * Ancell, Lond. Lancet, Dec. 16, 1842, p. 419. 3 Annales des Sciences Naturelles, Oct, 1842, or Edinb. Med. and Surg. Journal, Jan, 1843. 600 DIGESTION. in the stomach. They proceed into the duodenum forming an emulsion with alkalies furnished by the liver and pancreas. This emulsion is found abundantly throughout the whole course of the intestines. Seventhly. The chyle appears somewhat less abundant, but presents similar characters in animals that are killed after long fasting; as in those killed after having taken copious meals of albuminous matters and fecula. In those, however, that had been -fed on fatty matters fat was found in it in considerable proportion. According to those views—which were favourably reported upon to the Academie Royale des Sciences of Paris, by MM. Payen, Magendie, Flourens, Milne Edwards and Dumas,1 and "the authors encouraged to persevere in a study that still presents so many problems for solution, and into which they have but entered, although they have already made some curious observations,"—most articles undergo complete digestion in the stomach; but fat requires an admixture with the secre- tions poured into the intestines, and is taken up only by the chyliferous vessels. MM. Bouchardat and Sandras do not,' however, restrict the agency of those vessels to the absorption of fat. They suggest—and it can only be regarded as a suggestion—that the abdominal glands prepare for the chyliferous vessels and thoracic duct a chyle, the alka- line character of which is in a direct ratio with the acidity developed in the stomach during digestion. This chyle—not obtained from the food but by a true process of secretion1—enters the blood through the chyliferous apparatus, to neutralize the acid, that is indispensable for the solution of the food in the stomach to prepare it for absorption from that organ. . Should the views of MM. Bouchardat and Sandras be established, they would modify materially former notions in regard to the physio- logy of the digestion of solids. It need hardly be said, however, that a succession of repeated and careful experiments tending to the same results will be necessary before they can be regarded as worthy of more than a passing notice. Certain of the positions of these gentlemen have received support from the investigations of M. Blondlot.2 He is of opinion, that of all the simple alimentary substances, those that are fluid at the ordinary temperature of the stomach, and those that are readily soluble in its secretions, as fluid albumen, sugar, gum, pectin, &c, are at once absorbed by the veins. It would seem, indeed, that in cases of scirrhus of the pylorus, and where a cancerous communication has existed between the stomach and colon,3 nutritious matter must necessarily be absorbed from the stomach: except, however, in such cases, the view, that digestion can be accqmplished by the gastric veins, independently of the action of any gastric secretions, can scarcely be maintained.4 It would seem, moreover, that certain aliments, after having experienced the necessary stomachal and intestinal changes, are received by imbibition into the veins of the intestines. MM. Bouchardat 1 Encyclographie des Sciences Medicates, Fevr, 1843, p. 159. 2 Traite Analytique de la Digestion, Paris, 1844. 3 Such a case is given by Dr. William Waters, in Philadelphia Med. Examiner, p. 201, April, 1845. 4 A Physiological Essay on Digestion. By Nathan R. Smith, M.D, &c. New York, 1S25. CHYMIFICATION. 601 and Sandras affirm, that after herbivorous animals have been fed on farinaceous substances, more dextrin, grape sugar and lactic acid are detected in the blood of the vena porta than in that of any other blood- vessel.1 Trommer, also, detected grape sugar in the blood of the portal vein, but not jn. that of the hepatic vein in animals to which that sub- stance had been given with their food.2 The bearing of such observa- tions on the production of sugar by the liver will be shown hereafter. In conclusion:—Let us inquire into the various agencies to which the food is exposed during the progress of chymification. First. It becomes mixed with the secretions, already existing in the stomach, as well as with those excited by its presence. Secondly. It is agitated by the peristaltic motion of the stomach itself, and the movement of the neighbouring organs. Thirdly. It is exposed to a temperature of at least 100° of Fahrenheit, which, during the ingestion of food, does not rise 'higher: exercise elevates, whilst sleep, or rest, or a recum- bent posture, depresses it.3 After food has been subjected to these influences, the conversion into chyme commences. This always takes place from the surface towards the centre: the nearer it lies to the surface of the stomach, the more it is acted on; and the part that is in contact with the lining membrane is more digested than any other;— appearing as if corroded by some chemical substance capable of dis- solving it. Dr. Wilson Philip4 asserts, that the new food is never mixed with the old; the former being always found in-the centre, surrounded on all sides by the latter. If the old and new be of different kinds, the line of separation between them is so evident, that the former may be completely removed without disturbing the latter; and if they be of different colours, the line of demarcation can frequently be distinctly traced through the parietes of the stomach before they are laid open. Dr. Beaumont,5 however, affirms, that this statement is not correct; that, in a very short time, the food, already in the stomach, and that subsequently eaten, become commingled. In the subject of his experi- ments, he invariably found that the old and new food, if in the same state of comminution, were readily and speedily combined. The conversion of the food into chyme, it has been conceived, com- mences in the splenic portion, is continued in the body of the viscus, and completed in the pyloric portion. On this point, the observations of Dr. Philip differ somewhat from those of M. Magendie,6 the former appearing to think, that chymification is chiefly accomplished in the splenic portion and middle of the stomach; whilst the latter affirms, that it is mainly in the pyloric portion that chyme is formed;—the ali- mentary mass appearing to pass into it by little and little, and during its stay there to undergo transformation. He further affirms, that he has frequently seen chymous matter at the surface of the alimentary 1 Gazette Medicate de Paris, Jan, 1845. 2 Kirkes and Paget, Manual of Physiology, Amer. edit, p. 191, Philad, 1849. 3 Beaumont, On the Gastric Juice, p. 274. 4 Exper Inquiry, ch. vii. sect. 1; and Treatise on Indigestion, Lond, 1821. 6 Op. citat, p. 89. 6 Pn*is, &c, edit, cit, ii. 88. \ 602 DIGESTION. mass filling the splenic half; but that it commonly preserves its pro- perties in this part of the organ. The precise steps of the change into chyme cannot be indicated. Some of the results, at different stages of the process, have been ob- served on animals; and pathological cases have occasionally occurred, which enabled the physiologist to witness what was going on in the interior of the stomach; but, with perhaps one exception, those oppor- tunities have not been much improved. Dr. Burrows1 relates a case of fistulous opening into the organ. The subject of the case was not seen by him until twenty-seven years after the injury, at which time the man was, to all appearance, healthy; but he was drunken, and dissipated, and the following year died. A case is related by Schenk;2 and Louis3 refers to similar cases that occurred to Foubert and Coyillard. Helm, of Vienna,4 published a case, to which reference has already been made; and one of an interesting character occurred at the Hospital La- CharitS of Paris, which sheds some little light on the subject.5 The aperture, which was more than an inch and a half long, and an inch broad, ex- posed the interior of the organ. At the admission of the female into the hospital, she ate three times as much as ordinary persons. Three or four hours after a meal, an irresistible feeling compelled her to re- move the dressings from the fistulous opening, so as to allow the escape of food which the stomach could no longer contain,—when the contents came out quickly, accompanied by more or less air. They possessed a faint smell, but had neither acid nor alkaline properties; and the gray- ish paste, of which they consisted when diluted, with distilled water, did not affect vegetable blues. Digestion was far from complete; yet, frequently the odour of wine was destroyed; and bread was reduced to a soft, viscid, thick substance, resembling fibrin recently precipitated by acetous acid, and swimming in a stringy fluid of the colour of com- mon soup. Experiments, made on this half-digested food, at the Ecole de Medecine, showed that the changes, which it had undergone, were an increase of gelatin; the formation of a substance like fibrin; and a considerable .portion of chloride of sodium, phosphate of soda and phosphate of lime. The patient could never sleep until she had emptied her stomach, and washed it out by drinking infusion of chamomile. In the morning, it contained a small quantity of thick, frothy liquid, analogous to saliva, which did not affect vegetable blues; with matters of greater consistence, and some opaque, albuminous flocculi mingled with the liquid portion. The results of chemical experiments on this liquid were similar to those obtained on the analysis of saliva. But the most interesting case in its observed phenomena is one that occurred to Dr. Beaumont,6 of the United States Army, now of Saint Louis, which the author had an opportunity of examining. To this case, reference has already been made repeatedly. A Canadian lad, 1 Transactions of the Royal Irish Academy, vol. iv. 2 Observ. Medic. Rar. Nov, &c, lib. iii,Francof, 1609. 3 Memoir, de l'Academie Royale de Chirurgie, vol. iv. p. 213, Paris, 1819. 4 Rudolphi, Grundrjssder Physiologie, 2ter Band, 2te Abtheil, s. 114, Berlin, 1828. 5 Richerand's Elemens de Physiologie, edit, cit, p. 72. 6 Op. citat. Introduction, p. 10; and the Author's Elements of Hygiene, p. 216, Philad, 1835. CHYMIFICATION. 603 Alexis San Martin, eighteen years of age, received a charge of buck- shot in his left side, which carried away integuments and muscles of the size of the hand; fracturing, and removing the anterior half of the sixth rib; fracturing the fifth; lacerating the lower portion of the left lobe of the lung and the diaphragm, and perforating |the stomach. When Dr. Beaumont saw the lad, twenty-five or thirty minutes after the accident, he found a portion of the lung, as large as a turkey's egg, protruding through the external wound, lacerated and burnt; and, immediately below this, another protrusion, which, on inspection, proved to be a portion of the stomach, lacerated through all its coats, and suf- fering the food he ha.d taken at breakfast to escape through an aperture large enough to admit the forefinger. It need scarcely be said, that numerous untoward symptoms occurred in the cicatrization of so formi- dable a wound. Portions of the ribs exfoliated; abscesses formed to allow the exit of extraneous substances; and the patient was worn down by febrile irritation. Ultimately, however, the care and attention of Dr. Beaumont were crowned with success, and the instinctive actions of the system repaired the extensive injury. The wound was received in 1822, and on the 6th of June, 1823, one year from the date of the accident, the injured parts were sound, and firmly cicatrized^ with the exception of the perforation leading into the- stomach, which -\yas about two inches and a half in circumference. Until the winter of ,1823-4, compresses and bandages were needed to prevent the escape of the food. At this period, a small fold or doubling of the inner coat of the stomach appeared forming at the superior margin of the orifice, slightly pro- truding, and increasing in size until it filled the aperture. This val- vular formation adapted itself to the opening into the organ, so as to completely prevent the escape of the contents, when the stomach was full; but it could be readily depressed by the finger. Since the spring of 1824, San Martin has enjoyed general good health; he is active, athletic, and vigorous; eating and drinking like a healthy individual. From the summer of 1825, Dr. Beaumeut had been engaged in the prosecution of numerous experiments upon him; some of the results of which he has given to the world. In the winter of 1833, he was in Washington, when the author—at the time, Professor of Medicine in the University of Virginia—was politely invited to examine him for physiological purposes. Many of the results of this examination are given by Dr. Beaumont, and have already been, or will be, referred to in the present work. Dr. Beaumont's researches into the comparative digestibility of different alimentary substances belong to another de- partment of medical science, and have accordingly received attention from the author elsewhere. - What, then, it may be asked, are the changes wrought on the food in the stomach by the gastric secretions? J)r. Prout1 classes them under three operations;—the reducing, converting, and organizing and vital- izing. The first of these is probably the main operation. In order to decide, whether the action of the stomach in digestion be a simple solu- tion, or a total or partial conversion, certain compounds of organization, easy of detection—as gelatin, albumen, and fibrin—were introduced, 1 Bridgewater Treatise, Amer. edit, p. 235, Philad, 1834. 604 DIGESTION. at the author's suggestion, into the stomach through the fistulous open- ing in the subject of Dr. Beaumont's case; whilst other portions were digested artificially in gastric juice obtained from the same individual. The solutions presented the same appearance, and were similarly affected by reagents ; and in all cases, whether the digestion was arti- ficial or real, the proximate principles could be thrown down jn the state of gelatin, fibrin or albumen, as the case might be. These experi- ments, so far as they go, justify the conclusion, that the digestive process in the stomach is a simple solution or division of alimentary substances, and an admixture with the mucous secretions of that organ, and the various fluids from the supra-diaphragmatic portion of the digestive tube. With regard to the existence of the other gastric opera- tions described by Dr. Prout, well-founded doubts may be entertained. To his proposition that, whatever maybe the nature of the food, the general composition and character of the chyle remain always the same, no objection can be urged; but, admitting its accuraqy, it by no means follows, that the conversion must be effected in the stomach, or that any organizing or vitalizing powers are exerted upon the chyme in that organ. On the contrary, it appears to us, that the essential changes effected on solid aliment in the stomach are of a purely physical charac- ter, so as to adapt it for the separation of the chylous portion in the intestines by organs whose vital endowments and influences cannot be contested. Dr. T. J. Todd1 is disposed to believe, from his experiments on artificial digestion, that the various vegetable and animal substances subjected to the action of the digestive fluids at the ordinary tempera- ture of the atmosphere are, in all instances, reduced—not to their chymical, but to their organic elements ; and he is of opinion, that this applies equally to digestion in the stomach. From what has been already shown of the close approximation to each other in chemical composition of several of the compounds of organi- zation, it may be understood, that many vegetable principles might be converted into animal principles without any material change of com- position. They might all perhaps be changed into albumen, from which, as elsewhere seen, fibrin differs but little except in its organizable power. Saccharine matters—it has been conceived—may be converted, in the digestive tube, partly into albumen, and partly into oleaginous matter, the nitrogen of the former being furnished, according to some, by the pepsin or by some highly nitrogenized substance secreted in the stomach or duodenum or both;2 but whether such conversion really occurs is exceedingly questionable. The oleaginous matters themselves are ab- sorbed by simple imbibition as an emulsion formed by their union with the alkali of the pancreatic fluid.3 On the whole, in the present state of our knowledge of this import- ant function, we are perhaps justified in concluding -.—First. That by the operation of the gastric secretions the nitrogenized principles of the food, whether animal or vegetable, are dissolved in the stomach. Se- 1 Brit. Annals of Medicine, Jan,, 1837. 2 Prout, on the Stomach and Urinary Diseases, p. xxviii, note. 3 Matteucci, Lectures on the Physical Phenomena of Living Beings, by Pereira, Amer. edit, p. 110, Philad, 1848, and C. Bernard, Archives Generales, xix. 60, cited in British and Foreign Medico-Chirurgical Review, p. 528, April, 1849. CHYMIFICATION. 605 condly. That amylaceous matters are converted into saccharine, and these last are absorbed; or they undergo a farther change, by which they are partly converted into lactic acid, and partly into oleaginous matter, and are absorbed in one of these states. Thirdly. That the oleaginous principles are either formed into an emulsion or absorbed without alteration; and Fourthly. That with the exception of certain mineral substances, matters that cannot be reduced to either of these forms are rejected as excrement. In proportion as the food is digested, it passes through the pylorus. After the. layer, that lies next to the mucous membrane, has experi- enced the requisite change, and is propelled onwards by the muscular action of the organ, the portion lying next to it becomes subjected to the same process.. The gastric fluid, at the same time, penetrates, in a greater or less degree, the entire-alimentary mass, so that, when the central portion comes in contact with the surface of the stomach, its conversion is already somewhat advanced. The chyme, thus success- ively formed, does not remain in that organ, until the whole alimentary mass has undergone chymification; but as it is completed, it is trans- mitted, by the peristaltic action, through the pylorus into the duode- num. In the early stages of digestion, the passage of the chyme from the stomach is more slow than in the later. At first, it is more mixed with the undigested portions of food, and, as Dr. Beaumont1 suggests, is probably separated with difficulty by the powers of the stomach. In the more advanced stages, as the wnole mass becomes chymified, the process is more rapid, and is accelerated by the peculiar contraction of the stomach, already described. After the expulsion ofthe last parti- cles of chyme, the.organ becomes quiescent, and no more gastric secre- tion takes place, until a fresh supply of food is received, or some me- chanical irritation is produced in its inner coat. The time, required for the complete chymification of a meal, is stated by the generality of physiologists to be about four or five hours. In Dr. Beaumont's case,2 a moderate meal of meat, with bread, &c, was digested in from three hours to three hours and a half. We believe that, in by far the majority of cases, a longer time than this is neces- sary ; and in laborious digestions, the'presence of food can be distin- guished by eructations for more than double the time. It is manifest, that no fixed period can be established for the production of this effect. It must vary, according to the digestive capability of the individual; the state of his general health ; and the relative digestibility of the ali- ments employed; all which, as we have already seen, admit of great diversity. During chymifieation, only a very small quantity of air is found in the stomach ; sometimes, none. When met with, it is near the cardiac orifice, or at the upper part of the splenic portion. The experiments of M. Magendie, on this point, have been referred to. The small quan- tity of air, discovered in the stomachs of animals, disproves the idea of M. Chaussier, that we swallow a bubble at each effort of deglutition. If so, the stomach ought to be always inflated, especially after eating, 1 On the Gastric Juice, p. 96. 2 Ibid., p. 275. 606 DIGESTION. which is not the case. MM. Leuret and Lassaigne1 found the air, ob- tained from the stomach of a dog fed on meat, to consist of carbonic acid, 43 parts; sulphuretted hydrogen, 2 parts; oxygen, 4 parts; nitrogen, 31 parts ; carburetted hydrogen, 20 parts. Whence these gases proceed will be a subject of future inquiry. In a robust individual, chymification is effected without conscious- ness of the process. He finds, especially if the stomach be over-dis- tended, that the feeling of fulness and the oppression of respiration, produced by the distension of the organ, gradually disappear. It is not uncommon, however, for slight shivering or chilliness to be felt at this time; for the sensations, and mental and moral manifestations to be blunted; and a disposition to sleep to be experienced. " This con- centration of the whole vital activity," according to M. Adelon,2 " is so natural to the animal economy, that there is always danger in oppos- ing or crossing it by any extraneous or organic influence ; as by bath- ing? the use of medicine, violent exercise, mental emotions, intense intellectual effort, &c." Gentle exercise, however, would seem to favour digestion. Such is the conviction of Dr. Beaumont,3 from his observa- tions. In the subject of his experiment, he found the temperature«of the stomach generally raised by it a degree and a half, and chymifica- tion expedited. Where digestion is imperfect, the signs,, already men- tioned, will be accompanied by the disengagement of air and conse- quent eructations ; a sense of weight, or heat, or of unusual distension in the epigastric region, &c.; but these, as w,ell as the developement of sulphuretted hydrogen, discharged by eructation, are the products of ordinary decomposition or fermentation, and appertain to. the morbid condition of the function or to indigestion. Yet, as M. Magendie4 has remarked, it does not seem, that these laborious digestions are much less profitable than others. The food, habitually received into the stomach, contains far more nutritive matter than is necessary to supply the wants ofthe system; and, in the cases in question, enough chyle is always sepa- rated in the small intestine to supply the losses, and even to add to the bulk of the body. It has been already remarked, that the chyme, first formed, does not continue in the stomach until the whole meal has undergone chymifica- tion ; but that, as soon as it has experienced the necessary changes, it passes through the.pylorus into the duodenum. It would appear, that the accumulation of chyme in the pyloric portion of the stomach never exceeds four ounces at any one time. M. Magendie states, that, rn the numerous experiments, in which he has had an opportunity of noticing it, he uniformly found, when the quantity amounted to about two or three ounces, it was permitted to pass through the pylorus into the duodenum. This passage of the chyme is effected by the peristaltic action. At the commencement of digestion, the duodenum contracts inversely, and the pyloric portion of the stomach, at the same time, drives its contents into the splenic. This movement is, however, soon followed by one in an opposite direction ; and, after a time, the inverted action ceases, 1 Recherches sur la Digestion, Paris, 1825. 2 Physiologie de l'Homme, edit, cit, ii. 433. 3 On the Gastric Juice, p. 93. 4 Precis, &c, ii. 104. ACTION OF THE SMALL INTESTINE. 607 and the movement is altogether in one direction ;—from the stomach towards the intestine. The movement by which the chyme is immedi- ately sent into the duodenum, is thus effected:—the longitudinal fibres, which pass from the cardiac to the pyloric orifice, contract, and approxi- mate the two orifices ; the pyloric portion, then contracts, not so as to direct the chyme into the splenic portion, but towards the duodenum: in this manner, the chyme passes from the stomach : and, as fresh por- tions are formed,.they are successively sent onwards; the peristaltic action becoming more and more marked and frequent, and extending over a larger portion of the organ, as chymification approaches its ter- mination. As the chyme is discharged into the small intestine, the stomach gradually returns to its former.dimensions and situation. f. Action of the Small Intestine. The changes in the alimentary mass in the small intestine, are not less important than those already considered. They consist in a farther change of the chyme into a substance, whence chyle can be extracted by the action of the chyliferous vessels or lacteals. Whether chyle be separated in the intestine, in a state fit for chyliferous absorption, or be formed by those vessels, will have to be canvassed hereafter. In common language, however^ it is said to be separated there, and the process, by which this is accomplished, is called chyUfication. As the chyme proceeds into the duodenum, it readily finds space, until towards the end of chymification, when the intestine not unfre- quently experiences considerable dilatation. The presence of the ali- mentary mass augments the secretion from the mucous membrane; and occasions a greater flow of the biliary and pancreatic juices. MM. Leuret and Lassaigne1 foUnd, when they applied vinegar, diluted with water, to the external surface of the small intestine in. a living animal, that a considerable quantity of serous fluid was immediately exhaled. The same application, made to the follicles of the intestine, excited the secretion of a greater quantity of mucus; and its application to the mouths of the choledoch and pancreatic ducts caused the orifices to dilate, and a greater discharge of bile and pancreatic juice. It is in this local manner that many of the cholagogue purgatives produce their effect. Calomel exerts its agency on the upper part of the intes- tinal canal more especially; and the irritation it induces in the mucous membrane at the mouth of the ductus communis choledochus is propa- gated along the biliary ducts to the liver, the secretion of which is thus augmented,—but not by any specific action exerted on the organ, as has been often imagined. As the chyme is acid, it induces the same effects on the follicles as the acid employed in the experiments of MM. Leuret and Lassaigne. The chyme does not remain so long in the intestine as food does in the stomach. The successive arrival of fresh portions propels the first onwards; and the same effect is induced by the peristaltic action of the intestines,—an involuntary, muscular movement of an irregular, undulatory, oscillatory or vermicular character, which consists in an 1 Recherches sur la Digestion, Paris, 1825. 608 DIGESTION. alternate contraction and dilatation of the organ, proceeding generally from above to below, so as to propel the chyme downwards. When it reaches any point of the intestine, its contact excites the contraction of the circular fibres of the part; so that it is sent forwards to another portion of the canal; the circular fibres of which contract, whilst the former are relaxed; and this occurs successively through the whole tract of the intestines. The longitudinal fibres, by their contrac- tion, shorten the intestine, and in this manner meet the chyme, so as ,to facilitate its progress; but their effect cannot be considerable. When digestion is not going on, the peristaltic action occurs only at intervals; always slowly and irregularly; and, perhaps, as has been suggested, only when sufficient mucous secretion has collected on the inner coat of the intestine to provoke it. During digestion, it is much more energetic and frequent, and more marked in the duodenum and small intestine than in the large; occurring not continuously, but at intervals, as the chyme arrives and excites it. When the small intes- tine is surcharged, it may take place in several parts of the canal at once; and, at times, the action is inverted: >■ The secretions poured into the intestinal canal lubricate it, and facilitate the progress of the chyme. This is aided by the free and floating condition of the intestine; and by the agitation of the diaphragm and abdominal muscles in respiration. Yet its course along the small intestine is slow. The chyme is not transmitted from the stomach continuously; and the peristaltic action of the intestines occurs only at intervals. Moreover, owing to the convolutions of the intestinal canal, the chyme must, in many cases, proceed against its own gravity; and be retarded by the numerous valvulse conniventes, which bury them- selves in it, when the canal is contracted by the action of the1 circular fibres. All these circumstances must cause it to proceed slowly along this part of the tube,—:a point of some importance, when we reflect, that an essential change is effected on it through the influence chiefly of the bile and pancreatic juice, and that its nutritive portion is here absorbed. In the duodenum, the course of the chyme is slow. In the jejunum it is more rapid, hence the name, which indicates, that it is almost always found "empty:" in the ileum again it is slower on account of the greater consistence acquired by the absorption of the chylous portion. Whilst the food is in progress along the small intestine, it experiences the change in its physical properties, which enables the chyle to be separated from it by absorption. These two actions have been termed respectively chylification and the absorption of chyle; although by some the former term has been applied to both processes. Above the point, at which the common choledoch and pancreatic ducts open into the duodenum, no change.is observable in the chyme. It preserves its colour, semi-fluid consistence, sour- smell, and slightly acid taste; having been simply mixed with' the exhaled and follicular secretions ofthe lining membrane; but, immediately after it has passed the part, at which the hepatic and cystic bile and the pancreatic juice are poured into the intestine, it assumes a different appearance; its colour is found to be changed; it becomes yellowish; of a bitter taste; its sour smell diminishes; and chyle can now be separated by the lac- ACTION OF THE SMALL INTESTINE. 609 teals. Accordingly, at this part of the canal, chyliferous vessels are first perceptible. The change effected upon the chyme in the small intestine is pro- bably,—like that produced on the food in the stomach,—of an entirely physical character. The chyle itself, we shall endeavour to show hereafter, is formed by an action of elaboration and selection exerted by the chyliferous vessels. No difference is observable between the chylous and excrementitious portion of the chyme in any part of the small intestine; nor can it be separated by pressure or by any other physical process. M. Magendie,1 indeed, has affirmed, that if the chyme proceeds from animal or vegetable substances that contain fat or oil, irregular filaments are observed to form, here and there, on the surface,—sometimes of a flat, at others, of a round shape,—which speedily attach themselves to the surfade of the valvulse, and appear to be brute chyle; but this is not observed when the chyle proceeds from food, that does not contain fat. In this case, a grayish layer, of greater or less thickness, adheres to the mucous membrane, and appears to contain the, elements of chyle. MM. Leuret and Lassaigne2 state, that if an animal be opened while digestion is going on,—on the sur- face, of the chyme, between the pylorus and the orifice of the ductus communis choledochus, a grayish-white, homogeneous, dense, fluid, and acid substance is perceived on the villi of the intestine. Neither of these, however, is chyle. It is merely the substance whence chyle is obtained by the action of the chyliferous vessels. The fact, mentioned byM. Magendie,—regarding the appearance of irregular filaments, when animal or vegetable substances, containing fat or oil, have been taken as diet,—has been the occasion of other erroneous deductions of a pathological character. Frank3 asserts, that he was requested to see a prince, who was attacked with epilepsy. His physician,—a respectable old practitioner,—assured Frank, that he could make his patient void thousands of filiform worms at pleasure. As he was unable to define either the genus or species of these worms,—the quantity of which, from his account, seemed to be prodigious,—Frank requested to be a witness of the phenomenon. The physician administered a dose of castor oil, which produced numerous evacuations, containing thousands of whitish filaments similar to small eels; but on an attentive examination of these pretended worms, they were found to consist entirely of the castor oil, in a state of fine division. The alteration of the aliment in,the small intestine is probably of a chemical nature ; yet its essence is impenetrable. It has, accordingly, been conceived to be organic and vital. The same remarks are appli- cable here as were indulged upon the supposed organic and vital action of the stomach exerted in the formation of chyme. The agents of this conversion are:—the fluids secreted from the mucous membrane of the small intestine, and the biliary and pancreatic juices, aided by the tem- perature of the parts, and the peristole. Haller4 was of opinion, that the first of these is a,principal agent. Reflecting on the extensive 'Precis &c ii. HI- 2 Op. citat. 3 De Curandis Hominum Morbis Epitome, lib. vi. p. 218. 4 Element. Physiol, xix. 5. vol. I.—39 610 DIGESTION. surface of the small intestine, on the number of arteries distributed to the organ, and on the size of these arteries, he asserted, that the lining membrane of the intestine, at the time of chylification, secretes a juice, which he estimated at the enormous quantity of eight pounds in the twenty-four hours. To this he gave the name succus intestinalis, apd assigned it as important a part in chylification as he attributed to the gastric juice in chymification. It is probable, however, that the fluids secreted by the mucous membrane of this portion of the canal resemble those of the rest of the intestinal mucous membrane; and that their main function is that of lubricating the intestine, and of still further diluting the chymous mass. MM. Leuret and Lassaigne endeavoured to procure some of them by making animals, whilst fasting, swallow small sponges, enveloped in fine linen, and killing them twenty-four hours afterwards. Some of these sponges had not gone further than the stomach, and were filled with gastric juice; others, which had reached the small intestine, had imbibed the succus intestinalis, which was more yellow, and manifestly less acid than the gastric secretion. On attempting to dissolve a crumb of bread in each of these juices, they discovered that the gastric secretion communicated a sour smell to the bread; but that the intestinal secretion allowed the bread to be precipitated, and dissolved no part of it. From this experiment, it has been concluded, that the succus intestinalis is not a great agent in chyli- fication. The deduction is probably correct; but no weight can be placed upon results obtained in so unsatisfactory a manner; for it is obvious, that no certainty could exist as to the identity between the gastric and intestinal juices and the fluids found in the respective sponges. We have strong reason for believing, that, even if food should escape the action of the stomach, it is capable of being digested in the small intestine. This may be owing to some of the true gastric juice passing into the intestinal canal, and impregnating it; or it may be a similar secretion from follicles seated there. The lining membrane of the small intestine possesses the property of coagulating milk; and pathological cases occur in which the stomach is, to all appearance, completely dis- organized; yet patients survive so long as to compel us to presume, that digestion must have been effected elsewhere than in that organ. M. Magendie1 placed a piece of raw meat in the duodenum of a healthy dog. At the expiration of an hour it had reached the rectum, and its weight was found to be but slightly diminished; the only change ap- peared to be at its surface, which was discoloured. In another experi- ment, he fixed a piece of muscle with a thread, so that it could not pass out of the small intestine. TJiree hours afterwards, the animal was opened. The piece of meat had lost about half its weight. The fibrin was especially attacked; and what had resisted, which was almost all areolar tissue, was extremely fetid. In experiments by M. Voisin,2 aliment was introduced into the small, intestines of animals,—in one case masticated and mixed with saliva; in another without any prepara- tion. In a few hours, in the first instance, and after a longer period in 1 Precis, &c, ii. 113. 2 Nouvel Apergu sur la Physiologie du Foie, etc., Paris, 1833. ACTION OF THE SMALL INTESTINE. 611 the second, the food was as completely chymified as if the process had taken place in the stomach. The same experiments were repeated upon animals whose pylorus had been secured by ligature, and with similar results. One of them lived for a month after the ligature, nourished for that period by food introduced into the duodenum. These facts sufficiently show, that a solvent action is exerted in the small intestine. The biliary and pancreatic juices are usually esteemed great agents in chylification. It has been already remarked, that the chyliferous ves- sels do not begin to appear above the part at which these juices are poured into the duodenum ; that in the rest of the small intestine they are less and less numerous as we recede from the. duodenum ; and that the chyme does not exhibit any marked change in its properties, until after its admixture with those fluids. Direct experiments have been made for the purpose of testing the use of the bile in digestion. Sir Benjamin Brodie tied the ductus communis choledochus in young cats, so as to prevent both hepatic and cystic bile from reaching the intes- tine. He found, that chylification was interrupted, and there were neither traces of, chyle in the intestines nor in the chyliferous vessels. The former contained only chyme, similar to that of the stomach, which became solid at the termination of the ileum; and the latter, a trans- parent fluid, which appeared to be a mixture of lymph, and of the more liquid portion of the chyme. Mr. Mayo,1 likewise, found, that when the ductus communis choledochus was tied in the cat or clog, and the animals were killed at various intervals after eating, there was no trace whatever of chyle in the lacteals. M. Magendie,2 however, repeated these experiments on adult animals, and with dissimilar results. The greater part died of the consequences of opening the abdomen, and of the operation required for tying the duct. But in two cases, in which they survived some days, he discovered that digestion had per- sisted ; white chyle had been formed, and stercoraceous matter pro- duced. This last had not the usual colour; but this, as he remarks, is not surprising, as it contained no bile. The experiment was repeated by MM. Leuret and Lassaigne,3 and with results similar to those ob- tained by M. Magendie. In the duodenum and jejunum, a whitish chyme adhered to the parietes of the organ;. and in the thoracic duct there was a fluid of a rosy-yellow colour, which afforded, on analysis, the same constituents as chyle; although the subjeets of the operation had been kept, for some time, without food. The experiments of Messrs. Tiedemann and Gmelin4 on this subject were marked by the usual care and accuracy of those observers. They found, that the animals were attacked with vomiting, soon after the operation, and afterwards with thirst and aversion for food; on the second or third day, the conjunctiva became yellow, the evacuations chalky, and very fetid, and the urine yellow. Some of the animals died; others were killed: of the latter, some had previously recovered from the jaundice, owing to a singular recuperative phenomenon, noticed 1 Lond Med. and Physical Journal, Oct, 1826; and Outlines of Physiology, 4th edit, p. 125, London, 1837. 2 Op. citat, ii. 117. 3 Recherches sur la Digestion, p. 147, Pans, 1825. 4 Recherches Experimentales, &c, sur la Digestion, u. 53, Pans, 1827. 612 DIGESTION. by Dr. Blundell1 and Sir B. Brodie in their experiments—to the re- establishment of the choledoch duct, by the effusion of lymph around the tied part, and the subsequent dropping off of the ligature. Like Sir B. Brodie, Mayo, Leuret and Lassaigne, and Voisin, they observed that chymification went on as in the sound animal. The thoracic duct and chyliferous vessels, in animals fed a short time before death, always contained an abundant fluid, which was generally of a yellowish colour. It coagulated like ordinary chyle; the crassa- mentum acquired the usual red colour; and the only difference between it and the chyle of a sound animal was, that after tying the duct it was never white. They conceived the reason of the difference to be, that the white colour is owing to fatty matter taken up from the food by the agency of the bile, which possesses the power of dissolving fat; and may probably, therefore, aid in effecting its solution in the chyle in the radicles of the chyliferous vessels. Sir Benjamin Brodie and Mr. Mayo are considered to have been misled by the absence of the white colour, usually possessed by the chyle, but which is wanting in ordinary diges- tion, if the food does not contain fatty matter.2 The experiments of Dr. Beaumont showed, that oil undergoes but little change in the sto- mach, and that bile is probably necessary to give it the requisite physical constitution, in order that chyle may be separated from it. Messrs. Tiedemann and Gmelin restrict the agency of the bile in chylification to the accomplishing of the solution of the fatty matter, and to the nitrogenizing or animalizing of food that does not contain nitrogen. The experiments of M. Voisin equally show, that the ligature of the choledoch duct does not prevent the formation of chyle, provided the passage of the pancreatic fluid is not at the same time prevented. In a number of dogs, a ligature was applied so* as to completely prevent the passage of bile into the intestine. Two lived three months after the experiment; three, six weeks; and five died shortly after the appli- cation of the ligature. In no instance did death appear to be owing to the suspension of digestion or assimilation. Almost all the animals had begun to eat; and, in the majority, food perfectly chymified was found in the duodenum; and well elaborated chyle in the chyliferous vessels. It would appear, therefore, that the bile, although an import- ant, is not an essential agent in digestion in the duodenum. This is signally corroborated by the cases of two infants, four or five months old, recorded by Dr. Blundell. The hepatic ducts in both cases ter- minated blindly, so that no bile entered the intestines; the evacuations were white like spermaceti, and the skin jaundiced. Yet they grew rapidly, and throve tolerably. No certain knowledge exists, whether any of the elements of the bile are absorbed in the form of chyle; or whether it acts mainly as a precipitate, and is thrown off with the excrement. As elsewhere shown, however, it is largely excrementitious or depurative. As to the mode in which the biliary and pancreatic fluids act on the 1 Researches, Physiological and Pathological, London, 1825; and Elliotson's Physiology, p. 124, London, 1840. 2 Edinb. Med. and Surg. Journal, xciii.; and Mayo, Outlines of Human Physiology, 4th edit, p. 139, London, 1837. ACTION OF THE SMALL INTESTINE. 613 chyme, we have not had, until recently, much more than conjectures to guide us. MM. Tiedemann and Gmelin suggest, that the soda of the bile unites with the chlorohydric and acetic acids of the chyme; and simultaneously the latter precipitates the mucus of the bile and its colouring principle and resin, which are evacuated with the excrements. The majority of physiologists believe, that bile is divided into two parts, by the action of the chyme; the one—containing the alkali, salts, and a part of the animal matter—uniting with the chyle; the other—con- taining the coagulated albumen, the coloured, concrete, acrid, and bitter oil—uniting with the faeces, to be discharged along with them. Ac- cording to this view, the action of the bile would be purely chemical; a part would be recrementitial or taken up again; and a part excre- mentitial, giving to the excrements their smell and colour; and, accord- ing to some, the necessary stimulating property for exciting the flow of the intestinal fluids, and soliciting the peristaltic action of the intestines so as to produce their evacuation. It is more than doubtful, however, whether the bile have any such influence as the last. It is a law in the economy, that no secretion irritates the part over which it passes, or is naturally destined to pass, unless such part is in a morbid condition ; and were it otherwise, the mucous membrane of the intestine would be soon accustomed to the stimulation; and, the effect be null. MM. Tiedemann and Gmelin further suggest, that from the abundance of highly nitro- genized principles, which the bile contains, it probably contributes to animalize those articles of food, that do not contain nitrogen; and that it may tend to prevent the putrefaction of the food in its course through the intestines, inasmuch as when it is prevented from flowing into them, their contents appear much farther advanced in decay than in the healthy state. It has been held of late, that bile has the power of transforming saccharine aliments into fat; a circumstance, which is favoured by the discovery Of H. Meckel,1 that when sugar is mixed with bile out of the body a part of it is converted into fatty matter. Ad- mixture with the pancreatic juice would then render its absorption easy. (See Secretion of Bile.) We were not instructed until of late in regard to the precise uses of the pancreatic juice; although many have been assigned to it, which being founded in ignorance of its nature and properties, it would be a waste of time to notice. Messrs. Tiedemann and Gmelin affirm, that it yields to the chyme the richly nitrogenized principles, that enter into its com- position; and, consequently, aids in assimilation. In testimony of this, they remark, that the pancreas is larger in herbivorous than in carnivo- rous animals; and that, in proportion as the chymous matter proceeds along the intestinal canal, it exhibits itself less rich in albumen and other nitrogenized matters, which have probably been abstracted from it by absorption. Dr. Marcet2 discovered in the chyme of the small intestine a notable development of albumen, which was first perceptible a few inches from the pylorus, and did not exist in the large intestine; and Messrs. Tiedemann and Gmelin found in the intestinal contents of 1 Henle und Pfeufer, Zeitschrift fur rationelle Medicin; cited by Mr. Paget in Report in British and Foreign Medical Review, p. 261, July, 1846. 2 Medico-Chirurgical Trans, vi. 618. 014 DIGESTION. animals, that had swallowed pebbles while fasting, more albumen than the pancreatic juice could account for. If such be the fact, albumen must be either developed from the food, or secreted from the mucous membrane. There is a striking resemblance in chemical properties between the pancreatic juice and saliva; and the views applicable to both one and the other, embraced, as the result of numerous experiments by MM. Bernard and Barreswil, have been already stated. The recent experi- ments of M. C. Bernard1 have shed important light on this matter. Exposure of fatty bodies to the pancreatic juice out of the body pro- duced at once a complete emulsion, and resolved them into glycerin and fatty acid;—in the case of butter, butyric acid; whilst no such effect was produced on such bodies by admixture with other fluids—saliva, gastric juice, or serum of the blood, for example. These experiments were frequently repeated with like results in the presence of distin- guished observers—MM. Magendie, Berard, Andral, &c. When dogs to which fatty substances had been given were killed during digestion, these substances were found unaltered until they came in contact with the pancreatic fluid; and if the duct of the pancreas was tied all change was prevented. It would seem, therefore, that although the pancreatic fluid resembles the saliva in many respects-—so much so, indeed, that the pancreas has been styled " the abdominal salivary gland,"—it is pos- sessed of properties as a digestive fluid which the saliva has not. In a remark upon a subsequent me'moire by M. Bernard—the commission, consisting of MM. Magendie, Milne Edwards and Dumas—do not hesi- tate to conclude, that M. Bernard has completely established the physiological office of the pancreas and made known the mechanism of the digestion of fatty matters.2 The influence of the temperature of the interior of the intestine, and of the peristaltic motion, on chylification, can be looked upon as only accessory and indirect. Whilst the chyme is passing through the small intestine, it is sub- jected to the action of the chyliferous vessels, which extract from it the nutritious part or chyle,—the fluid especially destined for the re- novation of the blood. How this is accomplished will be treated of under the head of Absorption. In proportion as this absorption is effected, the chyme changes its properties. In the commencement of the jejunum, it is the same as in the duodenum; but, lower down, the grayish layer, that existed at its surface, is observed to gradually dis- appear. It assumes greater consistence; its yellow colour becomes more marked; and, in the ileum, it has a greenish or brownish tint; and from being acid becomes alkaline, until, at the lower part of the small intestine, it seems to be the useless residue of the alimentary matter, and the various secretions from the upper portion of the digestive ap- paratus. It is now mere excrementitious matter or faeces, although not possessing the entire fecal odour. Its alkaline character has generally been ascribed to admixture with the bile, pancreatic fluid, and the secre- 1 Archives Generales, xiv.; translated in the Provincial Medical and Surgical Journal for March 31, 1849. 2 Gazette Medicale, No. 9, Paris, 1849. ACTION OF THE LARGE INTESTINE. 615 tion from the intestinal glandulse. The agency of the bile was sup- posed to be through its free soda, or the carbonate or tribasic phosphate of soda. The bile, however, as shown elsewhere, is neutral; and accord- ingly it has been suggested as more probable, that the chyme is made alkaline by the ammonia, which is one of the products of the spontaneous decomposition'of bile in the intestines.1 The pancreatic juice is cer- tainly also alkaline. During the formation of chyle, gases are almost always present in the small intestine. They were first examined by Jurine; but chemical analysis was by no means as advanced at that day as it is now; MM. Magendie2 and Chevreul have more recently analyzed those, which they found in the small intestines of three criminals; all young and vigorous. The results of this analysis have been given already (p. 599). The gases might originate in various ways. They might pass, for example, from the stomach with the chyme. There is this objection, however, to the view; that the air in the stomach contains oxygen and very little hydrogen; whilst a considerable quantity of the latter gas is almost always found in the small intestine, and never oxygen. Again, they might be secreted by the mucous membrane of the intestine. So far as we.know,, however,* carbonic acid and nitrogen are alone exhaled from the tissues. We would still have to account, for the hydrogen. Lastly, they might arise from the reaction of the elements of the chyme upon each other, and this has been considered the most probable origin. M. Magendie3 has frequently seen bubbles of gas escaping from the chymous mass, between the mouth of the ductus communis choledochus and the ileum; but never from that of the ileum, the upper part of the duodenum, or stomach; and he affirms, that Chevreul, in prosecuting some experiments, found that when the mass obtained from the small intestine was suffered, to ferment for some time in a stove, at the tem- perature of the body, the same gases were obtained as those met with in the small intestine. When the food has attained the lower part of the ileum, the process of chylification has been accomplished, and the residuary matter is transmitted, by the peristaltic action, into the large intestine. The movement, however, recurs irregularly and at long intervals. In the living animal it can rarely be perceived; but may be noticed in one recently killed, and appears to have no coincidence with that of the pylorus. g. Action of the Large Intestine. The large intestine acts as a reservoir and excretory canal for the faeces. The residue of the alimentary matter is sent on through the valve of Bauhin by the peristaltic action of the ileum. This valve, we have seen, is so situate at the point of union between the ileum and cajcum as to permit a free passage from the former to the latter, but to prevent return. The chymous mass is sufficiently soft to pass rea- dily ; and the quantity of mucus poured out from the lining membrane, 1 Valentin Lehrbuch der Physiologie des Menschen, i. 338, Braunschweig, 1S44. 2 Precis, ii. 115. 3 Ibid, 117. 616 DIGESTION. facilitates its course. When it has reached the large intestine, it first accumulates in the csecum, which—being cellular or pouched like the colon—necessarily detains it for some time. In proportion, however, as the csecum becomes filled, the peristaltic action is extended from the small intestine, and the matter is sent into the colon, the cells of which are successively filled; first, those of the ascending, and then those of the transverse and descending colon, as far as the annu- lus or commencement of the rectum. The whole of its progress through the large intestine is slowly accomplished. Independently of the pouched arrangement, which retards it, a part of the colon ascends, so that the fsecal matter must often proceed contrary to gravity. It becomes, moreover, more and more inspissated in its progress towards the outlet; and the peristaltic action recurs at greater intervals than in the upper portions of the tube. The importance of such a reservoir as the large intestine is obvious. Without it, we should be subjected to the inconvenience of evacuating the fasces incessantly. Before the excrementitious matter reaches the lower portion of the small intestine, it has not the fecal odour ; but acquires it after having remained there for a short time., The brownish-yellow hue becomes deeper; but its consistence, smell, and colour, vary considerably, according to the character of the alimentary matter; the mode and degree in which chymification and chylification have been accomplished; the habit of the individual, &c. &c. The fsecal matter, as we find it, consists of the excrementitious part of the food, as well as of the juices of the upper part of the canal, that have been subjected to the digest- ive process ; of the secretions, poured out from the lower part of the intestine, and also, of substances, that have escaped the digestive actions of the stomach and small intestine, and are often perceptible in the evacuations. The peculiar fsecal impregnation is probably depend- ent upon a secretion from appropriate follicles—those of Peyer, for example ; and we can thus understand, if we take into consideration the digestion of the different secretions, why fsecal evacuations may exist, when the individual has not eaten for some time, or taken but little nourishment. Some physiologists have believed, that chylification takes place even in the large intestines, and that chylous' absorption is more or less effected there. M. Viridet1 asserted, that the csecum is a second sto- mach, in which a last effort is made to separate from the food the digestible and soluble portions it may still contain. In herbivorous animals, according to him, an acid solvent is secreted in it. MM. Tiedemann and Gmelin seem to admit the fact; and likewise think, that the fluid, secreted by the inner membrane of the intestine, assists in the assimilation of the food by means of the albumen it contains, and that fsecal matter is formed there. From various experiments insti- tuted by Professor Schultz,2 of Berlin, he infers, that the food in the csecum becomes not only a second time sour, but that the acid chyme is there neutralized by the access of bile in the same way as in the duo- 1 Tractatus Novus de Prima Coctione, &c, Genev, 1691. 2 Lond. Med. and Surg. Journ, Oct. 31, 1835 ; cited in Amer. Journal of the Medical Sci- ences. Nov, 1836, p. 203. ACTION OF THE LARGE INTESTINE. 617 denum. M. Blondlot,1 however, states, that in many herbivorous ani- mals and granivorous birds, as sheep, goats, pigeons and chickens, the contents of the csecum were never acid unless sugar in some form had been mixed with their food. The acidity of the csecum which then ensues, he thinks is the result of that part of the starch or sugar, which has not been absorbed in the small intestine, being transformed into lactic acid. The fact of the separation of chyle in the csecum and colon is proved^ by the experiments of M. Voisin,2 which consisted in introducing food into these intestines after the ileo-csecal valve had been closed by ligature. The physical characters of the faeces have been already described. When extruded, they have the shape of the large intestine, or of the aperture, through which they have been evacuated. If the form of either of these be modified, that of the excrement will be so likewise. In stricture of the colon—especially about the sigmoid flexure—and of the rectum, the faeces are squeezed through the narrowed portions, and often evacuated in the shape of ribands. The quantity must, of course, vary according to circumstances, and cannot be rigidly estimated. Ap- proximately, they have been presumed to be, in the adult male, from a quarter to half a pound in the twenty-four hours, the evacuation being usually made once only in this time. The biliary secretion appears to modify the appearance of the fseces greatly. If, as in jaundice, it be prevented from flowing into the intestine, they are clay-coloured. M. Adelon3 affirms, that, under such circumstances, they are more fre- quent. This is not the result of our experience, nor does it appear to be deduced from his own; as, a few pages before, he remarks, "it is certain, that if the bile does not flow, the excrements are dry, devoid of colour, and there is constipation." On the other hand, if the bile flows in too great quantity the fseces are darker coloured. It is doubtful, whether the varying quantity of the biliary secretion have much influ- ence on the number of evacuations, unless the canal, through which it has to pass, is in a morbid condition. Many of the appearances in the fseces, which are conceived to be owing to a morbid condition of the biliary secretion, are the effect of admixture with products of morbid changes in the stomach or intestines. In elucidation of this, it may be observed, that the green evacuations of children are often referred to some pathological condition of the biliary secretion ; whereas the colour is commonly owing to unusual formation of acid in the stomach, the admixture of which with healthy bile produces the colour in question. The chemical properties of the fseces have been repeatedly inquired into. They must, of course, vary according to the nature of the food, its quantity, the kind of digestion, &c. Human fseces were examined by Rawitz4 after animal and vegetable food had been taken. But few fragments of muscular tissue were met with; but the cells of cartilage and fibro-cartilage—excepting those of fish—were found unchanged. Elastic fibres and fatty matters, which had escaped absorption, appeared 1 Traite Analytique de la Digestion, Paris, 1844. ,/-,-.. 2 Nouvel Apercu sur la Physiologie du Foie, &c, Paris, 1833. 3 Op, citat. 4 Ueber die Einfachen Nahrungsmittel, Breslau, 184b, cited by Kirkes and Paget, Manual of Physiology, Amer. edit, p. 176, Philad, 1849. 618 DIGESTION. to be unchanged; for fat cells were sometimes unaltered in the fseces; and crystals of cholesterin might generally be obtained from them especially after the use of pork fat as diet. Of vegetable aliments, large quantities of cell membrane were unal- tered; and starch cells were commonly deprived of only part of their contents: the green colouring matter—chlorophyll—was unaffected, and the walls of sap vessels and spiral vessels were usually found in large quantities in the faeces,—their contents.having been probably removed during digestion. The fseces differ in each animal species. Those of the herbivora con- tain less animal matter than those of the carnivora and omnivora; and the agriculturist is well aware, that the excrements of all animals are not equally valuable as manure. The dung of the pigeon is alkaline and caustic; and hence has been employed in tanning for softening skins. The excrement of dogs, that have fed only on bones, is white, and ap- pears to be almost wholly composed of the earthy matter of bone. It has not, however, been examined by modern chemists. This white ex- crement is the album graeeum, cynocoprus, .spodium draecorum, album canis or stercus caninum album, of the older writers. It was formerly employed as a discutient to the inside of the throat in quinsies, but is now justly discarded. M. Vauquelin,1 on comparing the nature and quantity of the earthy parts of the excrements of fowls with those of the food on which they subsisted, arrived at some results that are of interest to the physiolo- gist. He found that a hen devoured, in ten days, 11111*843 grains troy of oats. These contained of phosphate of lime 136*509 grains; and of silica 219*548 grains; in the whole 356*057 grains. During these ten days she laid four eggs, the shells of which contained 98*779 grains of phosphate, and 58*494 grains of carbonate of lime; and she passed 185*266 grains of silica. The fixed parts, thrown out of the system during the time, consisted of:— Phosphate of lime,........274-305 grains. Carbonate of lime,......- . 511-911 Silica, ..........185-266 Given out, . . . . . . . . 971-482 Taken in, ........ 356-057 Surplus,.........615-425 The quantity of fixed matter, therefore, given out of the system in ten days, exceeded the quantity taken in by this last amount. The phosphate of lime, taken in, amounted to 136-509 grains. That given out, to ........274-305 137-796 There must, consequently, have been formed 137*796 grains of phos- phate of lime, besides 511*911 grains of the carbonate. The inferences, deduced from these experiments, were, that lime, and perhaps also phos- phorus, is not a simple substance, but a compound formed of ingredients 1 Annales de Chimie, torn. xxix. p. 3. ACTION OF THE LARGE INTESTINE. 619 that exist in oats, water, or air; the only substances to which the fowl had access; and that silica must enter into its composition, as a part had disappeared. Before, however, we adopt these conclusions, the experiments ought to be repeated more than once. The chicken should be fed on oats some time before the excrements and shells are subjected to analysis; as the carbonate of lime, and the excess of phosphate de- tected on analysis, might have proceeded, not only from the food, but from earthy matters previously swallowed. Care should also be taken, that it has no access to any calcareous earth; and we must be certain, that it has not diminished in weight; as, in such case, the earth may have been supplied from its own body. These precautions are the more requisite, seeing, that experiments have shown, that certain birds cannot produce eggs unless they have access to calcareous earth. There are some very remarkable instances of chemical changes, in mysterious actions, more immediately concerned in the decomposition and renovation of the frame; or, in what has been abstractedly termed— the function of nutrition. Dr. Henry1 has announced, that the follow- ing substances have been satisfactorily proved to exist in healthy urine; —water, free phosphoric acid, phosphate of lime, phosphate of mag- nesia, fluoric acid, uric acid, benzoic acid, lactic acid, urea, gelatin, albumen, lactate of ammonia, sulphate of potassa, sulphate of soda, fluate of lime, chloride of sodium, phosphate of soda, phosphate of ammonia, sulphur, and silex;—yet we have no proof that these sub- stances are obtained from any other source than the food; and some of them are with difficulty obtained any where. Every one of them is necessary for the constitution of the urine; and many must be formed by a chemical union of their elements under the vital agency. Some are met with in the animal body exclusively. Berzelius2 found, in 100 parts of human faeces:—water, 73*3 ; unaltered residue of animal and vege- table substances, 7*0; bile, 0*9; albumen, 0*9; peculiar extractive mat- ter, 2*7; substance, formed of altered bile, resin, animal matter, &c, 14; salts, 1*2. Seventeen parts of these salts contained, of carbonate of soda, 5; chloride of sodium, 4; sulphate of soda, 2 ; ammoniaco-mag- nesian phosphate, 2 ; phosphate of lime, 4. The excrements have like- wise been examined by MM. Leuret and Lassaigne, and others; but none of the analyses have shed much light on the physiology of digestion. Analyses of the ashes of firm human fseces by Enderlin3 yielded the following results:—chloride of sodium and alkaline sulphate, 1*367; tribasic phosphate of soda, 2*633; phosphate of lime, and phosphate of magnesia, 81*372 ; phosphate of iron, 2*091; sulphate of lime, 4*56 - silica, 7*97. In the large intestine, gases are met with, along with the fseces These were examined by MM. Magendie4 and Chevreul in the three cri minals already referred to (page 599). The results accord with those of Jurine,5 obtained long ago, as regards the nature of the gases; but 1 Elements of Chemistry, 9th edit, ii. 435, Lond, 1823. 2 Traite de Chimie, trad, par Jourdan et Esslinger, torn, vn, and Simon s Animal Che- mistry, Sydenham Society edit., ii. 372, Lond, 1846, or Amer. edit Philad, 1S46 3 Annalen der Chemie und Pharmacie, Mars, 1844, cited by Mr. Paget, Brit, and For. Med. Rev, Jan, 1845, p. 277. . 4 Precis &c, ii. 126. 5 Memoir, de la Soc. Royale de Med, x. 72. 620 DIGESTION. they do not correspond with what he says relating to the carbonic acid; the quantity of which, according to him, goes on decreasing from the stomach to the rectum. The analyses of MM. Magendie and Chevreul show, that the proportion instead of decreasing, increases. Concerning the origin of these gases, the remarks made on those in the small intes- tine are equally applicable here. When the fsecal matter has accumulated to the necessary extent in the rectum, its expulsion follows; and to this function the term defeca- tion has been assigned. The fseces collect gradually in the large intes- tine, without any consciousness on the part of the individual. Sooner or later, the desire or want to evacuate them arises. This is usually classed among the internal sensations or desires. It is, however, of a mixed character. It is not always in a ratio with the quantity of fseces as is shown by the fact, that occasionally the intestine is filled without the want arising; and, if they be unusually thin or irritating, the desire is developed, when an extremely small quantity is present,—as in cases of tenesmus. The period, at which the desire returns, is variable, according to the amount and character of the food employed, as well as the habit of the individual. Whilst the generality of persons evacuate the bowels at least once a-day,—and this at a period often regulated by custom,—others pass a week or two without any alvine discharge, and yet may be in perfect health. Nay, some of the collectors of rare cases1 have affirmed, on the authority of Rhodius, Panarolus, Salmuth, and others, that persons may remain in health, with the bowels moved not oftener than once a month, three months, half a year, two years, and even seven years! Sir Everard Home2 refers to the case of General Grose, who was in the Dutch service, under the Duke of Cumberland, in the Flanders war; and who for thirty years had no passage through the bowels. General Gage noticed that he ate heartily; but in two hours left the table and rejected his meal. He was healthy, and capa- ble of exercise like other men. Dr. Heberden3 mentions the case of a person, who had naturally an evacuation once a month only; and an- other who had twelve evacuations every day during thirty years, and then seven every day for seven years, and grew fat rather than other- wise. A young lady referred to by M. Pouteau,4 had no evacuation for upwards of eight years; although during the last year she ate abundantly of fruit, and drank coffee, milk, tea, and broth with yolks of eggs; but she had copious greasy sweats;—and many similar extraordinary cases have been recorded by Dr. Chapman5 of Philadelphia. When the desire to evacuate has once occurred, it generally persists until the faeces are expelled. Sometimes, however, it disappears and recurs at an uncertain interval; and, if again resisted, may become the source of pain, and ultimately command implicit obedience. That the pressure and irrita- tion of the faeces develope the sensation is evidenced by the fact, that the momentary relief experienced at times, when the desire is urgent, 1 Art. Cas Rares, in Diet, des Sciences Medicales. 2 Lect. on Comp. Anat, v. 12, Lond, 1828. 3 Commentarii. p. 14, 4 ffiuvres Posthumes, i. 27, Paris, 1783. 5 Lectures on the more important Diseases of the Thoracic and Abdominal Viscera, p. 294, Philad, 1844. DEFECATION. 621 is usually accompanied by a manifest upward return of the fgecal mat- ters from the sigmoid flexure into the colon. In evacuating the fseces, the object to be accomplished is,—that the contents of the large intestine shall be pressed upon with a force supe- rior to the resistance presented by the annulus or upper extremity of the contracted rectum, and the muscles of the anus. The contraction of the rectum is generally insufficient to effect this last object, notwith- standing the great thickness of its muscular layer. In cases, however, of irritability of the rectum, the sphincter is incapable of resisting the force developed by the proper muscular fibres of the gut. Under ordi- nary circumstances, the aid of the diaphragm and abdominal muscles is invoked, and it is chiefly through these muscles, that volition influ- ences the act of defecation,—suspending, deferring, or accelerating it, as the case maybe. After a full inspiration, the muscles that close the glottis; and the expiratory muscles,—especially those of the anterior part of the abdomen, contract simultaneously. The air cannot escape from the lungs; the diaphragm is depressed upon the abdominal viscera, and the whole thorax presents a resisting body; so that all the expira- tory power of the muscles bears upon the viscera, and presses them against the vertebral column. In this way, considerable force is exerted upon the contents of the colon and rectum; the resistance of the sphincter,—already diminished by the direct exercise of volition,— is surmounted; it yields, and the fseces are extruded. The levator ani and ischio-coccygeus, aided by the transversus perinei muscle, support the anus during the expulsory efforts, and restore it to its place after the efforts have ceased. Whilst straining is effected by the diaphragm and abdominal muscles, the longitudinal muscular fibres of the rectum contract, so as to shorten the intestine, and, consequently, the space over which the fseces have to pass. At the same time, the circular fibres contract from above to below, so as to propel the excrement downwards, and to cause the mucous membrane to extrude, and form a ring or bourrelet, like that which occurs at the cardiac orifice of the stomach, when the food is passing from the oesophagus into that organ. If this extrusion occurs to a great extent, it constitutes the disease called prolapsus ani. Dr. O'Beirne1 of Ireland, guided by the following facts and argu- ments;—that great irritation would be produced in the sphincter ani, and bladder, if the fseces descended readily into the rectum;—that the difficulty experienced in throwing up an injection is inconsistent with the idea of the gut being open, and proves that it is firmly contracted and closed;—that when the surgeon has occasion to pass his finger up the rectum, he rarely encounters either solid or fluid faeces;—that the two sphincter muscles of the anus are weakened, in certain diseases, and divided in operations, and yet it rarely happens, that the power of retaining the faeces is destroyed;—that on passing a stomach-tube to the height of half an inch up the rectum, in a number of healthy per- sons, it was found, that nothing escaped, and that the tube could be 1 New Views of the Process of Defecation. &c, Dublin, 1833; reprinted in this country, Washington, 1834. 622 DIGESTION. moved about freely in a space, which, on introducing the finger, was ascertained to be the pouch of the rectum; but that from the highest part of the pouch to the upper extremity of the gut—generally a distance of from six or seven to eight inches—it could not be passed upwards without meeting with considerable resistance, and without using a degree of force to mechanically dilate the intestine, which was plainly felt to be so contracted as to leave no cavity for this extent;— that when the instrument reached, in this way, the highest point of the rectum, the resistance to its passage upward was felt to be sensibly increased, until, at length, by using a proportionate degree of pressure, it passed rapidly forward, as if through a ring, into a space in which its extremity could be moved with great freedom, and as instantly a rush of flatus, of fluid fseces, or of both, took place through the tube;— and that in every instance, where the tube presented the least appear- ance of faeces after being removed, this appearance was confined to that portion which had entered the sigmoid flexure:—guided by these and other facts, Dr. O'Beirne properly concluded, that in the healthy and natural state, all the part of the rectum above its pouch is at all times, with the single exception of a few minutes previous to the evacuation of the bowels, firmly contracted, and perfectly empty, at the same time that the pouch itself, as well as the sigmoid flexure of the colon, is always more or less open, and pervious,—and that the sphincter ani muscles are but subsidiary agents in retaining the faeces. When the fseces are firm, considerable-muscular effort is necessary to expel them; but when they are of a softer consistence, the contraction of the rectum is sufficient. The sphincters—as elsewhere shown—afford examples of reflex action. After sensation and volition. are suspended, they contract under direct irritation. Yet, like the respiratory muscles, they are of a mixed character,—partly voluntary and partly involuntary. They are involuntary, but capable of being aided or impeded by a voluntary effort. The state of gentle contraction, in which they constantly are, is evidently dependent upon their connexion with the spinal cord; for the experiments of Dr. Marshall Hall have exhibited, that it ceases, when the connexion is destroyed. Air, contained in the intestinal canal, readily moves about from place to place, and speedily reaches the rectum by the peristaltic action alone. Its expulsion, however, is commonly accomplished by the aid of the abdominal muscles; when it issues with noise. If discharged by the contraction of the rectum alone, it is generally in silence. Children are extremely subject to flatulence; in the adult it is not so common. Certain kinds of diet favour its production more than others, especially in those of weak digestive powers, of which condition its undue evolu- tion is generally an indication. The leguminous and succulent vegeta- bles in general belong to this class. Where digestion is tardily accom- plished, they give occasion to the copious disengagement of gas. Too often, however, the disgusting habit of constantly discharging air stre- perously from the bowels is encouraged, rather than repressed; and there are persons, who are capable of effecting the act almost as fre- quently as they attempt it. LIQUIDS. 623 The noise, made by the air, as it passes backwards and forwards in the intestinal canal, constitutes the affection called borborygmus. So much for the digestion of solid food. In so delicate and compli- cated an apparatus, it would seem, that mischief ought more frequently to result from the various heterogeneous substances that are received into the digestive tube. Its resistance, however, to morbific agencies is astonishing. In the Museum of the Boston Society for Medical Improvement1 an open penknife is preserved, which was swallowed by a child between three and four years of age, and passed from the bowels after the expiration of fifty-one hours; the child, in the meantime, play- ing about as usual, and not seeming to suffer. The story of the luna- tic, under the care of Dr. Fox of Bristol, who swallowed "some inches" of a poker, which came away without any suffering, is regarded as authentic;2 and there is no question in regard to the authenticity of the case of the sailor recorded by Dr. Marcet,3 who swallowed a number of clasp knives with impunity, but ultimately fell a victim to his idle temerity,—having swallowed, in the whole, thirty-seven! 5. DIGESTION OP LIQUIDS. In inquiring into the digestion of liquids, we shall follow the same order as that observed in considering the digestion of solids; but as many of the acts are accomplished in the same manner, it will not be necessary to dwell upon them. Thirst or the desire for drink is an internal sensation; in its essence resembling that of hunger, although not referred to the same organs. It arises from the necessities of the system; from the constant drain of the fluid portions of the blood; and is instinctive or essentially allied to organization. The sensation differs in different persons, and is rarely alike in the same. Usually, it consists of a feeling of dryness, con- striction, and heat in the back part of the mouth, pharynx, oesophagus, and occasionally in the stomachy and, if prolonged, redness and tume- faction of the parts supervene, with a clammy condition of the mucous follicular—and diminution and viscidity of the salivary—secretions. These phenomena are described as being accompanied by restlessness, general heat, injected eyes, disturbed mind, acceleration of the circula- tion, and short breathing, the mouth being frequently and largely open, so as to admit the air to come in contact with the irritated parts, and thus afford momentary relief. Thirst is a very common symptom of febrile and inflammatory dis- eases, in which fluid—especially cold fluid—is desired in consequence of the local relief it affords to the parched and heated membrane of the alimentary canal. It is also developed by extraneous.circumstances: as in summer, when the body sustains considerable loss of fluid; as well as in those diseases—dropsy, diabetes, &c.—which produce the same effect. There are many other circumstances, however, that excite it;— 1 J. B. S. Jackson, A Descriptive Catalogue of the Anatomical Museum of the Boston Society for Medical Improvement, p. 158, Lond, 1847. 2 Southey, The Doctor, iv. 297, Lond, 1837. 3 Medico-Chirurgical Transactions, xii. 52, Lond, 1822. 624 DIGESTION. long speaking or singing; certain kinds of diet as the saline and spicy, —and especially the habit, acquired by some, of drinking frequently. Whilst individuals, thus circumstanced, may need several gallons a day to satisfy their wants;—others, who have, by resistance, acquired the habit of using very little liquid, may be enjoying health and not expe- riencing the slightest inconvenience from the privation of liquid; so com- pletely are we, as regards the character and quantity of our aliment, the creatures of habit. This privation, it is obvious, cannot be abso- lute or pushed beyond a certain extent. There must always be fluid enough taken to administer to the necessities of the system. As in the production of all sensations, three acts are required for accomplishing that of thirst;—rimpression, conduction, and perception. The last, as in every similar case, is effected by the brain; and the second by the nerves passing between the part impressed and that organ. The act of impression—its seat and cause—will alone arrest our attention, and it will be found that we are still less instructed on these points than on the physiology of hunger. Even with regard to the seat ofthe impression, we are in a state of uncertainty. It appears to be chiefly in the back part of the mouth and fauces; but whether pri- marily there, or experienced there by sympathy with the condition of the stomach, is by no means clear. The latter opinion, however, appears the more probable. In a remarkable case, published by Dr. Gairdner of Edinburgh, it was found impracticable to allay thirst by merely supplying the mouth, tongue, and fauces with fluid. A man had cut through the oesophagus. An insatiable thirst arose; several pailfuls of water were swallowed daily, and discharged through the wound without removing the desire for drink; but on injecting water, mixed with a little spirit, into the stomach, it was soon quenched. That the sensation is greatly dependent upon the quantity of fluid cir- culating in the vessels is shown by the fact, mentioned by M. Dupuytren, that he succeeded in allaying the thirst of animals, by injecting milk, whey, water or other fluids into the veins; and M. Orfila states, that, in his toxicological experiments, he frequently allayed in this way the excessive thirst of animals, to which he had administered poison; and which were incapable of drinking, owing to the oesophagus having been tied. He found, also, in his experiments, that the blood of animals was more and more deprived of its watery portions as the abstinence from liquids was more prolonged.1 Like all other sensations, that of thirst arises from an inappreciable modification of the nerves of the organ : hence, all the hypotheses proposed to account for it have been mere fantasies undeserving of enumeration. The prehension of liquids differs somewhat from that of solids. The fluid may be simply poured into the mouth, or a vacuum may be formed in it: the pressure of the atmosphere then forces it in. When we drink from a vessel, the mouth is applied to the surface of the fluid; the chest is then dilated, so as to dimmish the pressure of the atmo- sphere on the portion of the surface of the liquid intercepted by the 1 Adelon, Physiologie de l'Homme, 2de edit, ii. 525, Paris, 1829. LIQUIDS. 625 lips; and the atmospheric pressure on the surface of the fluid in the vessel forces it into the mouth, to replace the air that has been drawn from the mouth by the dilatation of the thorax. In sucking, the mouth may be compared to an ordinary syringe; the nozzle of which is re- presented by the lips; the body by the cheeks, palate, &c, and the piston by the tongue. To put this in action, the lips are accurately adjusted around the.body from which the liquid has to be extracted. The tongue is likewise applied, contracts, and is carried backwards; so that an approach to a vacuum is formed between its upper surface and the palate. The fluid, no longer compressed equally by the atmo- sphere, is displaced, and enters the mouth. As neither mastication nor insaliva^tion is required in the case of liquids, they do not remain long in the mouth, unless their temperature is too elevated to admit of their being passed down into the stomach immediately, or they are of so luscious a character, that their prolonged application to the organ of taste affords pleasure. Their deglutition is effected by the same mechanism as that of solids; and, as they yield readily to the slightest pressure, with less difficulty. Their accumula- tion in the stomach takes place in much the same manner. They arrive by successive mouthfuls; and, as they collect, the thirst disappears with all its local and general attendants. If, however, the organ be over-distended a disposition to vomiting is induced. The changes, which liquids undergo in the stomach, are of different kinds. All acquire the temperature of that viscus, and become mixed with the secretions from its internal surface, as well as from that of the supra-diaphragmatic portion of the digestive tube. Some, however, undergo the operation of chymification; others not. To the latter class belong,—water, weak alcoholic drinks, the vegetable acids, &c. Water experiences the admixture already mentioned; becomes turbid, and gradually disappears, without undergoing any transformation. Part passes into the small intestine; the other is directly absorbed. When any strong alcoholic liquor is taken, the effect is different. Its stimulation causes the stomach to contract, and augments the secre- tion from the mucous membrane ; whilst, at the same time, it coagu- lates all the albuminous and mucous portions; mixes with the watery part of the mucous and salivary fluids, and rapidly disappears by ab- sorption ; hence, the speedy supervention of inebriety, or death, after a large quantity of alcohol has been taken into the stomach. The substances, that have been coagulated by the action of the alcohol, are afterwards digested like solid food. We can thus understand the good effects of a small quantity of alcohol, taken after a substance difficult of digestion,—a custom which has existed from high antiquity, and has physiology in its favour. It is, in such cases,—to use the language of the eccentric Kitchener,1—a good "peristaltic persuader." Oil remains longer in the stomach than any other liquid, experiences little change there, but passes into the small intestine, where it forms an emulsion and enters the veins and chyliferous vessels. Milk, as is 1 Directions for Invigorating and Prolonging Life; or the Invalid's Oracle, &c, Amer. edit, from the 6th London, by T. S. Barrett, New York, 1831. VOL. I.—40 626 DIGESTION. well known, coagulates in the stomach soon after it is swallowed, after which the clot is digested, and the whey absorbed. Yet the existence of coagula in the stomach is constantly regarded by the unprofessional as a pathological condition ! Where the liquid, aqueous or spirituous, holds in suspension the immediate principles of animals or vegetables, as gelatin, albumen, osmazome, sugar, gum, fecula, colouring matter, &c, there is reason to believe that they enter immediately into the veins of the stomach and small intestine. The salts, united with these fluids, are taken up along with them. Red wine, according to M. Magendie,1 first becomes turbid by admixture with the juices formed in or carried into, the stomach: the albumen of these fluids speedily undergoes coagulation, and becomes flocculent; and, subsequently, its colouring matter—entangled, perhaps, with the mucus and albumen— is deposited on the mucous membrane of the stomach. The aqueous and alcoholic portions soon disappear. Liquids reach the small intestine in two forms;—in the state of chyme; and in their unaltered condition. In the former case, they proceed like the chyme obtained from solid food. In the latter, they undergo no essential change ; being simply united with the fluids poured into the small intestine,—the mucous secretions, bile and pancreatic juice. Their absorption goes on as they proceed, so that very little, if any, attains the large intestine. The mode in which they are expelled is the same as in the case of solids. 6. ERUCTATION, REGURGITATION, AND RUMINATION. Although the contraction of the oesophagus generally prevents the return of matters from the stomach, occasionally this occurs, giving rise to eructation, regurgitation, or vomiting. a. Eructation.—Eructation or belching is the escape of gas from the stomach. If air exists in the organ, it is necessarily situate near the cardiac orifice. When the aperture relaxes, it passes out, and, unless forced back by the contraction of the oesophagus, speedily reaches the pharynx, causing the edges to vibrate, hence the sound by which it is accompanied. b. Regurgitation.—If, instead of air, liquid or solid food ascends from the stomach into the mouth, the action is called regurgitation. Of this we have an instance in the puking of the infant at the breast; and in the adult, when the stomach is surcharged. Occasionally, too, it occurs when the organ is empty,—in the morning, for example ;—when it is frequently preceded by eructations, by which the air, contained in the organ, is got rid of. The mode in which it takes place is analo- gous to that of eructation. The substances, contained in the stomach become accidentally engaged in the cardiac orifice, during the open state of the orifice, and the relaxation of the lower part of the oeso- phagus, owing to the direct pressure of the stomach on its contents, and the abdominal muscles contracting', and compressing that viscus. When they have once passed into the oesophagus, the latter contracts upon them but inversely, or from below to above. In this way they 1 Precis, &c, ii. 143. VOMITING. 627 ascend into the pharynx, and ultimately into the mouth. Generally, regurgitation takes place in an involuntary manner; but there are • some who are capable of effecting it at will; and can discharge the con- tents of their stomachs at pleasure. To accomplish this,—a deep inspi- ration is taken, by which the diaphragm is forcibly depressed upon the stomach ; the abdominal muscles are then contracted so as to compress the organ; and this effect is occasionally aided by pressing strongly with the hands on the epigastric region. When these efforts are simul- taneous with the relaxation of the lower third of the oesophagus, the alimentary matters pass into the oesophagus. This voluntary regurgi- tation seems to be what is called vomiting at pleasure. c. Rumination.—Some individuals have taken advantage of this power to chew the food over again, and subject it to a second deglu- tition. The function of rumination is peculiar to certain animals; yet man has occasionally possessed it. Peyer,1 as well as Percy and Lau- rent,2 has given numerous examples. The wife of a frotteur or rubber of the floors, in the establishment of the then Duke of Orleans,—after- wards King Louis Philippe—could bring up a glassful of water into her mouth immediately after she had swallowed it. Dr. Copland3 appears to have seen more than one instance of human rumination, and he de- scribes it as an affection rather to be courted than shunned, so far as regards the sensations of the individual. Under usual circumstances, according to him, rumination commences from a quarter of an hour to an hour and a half after a meal. The process is never accompanied with the smallest degree of nausea, pain, or disagreeable sensation. The returned alimentary bolus is attended with no unpleasant flavour; is in no degree acidulous [ ?]; is agreeable ; and masticated with addi- tional pleasure,' and greater deliberation than at first. The whole of the food swallowed at a meal is not returned in order to undergo the process; but chiefly the part that has been insufficiently masticated. The more fluid portions are sometimes, however, regurgitated along with the more solid ; and when the stomach is' distended by a copious meal the fluid contents are frequently passed up to be again swallowed.4 d. Vomiting.—This inverted action of the stomach, preceded—as it always is—by manifest local and general disturbance, cannot properly be regarded as within the domain of physiology. In the language of Haller, vomitus totus morbosus est. It is, however, so nearly allied to the phenomena we have just considered, and has engaged so much of the time of the physiologist, as well as pathologist, that it requires mention here. From regurgitation it differs essentially,—in the sensa- tion that precedes ; the retching that accompanies; and the fatigue that generally succeeds it; in short, whilst in regurgitation no indisposition may be felt, in vomiting it is always present to a greater or less extent. The sensation of the desire to vomit is termed nausea. It is an in- 1 Merycologia, &c, Basil, 1685. _ 2 Art. Merycisme, in Diet, des Sciences Medicates; Berard, Cours de Physiologie, 13te livraison, p. 274, Paris, 1849. 3 Edition ofDe Lys's translation of Richerand's Physiology. 4 An interesting case of rumination is cited from the London Lancet, in the Philadelphia Med. Examiner, p. 315, for May, 1845. 628 DIGESTION. describable feeling of general indisposition; sometimes accompanied with one of circumgyration, either in the head or epigastric region; trembling of the lower lip, and copious flow of saliva. Along witff these signs, there 'is manifest diminution of the powers of the vascular and nervous systems; hence the utility of nauseating remedies when these systems are inordinately excited. The causes, which produce nausea, show that it may be either an external or internal sensation. Those, that occasion it directly or externally, are emetics; too great distension of the stomach, or the presence of food that disagrees by its quality ; morbid secretions ; reflux of bile from the duodenum, &c. All these are so many immediate irritants, which develope the sensation, as external sensations in general are developed. In other cases, the cause acts at a distance. Between the stomach and various organs of the body, such extensive sympathetic relations exist, that if one be long and painfully affected, the stomach sooner or later sympathizes; and nausea, or vomiting, or both are induced. In many instances, indeed, the cause is much more remote than this; the sight of a disgusting object, an offensive smell, or a nauseous taste, will as certainly produce the sensation as any of the more direct agents. To this class of causes belongs the nausea produced by riding in ■a, carriage with the back to the horses, by swinging, and particularly by sailing on the ocean. How the motion, which obviously excites the nausea in these cases, acts, has been the subject of many speculations, especially as regards sea-sickness. Darwin1 refers it to an association with some affection of the organs of vision, which, in the first instance, produces vertigo; and M. Bourru, in his French translation of the work of Gilchrist, " On the utility of sea voyages in the Cure of different diseases,"—ascribes it to irritation of the optic nerves, caused by the impossibility of fixing the eyes on objects soon after embarking. The objections to these views are, that it ought to be prevented by simply covering the eyes, and that the blind ought to be exempt from it, which is not the case. Dr. Wollaston2 at- tempted to explain it, by some change in the distribution of the blood; —the descending motion of the vessel causing an accumulation in the brain, as it causes the mercury to rise in the tube of a barometer. But the explanation is too physical. The mercury, in an unyielding tube, is readily influenced by the motions of the vessel; but the blood in the living animal is circumstanced far otherwise. It is under the influence of a vital force, which interferes greatly with the action of purely physi- cal causes. Were it' otherwise, we should be liable to alarming accidents, whenever the body is exposed to the slightest concussion. The generality of pathologists consider, that the first effect is upon the brain, the sensation being produced consecutively through the in- fluence of that organ on the stomach; and it is difficult not to accord with this view; whilst it must be admitted, that the precise mode, in which it is effected, is beyond our cognizance—as in the case, indeed, of every other phenomenon of the nervous system. In nausea, pro- duced by the sight of a disgusting object, we have this catenation of actions somewhat more clearly evidenced. The impression is manifestly, 1 Zoonomia, iv. 252, 3d edit, Lond, 1801. 2 Philos. Transact, for 1810- VOMITING. 629 conveyed to the brain by the optic nerves, and from that organ the sensation must emanate. It is probable, too, that when emetics are injected into the veins, the first effect takes place on the brain, and the stomach is affected secondarily. When the state of nausea, howsoever induced, continues for any length of time, it is usually followed by vomiting. The rejected mat- ters are generally from the stomach; but if the retching or violent contractile efforts of the muscles concerned be long continued, the con- tents of the small intestine also form part; hence, we account for the universality of the presence of bile in the rejected matters after an emetic has been taken. Its presence is, therefore, in the generality of cases, no evidence of the person's being what is termed bilious. The contents of the small intestine are returned into the stomach by the antiperistaltic action. The longitudinal fibres take their fixed point below, and contract from above downwards; so that the chymous mass is forced towards the upper part ofthe canal, whilst the circular fibres contract from below to above. In cases of colica ileus or iliac passion, the inverted action extends through the whole intestinal canal; so that fsecal matters, and even substances injected into the rectum, pass the ileo-caecal valve,> and are discharged by the mouth. Of old, it was universally maintained, that vomiting is caused by the sudden and convulsive inverted contraction of the stomach; and they, who admitted that the diaphragm and abdominal muscles take part in the action, looked upon them simply as accessories. Francis Bayle,1 Professor in the University of Toulouse, in 1681, appears to have been the first who suggested, that the stomach is nearly passive in the act; and that vomiting is caused almost exclusively by the pressure exerted upon that organ by the diaphragm and abdominal muscles. His reason for the belief was founded on the fact, that having introduced his finger into the abdomen of a living animal whilst it was vomiting he could not perceive any contraction of the stomach. In 1686, M. Chirac repeated the experiment with similar results; after which, the views of Bayle were embraced by many of the most eminent physiologists and patho- logists,—Senac, Van Swieten, and Schwartz,2 and, at a later period, by the celebrated John Hunter,3 who maintained, that the contraction* of the muscular fibres of the stomach is not essential to the act. Many distinguished physiologists ranged themselves on the opposite side. M. Littre maintained, that the stomach is provided with considerable muscular bands, capable of powerful contraction; and that vomiting, as in the case of ruminant animals, is often caused without the partici- pation of the abdominal muscles. We have seen, however, that the rumination of animals more resembles regurgitation. M. Lieutaud4 argued, that, according to Bayle's theory, vomiting ought to be a vo- luntary phenomenon; that the stomach is too deeply seated to be com- pressed, so as to empty it of its contents, by the neighbouring muscles; 1 Problemata Medico-physica et Medina, Hagas Comitis, 1678. 2 Haller, E-lementa Physiol, lib. xix. § 4, Bern, 1764. 3 Observations on certain parts of the Animal Economy, with Notes by Prof. Owen, Amer. edit, p. 121, Philad, 1840. * Memoir, de l'Acad. pour 1752, p. 223. 630 DIGESTION. and he details the singular case of a female, who, whilst labouring under an affection, for which emetics seemed to be required, resisted the action of the most powerful substances of that nature. After her death, M. Lieutaud, feeling desirous to detect the cause of this resistance, had the body opened in his presence: the stomach was found enormously distended, but its structure unaffected. He, consequently, inferred, that the stomach had become paralysed from over-distension, and that the effect produced was similar to that, so often met with in the bladder, when it has been long and largely distended. This case seemed to prove to him, that the stomach is most concerned in the act of vomiting, as the abdominal muscles and diaphragm appeared healthy, and no obstacle existed to their contraction. It is singular, however, that emetics should not have excited the contraction of the diaphragm and abdominal mus- cles; especially as there is reason for believing, that many of them at least, under ordinary circumstances, are taken into the bloodvessels, and affect the brain first, and through its agency the muscles con- cerned in the act of vomiting. The case seems to have been one of unusual resistance to the ordinary effects of nauseating substances, and cannot be looked upon as either favourable or unfavourable to the views of Bayle. We find, that vomiting does not follow the exhibition of the largest doses of the most powerful.emetics, if the energy of the nervous system be suspended by the inordinate use of narcotics, or by violent injuries of the head. M. Lieutaud farther remarks, that according to Bayle's theory vomiting occurs at the time of inspiration; but this cannot be, as the lower part of the oesophagus is then contracted, and if the vomited matters could reach the pharynx, they would pass into the larynx. Dr. Marshall Hall1 has attempted, and successfully, to show, that the larynx is closed during vomiting; and has concluded, that the act is a modification of expiration,—or that the muscles of expiration, by a sud- den and violent contraction, press upon the contents of the stomach, and project them through the oesophagus. Perhaps—as Dr. Hall has re- marked—no act affords a better illustration of the action of the excito- motory or reflex system of nerves than this. If the upper part of the throat be tickled with a feather, vomiting results; but if the feather be passed too far down, deglutition is induced and not vomiting. The ex- citor nerves, in the former case, are the glosso-pharyngeal, and perhaps the fifth pair. When vomiting is caused by an emetic, the pneumogas- tric is the excitor. When the impression is first made on the brain, the stimulus must be conveyed by the medulla oblongata and medulla spinalis to the muscles concerned. Haller2 maintained the ancient doctrine, that the stomach, alone, is competent to the operation. His views were chiefly founded on his theory of irritability, which compelled him to admit contraction wherever there are muscular fibres; and on certain experiments of Wepfer,3 who asserted, that when he produced vomiting by mineral substances, he observed the stomach contract. The AcadSmie des Sciences of Paris, 1 Journal of Science and Arts, xv. 388. 2 Loc. citat. 3 Cicutas Aquaticae Historia, &c, Basil, 1679. VOMITING. 631 unsatisfied with the results of previous observations, appointed M. Duverney1 to examine into the question, experimentally and otherwise; who,—although he did not adopt the whole theory of Chirac—confirmed the accuracy of the facts on which it rested. He demonstrated, that the stomach is but little concerned in the act; and that it is chiefly depend- ent upon the contraction of the diaphragm and abdominal muscles, which enclose the stomach as in a press, so that its contents are compelled to return by the oesophagus. On the other hand, in 1771, M. Portal,2 in his lectures at the College of France, endeavoured to show, that the stomach is the great agent. He administered to two dogs arsenic and nux vomica, which produced vomiting. The abdomen was immediately opened; and, according to. Portal, the contractile movements of the sto- mach could be both seen and felt; and it was noticed, that instead of the vomiting being dependent upon the pressure of the diaphragm on the stomach, it occurred at the time of expiration; and was arrested during inspiration, because the depressed diaphragm then closes the inferior extremity, of,the oesophagus with such strength, that the contents can- not be forced into the oesophagus when we press upon the organ with both hands. The views of Portal wrere confirmed by the experiments of Dr. Haighton.3 He opened several animals during the efforts of vomiting; and states that he distinctly saw the contractions of the stomach. In more recent times, the physiological world has been again agitated with this question. In 1813, M. Magendie4 presented to the French Institute the results of a series of experiments on dogs and cats,— animals, that vomit with facility. Six grains of tartrate of antimony and potassa were given to a dog, and, when he became affected with nausea, the linea alba was divided, and the finger introduced into the abdomen to detect the state of the stomach. No contraction was felt; the organ appeared simply pressed upon by the- liver and intestines crowded upon it by the contracted diaphragm and abdominal muscles. Nor was any contraction of the stomach perceptible to the eye; on the contrary, it appeared full of air, and three times its usual size. The air manifestly came from the oesophagus, as a ligature, applied round the cardia, completely shut it off. From this experiment* M. Magendie inferred, that the stomach is passive in vomiting. A solution of four grains of tartrate of antimony and potassa in two ounces of water was injected into the veins of a dog; and, as soon as nausea took place, an incision was made into the abdomen, and the stomach drawn out of the cavity. Although the retching continued, the viscus remained immova- ble; and the efforts were vain. If, on the other hand, the anterior and posterior surfaces of the stomach were pressed upon by the hands, vomiting occurred, even when no tartrate was administered,—the pres- sure pro°voking the contraction of the diaphragm and abdominal muscles, and thus exhibiting the close sympathetic connexion, existing between those acts. A slight pull at the oesophagus was attended with a similar 1 Memoir de VAcadem. pour 1700, Hist., p. 27. 2 Cours d'Anatomie Medicale, Paris, 1S04. 3 Memoirs of the Lond. Med. Society, vol. ii. „ , ^ , . ,...., 4 Memoire-sur le Vomissement, Paris, 1813; and Precis Elementaire, edit, cit, n. 152. 632 DIGESTION. result. In another dog, the abdomen was opened; the vessels of the stomach tied; and the viscus extirpated. A solution of two grains of tartrate of antimony and potassa in an ounce and a half of water was then injected into the veins of the animal, when nausea and fruitless efforts to vomit supervened. The injection was repeated six times: and always with the same results.—In another dog, the stomach was extir- pated, and a hog's bladder fitted to the oesophagus in its stead, con- taining a pint of water, which distended but did not fill it. The whole was then put into the abdomen; the parietes of which were closed by suture. A solution of tartrate of antimony and potassa was noty in- jected into the jugular vein: nausea—and, afterwards, vomiting—super- vened, and the fluid was forced from the bladder.—In another dog, the phrenic nerves were divided; by which three-fourths" of the diaphragm were paralysed; the dorsal being the only nerves'of motion remaining untouched. When tartrate of antimony and potassa was injected into the veins of this animal, but,slight vopaiting occurred; and this ceased, when the abdomen was opened, and the stomach forcibly pressed upon.— In another dog, the abdominal muscles, were detached from the sides and linea alba;—the only part of the parietes remaining being the peritoneum. A solution of tartrate of antimony and potassa was now injected into the veins: nausea and vomiting supervened; and, through the peritoneum, the stomach was observed immovable; whilst the dia- phragm pressed down the viscera so strongly against the peritoneum, that it gave way, and the linea alba alone resisted.—In a final experi- ment, he combined the two last. He cut the phrenic nerves to paralyse the diaphragm; and removed the abdominal muscles. Vomiting was no longer excited. From these different results, M. Magendie decided, that' vomiting takes place independently of the stomach; and, on the other hand, that it cannot occur without the agency of the diaphragm and abdominal muscles; and he concluded, that the stomach is almost passive in' the act;—that the diaphragm and abdominal muscles, especially the first, are the principal agents;—that air is constantly swallowed at the time of vomiting, to give the stomach the bulk which is necessary, in order that it may be compressed by those muscles; and lastly, that the dia- phragm and abdominal muscles are largely concerned in vomiting, as is indicated by their evident and powerful contractions, and by the fatigue felt in them afterwards. In corroboration of his view, M. Magendie refers to cases of scirrhous pylorus, in which there is constant vomiting, although a part of the tissue of the stomach has become of cartilaginous hardness, and, consequently, incapable of contraction. Clear as the results obtained by this practiced experimenter seem to be, they have been controverted; and attempted to be overthrown by similar experiments. Soon after the appearance of his memoir, M. Maingault1 laid before the Society of the FacultS de Medecine of Paris, a series of experiments, from which he deduced very different results. In all, vomiting was produced without the aid of the diaphragm and abdominal muscles. The vomiting was excited, by pinching a por- 1 Memoire sur le Vomissenient, Paris, 1813. t VOMITING. 633 tion of intestine, which acts more speedily than the injection of sub- stances into the veins. The abdomen of a dog was opened, and a ligature passed round a portion of intestine, which was returned into the abdo- men, and the wound closed by suture: vomiting took place. All the abdominal muscles were next extirpated,—the skin, alone, forming the parietes of the cavity. This was brought together, and the vomiting continued. On another dog, three-quarters of the diaphragm were paralysed by the section of the phrenic nerves. The abdomen was now opened, and a ligature placed round a portion of intestine. Vomit- ing occurred. Lastly;—these two experiments were united into one. The abdominal muscles were cut crucially, and removed; the phrenic nerves divided; and the diaphragm was cut away from its fleshy portion towards its tendinous centre; leaving only a portion as broad as the finger under the sternum. The integuments were not brought together; yet vomiting continued. As these results were obtained on numerous repetitions of the experi- ment, M. Maingault conceived himself justified in deducing inferences opposite to those of M. Magendie, namely,—that the contraction of the diaphragm and abdominal muscles is only accessory to the act of vomiting; that the action of the stomach is its principal cause;—that the latter is not a convulsive contraction, which strikes the eye, but a slow, antiperistaltic action ; and that the only convulsive movement is the contraction of the oesophagus, which drags the stomach upwards. He adduces, moreover, various considerations in favour of his deduc- tions. If the stomach, he asks, be passive, why does it possess nerves, vessels, and muscular fibres? WThy is vomiting more energetic, when the stomach is pinched nearer to its pyloric orifice? Why are the rugae of the mucous membrane of the stomach, during vomiting, directed in a divergent manner from the cardiac and pyloric orifices towards the middle portion of the organ ? If the diaphragm does all, why do we not vomit whenever that muscle contracts forcibly ? Why does not the diaphragm produce the discharge of urine in paralysis of the bladder? Why is vomiting not a voluntary phenomenon? And, lastly, how is it that it occurs in birds, which have no diaphragm ? The minds of physiologists were of course distracted by these conflict- ing results. M. Richerand1 embraced the views of M. Magendie; and affirmed, that he had never observed contraction of the stomach; and that it seemed to him the least contractile of any part of the intestinal canal. With regard to the experiments of M. Maingault, he con- sidered, that the stomach had not been wholly separated from the sur- rounding muscles; that the action of the pillars of the diaphragm, and the spasmodic constriction of the hypochondres are sufficient to com- press the viscus; that nothing-is more difficult to effect than the section of the phrenic nerves below their last root; and, moreover, such section does not entirely paralyse the diaphragm, as the muscle still receives twigs from the intercostal nerves and great sympathetic; that the car- if dia, being more expanded than the pylorus, the passage of substances / through it is rendered easy; and that it is incorrect to say, that the ' Nouveaux Elemens de Physiologie, 7eme edit, Paris, 1817. 634 DIGESTION. cardiac orifice, during inspiration, is closed between the 'pillars of the diaphragm. Again, to object that, according to the theory of M. Ma- gendie, vomiting ought to be a voluntary phenomenon, is a feeble argument; for it is admitted, that the muscles, which, at the time, compress the stomach, act convulsively. If the diaphragm, in paraly- sis of the bladder, cannot effect the excretion of the urine, it is because that reservoir is not favourably situate as regards the muscle; and, lastly, the arguments deduced from birds, that they are capable of vomiting, although they have no diaphragm, is equally insufficient, for it is not absolutely necessary that it should be a diaphragm, but any muscle that can compress the stomach. When the Memoir of M. Maingault was presented to the society of the Faculte de Medecine, M. Legallois and Professor Beclard were named reporters. The experiments were repeated before them by M. Maingault; but, instead of appearing contradictory to those of Ma- gendie, these gentlemen declared, that -they were not sufficiently mul- tiplied, nor sufficiently various, to lead to any positive conclusion. MM. Legallois and Beclard subsequently repeated and varied them; and instituted others, from which they deduced corollaries, entirely conformable to those of M. Magendie;1 and lastly, M. Begin2 boldly affirms, "without fear of being contradicted by facts, that there is no direct or authentic experiment, that demonstrates the activity of the stomach during vomiting:"—and he adds, "I have repeated the greater part of the experiments of Magendie; he has performed all in presence of a great number of spectators, of whom I was one; and I can say, with the commissioners of the Acade"mie des Sciences, that I have seen, examined, touched, and my conviction is full and entire." Still, many eminent physiologists have adhered to the idea, that the stomach is the main agent in vomiting ; and-among tnese was M. Broussais.3 He manifestly, however, confounded the phenomena of regurgitation with those of vomiting; which, we have endeavoured to show, are distinct. A case of wound of the left hypochondrium with escape of the sto- mach was described to the Academie Royale de MSdecine, by M. Le'pine, and reported upon by MM. Lagneau, Gimelle, and Be'rard,4 which confirms the views adopted by M. Magendie. During the whole of the period, that the stomach remained out of the abdominal cavity, there was no apparent contraction of the muscular fibres of the organ, and none of its contents were expelled, although the patient made violent efforts to vomit. As ■ soon, however, as the stomach had been returned into the abdomen, the efforts were followed by the expulsion of its contents. M. Le'pine confirms the observations of Magendie in another point. After each act of vomiting, the patient appeared to swallow air. "I observed him," says M. Le'pine, "execute repeated 1 Bulletin de la Faculte et de la Societe de Med, 1813, No. x, and OZuvres de Legallois, Paris, 1824. 2 Traite de Therapeutique, Paris, 1S25. 3 Traite de Physiologie, etc, Drs. Bell and La Roche's translation, p. 345, Philad, 1832. 4 Bulletin de l'Academie Royale de Medecine, 1844. See the cases cited in Philad. Med. Examiner, April 20, 1844, p. 92; also a case of Wound of Abdomen, in Amer. Journ. of the Med. Sciences, Oct, 1846, p. 379. I ABSORPTION. 635 acts of deglutition, each of which was accompanied by a noise, that seemed to be owing to the passing back of air." On the whole, we are, perhaps, justified in concluding, that the ancient doctrine regarding vomiting is full of error, and ought to be discarded; that the inverted action of the stomach, although not ener- getic, is necessary,—that the pressure, exerted on the parietes of the stomach by the diaphragm and abdominal muscles, is a powerful cause, —and that the more or less complete paralysis of the diaphragm, or destruction of the abdominal muscles, renders vomiting more feeble and more slow in manifesting itself. The deep inspiration preceding the act of vomiting, is terminated by the closure of the glottis: after this the diaphragm cannot move without expanding or compressing the air in the lungs. It, consequently, presents a resisting surface, against which the stomach may be pressed by the contracting abdominal mus- cles. The order of the phenomena seems to be as follows. The brain is affected directly or indirectly by the cause exciting vomiting;— through the brain and medulla, the glottis is closed, and the diaphragm and abdominal muscles are thrown into appropriate contraction, and press upon the stomach; this organ probably contracts from the pylorus towards the cardia; and, by the combination of efforts, the contents are propelled into the oesophagus, and out. of the mouth. These efforts are repeated several times in succession, and then cease, —to reappear at times. Whilst the rejected matters pass through the pharynx and mouth, the glottis closes; the velum palati rises and be- comes horizontal as in deglutition ; but owing to the convulsive action of the parts, these apertures are less accurately closed, and more or less of the vomited matter passes into the larynx or nasal fossae. On account of the suspension of respiration impeding the return of blood from the upper parts of the body, and partly owing to the force with which the blood is sent through the arteries, the face is flushed, or livid, the perspiration flows in abundance, and the secretion of tears is largely augmented. CHAPTER II. ABSORPTION. In the consideration of the preceding functions, we have seen the alimentary matter subjected to various actions and alterations; and at length, in the small intestine, possessed of the necessary physical con- stitution for the chyle to be separated from it. Into the mode in which this separation,—which we shall find is not simply a secerning action, but one of vital elaboration,—is effected, we have now to inquire. It constitutes the function of absorption, and its object is to convey the nutritive fluid, formed from the food, into the current of the circula- tion. Absorption is not, however, confined to the formation of this fluid. Liquids can pass into the blood directly through the coats of the containing vessel, without having been subjected to any elabora- tion; and the different constituents of the organs are constantly sub- 636 ABSORPTION. jected to the absorbing action of cells, by which their decomposition is effected, and their elements conveyed into the blood; whilst antago- nizing cells elaborate from the blood, and deposit fresh particles in the place of those that have been removed. These various substances, —bone, muscle, hair, nail, as the case may be,—are never found, in their compound state, in the blood; and the inference, consequently, is that at the very radicles of the absorbents and exhalants, the sub- stance on which absorption or exhalation has to be effected, is reduced to its constituents, and this by an action, to which we know nothing similar in physics or chemistry: hence, it has been inferred, that the operation is one of the acts-of vitality. All the various absorptions may be classed under two heads:—the external and the internal; the former including those that take place on extraneous matters from the surface of the body or its prolongation —the mucous membranes; and the latter, those that are effected inter- nally, on matters proceeding from the body itself, by the removal of parts already deposited. By some physiologists, the action of the air in respiration has been referred to the former of these; and the whole function of absorption has been defined;—the aggregate of actions, by which nutritive substances—^external and internal—are converted into fluids, which serve as the Jbasis of arterial blood. The function of respi- ration will be investigated separately. Our attention will, at pre- sent, be directed to the other varieties; and, first of all to that which occurs in the digestive tube. I. DIGESTIVE ABSORPTION. The absorption, effected in the organs of digestion, is of two kinds; according as it concerns liquids of a certain degree of tenuity, or solids. The former, it has been remarked, are subjected to no digestive action, but disappear chiefly from the stomach, and in part from the small intestine. The latter undergo conversion, before they are fitted to be taken up from the intestinal canal. a. Absorption of Chyle or Chylosis. 1. ANATOMY OF THE CHYLIFEROUS APPARATUS. In the lower animals, absorption is effected over the whole surface of the body, both as regards the materials necessary for nutrition and the supply of air. No distinct organs for the performance of these func- tions are perceptible. In the upper classes of animals, however, we find an apparatus, manifestly intended for the absorption of chyle, and constituting a vascular communication between the small intestine and left subclavian. Along this channel, the chyle passes, to be emptied into that venous trunk. The chyliferous apparatus consists of chyliferous vessels, mesenteric glands, and thoracic duct. The chyliferous vessels or lacteals, arise from the inner surface of the small intestine;—in the villi, which are at the surface of, and between, the valvulse conniventes. Prof. E. H. Weber1 has, however, seen them distributed in the interspaces between the 1 Miiller's Archiv, u. s. w, s. 400, Berlin, 1847. CHYLIFEROUS APPARATUS. 637 villi; the lacteals Fig. 249. and bloodvessels forming a close net- work; but he could not detect them in the parietes of the perceptible; and, accordingly, nature of arrangement given occasion much diversity of sentiment amongst anatomists. 'Lie- berkiihn1 affirms, Chyliferous Vessels. that, by the micro- scope, it may be shown that each villus terminates in an ampullula or oval vesicle, which has its apex perforated by lateral orifices, through which the chyle enters. The doctrine of open mouths of lacteals and lym- phatics was embraced by Hewson,2 Sheldon,3-Cruikshank,4 Hedwig,5 and Bleuland,6 and by some of the anatomists and physiologists of the present day;7 but, on the other hand, it has been contested by Mascagni,8 and others; whilst Rudolphi,9 Meckel,10 and numerous others11 believed, that the lacteals have not free orifices; but that in "the villi, in which ab- sorption is effected, a spongy or sort of gelatinous tissue exists, which accomplishes absorption, and, being continuous with the mouths of chyliferous vessels, conveys the product of absorption into them. Bichat conceived them to commence by a kind of sucker or absorbing mouth, the action of which he compared to that of the puncta lachry- malia or of a leech or cupping-glass; and lastly,—from the observation, often made, that different coloured fluids, with which the lymphatics have been injected, have never spread themselves, either into the areo- lar tissue, or the parenchyma of the viscera,—M. Mojon,12 of Genoa, affirmed, that lymphatics have no patulous orifice, and that they take 1 Dissert, de Fabric. Villor. Intest. passim. Lugd, Bat, 1745. 2 Experimental Inquiries; edited by Falconer, Lond, 1774, 1777, and 1780, or Hewson's Works, Sydenham Society's edit, p. 181, Lond, 1846. 3 The History ofthe Absorbent System, &c, p. I, Lond, 1784. 4 Anatomy ofthe Absorbing Vessels, 2d edit, Lond, 1790. 6 Disquisit. Ampull. Lieberkiihnii, Lips, 1797. 6 Exper. Anatom, 1784 j and Descript. Vasculor. in Intestinor Tenuium Tunicis, Ultraj, 1797. 7 See Henle, Allgemeine Anatomie, u. s. W. s. 569, Leipz, 1841. 8 Vasorum Lymphaticorum Corporis Humani Historia, &c, Senis, 1787; and Prodromo d'un Opera sul Sistemo de Vase Linfatice, Siena, 1784. » Anatomisch. Physiologisch. Abhandlung, Berlin, 1802. 10 Handbuch, u. s. w. translated by Jourdan and Breschet, p. 179, Paris, 1805. 11 F. Arnold, Lehrbuch der Physiologie des Menschen, Zurich, 1836-7; noticed in Erit. and For. Med. Rev, Oct, 1839, p. 479. 12 Journal de la Societe des Sciences Physiques, &c. Nov, 1833. 638 ABSORPTION. their origin from a cellular filament, which progressively becomes a villosity, an areolar spongiole, a capillary, and, at length, a lymphatic Fig. 250. Chyliferous Apparatus. A, A. A portion of the jejunum, b, b, b, b. Superficial lacteals. c, c, c. Mesentery d, d, d First row of mesenteric glands, e, e, e. Second row. /,/. Receptaculum chyli.' g. Thoracic duct. h. Aorta, i, i. Lymphatics. trunk;—the absorbent action of these vessels being a kind of imbibition. Lastly, Professor Miiller1 affirms, that he has never perceived any opening at the extremity of the villi: in his earlier examinations, he was unable to see appearances of foramina on any part of their sur- face, but he has observed, in portions of the intestines of the sheep and the ox, which had been exposed for some time to the action of water, that over the whole surface of the villi indistinct depressions were scattered, which might be regarded as oblique openings. He adds, however, that he makes this observation with great hesitation and distrust. 1 Handbuch der Physiologie, u. s. w,and Balys translation, p. 269, Lond, 1838. 93 CHYLIFEROUS APPARATUS. 639 Fig. 252. Section of Intestinal Villus. (Gerlach.) a. Artery, b. Vein. c. Lymphatic. — Magnified 250 diameters. . Intestinal Villus with the commencement of a Lacteal. (Krause.) All these are mere speculations, too often entirely gratuitous: and the view, that they never open by free orifices on the surface of the intestine, as was formerly imagined, is entirely in accordance with the results of modern histological inquiries. The marginal illustration, Fig. 252, from Krause exhibits the appear- ance presented by the incipient chyliferous vessels in the villi of the jejunum of a young man, who had been hanged soon after taking a full meal of fa- rinaceous food. The chylife- rous vessel issuing from each villus appeared to arise by seve- ral small branches, in some of which free extremities could be traced, whilst others anas- tomosed with each other. The arrangement of the different anatomical constituents is well seen in Fig. 251, which re- presents an injected intestinal villus of a cat, which was killed during digestion. When they become perceptible to the eye, they are observed\as in Fig. 249, communicating frequently with eachother; and forming a minute network, first between the muscular and mucous membranes, and after- wards between the muscular and peritoneal, until they terminate in larger trunks, a, a, a, a. When they attain the point at Avhich the peritoneal coat quits the intestine, they also leave it; creep for an inch or two in the substance of the mesentery; and enter a first row of mesenteric glands. From these they issue, of a greater size and in less number; proceed still farther along the mesentery, and reach a second row, into which they enter. From these, again, they issue, larger and less numerous; anastomosing with each other; and proceeding towards the lumbar portion of the spine, where they terminate in a common reservoir,—the reservoir of Pecquet, receptaculum seu cisterna chyli, (Figs. 250 and 253)—which is the commencement of the thoracic duct. This reservoir is situate about the third lumbar vertebra; behind the right pillar of the diaphragm, and the right renal vessels. The chy- liferous vessels generally follow the course of the arteries; but some- times proceed in the spaces between them. They exist in the lower part of the duodenum, throughout the whole of the jejunum, and in the upper part of the ileum. M. Voisin1 affirms, that all, or at least the major part, of them pass through the substance of the liver, before they empty their contents into the thoracic duct. After proceeding a certain distance, they anastomose, he says, with each other, enlarge in size, and are collected together so as to form a kind of plexus below the 1 Nouvel Apergu sur la Physiologie du Foie,&c, Paris, 1833. 640 ABSORPTION. lobe of Spigelius, towards which they converge. From this point, they penetrate the substance of the liver, through which they ramify with great minuteness, and finally empty themselves into the receptaculura chyli. To prove, that the chyliferous vessels do pass through the liver, he put a ligature around the duct below the diaphragm, in a dog which had eaten largely, and when digestion was in full activity. The chy- liferous vessels were observed to swell, and their whitish colour was distinctly perceived. They could be traced, without much difficulty, from the interior of the intestinal canal, through the mesenteric glands, as far as their entrance into the liver. The chyliferous vessels are composed of two coats; the outer of a fibrous and firm character; the inner very thin, epithelial, and^ gene- rally considered to form, by its duplicatures, valves. These are of a semilunar form, arranged in pairs, and with the convex side towards the intestine. Their arrangement has appeared to be well adapted for permitting the chyle to flow from the intestine to the thoracic duct, and for preventing its retrograde course; but M. Magendie1 affirms, that their existence is by no means constant. These reputed valves are considered by M. Mojon2 to be true sphincters. By placing the lymph- atic vessels on a glass plate, and opening them through their entire length, he observed by the microscope, that they are formed of circular fibres, which, by diminishing the size of the vessel at different points, give rise to the nodosities observed externally. If the ends of a varicose lymphatic be drawn in a contrary direction, these nodosities disappear, as well as the supposititious valves. Mojon observed, more- over, that the fibrous membrane of the lymphatics has longitudinal, as well as oblique, filaments passing from one narrow portion to another. The longitudinal fibres have their two extremities attached to the trans- verse fibres, which, according to him, constitute the sphincters or contractors of the lymphatics. He explains the difficulty often ex- perienced in attempting to inject the lymphatic vessels in a direction contrary to the course of the lymph, by the circumstance, that the little pouches formed by the sphincters, and the relaxation or disten- sion of their parietes on filling them with injected matter, diminish the calibre of the tube, and can even close it entirely. The smallest lacteals appear to be destitute of valves; but valves are perceptible in those of less than one-third of a line in diameter, and they have the same structure as those of the veins. The minute lacteals in the villi are said to consist of a single membrane with elongated cell-nuclei, corre- sponding to the longitudinal fibrous membrane of the veins, but not lined by epithelium. Some anatomists describe an external coat, formed of condensed areolar tissue, which unites the chyliferous vessels to the neighbouring parts. The mesenteric glands or ganglions are smalf, irregularly lenticular organs; varying in size from the sixth of an inch to an inch; nearly one hundred in number, and situate between the two laminae of the mesentery. In them, the lymphatic vessels of the abdomen termi- 1 Precis Elementaire, 2de edit, ii. 177, Paris, 1825. 2 Op. citat. and Amer. Journal, &c, for Aug. 1834, p. 465. CHYLIFEROUS APPARATUS. 641 nate; and the chyliferous vessels traverse them in their course from the intestine to the thoracic duct. Their substance is of a pale rosy colour; and their consistence moderate. By pressure, a transparent and inodorous fluid canbe forced from them; which has never been examined chemically. Anatomists differ with regard to their structure. According to some, they consist of a pellet of chyliferous ves- sels, folded a thousand times upon each other; subdividing and anastomosing almost ad infinitum; united by areolar tissue, and receiving a number of bloodvessels. In the opinion of others, again, cells exist in their interior, into which the afferent chy- liferous vessels open; and whence the effe- rent set out. These are filled with a milky fluid, carried thither by the lacteals or ex- haled by the bloodvessels. Notwithstand- ing the labours of Nuck,1 Hewson, Abei*- nethy, Mascagni, Cruikshank; Haller,2 Be'clard,3 and other distinguished anato- mists, the texture of these, as well as of the lymphatic glands or ganglions in general, is not demonstrated. The chyliferous and san- guiferous vessels become extremely minute in their substance; and the communication between the afferent and efferent vessels is very easy; as mercurial injections pass readily from the one to the other. Accord- 1. Arch of aorta. 2. Thoracic aorta, i 3. Abdominal aorta; showing its principal branches divided near their origin. 4. Arteria innominat'a, divided into right carotid and right subclavian arteries. 5. Left carotid. 6. Left subclavian. 7. Superior cava, formed by the union of 8, the two venae inno- minate; and these by the junction 9 of internal jugular and subclavian vein at each side. 10. Greater vena azygos. 11. Termination of the lesser in greater vena azygos. 12. Reeeptaculum chyli; seve- ral lymphatic trunks are seen opening into it. 13. Thoracic duct, dividing opposite middle of dorsal vertebra? into two branches which soon reunite ; course of duet behind arch of aorta and left subcla- vian artery is shown by a dotted line. 14. The duct making its turn at root of the neck and receiving several lymphatic trunks previously to terminating in posterior aspect of junction of internal jugular and subclavian vein. 15. Termination of trunk of ductus lymphaticus dexter. ing to Mr. Goodsir, the absorbent vessels within the chyliferous and lymphatic glands lay aside all but their internal coat; and the epi- thelium, instead of forming a thin lining of flat transparent scales, as in the extra-glandular lymphatics, acquires an opaque granular aspect, and is converted into a thick irregular layer of spherical nucleated corpuscles, measuring on an average j^jth part of an inch in dia- meter, so as to suggest the idea of lymph or chyle corpuscles generated on the internal membrane after the ordinary manner of epithelium cells, and about to be thrown off into the vessel. This layer, according to Mr. Goodsir, is thickest in those lymphatics that are situated towards 1 Adenologia, Lugd. Bat, 1696. 2 Element. Physiol, lib. ii. § 3, Lausar, 1757. 3 Addit. a Bichat, p. 128, Paris, 1821. VOL. I.—41 Fig. 253. Thoracic Duct. ABSORPTION. Fig. 254. Fig. 255. © ©3 ^ ee ^ Diagram of a lymphatic gland, showing the intra-glandular network, and the tran- sition from the scale-like epithelia of the extra-glandular lymphatics, to the nu- cleated cells of the intra-glandular. Portion of the intra-glandular lymphatic, showing along the lower edge the thick- ness of the germinal membrane, and upon it, the thick layer of glandular epithelial cells. the centre of the gland, becomes gradually thinner towards the afferent and efferent vessels, and passes continually into the ordinary epithe- lium. The thoracic duct, g, Fig. 250, and 13, Fig. 253, is formed by the junction of the chyliferous trunks with the lymphatic trunks from the lower extremities. The receptaculum chyli, already described, forms its commencement. After passing from under the diaphragm, the duct proceeds, in company with the aorta, along the right side of the. spine, until it reaches the fifth dorsal vertebra; where it crosses over to the left side behind the oesophagus. It then ascends behind the left carotid artery; runs up to the interstice between the first and second vertebrae of the chest; where, after receiving the lymphatics, which come from the left arm and left side of the head and neck, it suddenly turns down- wards, and terminates at the angle formed by the meeting of the sub- clavian and internal jugular veins of the left side. To observe the chyliferous apparatus to the greatest advantage, it should be examined in an individual recently executed, or killed sud- denly two or three hours after having eaten; or in, an animal, destroyed for the purpose of experiment, under similar circumstances. The lac- teals are then filled with chyle, and may be readily recognised, especially if the thoracic duct has been previously tied. These vessels were un- known to the ancients. The honour of their discovery is due to Gaspard Aselli,1 of Cremona, who, in 1622, at the solicitation of some friends, undertook the dissection of a living dog, which had just eaten, in order to demonstrate the recurrent nerves. On opening the abdomen, he perceived a multitude of white, very delicate filaments crossing the mesentery in all directions. At first, he took them to be nerves; but having accidentally cut one, he saw a quantity of a white liquor exude, analogous to cream. Aselli also noticed the valves, but he fell into an important error regarding the destination of the lacteals; believing them to collect in the pancreas, and from thence proceed to the liver. In 1628, the human lacteals were discovered. Gassendi2 had no sooner heard of the discovery of Aselli, than he spoke of it to his friend Nicholas-Claude-Fabrice de Peiresc, senator of Aix; who seems to have been a most zealous propagator of scientific knowledge. He immedi- 1 De Lactibus seu Lacteis Venis, &c, Mediol, 1627; also, in Collect. Oper. Spigelii, edit. Van der Linden; and in Manget. Theatr. Anatom. 2 Vita Peirescii, in Op. omnia, v. 300. CHYLE. 643 ately bought several copies of the work of Aselli, which had only ap- peared the year previously; and distributed them amongst his profes- sional friends. Many experiments were made upon animals, but the great desire of De Peiresc was, that the lacteals should be found in the human body. Through his interest, a malefactor, condemned to death, was given up, a short time before his execution, to the anatomists of Aix; who made him eat copiously; and, an hour and a half after execu- tion, opened the body, in which, to the great satisfaction of De Peiresc, the vessels of Aselli were perceived in the clearest manner. Afterwards, in 1634, John Wesling1 gave the first graphic representation of them as they exist in the human body; and subsequently pointed out more clearly than his predecessors the thoracic duct and lymphatics. Prior to the discovery of the chyliferous and lymphatic vessels, the veins, w7hich arise in immense numbers from the intestines, and, by their union with other veins, form the'vena porta, were esteemed the agents of absorp- tion; and, even at the present day, they are considered, by some physio- logists, to participate with the chyliferous vessels in the function;— with what propriety we shall inquire hereafter. 2. CHYLE. The chyle, as it circulates in the chyliferous vessels, has only been submitted to examination in comparatively recent times. It varies in different parts of its course. The best mode of obtaining it is to feed an animal; and, when digestion is in full progress, to strangle it, or divide the spinal marrow beneath the occiput. The thorax must then be opened through its whole length, and a ligature be passed round the aorta, oesophagus, and thoracic duct, as near the neck as possible. If the ribs of the left side be now turned back or broken, the thoracic duct is observed lying against the oesophagus. By detaching the upper part, and cutting into it, the chyle flows out. A small quantity only is thus obtained; but, if the intestinal canal and chyliferous vessels be repeatedly-pressed upon, the flow may be sometimes kept up for a quarter of an hour. It is obviously impossible, in this way, to obtain the chyle pure; inasmuch as the lymphatics, from various parts of the body, are constantly pouring their fluid into the thoracic duct. From the concurrent testimony of various experimenters, chyle is a liquid of a milky-white appearance; limpid and transparent in herbi- vorous animals, but opaque in the carnivorous; neither viscid nor glu- tinous to the touch; of a consistence, varying somewhat according to the nature of the food; a spermatic smell; sweet taste, not dependent on that of the food; neither acid nor alkaline; and of a specific gravity greater than distilled water, but less than the blood. Magendie,2 Tiede- mann and Gmelin,3 and Miiller,4 however, state it to possess a saline taste; to be clammy on the tongue; and sensibly alkaline. Its milky colour is generally supposed to be owing to oily matter which occurs in it in the form of globules of various sizes, from ^fo^th to a^^th of an inch in diameter, and which are more abundant in the chyle of man 1 Syntagm. Anatom, viii. 170. , 2 Precis, &c, ii. 172. 3 Die Verdauung nach Versuchen, i. 353, Heidelb, 1826 ; or French translation, by Jourdan, Paris, 1827. * Elements of Physiology, by Baly, p. 258, London, 18J8. 644 ABSORPTION. and of the carnivora, than in that of the herbivora. Mr. Gulliver1 has, however, affirmed, that the colour is due to an immense multitude of minute particles, which he regards as forming the matrix or molecular base of the chyle. These are generally spherical and extremely small,— their diameter being estimated at from ^g^th to ^^h of an inch. They are of a fatty nature, and their number appears to be dependent upon the amount of fatty matter in the food. Their fatty nature is shown by their solubility in ether, and, when the ether evaporates, by their forming drops of oil. As, however, they do not run together, it has been suggested, that each molecule consists of oil coated with albu- men, a view which is supported by the fact, that when water or dilute acetic acid is added to chyle, many of the molecules are lost sight of, and oil drops appear in their place; as if the envelopes of the mole- cules had been dissolved, and their oily contents had run together.2 The chemical character of the chyle of animals has been examined by Emmert,3 Vauquelin,4 Marcet,' Prout,6 Simon,7 and Nasse ;8 and is found to resemble greatly that of the blood. In a few minutes after its removal from the thoracic duct it becomes solid ; and, after a time, separates, like the blood, into two parts; a coagulum, and a liquid. The coagulum is an opaque white substance ; of a slightly pink hue; insoluble in water ; but readily soluble in the alkalies, and alkaline car- bonates. M. Vauquelin regards it as fibrin in an imperfect state, or as intermediate between that principle and albumen ; but M. Brande9 thinks it more closely allied to the caseous matter of milk than to fibrin. The analyses of Drs. Marcet and Prout agree, for the most part, with that of M. Vauquelin. The existence of fibrin in it can scarcely be doubted. Like blood, again, chyle often remains for a long time in its vessels without coagulating, but coagulates rapidly on being removed from them.10 Dr. Prout has detailed the changes, which the chyle experiences in its passage along the chyliferous apparatus. In each successive stage, its resemblance to blood was found to be increased. Another point of analogy with blood is the fact, observed by Mr. Bauer,"and subsequently by MM. PreVost and Dumas,12 and others, that the chyle, when examined by the microscope, contains globules ; differing from those of the blood in their being of a smaller size, the average being ^g^th 0I* an incn> and devoid of colouring matter* The nature and source of these glob- ules, as well as of those of the lymph which resemble them in all respects, is not determined. They have been supposed to be the nuclei or pri- mordial cells from which all the tissues originate,13 and to be the source of the blood globule. 1 Gerber's General Anatomy, by Gulliver, Appendix, p. 88, London, 1842. 2 Kirkes and Paget, Manual of Physiology, Amer. edit, p. 207, Philad, 1849. 3 Annales de Chimie, torn. lxxx. p. 81. 4 Ibid, lxxx. 113; and Annals of Philosophy, ii. 220. 5 Medico-Chirurg. Transactions, vol. vi. 618, London, 1815. 6 Thomson's Annals of Philosophy, xiii. 121, and 263. 7 Animal Chemistry, Sydenham Soc. edit, p. 354, London, 1845, or Amer. edit, Philad, 1846. « Wagner's Handworterbuch, u. s. w, i.235, art. Chyle ; and Simon, op. cit. 9 Phil. Transact, for 1812. >° Bouisson, Gazette Medicale de Paris, 1844. 11 SirE. Home, op. cit, iii. 25. 12 Biblioth. Universelle de Geneve, p. 221, Juillet, 182*. 13 Gulliver, in Gerber's Anatomy, p. 83, note. CHYLE. 645 Although chyle has essentially the same constituents, whatever may be the food taken, and separates equally into a clot and serous portion, the character ofthe aliment may have an effect upon the relative quan- tity of those constituents, and thus exert an influence on its compo- sition. That it scarcely ever contains adventitious substances will be seen hereafter ; but it is obvious, that if an animal be fed on diet con- trary to its nature, the due proportion of perfect chyle may not be formed; and that, in the same way, different alimentary articles may be very differently adapted for its formation. MM. Leuret and Las- saigne,1 indeed, affirm, that in their experiments they found the chyle differ more according to the nature of the food than to the animal spe- cies; but that, contrary to their expectation, the quantity of fibrin in it bore no relation to the more or less nitrogenized character of the ali- ment. They assign it, as constituents, fibrin, albumen, fatty matter, soda, chloride of sodium, and phosphate of lime. Messrs. Tiedemann and Gmelin have communicated the following data in regard to the influence of diet on the "ehyle. The experiments were made on dogs, and the chyle was taken from the thoracic duct. First. After taking, cheese, the chyle coagulated slightly. The clot was little more than a pale red transparent film, and the serum slightly milky. It contained water, 950*3 ; clot, 1*71 : residue of serum, 48*0. Secondly. After the use of starch, the chyle was of a pale yellowish- white colour, and coagulated rapidly. It contained water 930*0 ; clot and residue of serum, 70*0. The clot was of pale red colour. Thirdly. After taking flesh, and bread and milk, it was of a reddish-white colour, and coagulated rapidly, the clot being of a pale red tint, and the serum very milky. It consisted of water, 915*3 ; clot, 2*7 ; residue of serum, 83*8. Fourthly. After the use dfmilk it presented a milky appearance, and the clot was transparent, and of a pale red colour. Fifthly. After oread and milk, it contained water, 961*1; clot 1*9 ; residue of serum, 37*0! Sixthly. After flesh, bread, and milk, it was of a yellowish red colour; coagulated firmly, separating into a bright red clot, and turbid yel- lowserum; and contained water, 933*5; clot, 5*6; residue of serum, 60*9.2 The chief object of Dr. Marcet's experiments was to compare the chyle from vegetable, with that from animal food, in the same animal. The experiments made on dogs led him to the following results. The specific gravity of the serous portion is from 1*012 to 1*021, whether it be formed from animal or vegetable diet. Vegetable chyle, when sub- jected to analysis, furnishes three times more carbon than animal chyle. The latter is highly disposed to become putrid ; and this change generally commences in three or four days ; whilst vegetable chyle may be kept for several weeks, and even months, without being putrid.3 Putrefaction attacks rather the coagulum of the chyle than its serous portion. The chyle from animal food is always milky ; and, if kept at rest, an unctuous matter separates from it, similar to cream, which swims on the surface. The coagulum is opaque, and has a rosy tint. On the 1 Recherches sur la Digestion, Paris, 1825. 2 Simon, op. cit, p. 358. 3 M. Thenard has properly remarked, that the difference in the time of putrefaction of these two substances, appears very extraordinary. It is. indeed, inexplicable. Traite de Chimie Elementaire, &c, 5emeedit, Paris, 1827. 646 ABSORPTION. other hand, chyle from vegetable food is almost always transparent, or nearly so, like ordinary serum. Its coagulum is nearly colourless, and resembles an oyster; and its surface is not covered with the substance analogous to cream. M. Magendie,1 too, remarks, that the proportion of the three substances, into which chyle separates when left at rest ;— namely, the fatty substance on the surface, the clot, and the serum, varies greatly according to the nature of the food;—that the chyle, proceeding from sugar, for example, has very little fibrin; whilst that from flesh has more; and that the fatty matter is extremely abundant when the food contains fat or oil; whilst scarcely any is found if the food contains no oleaginous matter. Lastly:—the attention of Dr. Prout2 has been directed to the same comparison. He found, on the whole, less difference between the two kinds of chyle than had been noticed by Dr. Marcet. In his experiments, the serum of chyle was ren- dered turbid by heat, and a few flakes of albumen were deposited ; but, when boiled, after admixture with acetic acid, a copious precipitation ensued. To this substance, which thus differs slightly from albumen, Dr. Prout gave the inexpressive name of incipient albumen. The fol- lowing is a comparative analysis, by him, of the chyle of two dogs, one of which was fed on animal, and the other on vegetable substances. The quantity of pure albumen, it will be observed, was much less in the latter case. Vegetable Food. Animal Food. Water ........936 89-2 Fibrin ,........ 0-6 0-8 Incipient albumen ...... 4'6 4*7 Albumen, with a red colouring matter . . . 0-4 4-6 Sugar of milk ....... a trace. Oily matter ........ a trace. a trace. Saline matters....... 0-8 0-7 100-0 100-0 ' The difference between the chyle from food of such opposite cha- racter, as indicated by these experiments, is insignificant, and indicative of the great uniformity in the action of the agents of absorption. Researches by Messrs. Macaire and Marcet,3 tend, indeed, to establish the fact, that both the chyle and the blood of herbivorous and carnivo- rous quadrupeds are identical'in their composition, in as far, at least, as regards their ultimate analysis. They found the same proportion of nitrogen in it, whatever kind of food the animal consumed habitually; and this was the case with the blood, whether of the carnivora or herb- ivora ; but it contained more nitrogen than the chyle. These results are not so singular, now that we know that the animal and vegetable compounds of protein are almost identical in composition. (See page 545.) All the investigations into the nature of the chyle exhibit the inac- curacy of the view of Boose,4 that chyle and milk are identical. 1 Op. citat, p. 174. 2 Annals of Philosophy, xiii. 22, and Bridgewater Treatise, Amer. edit, p. 272, Philad, 1834. 3 Memoir, de la Societe de Physique et de l'Histoire Naturelle de Geneve, v. 389. * Weber's Hildebrandt's Handbuch der Anatomie, i. 102, Braunschweig, 1830. CHYLOSIS. 647 With regard to the precise quantity of chyle, formed after a meal, we know nothing definite. When digestion is not going on, there can of course be none formed except from the digestion of the secretions of the digestive tube itself; and, after an abstinence of twenty-four hours, the contents of the thoracic duct are chiefly lymph. During digestion, the quantity of chyle formed will bear some relation to the amount of food taken, the nutritive qualities of the food, and the digestive powers of the individual. M. Magendie,1 from an experiment made on a dog, estimated, that at least half an ounce was conveyed into the mass of blood, in that animal, in five minutes: and the flow was kept up, but much more slowly, as long as the formation of chyle continued. In experiments on a cat, Professor F. Bidder2 found the amount that passed through the thoracic duct in the twenty-four hours, to be in proportion to the weight of the body as 1 to 5*34; or about that which—as else- where shown—the mass of blood has been generally conceived to bear to the weight of the body. In dogs, the proportion was as 1 to Q-Q6. It is difficult, however, to establish an average amount where so many elements have to enter into the calculation and so much variation must occur, according to the greater or less amount of aliment taken and numerous other circumstances;3 but that so large a quantity passes as is stated by these observers, almost exceeds belief. 3. PHYSIOLOGY OF CHYLOSIS. The facts referred to,—regarding the anatomical arrangement of the chyliferous radicles and mesenteric glands,—will sufficiently account for the obscurity of our views on many points of chylosis. The diffi- culty in detecting the extremities of the chyliferous radicles has been the source of different hypotheses; and, according as the view of open mouths or of spongy gelatinous tissue has been embraced, the chyle has been supposed to enter immediately into the vessels, or to be received through the medium of this tissue; or, again, to pass through the parietes of the vessels by imbibition. Let it be borne in mind, how- ever, that the action of absorption is seen only by the "mind's eye;" and that chyle does not seem to exist any where but in the chyliferous vessels. In the small intestine, we see a chymous mass, possessing all the properties we have described, but containing nothing resembling true chyle; whilst, in the smallest lacteal that can be detected, it always possesses the same essential properties. Between this impercep- tible portion of the vessel, theri, and its commencement,—including the latter,—the elaboration must have been effected. MM. Leuret and Lassaigne,4 indeed, affirm, that they have detected chyle in the chymous mass within the intestine, by the aid of the microscope. They state, that globules appeared in it similar to those that are contained in chyle, and that their dissemination amongst so many foreign matters alone prevents their union in perceptible fibrils. These globules they regard 1 Op. citat, ii. 183. 2 Muller's Archiv. fur Anat, s. 46, Berlin, 1845. 3 Prof. Th. L. W. Bischoff, Muller's Archiv, s. 125, Berlin, 1846. * Recherches Physiologiques et Chimiques, pour servir a l'Histoire de la Digestion, p. 60, Paris, 1825. 648 ABSORPTION. as true chyle,—for the reason, that they observed similar globules in artificial digestions; and, on the other hand, never detected them in the digestive secretions. In their view, consequently, chyliferous absorption is confined to the separation of chyle, ready formed in the intestine, from the excrementitious matters united with it. But we must have stronger evidence to set aside the overwhelming testimony in favour of an action of selection and elaboration by the absorbents of all organ- ized bodies—vegetable as well as animal. The nutriment of the vege- table may exist in the soil and the air around it; but it is subjected to a vital agency the moment it is laid hold of, and is decomposed to be again combined to form sap. A like action is doubtless exerted by the chyliferous radicles;1 and hence all the modes of explaining this part of the function, under the supposition of their being passive, mechanical tubes, are inadequate. Boerhaave2 affirmed, that the peristaltic motion of the intestines has a considerable influence in forcing chyle into the mouths ofthe chyliferous vessels; whilst Dr. Young3 is disposed to ascribe the whole effect to capillary attraction; and he cites the lachry- mal duct as an analogous case, the contents of which, he conceives,— and we think with propriety,—are entirely propelled in this manner. The objections to these views, as regards the chyliferous vessels, are sufficiently obvious. The chyle must, according to them, exist in the intestines; and, if that of Boerhaave were correct, we ought to be able to obtain it from the chyme by pressure. As the chyle is not present, ready formed, in the intestine, the explanations by imbibition and by capillary attraction are equally inadmissible. There is no analogy between the cases of the lachrymal duct and the chyliferous vessels; even if it were admitted, that the latter have open mouths, which is not the case. In another part of this work, it was affirmed, that the passage of the tears through the puneta lachrymalia, and along the lachrymal ducts, is one of the few cases in which capillary attrac- tion can be invoked, with propriety, for the explanation of functions executed by the human frame. In that case there is no conversion of the fluid. It is the same on the conjunctiva as in the duct; but, in the ease of the chyliferous vessels, a new fluid is formed: there must, therefore, have been an action of selection exerted; and this very action would be the means of the entrance of the new fluid into the mouths of the lacteals. If, therefore, we admit, in any form, the doctrine of capillary tubes, it can only be, when taken in conjunction with that of the elaborating agency. "As far as we are able to judge," says Dr. Bostock,4 "when particles, possessed of the same physical properties, are presented to their mouths (the lacteals), some are taken up, while others are rejected; and if this be the case, we must con- ceive, in the first place* that a specific attraction exists between the vessel and the particles, and that a certain vital action must, at the same time, be exercised by the vessel connected with, or depending 1 F. Arnold, Lehrbuch der Physiologie des Menschen, Zurich, 1836-7; noticed in Brit.and For. Med. Review, Oct, 1839, p. 479. 2 Praelect. Academ. in Prop. Instit. Rei Med, § 103. 3 Medical Literature, p. 42, Lond, IS 13. 4 Physiology, edit, cit, 622, Lond, 1836. CHYLOSIS. 649 upon, its contractile power, which may enable the particles to be received within the vessel, after they have been directed towards it. This contractile power may be presumed to consist in an alternation of contraction and relaxation, such as is supposed to belong to all vessels that are intended for the propulsion of fluids, and which the absorbents would seem to possess in an eminent degree." This is specious; but it would be not the less hypothetical if the chyliferous vessels had open mouths, and we have seen they have not. By other physiologists, absorption is presumed to be effected by virtue of the peculiar sensibility or insensible organic contractility or irritability of the mouths [?] of the absorbents; but these terms, as M. Magendie1 has remarked, are the mere expression of our ignorance, regarding the nature of the phenomenon. The separation of the chyle is, doubtless, a chemical process; seeing that there must be both an action of decomposition and recomposition; but it is not regulated solely by the same laws as those that govern inorganic chemistry. Professor Goodsir,2 with almost all modern physiologists, has referred the function to the agency of cells. Having fed a dog with oatmeal, butter, and milk, he examined the intestinal villi three hours after- wards; when the chyliferous vessels were turgid with chyle, and the intestine was full of milky chyme mingled with a bilious-looking fluid. In the white portion of the fluid, which was situate principally towards the mucous membrane, numerous epithelium cells were found; some of which had evidently—from their form—been detached from the surface ofthe villi; whilst others have been thrown off from the inte- rior of the follicles of Lieberkiihn. The villi were turgid, and destitute of epithelium except at their bases. Each villus was covered by a very fine, smooth membrane, continuous with what Mr. Bowman terms the "basement membrane" of the mncous surface, which is reflected into the follicles. The villi were semitransparent except at their free or bulbous extremities, where they were white and nearly opaque. The summit of each villus was crowded beneath the enveloping mem- brane with a number of perfectly spherical vesicles, varying in size from To*oo~th to 53 (Jo^1 of an inch; the matter in the interior of which had an opalescent milky appearance. At the part where the vesicles approached the granular texture of the substance of the villus, minute granular or oily particles were situate in great numbers. The trunks of two lacteals could be easily traced up the centre of each villus; and as they approached the vesicular mass, they subdivided and looped; but in no instance could they be seen to communicate directly with any of the vesicles. These vesicles, in Mr. Goodsir's opinion, can scarcely be considered in any other light than cells, whose lives have but a very brief duration, which select from, and appropriate the ma- terials in contact with the surface of the villi into their own substance, and then liberate them, by solution or disruption of the cell-wall, in a situation where they can be absorbed by the lacteals. When the in- testine contains no more chyme, the_ developement of new vesicles 1 Precis, &c, ii. 179. 3 Edinb. New Philosophical Journal, July, 1842; and Anatomical and Pathological Ob- servations, p. 4, Edinb , 1845. 650 ABSORPTION. ceases; the lacteals empty themselves, and the villi become flaccid. During the interval of repose, the epithelium is renewed for the protec- tion of the surface of the villi, and for the secretion function of the follicles of Lieberkiihn. It is considered by Mr. Goodsir, that the epithelium cells have their origin in certain nuclei, which he has de- tected scattered through the basement membrane. These views were embraced by Dr. Carpenter; but they are by no means established. It is denied, indeed, by Reichert,1 from his own and Bidder's observations, that the epithelium is ever so shed from the diges- tive canal, in or after any act of digestion, as to leave any portion of the subjacent mucous membrane uncovered or raw; and Prof. E. H. Weber2 distinctly observed the chyliferous vessels filled with chyle, although the mucous membrane was covered with epithelium. The materials of the chyle, therefore, to enter the vessels must have passed through the epithelium. During absorption, he noticed the prismatic cells of the cylinder epithelium experiencing change of form and colour, and in rabbits and frogs becoming tumid, and containing chyle cor- puscles. In man, beneath the epithelium is a second layer of cells, which are neither conical, cylindrical, nor prismatic, but round; many of which are filled with an opaque white ; and others with a transparent, oleaginous fluid; so that different cells appeared to absorb different fluids. It has already been said, that chyle always possesses the same essential properties; that it may vary slightly according to the food, and the digestive powers of the individual; but rarely if ever contains any adventitious substance,—the function of the chyliferous vessels being restricted to the formation of chyle. The facts and arguments, in favour of this view of the subject, will be given hereafter. The course of the chyle is, as we have described, along the chylife- rous vessels, and through the mesenteric glands into the receptaculum chyli or commencement of the thoracic duct; along which it passes into the subclavian vein. The chief causes of its progression are,—first of all, the inappreciable action, by which the chyliferous vessels form and receive the chyle into them. This formation being continuous, the fresh portions must propel those already in the vessels towards the mesenteric glands, in the same way as the ascent of sap in plants, during the spring, appears to depend on the constant absorbing action of the roots.3 It is probable, too, that the vessels themselves are con- tractile:4 such is the opinion of Messrs. Sheldon,5 Schneider, Cruik- shank,6 and J. Miiller. M. Mandl7 affirms, that it can no longer be doubted; and that the irritability continues even for several hours after death. M. Mojon8 considers, that when the longitudinal fibres, which he has observed in the lymphatics, contract, they draw one sphincter nearer to another, whilst the oblique fibres diminish the diameter. All * Muller"s Archiv, 1844. 2 Ibid, s. 401, Berlin, 1847. 3 Breschet, Le Systeme Lymphatique, Paris, 1836. 4 Miiller's Handbuch, u. s. w., and Baly's translation, i. 284, Lond, 1838. 5 History of the Absorbent System, p. 28, Lond . 1784. « Op. citat, c. 12. 7 Manuel d'Anatomie generate, p. 211, Paris, 1S43. 8 Journ. de la Societe des Sciences Physiques, etc, Nov, 1833. CHYLOSIS. 651 these fibres, taking their point d'appui in the circular fibres, dilate the superior sphincters by drawing the circumference downwards. By this method, the fluid that enters a lymphatic irritates the vessel, which contracts upon itself, diminishes its cavity, and sends on the fluid through the open sphincter. A kind of peristaltic action, he conceives, —and in this view he is confirmed by MM. Lacauchie,1 Gruby, and Delafond,2—exists in the lymphatics similar to that of the intestines, which may be observed very distinctly, he says, in the lacteal vessels of the mesentery of animals, if opened two or three hours after they have been well fed. Moreover, that the lacteals and lymphatics are possessed of a power of contraction is corroborated—it is argued—by the following reasons. First. They are small; and tonic contractions are generally admitted in all capillary vessels. Secondly. The ganglions or glands, which cut them at intervals, would destroy the impulse given by the first action of the radicles; and hence require some contraction in the vessels to transport the chyle from one row of these ganglions to another. Thirdly. If a chyliferous vessel be opened in a living animal, the chyle spirts out, which could not be effected .simply by the absorbent action of the chyliferous radicles; and, Fourthly, in a state of abstinence, these ves- sels are found empty; proving, that notwithstanding there has been an interruption to the action of chylous absorption, the whole of the chyle has been propelled into the receptaculum chyli. It is obvious, however, that most of these reasons would apply as well to the elasticity as to the muscularity of the outer coat of these vessels.3 A more forcible argument is derived from an experiment by Lauth.4 He killed a dog towards the termination of digestion; and immediately opened its abdo- men, when he found the intestines marbled, and the chyliferous vessels filled with chyle. Under the stimulation of the air, the vessels began to contract, and, in a few minutes, were no longer perceptible. The result he found to be the same, whenever the dissection was made within twenty-four hours after death; but, at the end of this time, the irrita- bility of the vessels was extinct; and they remained distended with chyle, notwithstanding the admission of air. These experiments lead to a deduction, in the absence of less direct proof, scarcely doubtful;— that the chyliferous vessels possess a contractile action, by the aid of which the" chyle is propelled along the vessels. In addition to these propelling causes, the pulsation of the arteries in the neighbourhood of the vessels, and the pressure of the abdominal muscles in respiration have been invoked. The former has probably less effect than the latter. It is not, indeed, easy to see how it can be possessed of any. Of the agency of the latter we have experimental evidence. If the thoracic duct be exposed in the neck of a living animal, and the course of the chyle be observed, it will be found accelerated at the time of inspira- tion, when the depressed diaphragm forces down the viscera, or when the abdomen of the animal is compressed by the hands. We shall find, too, hereafter, that the mode in which the thoracic duct opens into the ■ Comptes Rendus, 15 Mai, 1843. 2 Ibid, 5 Juin, 1843. 3 Adelon, Physiologie, etc, iii. 31. 4 Essai sur les Vaisseaux Lymphat, Strasb, 1824. 652 ABSORPTION. subclavian exerts considerable effect on the progress of the chyle. We have reason to believe that its course is slow. It has been already stated, that in an experiment on a dog, which had eaten animal food at discretion, M. Magendie1 found half an ounce of chyle discharged from an opening in the thoracic duct in five minutes. Still, as he judiciously remarks, the velocity will be partly dependent upon the quantity of chyle formed. If much enters the thoracic duct, it will probably pro- ceed faster than under opposite circumstances. In the commencement of the thoracic duct it becomes mixed with lymph; and under the head of lymphatic absorption we shall show how they proceed together into the subclavian, and the effect produced by the circumstances under which the thoracic duct opens into that venous trunk. It has been a subject of inquiry, whether chyle varies materially in different parts of its course ; and what is the precise modification, impressed upon it by the action of the mesenteric glands. The experi- ments of Reuss, Emmert,2 and others, seem to show, that when taken from the intestinal side of the glands it is of a yellowish-white colour; does not become red on exposure to the air, and coagulates but imper- fectly, depositing only a small, yellowish pellicle. It is said, indeed, that chyle, drawn from the chyliferous vessels, which traverse the intes- tinal walls, contains albumen in a state of solution, but no fibrin, and abounds in oleaginous matter; whilst that from the other side of the glands, and near the thoracic duct, is of a reddish hue : contains chyle globules, coagulates entirely, and separates into a clot and serum. M. Vauquelin,3 too, affirms, that it acquires a rosy tint as it advances in the apparatus ; and that the fibrin becomes gradually more abundant. These circumstances have given rise to the belief, that as it proceeds it becomes more and more animalized, or transformed into the nature of the being. This effect has generally been ascribed to the mesenteric glands; and it has been presumed by some to be produced by the exha- lation of a fluid into their cells from the numerous bloodvessels with which they are furnished. Others, again, consider, that the veins of the glands remove from the chyle every thing that is noxious ; or purify it. From the circumstance, that the rosy colour is more marked on the thoracic, than on the intestinal side of the glands ; that the fluid is richer in fibrin after having passed through those glands; and that the rosy colour and fibrin are less when the animal has taken a large proportion of food, MM. Tiedemann and Gmelin4 infer, that it is to the action of the glands, that the chyle owes those important changes in its nature;—the fluid, in its passage through them, obtaining, from the blood circulating in them, new elements, which animalize it. There is much probability in the view, that some nitrogenized mate- rial is secreted from the lining membrane of the chyliferous vessels, in the mesenteric glands especially, through the agency of the nucleated cells described by Professor Goodsir, which may be a great agent in the changes effected on the chyle in its course. At the same time—as 1 Precis, &c, ii. 183. 2 Reil's Archiv, viii. s. 2; and Annales de Chimie, lxxx. 81. 3 Annales de Chimie, Ixxxi. 113 ; and Annals of Philosophy, ii. 220. * Die Verdauung nach Versuchen, u. s. w, or Jourdan's translat, Paris, 1827. CHYLOSIS. 653 has been well observed1—an important source of fallacy attends all deduc- tions founded upon the differences observed in the chyle in the several parts of its course through the lacteals,—which is, that we cannot be at all sure how far this may not be dependent upon an actual interchange of ingredients with the blood, by imbibition through the very thin parietes of the contiguous vessels. The whole question, as Dr. Carpen- ter properly remarks, offers a wide scope for farther inquiry. The following table, slightly modified from one by Gerber,2 exhibits concisely the relative proportions of the three main ingredients of the chyle—fat, albumen, and fibrin—in various parts of the absorbent sys- tem ; and affords some idea of its change in the process of assimilation. f Fat in maximum quantity (numerous fat or oil glob- I. In the afferent or peripheral lac- I ules). teals (from the intestines to the ■{ Albumen in minimum quantity (few or no chyle cor- mesenteric glands). | puscles). [ Fibrin almost entirely wanting. II. In the, efferent or central lacteals f F* in medium T™1^ (fe^er °il globules). (from the mesenteric glands to the J Mbm>im m ™aximum fanuty W« corpuscles very , ■ . .x i numerous, but imperfectly developed). thoracic duct). -,., . . ,. * . ■* r ' J ( tiorin in medium quantity. f Fat in minimum quantity (fewer or no oil globules). III. In the thoracic duct. J Albumm inA rnediu™ ^'"ity (c/h/fe corpuscles nume- j rous and more distinctly cellular). [_ Fibrin in maximum quantity. In another place, various hypotheses, that have been indulged re- garding the functions of the spleen, will be noticed. It is proper, how- ever, to refer, here, to one which has been proposed by MM. Tiede- mann and Gmelin. They consider the organ a dependent ganglion of the absorbent system, which prepares a fluid destined to be mixed with the chyle to effect its animalization; and assert, that the chyle coagu- lates little or not at all before it has passed through the mesenteric glands ; but, after this, fibrin begins to appear, and is much more abund- ant after the addition of the lymph from the spleen, which contains a large quantity of fibrin. Before passing the mesenteric glands, the chyle contains no red particles; but it does so immediately afterwards, and more particularly after it is mixed with the lymph from the spleen, which abounds with them, and with fibrin. M. Voisin,3 who, as we have seen, considers that the chyliferous vessels ramify in the substance of the liver, is of opinion that, by the action of the liver, a species of puri- fication is produced in the chyle, by which the latter is better fitted to mingle with, and form part of, the blood ; but neither his anatomical nor physiological views on the subject have met with much countenance. Prior to the discovery of the chyliferous vessels, the mesenteric veins were regarded as agents of chylous absorption ; and as these veins ter- minate in the vena portse, which is distributed to the liver, this last was considered the first organ of sanguification ; and to impress upon the chyle a primary elaboration. In this view, the great size of the organ compared with the small quantity of bile furnished by it, and the excep- tion which the mesenteric veins and vena portse present to the rest of 1 Carpenter, Human Physiology, 2d Amer. edit, p. 426, Philad, 1845. 2 Ibid, p. 4 27. 3 Nouvel Apercu sur la Physiologie du Foie, &c, Paris, 1833. 654 ABSORPTION. the venous system,—as well as the large size of the liver in the foetus, although not effecting any biliary secretion, and the fact of its receiv- ing immediately the nutritive fluid from the placenta were accounted for. The idea of the agency of the mesenteric veins is now nearly exploded, but not altogether so. There are yet physiologists, and of no little eminence, who esteem them participators in the functions of chylosis with the chyliferous vessels themselves. Some of the arguments, based on fallacious data, used by these gen- tlemen, are:—First. The mesenteric veins form as much an integrant part of the villi of the intestine as the chyliferous vessels; and they have also, free orifices [?] in the cavity of the intestine. Lieberkiihn,1 by throwing an injection into the vena portae, observed the fluid ooze out of the villi of the intestine; and M. Ribes2 obtained the same result by injecting spirit of turpentine coloured black. These experiments— it need hardly be said—are insufficient to establish the fact of open mouths. Situate, as those vessels are, in an extremely loose tissue, which affords them but little support, the slightest injecting force might be expected to rupture them. Secondly. Chyle has often been found in the mesenteric veins. Swammerdam asserts, that, having placed a ligature around these veins in a living animal, whilst digestion was going on, he saw whitish, chylous strise in their blood; and Tiedemann and Gmelin affirm, that they have often, in their experiments, observed the same appearance. If the fact of the identity of these striae with chyle were well established, we should have to bend to the weight of evidence. This is not, however, the case. No other reason for the belief is afforded than their colour. The arguments against the me- senteric veins having the power of forming chyle we think irresistible. A distinct apparatus exists, which scarcely ever contains any thing but chyle; and consequently, it would seem unnecessary, that the mesenteric veins should participate in the function, especially as the fluid which circulates in them is most heterogeneous; and, as we shall see, a compound of various adventitious and other absorptions. Grant- ing, however, that these strise are true chyle, it would by no means fol- low absolutely, that it should be formed by the mesenteric veins. A com- munication may exist between the chyliferous vessels and these veins. Wallaeus3 asserts, that having placed a ligature on the lymphatic trunks of the intestine, chyle passed into the vena portae. Rosen, Meckel,4 and Lobstein affirm, that by the use of injections they detected this inosculation. Lippi5 states, that the chyliferous vessels have numerous anastomoses with the veins, not only in their course along the mesentery before they enter the mesenteric glands, but also in the glands them- selves. Tiedemann and Gmelin concur in the existence of this last anastomosis, and MM. Leuret and Lassaigne found that a ligature ap- plied round the vena portae occasioned the reflux of blood into the tho- 1 Dissert, de Fabric. Villor. Intestin, Lugd. Bat, 1745. 2 Memoir, de la Societe Medicale d'Emulation, viii. 621. 3 Medica Omnia, &c, ad Chyli et Sanguinis Circul, Lond, 1660. * Diss. Epist. ad Haller. de Vasis Lymph, &c, Berol, 1757; Nov. Exper. de Finibus Ve- narum et Vas. Lymph, Berol, 1772; and Manuel d'Anatomie, &c, French edit, by Jourdan i. 179. 5 Illustrazioni Fisiologiche e Patologiche del Sistema Linfatico-Chilifero, Firenze, 1825. CHYLOSIS. 655 racic duct. Professors Meckel, E. H. Weber, Rudolphi, and J. Miiller doubt, however, the existence of an actual open communication between the lymphatics and minute veins in the glands. Meckel states, as a reason for his questioning this, that when the seminal duct of the epi- didymis of the dog is injected, the veins also are filled; and Miiller1 observes, that when glands are injected from their excretory duct, the small veins of the gland also frequently become filled with mercury; and the cases in which this occurred to him were always those in which the ducts had not been well filled,—their acini not distended. Thirdly. That the ligature of the thoracic duct has not always induced death, or has not induced it speedily; and, consequently, the thoracic duct is not the only route by which the chyle can pass to be inservient to nu- trition. In an experiment of this kind by M. Duverney, the dog did not die for fifteen days. M. Flandrin repeated it on twelve horses, which appeared to eat as usual, and to maintain their flesh. On killing and opening them a fortnight afterwards, he satisfied himself that the thoracic duct was not double. Sir Astley Cooper performed the expe- riment on several dogs: the majority lived longer than a fortnight, and none died in the first two days; although, on dissection, the duct was found ruptured, and chyle effused into the abdomen. The experiments of M. Dupuytren have satisfactorily accounted for these different re- sults. He tied the thoracic duct in several horses. Some died in five or six days, whilst others continued apparently in perfect health. In those that died in consequence of the ligature, it was impossible to throw any injection from the lower part of the duct into the subclavian. It was, therefore, presumable, that the chyle had ceased to be poured into the ,blood, immediately after the duct was tied. On the other hand, in those that remained apparently unaffected, it was always easy to send mercurial or other injections from the abdominal portion of the duct into the subclavian. The injections followed the duct until near the ligature, when they turned off, and entered large lymphatic vessels, which opened into the subclavian; so that, in these cases, the ligature of the thoracic duct did not prevent the chyle from passing into the venous system; and thus we can understand why the animals should not have perished.2 From every consideration, then, it appears that the chyliferous ves- sels are the sole organs concerned in chylosis; and we shall see pre- sently, that they refuse the admission of other substances, which must, consequently, reach the circulation through a different channel. The views of MM. Bouchardat and Sandras—who believe, that the absorption of the nutritive portion of most aliments takes place in the stomach,__fatty matters only being absorbed by these vessels, and that they moreover absorb a fluid of an alkaline character designed to neu- tralize the acidity developed in the stomach during digestion, as well as those of Matteucci and Bertrand in regard to the absorption of the same substances, have been given already. 1 Handbuch, u. s. w.; and Baly's translation, p. 273, Lond, 1838. 2 Richerand's Elemens de Physiologie, edit, cit, p. 90. 656 ABSORPTION. b. Absorption of Drinks. It has been stated, that a wide distinction exists between the gastric and intestinal operations that are necessary in the case of solid and liquid food. Whilst the former is converted into chyme and passes into the small intestine, to have its chylous part separated from it; the latter is usually absorbed from the stomach or small intestine. The chyliferous vessels; we have seen, are agents and exclusive agents of the absorption of chyle—the nutritive product from the digestion of solids. What, then, are the agents of the absorption of liquids ? There are but two sets of vessels on which we can rest for a moment. These are the lacteals or lymphatics of the digestive tube; and the veins of the same canal. But, it has been seen, the chyliferous vessels refuse the admission of everything but chyle. It would necessarily follow, then, that the absorption of liquids must be a function of the veins. Such is the conclusion of most physiologists, and on inferences that are logical. The view is not, however, universally admitted; some assign- ing the function exclusively to the lacteals; others sharing it between them and the veins. Let us inquire into the facts and arguments ad- duced in support of these different opinions. The advocates for the exclusive agency of the chyliferous vessels affirm, First, That whatever is the vascular system, that effects the absorption of drinks, it must com- municate freely with the cavity of the intestine; and that the chyliferous vessels do this. Secondly, That this system of vessels is the agent of chylous absorption:—a presumption, that it is likewise the agent of the absorption of drinks. Thirdly, That every physiologist, who has ex- amined the chyle, has described its consistence to be in an inverse ratio with the quantity of drink taken; and, lastly, that when coloured and odorous substances have passed into the intestine, they have been found in the chyliferous vessels and not in the mesenteric veins. The experi- ments, adduced in favour of this last position are, however, so few and inadequate, that it is surprising they could have, for a time, so com- pletely overturned the old theory. This effect was greatly aided by the zeal and ability of the Hunters, and of the Windmill Street School in general, who were the great improvers of our knowledge regarding the anatomy of the lymphatic system. John Hunter,1—who was one of the first that positively denied absorption by the veins, and maintained that of the lymphatics,—instituted the following ingenious and imposing experi- ment. He opened the abdomen of a living dog; laid hold of a portion of intestine, and pressed out the matters it contained with his hand. He then injected warm milk into it, which he retained by means of liga- tures. The veins, belonging to the portion of intestine, were emptied of their blood by puncturing their trunks; and were prevented from receiving fresh blood, by the application of ligatures to the correspond- ing arteries. The intestine was returned into the cavity of the abdo- men ; and, in the course of half an hour, was again withdrawn and scrupulously examined; the veins were still found empty, whilst the 1 Observations on certain parts of the Animal Economy, by John Hunter, F. R. S. with notes by Richard Owen, F.R.S, Bell's Library edit, p. 307, Philad, 1840. OF DRINKS. 657 chyliferous vessels were full of a white fluid. Mr. Hunter subsequently repeated the experiment with odorous and coloured substances, but without being able to detect them in the mesenteric veins. It may be remarked, also, that Musgrave,1 Lister,2 Blumenbach,3 Seiler and Fici- nus assert,4 that they have detected substances, which had been thrown into the intestines of animals, in the chyle of the thoracic duct. The experiments of Hunter, however, are those, on which the supporters of this, view of the question principally rely. Physiologists, who believe in the absorption of liquids by the mesen- teric veins, adduce similar arguments and much more numerous experi- ments. They affirm, that the mesenteric veins, like the chyliferous vessels, form constituent portions of. the villi;—that if the chyliferous system is manifestly an absorbent apparatus, the same may be said of the venous system;—that if the chyle has appeared more fluid after much drink has been taken, the blood of the mesenteric veins was seen by Boerhaave to be more fluid under like circumstances; and, lastly, against the experiments of Hunter, numerous others have been cited, showing clearly, that liquids, injected into the intestine, have been found in the.mesenteric veins, whilst they could not be detected in the chyliferous vessels. To the first experiment of Hunter it has been objected;—that in his time the art of performing physiological experiments was imperfect; and that, in order to deduce useful inferences from it, we ought to know, whether the animal was fasting, or digestion was going on at the time it was opened; that the lymphatics ought to have been ex- amined at the commencement of the experiment, to see whether they were full of chyle, or empty; as well as the milk, to notice whether it had experienced any change during its stay in the intestine; and lastly, that the reasons ought to have been assigned for the belief, that the lacteals were filled with milk at the end of the experiment, and not with chyle. Moreover, the experiment has been repeated several times by MM. Flandrin and Magendie,5—careful and accurate ob- servers,—yet, in no case, was the milk found in the chyliferous vessels. The first experiment of Hunter cannot, therefore, be looked upon as satisfactory. Some source of fallacy must have occurred, otherwise a repetition of the experiment should have been attended with like re- sults. We shall find, hereafter, that in another experiment, by that distinguished individual, a source of illusion existed, of which he was not unaware, that was sufficient to account for the appearance he noticed. The experiments of Hunter with odorous and coloured substances have been repeated by many physiologists, and found even less con- clusive than that with the milk. M. Flandrin, who was professor in the Veterinary School at Alfort, in France, thought that he could detect, in horses, an herbaceous odor of the blood of the mesenteric veins, but not of the chyle. He gave a horse a mixture of half a pound of honey, and the same quantity of asafcetida; and, whilst the smell of the latter 1 Philosoph. Transact, for 1701, p. 996. 3 Institut. Physiol, § 422. 5 Precis, &c, edit, citat, ii. 201. VOL. I.—42 2 Philosoph. Transact, 1701, p. 819. * Journal Complement, xviii. 327. 658 ABSORPTION. was distinctly perceptible in the venous blood of the stomach and intestine, no trace of it existed in arterial blood and chyle. Sir Everard Home1 having administered tincture of rhubarb to an animal, round whose thoracic duct he had placed a ligature, found the rhubarb in the bile and urine. M. Magendie gave to dogs, whilst digesting, a quantity of alcohol diluted with water; and solutions of camphor, and other odorous fluids: on examining the chyle, half an hour afterwards, he could not detect any of those substances; but the blood of the mesen- teric veins exhaled the odour, and afforded the substances by distilla- tion. He gave to a dog four ounces of a decoction of rhubarb; and, to another, six ounces of a solution of prussiate of potassa in water. Half an hour afterwards, no trace of these substances could be detected in the fluid of the thoracic duct; whilst they could be in the urine. On another dog, he tied the thoracic duct, and gave it two ounces of a decoction of nux vomica. Death occurred as speedily as in an animal in which the thoracic duct was pervious. The result was the same, when the decoction was thrown into the rectum, where no proper chy- liferous vessels exist. Having tied the pylorus in dogs, and conveyed fluids into their stomachs, absorption equally took place, and with the same results. Lastly, with M. Delille,2 he performed the following experiment on a dog, which had eaten a considerable quantity of meat, in order that the chyliferous vessels might be easily perceived. An incision was made through the abdominal parietes ; and a portion of the small intestine drawn out, on which two ligatures were applied at a short distance from each other. The lymphatics, which arose from this portion of the intestine, were very white, and apparent from the chyle that distended them. Two ligatures were placed around each of them; and they were divided between the ligatures. Every precaution was taken, that the portion of intestine drawn out of the abdomen should have no connexion with the rest of the body by lymphatics. Five mesenteric ar- teries and veins communicated with this portion ofthe intestine. Four of the arteries and as many veins were tied, and cut in the same manner as the lymphatics. The two extremities of the portion of intestine were now divided, and separated entirely from the rest. A portion, an inch and a half long, thus remained attached to the body by a mesenteric artery and vein only. These two vessels were separated from each other by a distance of four fingers' breadth; and the areolar coat was removed to obviate the objection, that lymphatics might exist in it. Two ounces of a decoction of nux vomica were now injected into this portion of intestine, and a ligature was applied to prevent the exit of the injected liquid. The intestine, surrounded by fine linen, was replaced in the abdomen ; and, in six minutes, the effects of the poison were manifested with their ordinary intensity:—every thing occurred as if the intestine had been in its natural condition. M. Segalas3 per- formed a similar experiment, leaving the intestine, however, communi- cating with the rest of the body by chyliforous vessels only. On inject- ing a solution of half a drachm of alcoholic extract of nux vomica into the intestine; the poisoning, which, in the experiment of M. Magendie, 1 Lectures on Comparative Anatomy, i. 221, Lond, 1814. 2 Precis, &c, ii. 203. 3 Magendie's Journal de Physiologie, torn. ii.; and Precis, &c, ii. 208. OF DRINKS. 659 took effect in six minutes, had not occurred at the expiration of half an hour; but when one of the veins was untied and the circulation re- established, it supervened immediately. Westrumb1 mixed rhubarb, turpentine, indigo, prussiate of potassa, and acetate of lead with the food of rabbits, sheep, and dogs. They were detected in the veins of the intestines and in the urine, but not in the chyle. The same facts were observed by Mayer2 when rhubarb, saffron, and prussiate of potassa were introduced into the stomach. MM. Tiedemann and Gmelin like- wise observed that the absorption of different colouring and odorous substances from the intestinal canal was effected exclusively by the veins. Indigo, madder, rhubarb, cochineal, litmus, alkanet, camboge, verdigris, musk, camphor, alcohol, spirits of turpentine, Dippel's animal oil, asafoetida, garlic, the salts of lead, mercury, iron, and baryta, were found in the venous blood, but never in the chyle. The prussiate of potassa and sulphate of potassa were the only substances, which, in their experiments, had entered the chyliferous vessels. Such are the chief facts and considerations on which the believers in the chyliferous absorption and venous absorption of drinks rest their respective opinions. The strength is manifestly with the latter. Let it be borne in mind, that no sufficient experiments have been made, to encourage the idea, that any thing is contained in the chyliferous ves- sels except chyle; and that nearly all are in favour of absorption by the mesenteric veins. An exception to this, as regards the chyliferous and lymphatic vessels, seems to exist in the case of certain salts. The prussiate and the sulphate of potassa—we have said—were detected in the thoracic duct by MM. Tiedemann and Gmelin ; the sulphate of iron and the prussiate of potassa were found there by Messrs. Harlan, Law- rence, and Coates3 of Philadelphia; and the last of these salts by Dr. Macneven of New York. " I triturated," says Dr. Macneven,4 " one drachm of crystallized hydrocyanate of potassa with fresh butter and crumbs of bread, which being made into a bolus the same dog swallowed and retained. Between three and four hours afterwards, Dr. Anderson bled him largely from the jugular vein. A dose of hydrocyanic acid was then administered, of which he died without pain, and the abdomen was laid open. The lacteals and thoracic duct were seen well filled with milk-white chyle. On scratching the receptaculum, and pressing down op the duct, nearly half a teaspoonful of chyle was collected. Into this were let fall a couple of drops of the solution of permuriate of iron, and a deep blue was the immediate consequence." Professor J. Muller5 placed a frog with its posterior extremities in a solution of prussiate of potassa, which reached nearly as high as the anus, and kept it so_ for two hours. He then carefully washed the animal, and having wiped the legs dry tested the lymph taken from under the skin with a persalt of iron * it immediately assumed a bright blue colour, while that of the serum of the blood was scarcely affected by the test. In a second 1 De Phamomenis, quae ad Vias sic dictas Lotii clandestinas referuntur, Gotting, 1819. 2 Meckel's Archiv, Band. iii. 3 Philad. Journ. of Med. and Phys. Sciences, vol. n.; and Harlans Medical and Physical Researches, p. 458, Philad, 1835. 4 New York Med. and Phys. Journ, June, 18i2. 6 Handbuch der Physiologie, u. s. w. Baly's translation, p. 279, Lond, 1838. 660 ABSORPTION. experiment, in which the frog was kept only one hour in the solution, the salt could not be detected in the lymph. These exceptions are strikingly corroborative of the rule. Of the various salts employed, only those mentioned appear to have been detected in the chyle of the thoracic duct. It is, therefore, legitimately presumable, that _ they entered adventitiously, and probably by simple mechanical imbibition: —the mode in which venous absorption seems to be effected. The property of imbibition, possessed by animal tissues, has already been the subject of remark (page 65). It was then shown, that they are not all equally penetrable; and that different fluids possess different penetrative powers. This view is confirmed by the experiments of MM. Tiedemann and Gmelin on the subject under discussion. Although various substances were placed in the same part of the intestinal canal, they were not all detected in the blood of the same vessels. Indigo and rhubarb, for example, were found in the blood of the vena portae. Camphor, musk, spirit of wine, spirit of turpentine, oil of Dippel, asafoetida, garlic, not in the blood of the intestines, but in that of the spleen and mesentery; prussiates of iron, lead, and potassa in that of the veins of the mesentery; those of potassa, iron, and baryta in that of the spleen ; prussiate of potassa, and sulphates of potassa, iron, lead, and baryta in that of the vena portae as well as in the urine; whilst madder and camboge were found in the latter fluid only. Experiments by MM. Flandin and Danger1 confirm the general rule of the absorption of poisons from the digestive canal by the branches of the vena portae, and the diversity of locality in which they are met with. Their latest examinations were made on the absorption of the salts of lead, which they detected in the digestive tube, liver, spleen, kidneys, and lungs, but not in the blood, heart, brain, muscles, or bones. The evidence in favour of the action of the chyliferous vessels being restricted to the absorption of chyle, whilst the intestinal veins take up other matters, is not, however, considered by some to be as incon- clusive as it is by us. M. Adelon,2 for example, concludes, that, as the sectators, on both sides, employ absolutely the same arguments, we are compelled to admit, that the two vascular systems are under exactly similar conditions; and both, consequently, participate in the function. We have seen, that whatever may be the similarity of argu- ments, the facts are certainly not equal.3 It, is proper, however, to remark, that chemical analysts experience great difficulty in detecting inorganic substances when these are mixed with certain of the com- pounds of organization; and this may account for such substances not having been discovered in the thoracic duct, even when present there. With regard to the mode in which the absorption of fluids is effected, a difference of opinion has existed, and chiefly as regards the question, —whether, as in the case of the chyle, any vital elaboration be con- cerned, or whether the fluid, when it attains the interior of the vessel, be the same as without. The arguments in favour of these different 1 Gazette Medicale. 3 Fevr, 1844. 2 Physiologie de l'Homme, edit. cit.. iii. 111. 3 Bostock's Physiol, 3d edit, p. 607, Lond, 1836. OF DRINKS. 661 views will be detailed under the head of Venous Absorption. We may merely observe, at present, that water,—the chief constituent of all drinks,—is an essential component of every circulating fluid;—that we have no evidence that any action of elaboration is exerted upon it: and that the ingenious and satisfactory experiments of Prof. J. K. Mitchell,1 of Philadelphia, have shown, that it penetrates most, if not all, animal tissues better than any other liquid; and, consequently, passes through them to accumulate in any of its own solutions. It is probably in this way,—that is, by imbibition,—that all venous absorp- tions are effected. But it has been said:—if fluids pass so readily through the coats of the veins,—by reason of the extensive mucous surface, with which they come in contact, a large quantity of extraneous and heterogeneous fluid must enter the abdominal venous system when we drink freely, and the composition of the blood be consequently modified; and, if it should arrive, in this condition, at the heart, the most serious conse- quences might result. It has, indeed, been affirmed by a distinguished member of the profession2 in this country, in a more ingenious than forcible argument to support a long-cherished—but now almost univer- sally abandoned—hypothesis, that " it must at least be acknowledged, that no substance, in its active state, does reach the circulation, since it is shown, that a small portion even of the mildest fluid, as milk or mucilage, oil or pus, cannot be injected into the bloodvessels without occasioning the most fatal consequences." But the effects are here greatly dependent on the mode in which the injection is made. If a scruple of bile be sent forcibly into the crural vein, the animal gene- rally perishes in a few moments. The same occurs, if a quantity of atmospheric air be rapidly introduced into a venous trunk. The ani- mal, according to Sir Charles Bell,3 dies in an instant, when a very little air is blown in;—and there is no suffering nor struggle, nor any stage of transition, so immediately does the stillness of death take pos- session of every part of the frame. In this way, according to Beau- chene, Larrey, Dupuytren, Warren of Boston, Mott and Stevens of New York, Delpech, and others, operations at times prove fatal;—the air being drawn in by the divided veins. If, however, the scruple of bile, or the same quantity of atmospheric air be injected into one of the branches of the vena portae, no apparent inconvenience is sustained. M. Magendie4 concludes, from this fact, that the bile and atmospheric air, in their passage through the myriads of small vessels into which the vena portae divides and subdivides in the substance of the liver, become thoroughly mixed with the blood, and thus arrive at the vital organs in a condition to be unproductive of mischief. This view is rendered the more probable by the fact, that if the same quantity of bile or of air be injected very slowly into the crural vein, no perceptible incon- venience is sustained. Dr. Blundell5 injected in this manner five drachms into the femoral vein of a very small dog, with only tempo- 1 American Journal of the Medical Sciences, vii. 44, 58. 2 Chapman, Elements of Therapeutics, 6th edit, p. 47, Philad, 1831. 3 Animal Mechanics, P. ii. p. 42, London, 1829. * Precis Elementaire, 2de edit, ii. 433. 6 MedicoChirurg. Trans, for 1818, p. 65. 662 ABSORPTION. rary inconvenience; and, subsequently, three drachms of expired air, without much temporary disturbance; and M. Lepelletier1 affirms, that in the amphitheatre of the Ecole Pratique of Paris, in the presence of upwards of two hundred students, he injected thrice into the femoral vein of a dog, of middle size, at a minute's interval, three cubic inches of air, without observing any other effect than struggling^ whining, and rapid movements of deglutition; and these phenomena existed only whilst the injection was going on. Since that he has often repeated the experiment with identical results,—"proving," he observes, "that the deadly action of the air is, in such case, mechanical, and it is pos- sible to prevent the fatal effects by injecting it so gradually, that the blood has power to disseminate, and perhaps.even to dissolve it with sufficient promptitude to prevent its accumulation in the cardiac cavi- ties." From the experiments of Mr. Erichsen, however, the cause of death in such cases, would appear to be asphyxia. As liquids are frequently passed off by the urinary organs soon after they have been swallowed, it has been believed by some,—either that there are vessels which form a direct communication between the sto- mach and bladder; or that a transudation takes place through the parietes of the stomach and intestine, and that the fluids proceed through the intermediate areolar tissue to the bladder. Both these views, we shall hereafter show, are devoid of foundation. In animals, in which the cutis vera is exposed, or the cuticle very thin, nutritive absorption is effected through that envelope. In the polypi, medusae, radiaria, and vermes, absorption is active, and accord- ing to Zeder and Rudolphi,2 entozoa, that live in the midst of animal humours, imbibe them through the skin. A few years ago, Jacobson3 instituted experiments on the absorbing power of the helix of the vine (Limagon des vignes). A solution of prussiate of potassa was poured over the body. This was rapidly absorbed, and entered the mass of blood in such quantity, that the animal acquired a deep blue colour when sulphate of iron was thrown upon it. In the frog, toad, sala- mander, &c, cutaneous absorption is so considerable, that occasionally the weight of water, taken in this way, is equal to that of the whole body. We shall see, hereafter, that the nutrition of the foetus in utero is mainly, perhaps, accomplished by nutritive absorption effected through the cutaneous envelope. II. ABSORPTION OF LYMPH OR LYMPHOSIS. This function is effected by agents, that strongly resemble those con- cerned in^the absorption of chyle. One part of the vascular apparatus is, indeed', common to both,—the thoracic duct. We are much less acquainted, however, with the physiology of lymphatic, than of chy- liferous, absorption. 1 Physiologie Medicale et Philosophique, i. 494, Paris, 1831. 2 Entozoorum Histor, i. 252, 275, Berlin, 1829. ' 3 Memoir, de 1'Acad. des Sciences de Berlin, 1825, and Tiedemann, Traite Complet de Physiologie de l'Homme, edit. Fr,p. 242, Paris, 1831. OF DRINKS. 663 1. ANATOMY OF THE LYMPHATIC APPARATUS. The lymphatic apparatus consists of lymphatic vessels, lymphatic glands or ganglia, and thoracic duct. The latter, however, does not form the medium of communication between all the lymphatic vessels and the venous system. 1. Lymphatic vessels.—These vessels exist in almost all parts of the body; and have the shape of cylindrical, transparent, membranous tubes, of small size, anastomosing freely with each other, so as to present, everywhere, a reticular arrangement. They are never, accord- ing to Professor Miiller, so small as the arterial and venous capillaries, and are, almost without exception, visible to the naked eye. G. R. Treviranus asserts, that their walls, like the areolar membrane and other tissues, are made up of minute elementary cylinders, of a diame- ter of from 0*001 to 0*006 millimetres, Fig. 256. 664 ABSORPTION. Fig. 257. branch, its size is sensibly diminished; and when a vein receives a branch, it is enlarged ; but when a lymphatic ramifies, there is generally little change of size, whether the branch given off be large or small. The lymphatics consist of two planes,—the one superficial, the other deep-seated. The former creep under the outer covering of the organ, or of the skin, and accompany the subcutaneous veins. The latter are seated more deeply in the interstices of the muscles, or even in the tissue of parts; and accompany the nerves and great vessels. These planes anastomose with each other. This arrangement occurs not only in the limbs, but the trunk, and in every viscus. In the trunk, the superficial plane is seated beneath the skin; and the deep-seated between the muscles and the serous membrane that lines the splanchnic cavities. In the viscera, one plane occupies the surface; the other appears to arise from the parenchyma. The two great trunks of the lymphatic system, in which the lym- phatic vessels of the various parts of the body terminate, are the tho- racic duct, and the great lymphatic trunk of the right side. The course of the thoracic duct has been described already. It is formed of three great vessels;—one, in which all the lymphatics and lacteals of the intestines terminate; and the other two, formed by the union of the lymphatics of the lower half of the body. Occasionally, the duct consists of several trunks, which unite into one before reaching the sub- clavian vein; but more fre- quently it is double. In ad- dition to the lymphatics of the lower half of the body, the thoracic duct receives a great part of those of the thorax, and all those from the left half of the upper part of the body. At its termination -in the sub- clavian, there is a valve so dis- posed as to allow the lymph to pass into the blood; and to prevent the reflux of the blood into the duct. We shall see, however, that its mode of ter- mination in the venous system possesses other advantages. The great lymphatic trunk of the right side is formed by the absorbents from that side of the head and neck, and from the right arm. It is very short, being little more than an inch, and sometimes not a quarter of an inch, in length,—but of a diameter nearly as great as . the thoracic duct. A valve the lymphatics from the genitals, abdomen, and external, 1^ „•„. , ..-, ,, „ portion of the thigh. also exists at the mouth of Lymphatic Vessels and Glands of the Groin of the Right Side. 1. Saphena magna vein. 2. Veins on the surface of abdomen. 3. External pudic vein. 4. Lymphatic ves- sels collected in fasciculi and accompanying the saphena vein on its inner side. 5. External trunks of the same set of vessels. 6. Lymphatic gland which receives all these vessels. It is placed on the termination of the sa- phena vein. 7. Efferent trunks from this gland; they become deep-seated and accompany the femoral artery. 8. One of the more external lymphatic glands of the groin. 9. A chain of four or five inguinal glands, which receive LYMPHOSIS. 665 this trunk, which has a similar arrangement and office with that of the left side. The lymphatics have been asserted to be more numerous than the veins; by some, indeed, the proportion has been estimated at fourteen superficial lymphatics to one superficial vein; whence it has been de- duced, that the capacity of the lymphatic is greater than that of the venous system. This must be mere matter of conjecture. The same may be said of the speculations that have been indulged regarding the mode in which the lymphatic radicles arise,—whether by open mouths or by some spongy mediate body. The remarks made regarding the chylous radicles apply with equal force to the lymphatic. It has been a matter of some interest to determine, whether the lymphatic vessels have other communications with the venous system than by the two trunks just described; or, whether, soon after their origin, they do not open into the neighbouring veins,—an opinion held by many of those, who believe in the doctrine of absorption by the lymphatics exclusively, to explain why absorbed matters are found in the veins. Several of the older, as well as more modern, anatomists, have professed this opinion; whilst it has been strenuously combated by Sommering, Rudolphi,1 and others. Vieussens affirmed, that, by means of injections, lymphatic vessels were distinctly seen originating from the minute arteries, and terminating in small veins. Sir William Bli- zard2 asserts, that he twice observed lymphatics terminating directly in the iliac veins. Mr. Bracy Clarke3 found that the trunk of the lymphatic system of the horse had several openings into the lumbar veins. M. Ribes,4 by injecting the supra-hepatic veins, saw the substance of the injection enter the superficial lymphatics of the liver. M. Alard5 considers that the lymphatic and venous systems communicate at their origins. Vincent Fohmann6 thinks, that the lymphatic vessels com- municate directly with the veins, not only in the capillaries, but in the interior of the lymphatic glands. Lauth,7 of Strasburg,—who went to Heidelberg to learn from Fohmann his plan of injecting,—announced the same facts in 1824. By this anatomical arrangement, Lauth ex- plains how an injection, sent into the arteries, reaches the lymphatics, without being effused into the areolar tissue; the injection passing from the arteries into the veins, and thence, by a retrograde route, into the lymphatics. M. Beclard believed, that this communication exists at least in the interior of the lymphatic glands; and he supported his opinion by the fact, that in birds, in which these glands are wanting, and are replaced by plexuses, the lymphatic vessels in the plexuses are distinctly seen opening into the veins. Lippi8 has made these communications the 1 Grundriss der Physiologie, u. s. w, 2ter Band, 2te Abtheilung, s. 247, Berlin. 1828. 2 Physiological Observations on the Absorbent System of Vessels, Lond, 1787. a Rees's Cyclopedia, art. Anatomy, Veterinary. " Magendie, Precis, etc, ii; 238. 5 Du Sie°e et de la Nature des Maladies, ou nouvelles considerations touchant la veritable action du Systeme Absorbant, etc, Paris, 1821. TT.,„ ,„„., , ta o e Ueber die Verbindung der Saugadern mit den Venen, Heidelb, 1821, und Das bauga- dersystem der Wirbelthiere, Heft 1, Heidelb, 1824; and Mem. sur les communications des vaisseaux lymphatiques avec les veines, Liege, 1832. 7 Essai sur les Vaisseaux Lymphatiques, Strasbourg, 1824. 8 Illustrazioni Fisiologiche, etc, Firenz, 1825. 666 ABSORPTION. subject of an express work. According to him, the most numerous exist between the lymphatic vessels of the abdomen, and the vena cava inferior and its branches. So numerous are they, that every vein re- ceives a lymphatic vessel, and the sum of all would be sufficient to form several thoracic ducts. Opposite the second and third lumbar vertebrae, the lymphatic vessels are manifestly divided into two orders:—some ascending, and emptying themselves into the thoracic duct; others descending and opening into the renal vessels and pelves of the kid- neys. Lippi admits the same arrangement, as regards the chyliferous vessels; and he adopts it to explain the prompt- Fig. 258. itude with which drinks are evacuated by the urine. Subsequent researches have not, in general, confirmed the statements of Lippi. G. Rossi,1 indeed, maintains, that the vessels, which Lippi took for lymphatics, were veins. It would ap- pear, however, that when Rossi was in Paris, he was unable to demonstrate, when requested to do so by M. Breschet, the very things, that he had previously figured and described. Panizza, too, affirms, that no direct union or continuity be- tween the venous capillaries and lymphatics has ever been made manifest to the eye, either in the human subject or the lower animals:2 and,on the whole, the observations of Lippi as to the alleged termination of lymphatics in various veins of the abdomen have generally been either rejected as erroneous or held to refer to deviations from the normal condition.3 It is proper to remark, however, that, recently, Dr. A. Nuhn,4 Prosector at Heidelberg, has main- tained, that there is a regular communication between the abdominal lymphatics and veins, and describes three cases of the kind which fell under his own observation. In two of these the lymphatics opened into the renal veins; in the third into the vena cava. The article contains a good history of the views of different observ- ers on the communication between the ab- sorbents and veins. We are perhaps justified in concluding with a, a, a, a. Afferent and effe- Panizza, that anatomy has not hitherto suc- S^S^SSSoSteduSrM. ?eedved in de the and silica ) extractive matters Oxide of iron - Loss - Reuss and Emmert. Gmelin. 1. Gmelin. 1 II. iassaigne. Rees. 960-0 961-0 967-70 925-00 96536 3-0 2-5 1-30 3-30 1-20; 27-5 14-85 12-00 ' 2-1 2-58 57-36 1319 39 6 6-9 9-69 240 00 traces a trace 14-34 585 a trace Nasse. 950-00 3911 3-25 1 63, 0-09 5-61 0S1 0-4 A comparative analysis of the chyle and lymph of the ass has been made by Dr. G. 0. Rees.3 The fluids were obtained from the chyli- ferous and lymphatic vessels seven hours after a full meal, previous to their entrance into the thoracic duct. Water ...... Albuminous matter .... Fibrinous matter - - - - - Animal extractive matter, soluble in water and alcohol Animal extractive matter, soluble in water only Fatty matter ..... Salts:—alkaline chloride, sulphate, and carbonate, with traces of alkaline phosphate and oxide of iron Chyle. Lymph. 90-237 96-536 3-516 1-200 0-370 0-120 0-332 0-240 1-233 1-319 3-601 a trace. 0-711 0585 100-000 100-000 The chyle—it will be observed—contains a larger proportion of de- cidedly organizable matters. Dr. Rees4 examined the contents of the thoracic duct of a human subject, procured an hour and a quarter after death by hanging. They amounted to six drachms, and yielded the following results:— Water Albumen, with traces of fibrinous matter .... Aqueous extractive (zomodine) ..... Alcoholic extractive (osmazome) - Alkaline chloride, carbonate, and sulphate, with traces of phosphate, and oxide of iron Fatty matters 90-48 7-08 0-56 0-52 0-44 092 100-00 1 Simon's Animal Chemistry, Sydenham Soc. edit, p. 353, Lond, 1845, or Amer. edit, * Wagner's Handworterbuch der Physiologie, 9te Lieferung, s. 396, Braunschweig, 1845. 3 Lond. Med. Gazette, Jan, 1841. * Proceedings of the Royal Society, Feb. 10, 1842. 672 ABSORPTION. Chyle and lymph strikingly therefore resemble each other; and ac- cording to M. Millon,1 when taken from the same animal at one time the analogy in composition is very great. Without impropriety they may, indeed, be termed rudimental blood. It is impossible to estimate the quantity of lymph contained in the body. It would seem, that notwithstanding the great capacity of the lymphatic vessels, there is, under ordinary circumstances, little fluid cir- culating in them. Frequently, when examined, they have appeared to be empty, or pervaded by a mere thread of lymph. M. Magendie2 endea- voured to obtain the whole ofthe lymph from a dog of large stature. He could collect but an ounce and a half; and it appeared to him that the quantity increased whenever the animal was kept fasting; but on this point he does not seem to express himself positively. 3. PHYSIOLOGY OF LYMPHOSIS. The term lymphosis has been proposed by Chaussier for the action of elaboration by which lymph is formed,—as chylosis has been used for the formation of chyle, and haematosis for that of the blood. In describing the organs concerned, the striking similarity—we might almost say—identity in structure and arrangement between them and the chyliferous organs will have been apparent. A part of the vascu- lar apparatus is common to both; and they manifestly constitute one and the same system. This would be sufficient to induce us to assign them similar functions; and it would require powerful and positive tes- timony to establish an opposite view. At one period, lymph was con- sidered to be simply the watery portion of the blood; and the lymphatic vessels were regarded as the continuation of ultimate arterial ramifi- cations. It was affirmed, that the blood, on reaching the terminal branches of the arteries, separated into two parts; the red and thicker portion returning to the heart by the veins; and the white, serous portion —liquor sanguinis—by the lymphatics.3 The reasons for this belief were, the great resemblance between lymph and the serum of the blood; and the facility with which an injection passes, in the dead body, from the arterial into the lymphatic capillary vessels. M. Magendie has revived the ancient doctrine; and, of consequence, no longer considers the lymphatics to form part of the absorbent system; but to belong to the circulatory apparatus, and to serve the office of waste pipes, in case of emergency. Without canvassing this subject now, we may assume it for granted, that the lymph which circulates in the lymphatic vessels is as identical in its nature, or as little subject to alteration, as the chyle; and that, consequently, whatever may be the materials that constitute it, an action of elaboration and selection must be exerted in its formation. It has been conceived, that many of the tissues of the body, the serous membranes, for example, do not receive red blood; and must, consequently, be nourished by white blood. The lymphatics, in such cases, have been considered to be to the white arteries what the veins 1 Archives Generales de Medecine, Fevr, 1850, p. 237. 2 Op. citat, ii. 192. 3 Kirkes and Paget, Manual of Physiology, Amer. edit, p. 256, Philad, 1S49. LYMPHOSIS. 673 are to the red. Such has been presumed to be one of their offices, but it will be seen, hereafter, that all the tissues supplied with vessels receive red blood; and hence it is unnecessary to suppose, that the lymphatics execute any venous function. Assuming, for the present, that lymph is wholly obtained from materials already deposited in the body; the next inquiry is,—the mode in which its formation and simultaneous absorption are effected. On this topic, we have no arguments to employ in addition to those adduced regarding the function of the chyliferous radicles. In every respect, they are situate identically, and to the history of the latter we must refer for an exposition of the little we know of this part of lymphosis. The causes of the progression of the lymph in the vessels are the same as those that influence the chyle. Fig. 260. In addition, however, to those mentioned under chyliferous ab- sorption, there is one that applies equally to the chyliferous and lymphatic ves- sels: this is the mode in which the thoracic duct enters the sub- clavian vein. It has been already observ- ed that it occurs at the point of junction between the jugular and subclavian, as at D, Fig. 260 Where J Termination of Thoracic Duct. '"' represents the jugu- lar, and V S the subclavian, in which the blood flows from V towards S, the cardiac extremity. Now, it is a physical fact, that when a small tube is inserted per- pendicularly into the lower side of a horizontal conical pipe, in which water is flowing from the narrower to the wider portion; and if the small vertical tube be made to dip into a vessel of water, not only will the water of the larger pipe not descend into the vessel; but it will draw up the water through the small tube so as to empty the vessel.1 Instead of supposing the canals in Fig. 260, to be veins and the tho- racic duct; let us presume that they are rigid mechanical tubes; and that the extremity of the tube D, which represents the thoracic duct, dips into the vessel B. As the fluid, proceeding from J to S and V to S, is passing from the narrower portions of conical tubes to wider, it follows, that the fluid will be drawn out of the vessel B, simply by traction, or, by what Venturi2 terms the lateral communication of fluids. This would happen in whatever part of the vessel the tube B D termi- 1 Sir C Bell, in Animal Mechanics, p. 41, Library of Useful Knowledge, Lond, 1829. 2 Sur la Communication Laterale du Mouvement dans les Fluides, Paris, 1798. vol. I.—43 674 ABSORPTION. nated. But its insertion at D has another advantage. By the mode in which the current from J towards S unites with that from Y towards S, a certain degree of diminished pressure must exist at D ; so that the atmospheric pressure, on the surface of the water in the vessel B, will be exerted in propelling it forwards. In the progress, then, of the chyle and lymph along the thoracic duct, not only may the traction of the more forcible stream along the veins draw the fluid in the thoracic duct along with it, but, owing to the diminished pressure at the mouth of the duct, atmospheric pressure may have some—although probably but little—influence, in forcing the chyle and lymph from the chylife- rous and lymphatic radicles onwards. The lymphatic glands have been looked upon as small hearts for the propulsion of lymph; and Malpighi accounts for the greater number in the groin in this way;—the lymph having to ascend to the thoracic duct against gravity: and this appears to have been somewhat the opinion of Bichat. There seems, however, to be nothing in thoir structure that ought to lead to this belief; and, if it be not muscular or contractile, it is manifest, that their, number must have the effect of retarding rather than accelerating the flow. The most prevalent sentiment is, that they are somehow concerned in the admixture of the lymph; and by many it is conceived, that some kind of elaboration is effected by them; but, on this topic, we have only conjectures. Of their true functions we know nothing definite. On the subject of the moving powers of the lymph, M. Adelon1 has remarked, that if we admit it to be the serous portion of the blood; and that the lymphatics are vessels of return, as the veins are, the heart might be considered to have the same influence over lymphatic, that it has been presumed to have over venous, circulation; and whether we admit this or not, as the thoracic duct opens into the subclavian vein, the influence of the suction power of the organ on the venous blood may affect the progression of the chyle also. It cannot, how- ever, as Miiller2 remarks, be the primary cause of the motion of the chyle, for Autenrieth, Tiedemann, and Carus observed, when a liga- ture was applied to the thoracic duct, that the part of the duct below the ligature became distended even to bursting. We shall see here- after, that during inspiration, absorption, it is imagined, may be facili- tated by the dilatation of the chest, and the necessary diminution of pressure on the heart and great vessels. Professor Miiller3 discovered, that the frog, and several other am- phibious animals, are provided with large receptacles for lymph, situate immediately under the skin, and, like the heart, exhibiting distinct and regular pulsations. The use of these lymph hearts appears to be to propel the lymph along the lymphatics. In the frog, four of them have been found; two posterior, behind the joint of the hip; and two anterior, on each side of the transverse process of the third vertebra, and under the posterior extremity of the scapula. The pulsations of 1 Art. Absorption, in Dict.de Medecine, 2de edit, i. 239, Paris, 1832; and Physiologie de l'Homme, edit, cit, iii. 92. 2 Handbuch, u. s. w.; and Baly's translation, p. 284, Lond, 1838. 3 Philos. Transact, for 1833 ; and op. cit. See, also, his Observations on the Lymphatic Hearts of Tortoises, in Muller's Archiv., Heft 1, 1840. LYMPHOSIS. 675 Fig. 261. an Lymph Heart of Python Bivit- tatus, after Weber. Heart 9 lines long; 4 broad. 4. External areolar coat. 5. Thick muscular coat; four mus- cular columns cross the cavity, which communicates with three lymphatics — only one, 1, seen here, and two veins, 2, 2. 6. Smooth lining membrane of the cavity. 7. An appendix or au- ricle, the cavity of which com- municates with the other. these lymphatic hearts do not correspond with those of the sanguiferous heart; nor do those of the right and left sides occur synchronously. They often alternate irregularly. Prof. E. H. Weber has described them in a larger species of serpent—python bivittatus;1 and Dr. Joseph J. Allison, of Philadelphia,2 a young and zeal- ous observer, who was cut off early in his ca- reer, saw them in the tadpole, the frog, the eauria, ophidia, and chelonia. His researches led him to conclude:—First. That the pulsa- tions of the lymphatic organs vary in different specimens (frogs and tadpoles) from 60 or less to 200 per minute. Secondly. That they vary in the same individual so as sometimes to be- come double in frequency. Thirdly. That the lymphatic pulsations bear no fixed relation to those of the pulmonary heart or to respira- tion, the lymphatic hearts beating—on average—with greater frequency. More recently, Professor Stannius3 has dis covered lymphatic hearts in various birds. Unlike that of the heart, the action of these lymph hearts appears to be dependent upon a certain limited portion of the spinal cord ; for Volkmann4 found, that by dividing the anterior or motor roots of the spinal nerves connected with them, the pulsations immediately ceased. The course of the lymph is by no means rapid. If a lymphatic be divided on a living individual, the lymph oozes slowly, and never with a jet. M. Cruikshank estimated its velocity along the vessels to be four inches per second or twenty feet per minute; but it is probably much less. M. Collard de Martigny5 obtained nine grains of lymph in ten minutes from the thoracic duct of a rabbit, which had taken no food for twenty-four hours. Having pressed out the lymph from the principal lymphatic trunk of the neck, in a dog, the vessel filled again in seven minutes: in a second experiment it filled in eight minutes. The data for any correct evaluation of this matter are altogether in- adequate, the deranging influence of all such experiments being con- siderable. In man and living animals, the lymphatics of the limbs, head, and neck rarely contain lymph; their inner surface appearing to be merely lubricated by a very thin fluid. Occasionally, however, the lymph' stops in different parts of the vessels; distends them; and gives them an appearance very like that of varicose veins, except as to colour. Sommering states, that he saw several in this condition on the top of 1 Miiller, op. citat, p. 275. 2 American Journal of the Medical Sciences, for August, 1838. 3 Muller's Archiv, 1843, Heft 5. 4 Ibid., 419, Berlin, 1844; and Valentin, Lehrbuch der Physiologie des Menschen, n. 769, Braunschweig, 1844. 6 Journal de Physiologie, torn. viii. 676 ABSORPTION. the foot of a female; and M. Magendie one around the corona glandis of a male. In dogs, cats, and other living animals, lymphatics, filled with lymph, are frequently seen at the surface of the liver, gall-bladder, vena cava, vena portse, and at the sides of the spine. Magendie re- marks, that he has never met with the thoracic duct empty, even when the lymphatics of the rest of the body were entirely so.1 It must be recollected, however, that the thoracic duct must always contain the product of the digestion either of food or of secretions from the aliment- ary tube. The stagnation of lymph in particular vessels has given occasion to the belief, that it flows with different degrees of velocity in different parts of the system; and this notion has entered into the pathological views of writers, who have presumed, that something like determinations of lymph may occur, and produce lymphatic swellings. M. Bordeu,2 indeed, speaks of currents of lymph. All the phenomena of the course of the lymph negative, however, this presumption; and in- duce'us to believe, that its progress is pretty uniform, and always slow; and when an accumulation, or engorgement, or stagnation occurs in any vessel, it is more probably owing to increased formation by the lymphatic radicles that communicate with the vessel in question, or to loss of tone in the parietes of the engorged lymphatics. The lymph, which proceeds by the thoracic duct, is emptied, along with the chyle, into the subclavian vein. At the confluence, a valve is placed, which does not, however, appear to be essential, as the duct opens so favourably between the two currents from the jugular and subclavian, that there is little or no tendency in the blood to reflow into it. It has been suggested, that its use may be, to moderate the instilla- tion of the fluid from the thoracic duct into the venous blood. With regard to the question, whether the lymph is the same at the radicles of the lymphatics as in the thoracic duct, or whether it does not gradually become more and more animalized in its course towards the venous system, and especially in its progress through the lymphatic glands, the remarks made upon this subject, as respects the chyle, apply with equal force to the lymph. Our ignorance is no less profound. The glands of the mesentery, and lymphatics in general, seem to be concerned in some of the most serious diseases. Swelling of the lymphatic glands of the groin may indicate the existence of a venereal sore on the penis. A wound on the foot produces tumefaction of the inguinal glands; one on the hand inflames those of the axilla. When- ever, indeed, a lymphatic gland is symptomatically enlarged, the source of irritation will be found at a greater distance from the vein into wh&h the great lymphatic trunks pour their fluid than the gland is. In plague, one of the essential phenomena is swelling of the lymphatic glands of the groin and axilla; hence, it has been termed adeno-ady- namic fever (from aSrjv, a gland). In scrofula, the lymphatic system is generally deranged; and, in the doctrine of Broussais, a very active sympathy is affirmed to exist between the glands of the mesentery, and the mucous surface of the stomach and intestines. This discovery, we are told, belongs to the "physiological doctrine," which has shown, that 1 Precis, &c, ii. 224. 2 CEuvres completes, par Richerand, Paris, 1818. VENOUS. 677 all gastro-enterites are accompanied by tumefaction of the mesenteric glands: although chyle may be loaded with acrid, irritating, or even poisonous^ matters, it traverses the glands with impunity, provided it does not inflame the gastro-enteric mucous surface. "Our attention," Broussais1 adds, "has been for a long time directed to this question, and we have not observed any instance of mesenteric ganglionitis, which had not been preceded by well-evidenced gastro-enteritis." The dis- covery will not immortalize the "doctrine." We should as naturally look for tumefaction of the mesenteric glands or ganglia, in cases of irritation of the intestine, as for enlargement of the glands of the groin in irritation of the foot. Lastly; the lymph, from whatever source obtained—united with the chyle—is discharged into the venous system. Both, therefore, go to the composition of the body. They are entirely analogous in proper- ties; but differ materially in quantity;—the nutritious fluid, formed from materials obtained from without, being far more copious. A due supply of it is required for continued existence; yet the body can live for a time, when the supply of nutriment is entirely cut off. Under Buch circumstances, the necessary proportion of nutritive fluid must be obtained from the decomposition of the tissues; but, from the perpetual drain, that takes place through the various excretions, this soon becomes insufficient, and death is the result. In a note to the recent editions of his "Principles of Human Physiology,"2 Dr. Carpenter remarks, that at the time of the publication of the first edition of his work (1842) he was under the impression, that the view maintained by him, "that the special function of the lymphatics like that of the lacteals is nutritive absorption," was altogether novel. The author attaches little value to originality in such matters; but he thinks it well to state, that the doc- trine in the text is, that adopted by him in the first edition of this work (1832), and taught by him ever since he has been a teacher; yet he is far from regarding it as Original with him. We have seen, then, that both chyle and lymph are poured into the venous blood;—itself a compound of the residue of arterial blood, and various heterogeneous absorptions. As an additional preliminary to the investigation of the agents of internal absorption, let us inquire into the nature and course of the fluid contained in the veins; but so far only as to enable us to understand the function of absorption; the other con- siderations relating to the blood appertain to the function of circulation. III. VENOUS ABSORPTION. The apparatus of venous absorption consists of myriads of vessels called veins, which commence in the very tissues, by what are called capillary vessels, and thence pass to the great central organ of the cir- culation—the heart; receiving, in their course, the products of the va- rious absorptions effected not only by themselves, but by the chyliferous 1 Traite de Physiologie, &c, and Bell and La Roche's translation, 3d Amer. edit, p. 362, Philadelphia, 1832. . 2 Fourth American edition, p. 506, Philad, 1850. See on this subject, Adelon, Art. Absorp- tion in Diet, de Medecine, i. p. 117, Paris, 1S21; arid Moultrie, American Journal of the Medical Sciences for 1827, and On the Organic Functions of Animals, Charleston, 1844. 678 ABSORPTION. and lymphatic vessels. The anatomy of the venous system will be given under Circulation. 1. PHYSIOLOGY OF YEXOTJS ABSORPTION. Whilst the opinion prevailed universally, that the lymphatics are the sole agents of absorption, the fluid, circulating in the veins, was con- sidered to consist entirely of the residue of arterial blood, after it had passed through the capillary system, and been subjected to the different nutritive processes. We have seen, however, that drinks are absorbed by the mesenteric veins; and we shall hereafter find, that various other substances enter the venous system. It is obvious, therefore, that ve- nous blood cannot be simply the residue of arterial blood; and we can thus account for the greater capacity of the venous than of the arterial system. The facts, which were referred to, when considering the ab- sorption of fluids from the intestinal canal, may have been sufficient to show, that veins are capable of absorbing; as odorous and colouring properties of substances were distinctly found in the mesenteric veins. A question arises, whether any vital elaboration is concerned, as in the case of the chyle, or whether the fluid, when it attains the interior of the vessel, is the same as without? M. Adelon,1—who, with many of the German physiologists, believes in both venous and lymphatic ab- sorption, and venous and chyliferous absorption,—conceives, that a vital action takes place at the very extremities of the venous radicles, pre- cisely similar to that which is presumed to be exerted at the extremities of the lymphatic and chyliferous radicles. In his view, consequently, an action of elaboration is exerted upon the fluid, which becomes, in all cases, converted into venous blood at the very moment of absorption. On the other hand, MM. Magendie,2 Fode'ra,3 and others maintain, that the substance when possessed of the necessary tenuity soaks through the vessel; and that this act of imbibition is purely physical. In their view, consequently, the fluid within the vessel must be the same as without. In favour pf the vital action of the veins we have none of that evi- dence, which strikes us in the case of the chyliferous and lymphatic vessels. In the last we invariably find fluids, identical—in all essen- tial respects—in physical characters ; and never containing extraneous matter,—if we make abstraction of certain salts, that have been occa- sionally met with in the thoracic duct. In the veins, on the other hand, the sensible properties of odorous and colouring substances have been frequently apparent. It may be remarked, however, that the fluid, flowing in the veins, is as identical in composition as the chyle or the lymph. This is true ; but it must be recollected, that the greater part of it is the residue of arterial blood; and that its hue and other sen- sible properties are such as to disguise any absorbed fluid, not itself possessing strong characteristics. The fact,—now indisputable,—that various substances, placed outside the veins, have been detected in the blood within, is not only a proof that the veins absorb; but that no 1 Art. Absorption, in Diet, de Medecine, 2de edit., i. 239, Paris, 1832 ■ and Physiologie de l'Homme, 2de edit, iii. 113, Paris, 1829. 2 Precis, &c, 2de edit, ii. 271. 3 Recherches Experimentales sur l'Exhalation et l'Absorption, Paris, 1823. VENOUS. 679 action of elaboration is exerted on the absorbed fluid. Of this we have the most convincing proof in certain experiments by M. Magendie.1 In exhibiting to his class the mode in which medicines act upon the sys- tem, he showed, on a living animal, the effects of introducing a quantity of water, of the temperature of 104° Fah., into the veins. In perform- ing this experiment, it occurred to him to notice what would be the effect produced by artificial plethora on the phenomena of absorption. Having injected nearly a quart of water into the veins of a dog of middle size, he placed in the cavity of the pleura a small dose of -a substance with the effects of which he was familiar, and was struck with the fact, that they did not exhibit themselves for several minutes after the ordi- nary period. He immediately repeated the experiment, and with a like result. In several other experiments, the effects appeared at the ordinary time, but were manifestly feebler than they ought to have been from the dose of the substance employed ; and were kept up much longer than usual. In another experiment, having introduced as much water as the ani- mal could bear without perishing,—which was about two quarts,—the effects did not occur at all. After having waited nearly half an hour for their developement, which generally required only about two minutes, he inferred, that if the distension of the bloodvessels was the cause of the defect of absorption, if the distension were removed, absorption ought to take place. He immediately bled the animal largely in the jugular; and, to his great satisfaction, found the effects manifesting themselves as the blood flowed. He next tried whether, if the quantity of blood were diminished at the commencement of the experiment, ab- sorption would be more rapid ; and the result was as he anticipated. An animal was bled to the extent of about half a pound ; and the effects, which did not ordinarily occur until after the second minute, appeared before the thirtieth second. As the results of these experiments seemed to show, that absorption is in an inverse ratio to the degree of vascular distension, he inferred, that it is effected physically ; is dependent upon capillary attraction; and ought to take place as well after death as during life. To prove this, he instituted the following experiments.—He took a portion of the external jugular of a dog, about an inch long and devoid of branches. Removing carefully the surrounding areolar tissue, he attached to each extremity a glass tube, by means of which he kept up a current of warm water within it. He then placed the vein in a slightly acid liquor, and carefully collected the fluid of the current. During the first few minutes, it exhibited no change; but, in five or six minutes, became sensibly acid. This experiment was repeated on veins taken from the human subject with like results; and not only on veins but on Similar experiments were next made on living animals. He took a young dog, about six weeks old, whose vessels were thin, and, conse- quently, better adapted for the success of the experiment, and exposed one of its jugular veins. From this he dissected entirely the surround- ing matter, and especially the areolar tissue, and the minute vessels that ramified upon it; and placed it upon a card, in order that there * Op. citat, ii. 273. 680 ABSORPTION. might be no point of contact between it and the surrounding parts. He then let fall upon its surface and opposite the middle of the card a thick watery solution of nux vomica,—a substance, that exerts a power- ful action on dogs. He took care, that no particle of the poison touched any thing but the vein and cord; and that the course of the blood, within the vessel, was free. Before the expiration of three minutes, the effects he expected appeared,—at first feebly, but afterwards with so much activity, that to prevent fatal results he had to inflate the lungs. The experiment was repeated on an older animal with the same results; except that, as might have been expected, they were longer in exhibiting themselves, owing to the greater thickness of the parietes of the veins. Satisfied, as regarded the veins, he now directed his attention to the arteries:—the results were the same. They were, however, slower in appearing than in the case of the veins, owing to the tissue of the arte- ries being less spongy. It required upwards of a quarter of an hour , for imbibition to be accomplished. In one of the rabbits, which died under the experiment, they had an opportunity of discovering, that absorption could not have been effected by any small veins, that had escaped dissection. One of the carotids,—the subject-vessel of the experiment,—was taken from the body; and the small quantity of blood, adherent to its inner surface, was found by M. Magendie, and his friends who assisted at the experiment, to possess the extreme bitterness that characterizes nux vomica. These experiments were sufficient to prove the fact of imbibition by the large vessels, both in the dead and in the living state. His attention was now directed to the smaller; which seemed, a priori, favourable to the action, from their delicacy of organi- zation. He took the heart of a dog, that had died the day before, and injected water, of the temperature of 86° of Fah., into one of the coronary arteries, which readily returned by the coronary vein into the right auricle, whence it was allowed to flow into a vessel. Half an ounce of water, slightly acidulated, was now placed in the pericardium. At first, the injected fluid did not exhibit any signs of acidity; but, in five or six minutes, the evidences were unequivocal. From these facts, M. Magendie1 draws the too exclusive deduction, that "all bloodvessels, arterial and venous, dead or living, large or small, possess a physical property capable of accounting for the principal phenomena of absorption." We shall endeavour to show, that it explains only certain varieties of absorption,—those in which the vessel receives the fluid unmodified,—but that it is unable to account for other absorption in which an action of selection and elaboration is necessary. After these experiments were performed, others were instituted by MM. Se'galas2 and Fodera,3 from which the latter physiologist attempts to show, that exhalation is simply a transudation of substances from the interior of vessels to the exterior; and absorption an imbibition or pas- sage of fluids from the exterior to the interior. The facts adduced by 1 Precis, &c, ii. 283. 2 Magendie's Journal de Physiol, ii. 217. 3 Recherches Experiment, sur l'Absorption,&c, Paris, 1824, and Magendie's Journal, &c, iii. 35. VENOUS. 681 M. Fode*ra in support of his views will be considered under the head of Secretion. They go chiefly to show the facility with which substances penetrate the parietes of vessels and other tissues of the body; an action which he found to be singularly accelerated by the galvanic influence. Prussiate of potassa was injected into the cavity of the pleura; and sul- phate of iron introduced into that of the peritoneum in a living animal. Under ordinary circumstances, it requires five or six minutes before the two substances meet by imbibition through the diaphragm; but the ad- mixture is instantaneous if the diaphragm be subjected to a slight gal- vanic current. The same fact is observed, if one of the liquids be placed in the urinary bladder, and the other in the abdomen; or the one in the lung, and the other in the cavity of the pleura. It was further found, that, according to the direction of the current, the union took place in the one or the other cavity. Dr. Bostock,1 in commenting on these cases, thinks it must be admitted, that they "go very far to prove that membranes, perhaps even during life, and certainly after death, before their texture is visibly altered, have the power of permitting the transu- dation of certain fluids." That such imbibition occurs during life, ap- pears to be indisputably proved. If the clear and decisive experiments of Magendie and Fode'ra were insufficient, the additional testimony,— afforded by Lawrence, Coates, and Harlan; by Dutrochet, Faust, Mit- chell, Rogers, Draper, and others,—would command it. By the different rates of penetrativeness of different fluids, and of permeability of dif- ferent tissues, we can explain why imbibition may occur in one set of vessels and not in another; and the constant current, established in the interior of the vessel is a sufficient reply to the suggestion, that there may not be the same tendency to transude after the fluid has entered it. M. Adelon2 is of opinion, that under the view of imbibition we ought to find substances in the arteries and lymphatics also; but a sufficient objection to this would be,—the comparative tardiness, with which the former admit the action; and the selection, and, consequently, refusal, exerted by the latter; but even here evidences of adventitious imbibition are occasionally met with; as in the case of salts, which—we have seen —have been detected in the thoracic duct, after having been intro- duced into the cavity of the abdomen. The two following experiments by Prof. J. K. Mitchell,'' which are analogous to numerous others, performed in the investigation of this subject, well exhibit endosmose in living tissues. A quantity of a solution of acetate of lead was thrown into the peritoneal cavity of a young cat; sulphuretted hydrogen being passed, at the same time, into the rectum. In four minutes, the poisonous gas killed the animal. Instantly on its death the peritoneal coat of the intestines, and the parietes of the cavity in contact with them, were found lined with a metallic precipi- tate which adhered to the surface, and was removable by nitric acid moderately diluted. It was the characteristic precipitate of sulphuretted hydrogen, when acting on lead. In another experiment on a cat, a solution of acetate of lead was placed in the thorax, and sulphuretted hydrogen in the abdomen. Almost immediately after the entrance of » Physiology, edit, cit, p. 629. 2 Op- cit. » American Journal of the Medical Sciences, vh. 44, Philada, 1830. 682 ABSORPTION. the sulphuretted hydrogen into the abdominal cavity, death ensued. On inspecting the thoracic side of the diaphragm, which was done as quickly as possible, the tendinous part of it exhibited the leaden appear- ance of the precipitate thrown down by sulphuretted hydrogen. ^ The experiment of J. Miiller, referred to in a preceding page, establishes the same fact. It may be concluded, then, that all living tissues imbibe liquid mat- ters which come in contact with them; and that the same occurs to solids, provided they are soluble in the humours, and especially in the serum of the blood. But although imbibition is doubtless.effected by living tissues, too great a disposition has been manifested to refer all the vital phenomena of absorption and exhalation to it. Even dead animal membrane has been supposed to exert a positive agency in re- spect to bodies placed on either side of it. In the early part of this work1 the phenomena of imbibition were investigated, and it was there explained how endosmose and exosmose are effected through organic membranes. A careful examination of those phenomena would lead to the belief, that in many cases the membrane exerts no agency except in the manner last suggested by M. Dutrochet. This is signally manifested in experiments with porous, inorganic substances; and it has been in- geniously and ably confirmed by Dr. Draper,2 of New York, who found, that the phenomena were elicited, when, instead of an organic tissue, fissured glass was employed. Still, as has been demonstrated, the nature of the septum or membrane has in other cases a marked effect on endosmose. Sir David Barry,3—in different memoirs laid before the Academie Royale de MSdecine, the Academie Royale des Sciences of Paris, and the Medico-Chirurgical Society of London,—maintained, that the whole function of external absorption is a physical result of atmospheric pres- sure; and "that the circulation in the absorbing vessels and in the great veins depends upon this same cause in all animals possessing the power of contracting and dilating a cavity around that point to which the centripetal current of their circulation is directed." In other words, it is his opinion, that, at the time of inspiration, a tendency to a vacuum is produced in the chest by its expansion; and as the atmospheric pressure externally thus ceases to be counterbalanced, the pressure without occasions the flow of blood towards the heart along the veins. The consideration of the forces that propel the blood will afford us an opportunity of saying a few words on this view; at present, we may only observe, that Sir David ascribes absorption,—which he explicitly states to be, in his opinion, extra vital,—to the same cause. In proof of this, he instituted numerous experiments, in which the absorption of poisons from wounds appeared to take place, or to be suspended, according as the wounds were, as he conceived, exposed to atmospheric pressure, or freed from its influence by the application of a cupping-glass. The same quantity of poison, which, under ordinary 1 See p. 65. 2 Amer. Journ. of the Med. Sciences, for Aug, 1836, p. 276; Nov, 1837, p. 122 ; May, 1838, p. 23, and August, 1838—more especially the two last. 3 Experimental Researches on the Influence of Atmospheric Pressure upon the Circulation, &c, Lond, 1826. VENOUS. 683 circumstances, destroyed an animal in a few seconds, was rendered com- pletely innocuous by the exhausted glass; and what is singular, even when the symptoms had commenced, the application of the cupping-glass had the effect of speedily and completely removing them;—a fact of es- sential importance in its therapeutical relations. In commenting on the conclusions of Sir D. Barry, Messrs. Addison and Morgan,1—who main- tain the doctrine, that all poisonous agents produce their specific effects upon the brain, and general system,'through the sentient extremities of nerves, and through the sentient extremities of nerves only; and that, when such agents are introduced into the current of the circulation in any way, their effects result from the impression made upon the sensible structure of the bloodvessels, and not from their direct application to the brain itself,—contend, that the soft parts of the body, when covered by an exhausted cupping-glass, must necessarily, from the pressure of the edges of the glass, be deprived for a time of all connexion, both nervous and vascular, with the surrounding parts;—that the nerves must be partially or altogether paralysed by compression of their trunks; and that, from the same cause, all circulation through the veins and arteries within the area of the glass, must cease; that the rarefaction of the air within the glass being still farther increased by means of the small pump attached to it, the fluids, in the divided extremities of the vessels, are forced into the vacuum, and, with these fluids, either a part or the whole of the poison, which had been introduced; and that, in such a condition of parts, the compression, on the one hand, and the removal of the poison from the wound on the other, will sufficiently explain the result of the experiment, either according to the views of those who conceive the impression to be made on the nerves of the bloodvessels, or of those who think, that the agent must be carried along with the fluid of the circulation to the part to be impressed. Thus far allusion has been made only to the passage of tenuous fluids into the veins. Insoluble substances have, however, been detected by Professor Oesterlen2 in the mesenteric veins. On administering levi- gated charcoal to animals for five or six days in succession, the blood of these veins exhibited distinctly particles of charcoal of different sizes, some of them so large, that it was a matter of surprise how they could have made their way into the blood through the epithelium, mu- cous membrane and the walls of the bloodvessels. We have no diffi- culty, consequently, in comprehending how the mild chloride and other insoluble preparations of mercury may be able to enter the bloodvessels in this manner. Such would seem to be the main facts regarding the absorbent action of the veins, which rests on as strong evidence as we possess regarding any of the functions of the body; yet, in the treatise on Animal and Vegetable Physiology by Dr. Roget,3 we find it passed by without a comment! We have still to inquire into the agents of internal and adventitious absorption. i An Essay on the Operation of Poisonous Agents upon the Living Body, Lond, 1829. 2 Heller's Archiv, Bd. iv. Heft 1, cited in Lond. Med. Gazette for July, 1847. 3 Bridgewater Treatise, Lond, 1834, Amer. edit.- Philad, 1836. 684 ABSORPTION. IV. INTERNAL ABSORPTION. On this point but few remarks will be necessary, after the exposition of the different vascular actions concerned in absorption. The term comprehends interstitial absorption, and the absorption of recrementitial fluids. The first comprises the agency by which the different textures of the body are decomposed and conveyed into the mass of blood. It will be considered more at length under the head of Nutrition; the second, that of the various fluids effused into cavities; and the third, that which is effected on the excretions in their reservoirs or excretory ducts. All these must be accomplished by one of the two sets of vessels previously described; lymphatics, or veins, or both. Now, we have attempted to show, that an action of selection and elaboration is exerted by lymphatics; whilst we have no evidence of such action in the case of the veins. It would follow, then, that all the varieties of internal absorption, in which the substance, when received into the vessel, pos- sesses different characters from those it had when without, must be executed by lymphatics; whilst those, in which no conversion occurs, take place by the veins. In the constant absorption, and corresponding deposition, incessantly going on in the body, the solid parts must be reduced to their elements, and a new compound be formed; inasmuch as we never find bone, muscle, cartilage, membrane, &c, existing in these states in any of the absorbed fluids; and it is probable, therefore, that, at the radicles of the lymphatic vessels, they are converted into the same fluid—the lymph—in like manner as the heterogeneous sub- stances in the intestinal canal afford to the lacteals the elements of a fluid the character of which is always identical. On the other hand, when the recrementitial fluid consists simply of the serum of the blood, more or less diluted, there can be no obstacle to the passage of its aqueous portion immediately through the coats of the veins by imbi- bition, whilst the more solid part is taken up by the lymphatic vessels. In the case of excrementitious fluids, there is reason to believe, that absorption simply removes some of their aqueous portions; and this, it is obvious, can be effected directly by the veins, through imbibition. The facts, connected with the absorption of substances from the interior of the intestine, have clearly shown, that the chyliferous vessels alone absorb chyle, and that the drinks and adventitious substances pass into the mesenteric veins. These apply, however, to external absorption only; but similar experiments and arguments have been brought forward by the supporters of the two opinions, in regard to substances placed on the peritoneal surface of the intestine, and other parts of the body. Whilst some affirm, that they have entered the lymphatics; others have only been able to discover them in the veins. Mr. Hunter, having in- jected water coloured with indigo into the peritoneal cavity of animals, saw the lymphatics, a short time afterwards, filled with a liquid of a blue colour. In animals, that had died of pulmonary or abdominal hemorrhage, Mascagni found the lymphatics of the lungs and peritoneum filled with blood; and he asserts, that, having kept his feet for some hours in water, swelling of the inguinal glands supervened, with trans- udation of a fluid through the gland; coryza, &c. M. Desgenettes INTERNAL. 685 observed the lymphatics of the liver containing a bitter, and those of the kidneys a urinous, lymph. Sommering detected bile in the lymph- atics of the liver; and milk in those of the axilla. M. Dupuytren relates a case, which M. Magendie conceives to be much more favourable to the doctrine of absorption by the lymphatic vessels than any of the others. A female, who had an enormous fluctuating tumour at the upper and inner part of the thigh, died at the Hotel Dieu, of Paris, in 1810. A few days before her death, inflammation occurred in the subcutaneous areolar tissue at the inner part of the tumour. The day after dissolu- tion, M. Dupuytren opened the body. On dividing the integuments, he noticed white points on the lips of the incision. Surprised at the ap- pearance, he carefully dissected away some of the skin, and observed the subcutaneous areolar tissue overrun by whitish lines, some of which were as large as a crow's quill. These were evidently lymphatics filled with puriform matter. The glands of the groin, with which these lymphatics communicated, were injected with the same matter. The lymphatics were full of the fluid, as far as the lumbar glands; but neither the glands nor the thoracic duct presented any trace of it.1 On the other hand, multiplied experiments have been instituted, by throw- ing coloured and odorous substances into the great cavities of the body; and these have been found always in the veins, and never in the lymphatics. To the experiments of Mr. Hunter, objections have been urged, simi- lar to those brought against his experiments to prove the absorption of milk by the lacteals; and sources of fallacy have been pointed out. The blue colour, which the lymphatics seemed to him to possess, and which was ascribed to the absorption of indigo, was noticed in the experiments of Messrs. Harlan, Lawrence, and Coates ;2 but they discovered that this was an optical illusion. What they saw was the faint blue, which transparent substances assume, when placed over dark cavities. Mr. Mayo3 has also affirmed that the chyliferous lymphatics always assume a bluish tint a short time after death, even when the animal has not taken indigo. The cases of purulent matter, &c, found in the lymph- atics, may be accounted for by the morbid action having produced dis- organization of the vessel, so that the fluid could enter the lymphatics directly; and, if once within, its progression could be readily under- stood. M. Magendie4 asserts, that M. Dupuytren and he performed more than one hundred and fifty experiments, in which they submitted to the absorbent action of serous membranes different fluids, and never found any of them within the lymphatic vessels. These fluids produced their effects more promptly, in proportion to the rapidity with which they were capable of being absorbed. Opium exerted its narcotic influence; wine produced intoxication, &c, and M. Magendie found, from nume- rous experiments, that the ligature of the thoracic duct in no respect diminished the promptitude with which these effects supervened. The 1 Magendie, Precis, &c, 2de edit, ii. 195, et seq.; and Adelon, art. Absorption, Diet, de Med, 2de edit, i. 239, and Physiologie de IHomme, 2de edit, iii. 65, Paris, 1829. 2 Harlan's Physical Researches, p. 459, Philad, 1835. 3 Outlines of Human Physiology, 3d edit, Lond, 1833. * Op. cit, ii. 211. 686 ABSORPTION. partisans of lymphatic absorption, however, affirm that even if these substances are met with in the veins, it by no means follows, that ab- sorption has been effected by them; for the lymphatics, they assert, have frequent communications with the veins; and, consequently, they may still absorb and convey their products into the venous system. In reply to this, it may be urged, that all the vessels—arterial, venous, and lymphatic—appear to have intercommunication; but there is no reason to believe, that the distinct offices, performed by them, are, under ordinary circumstances, interfered with; and, again, where would be the necessity for these intermediate lymphatic vessels, seeing that imbibition is so readily effected by the veins? The axiom—quod fieri potest per pauca, non debet fieri per multa—is here strikingly appro- priate. The lymphatics, too, as we have endeavoured to show, exert an action of selection and elaboration on substances exposed to them; but, in the case of venous absorption, there is not the slightest evidence, that any such selection exists,—odorous and coloured substances retain- ing, within the vessel, the properties they had without. Lastly. Where would be the use of organs of a distinct lymphatic circulation open- ing into the thoracic duct, seeing that the absorbed matters might enter the various venous trunks directly through these supposititious communicating lymphatics; and ought we not occasionally to be able to detect in the lymphatic trunks some evidence of those substances, which their fellows are supposed to take up and convey into the veins? These carrier lymphatics have obviously been devised to support the tottering fabric of exclusive lymphatic absorption,—undermined, as it has been, by the powerful facts and reasonings that have been adduced in favour of absorption by veins. From the whole of the preceding history of absorption, we are of opinion, that the chyliferous and lymphatic vessels form only chyle and lymph, refusing all other substances, with the exception of saline and other matters, that enter probably by imbibition,—that the veins admit every liquid, which possesses the necessary tenuity; and that whilst all the absorptions, which require the substances acted upon to be decom- posed and transformed, are effected by chyliferous and lymphatic vessels; they that are sufficiently thin, and demand no alteration, are accomplished directly through the coats of the veins by imbibition; and we shall see that such is the case with several of the transudations or exhalations. V. ACCIDENTAL ABSORPTION. The experiments, to which reference has been made, have shown, that many substances, adventitiously introduced into various cavities, or placed in contact with different tissues, have been rapidly absorbed into the blood, without experiencing any transformation. Within cer- tain limits, the external envelope of the body admits of this function; out by no means to the same extent as its prolongation, which lines the different excretory ducts. The absorption of drinks is sufficient evidence of the activity of the function as regards the gastro-enteric mucous membrane. The same may be said of the pulmonary mucous membrane. Through it, oxygen and nitrogen pass to reach the blood in the lungs, as CUTANEOUS. 687 well as carbonic acid in its way outwards. Aromatic substances, such as spirit ot turpentine, breathed for a time, are detected in the urine* proving that their aroma has been absorbed; and it is by absorption' that contagious miasmata probably produce their pestiferous agency' Dr. Madden,1 however, thinks that the lungs do not absorb watery vapour with the rapidity, or to the extent, that has been imagined; whilst Dr. A. Combe2 hazards the hypothesis, that owing apparently to the extensive absorption of aqueous vapour by the lungs, the inha- bitants of marshy and humid districts, as the Dutch, are remarkable for the predominance of the lymphatic system. Not only do the tissues, as we have seen, suffer imbibition by fluids, but by gases also: the experiments of Chaussier and Mitchell astonish us by the rapidity and singularity of the passage of the latter through the various tissues;—the rapidity varying according to the permeability of the tissue, and the penetrative power of the gas. a. Cutaneous Absorption. On the subject of cutaneous absorption, much difference of sentiment has prevailed;—some asserting it to be possible to such an extent, that life may be preserved, for a time, by nourishing baths. It has also been repeatedly affirmed, that rain has calmed the thirst of shipwrecked mariners who have been, for some time, deprived of water. It is obvious, from what we know of absorption, that, in the first of these cases, the water only could be absorbed; and even the possibility of this has been denied by many. Under ordinary circumstances, it can hap- pen to a trifling extent only, if at all; but, in extraordinary cases, where the system has been long devoid of its usual supplies of moisture, and where we have reason to believe, that the energy of absorption is increased, such imbibition may be possible. Sanctorius,3 Von Gorter * Keill,5 Mascagni,6 Madden,7 R. L. Young,8 Dill,9 and others believe, that this kind of absorption is not only frequent but easy. It has been affirmed, that after bathing the weight of the body has been manifestly augmented; and the last of these individuals has adduced many facts and arguments to support the position. Strong testimony has been brought forward in favour of extensive absorption of moisture from the atmosphere. This is probably effected rather through the pulmonary mucous surface than the skin. A case of ovarian dropsy is referred to by Dr. Madden,10 in which the patient, during eighteen days, drank 692 ounces of fluid; and discharged by urine and paracentesis 1298 ounces, being an excess of 606 ounces of fluid egesta over the fluid ingesta. Bishop Watson, in his Chemical Essays, states, that a lad at Newmarket, having been almost starved, in order that he might be reduced to the proper weight for riding a match, was weighed at 9, and again at 10, A. M., when he was found to have gained nearly 30 1 Experimental Inquiry into the Physiology of Cutaneous Absorption, p. 64, Edinb.. 1838. 1 Principles of Physiology applied to the Preservation of Health, 5th edit, p. 72, Edinb, 1836. 3 De Static. Medic, Lugd. Bat, 1711. 4 De Perspirat. Insensib, Lugd. Bat, 1736. 5 Tentamin. Medico-Physic, Lond, 1718. 6 Vas. Lyrnphat. Hist, Senis, 1783. i Op. cit, p. 58. 8 De Cutis Inhalatione, Edinb, 1813. 9 Edinb. Mcdico-Chir. Transact, ii. 350. I0 Op. cit, p. 55. 688 ABSORPTION. ounces in weight in the interval, although he had only taken half a glass of wine. Dr. Carpenter1 gives a parallel case, which was related to him by Sir G. Hill, Governor of St. Vincent. A jockey had been for some time in training for a race in which Sir G. Hill was much interested, and had been reduced to the proper weight. On the morning of the race, suffering much from thirst, he took one cup of tea, and shortly afterwards his weight was found to have increased six pounds, so that he was incapacitated for riding. These cases certainly appear difficult of belief: yet the authority is good. Dr. Carpenter presumes, that nearly the whole of the increase in Bishop Watson's case, and at least three fourths of it in Sir G. Hill's case, must be attributed to cutaneous absorption, which was probably stimulated by the wine that was taken in the one, and by the tea in the other. Bichat was under the im- pression, that, in this way he imbibed the tainted air of the dissecting room, in which he passed a large portion of his time. To avoid an objection, that might be urged against this idea,—that the miasmata might have been absorbed by the air passages, he so contrived his experiment, as, by means of a long tube, to breathe the fresh outer air; when he found, that the evidence, which consisted in the alvine evacu- ations having the smell of the miasmata of the dissecting-room, con- tinued. It is obvious, however, that such an experiment would hardly admit of satisfactory execution, and it is even doubtful, whether there was any actual relation between the assigned effect and the cause. The testimony of MM. Andral, Boyer, Dume'ril, Dupuytren, Serres, Lallemand, Ribes, Lawrence, Parent-Duchatelet, and that afforded by the author's own observation, are by no means favourable to the great unwholesomeness of cadaveric exhalations.2 Dr. J. Bradner Stuart3 found, after bathing in infusions of madder, rhubarb, and turmeric, that the urine was tinged with these substances. A garlic plaster affected the breath, when every care was taken, by breathing through a tube connected with the exterior of the apartment, that the odour should not be received into the lungs. Dr. Thomas Sewall4 found the urine coloured, after bathing the feet in infusion of madder, and the hands in infusions of madder and rhubarb. Dr. Mussey5 proved, that if the body be immersed in a decoction of mad- der, the substance may be detected in the urine, by using an appro- priate test. Dr. Barton found, that frogs, confined in dry glass ves- sels, became enfeebled, diminished in size, and unable to leap; but that, on the introduction of a small quantity of water, they soon acquired their wonted vigour, became plump, and as lively as usual in their motions.6 M. W. F. Edwards7 of Paris, is, also, in favour of absorp- tion being carried on by the skin to a considerable extent. 1 Human Physiology, § 462, Lond, 1842. 2 Parent-Dnchatelet, Hygiene Publique, Paris, 1836; and the remarks of the author in his Human Health, p. 77, Philad, 1844. 3 New York Med. Repos, vols. i. and iii. 1810-11. * Med. and Physical Journ, xxxi. 80, Lond, 1814. 5 Philad. Medical and Physical Journal, i. 288, Philad, 1808. 6 Klapp, Inaugural Essay on Cuticular Absorption, p. 30, Philad, 1805. 7 Sur lTnfluence des Agens Physiques; or Drs. Hodgkin and Fisher's translation p 61 and p. 187, &c, Lond, 1832. ' '' ' CUTANEOUS. 689 To deny cutaneous absorption altogether is impossible. It is a channel, in fact, by which we introduce one of our most active reme- dial agents into the system;—and it has not unfrequently happened, where due caution has been omitted, that the noxious effects of different mineral and other poisons have been developed by their application to the surface, but it is by no means common or easy, when the cuticle is sound, unless the substance employed possesses unusually penetrat- ing properties. M. Chaussier found, that to kill an animal, it is suffi- cient to make sulphuretted hydrogen gas act on the surface of the body, taking care that none gets into the air-passages; the researches of Prof. J. K. Mitchell1 have also shown that this gas is powerfully pene- trant. Unless, however, the substances, in contact with the epidermis, are of such a nature as to attack its chemical composition, there is usually no extensive absorption. It is only of comparatively late years, that physiologists have ven- tured to deny, that the water of a bath, or the moisture from a damp atmosphere, is taken up under ordinary circumstances; and if, in such cases, the body appears to have increased in weight, it is affirmed, and with some appearance of truth, that this may be owing to diminution of the cutaneous transpiration. It is, indeed, probable, that one great use of the epidermis is to prevent the inconveniences to which we should necessarily be liable, were such absorption easy. This is confirmed by the fact, that if the skin be deprived of the epidermis, and the vessels that creep on the outer surface of the true skin be thus exposed, ab- sorption occurs as rapidly as elsewhere. J. Miiller affirms, that saline solutions applied to the corium penetrate the capillaries in a second of time. To insure this result in inoculation and vaccination, the matter is always placed beneath the cuticle; and, indeed, the small vessels are generally slightly wounded, so that the virus gets immediately into the venous blood. Yet—it is proper to remark—the lizard, whose skin is scaly, after having lost weight by exposure to air, recovers its weight and plumpness when placed in contact with water; and if the scaly skin of the lizard permits such absorption, M. Edwards thinks it impos- sible not to attribute this property to the cuticle of man. When the epidermis is removed, and the system is affected by substances placed in contact with the true skin, we have the endermic method of me- dication. M. Se'guin2 instituted a series of experiments to demonstrate the ab- sorbent or non-absorbent action of the skin. His conclusion was, that water is not absorbed, and that the epidermis is a natural obstacle to the action. To discover, whether this was the case as regarded other fluids, he experimented on individuals labouring under venereal affec- tions ' who immersed their feet and legs in a bath, composed of sixteen pints' of water and three drachms of corrosive chloride of mercury, for an hour or two, twice a day. Thirteen, subjected to the treatment for twenty-eight days, gave no signs of absorption; the fourteenth was manifestly affected, but he had itchy excoriations on the legs; and the i Amer. Journal of the Med. Sciences, vii. 44; and p. 68 of this work. 2 Annales de Chimie, xc. 185. vol. I.—44 690 ABSORPTION. same was the case with two others. As a general rule, absorption ex- hibited itself in those only whose epidermis was not in a state of integrity. At the temperature of 74° Fahrenheit, however, the sublimate was oc- casionally absorbed, but never the water. From other experiments, it appeared evident, that the most irritating substances, and those most disposed to combine with the epidermis, were partly absorbed, whilst others were apparently not. Having weighed a drachm (seventy-two grains, poids de marc) of calomel, and the same quantity of camboge, scammony, salt of alembroth, and tartar emetic, M. Se'guin placed an individual on his back, washed the skin of the abdomen carefully, and applied to it these substances at some distance from each other, covering each with a watch-glass, and maintaining the whole in situ by a linen roller. The heat of the room was kept at 65°. M. Se'guin remained with the patient,' in order that the substances should not be displaced: and he protracted the experiment for ten hours and a quarter. The glasses were then removed, and the substances carefully collected and weighed. The calomel was reduced to 71^ grains. The scammony weighed 71f ; the camboge, 71; the salt of alembroth, 62 grains,1 and the tartar emetic 67 grains.2 It requires, then, in order that matters shall be absorbed by the skin, that they shall be kept in contact with it, so as to penetrate its pores, or the channels by which the cutaneous transpiration exudes; or else that they shall be forced through the cuticle by friction,—the iatraleptic mode. In this way, the substance comes in contact with the cutaneous vessels, and enters them probably by imbibition. Certain it is, that mercury has been detected in the venous blood by Colson, Christison, Cantu, Autenrieth, Zeller, Schubarth, and others.3 Not long after the period that M. Se'guin was engaged in his experi- ments, Dr. Rousseau,4 of Philadelphia, contested the existence of ab- sorption through the epidermis, and attempted to show, in opposition to the experiments we have detailed, that the pulmonary organs, and not the skin, are the passages by which certain substances enter the system. By cutting off all communication with the lungs, which he effected by breathing through a tube communicating with the atmo- sphere on the outside of the chamber, he found, that although the sur- face of the body was bathed with the juice of garlic, or the spirit of turpentine, none of the qualities of these fluids could be detected, either in the urine, or the serum of the blood. From subsequent experiments, performed by Dr. Rousseau, assisted by Dr. Samuel B. Smith,5 and many of which Professor Chapman6 witnessed, the following results were deduced. First, That of all the substances employed, madder and rhubarb were those only that affected the urine,—the latter of the two more readily entering the system; and secondly, that the power of ab- sorption is limited to a very small portion of the surface of the body. 1 Several pimples were excited on the part to which it was applied. 2 Magendie's Precis, &c, ii. 262. 3 The author's General Therapeutics and Materia Medica, 4th edit, i. 90, Philad, 1850. 4 Experimental Dissert, on Absorption, Philad, 1800. 5 Philad. Medical Museum, i. 34, Philad, 1811. 6 Elements of Therapeutics and Materia Medica, 6th edit, i. 65, Philad, 1831, ACCIDENTAL. 691 The only parts, indeed, that seemed to possess it, were the spaces be- tween the middle of the thigh and hip, and between the middle of the arm and shoulder. Topical bathing, with a decoction of rhubarb or madder, and poultices of these substances applied to the back, abdo- men, sides, or shoulders, produced no change in the urine; nor did immersion of the feet and hands for several hours in a bath of the same materials afford the slightest proof of absorption. From these and other facts, sufficiently discrepant it is true, we are justified in concluding, that cuticular absorption, under ordinary circum- stances, is not easy; but we can readily conceive, from the facility with which water soaks through animal tissues, that if the animal body be immersed sufficiently long in it, and especially if the vessels have been previously drained, imbibition may take place to a considerable extent. This, however, would be a physical absorption, and might be effected as well in the dead as in the living body. b. Other Accidental Absorptions. Amongst the adventitious absorptions have been classed all those that are exerted upon substances retained in the excretory ducts, or situate in parts not natural to them. The bile, arrested in one of the biliary ducts, affords us, in jaundice, a familiar example of such absorption by the positive existence of bile in the bloodvessels; although the yellow colour has been gratuitously supposed to be caused by an altered con- dition of the red globules, and not by the presence of bile. This con- dition of the red globules would account for some of the symptoms,— as the yellow colour of the skin, and urine,—but it does not explain the clayey appearance, which the evacuations present, and which has been properly ascribed to the absence of the biliary secretion. We have, moreover, examples of this kind of absorption, where blood is effused into the areolar membrane, as in the case of a common sprain, or in those accumulations of fluid in various cavities, that are found to dis- appear by time;—the serous portion being taken up at first with some of the colouring matter, and, ultimately, the fibrin. In the case of ac- cumulation of the serous fluid, that naturally lubricates cavities, it is of such a character—the aqueous portion at least—as to be imbibed with facility, and probably passes into the veins, in this manner,—the func- tions of exhalation and absorption consisting mainly, in such case, of transudation and imbibition. But absorption is not confined to these fluids. It must, of course, be exerted on all morbid deposits; and it is to excite the action of the ab- sorbents, that our remedial agents are directed. This absorption—in the case of solids—is of the interstitial kind; and, as the morbid forma- tion has to undergo an action of elaboration, it ought to be referred to lymphatic agency. To conclude the function of absorption:—All the products,—whether the absorption has been chyliferous, lymphatic, or venous,—are united in the venous system, and form part of venous blood. This fluid must, consequently, be variable in its composition, in proportion to the quan- tity of heterogeneous materials taken up by the veins, and the activity 692 ABSORPTION. of chyliferous and lymphatic absorption. It is also clear, that, between the parts of the venous system into which the supra-hepatic veins,— loaded with the products of intestinal absorption of fluids,—enter, and the opening of the thoracic duct into the subclavian, the blood must differ materially from that which flows in other parts of the system. All, however, undergo admixture in their passage through the heart; and all are converted into arterial blood by the function, that will next engage us,—Respiration. END OF VOL. I. jA.MERICAN JOURNAL OP THE MEDICAL SCIENCES. ^v™medicale, - rT~T~T~T~T~^^~T~ France. L'UNION MEDICALE,......... ZEITSCHRIFT EUR DIE GESAMMTE MEDECIN, - - . Austria VIERTELJAHRSCIIIIIFT FUR DIE PRAKTISCHE HEILKUNDE, Bohemia AND NUMEROUS OTHERS. An evidence of the success which has attended these efforts may be found in the constant and steady increase in the subscription list, which renders it advisable for gentlemen desiring the Journal, to make known their wishes at an early day, in order to secure a year's set with certainty, the publishers having frequently been unable to supply copies when ordered late in the year. To their old subscribers, many of whom have been on their list for twenty or thirty years, the publishers feel that no promises are necessary; but those who may desire for the first time to subscribe, can rest as- sured that no exertion will be spared to maintain the Journal in the high position which it has occupied for so long a period. With a character so well established, the publishers hardly deem it worth while to adduce any of the commendatory notices which the Journal has received from all quarters. A few are, however, subjoined, to show the estimation in which it is held, abroad as well as at home. Several of the American Journals are before us. * * * Of these, the American Journal of the Medical Sciences is by far the better periodical; it is, indeed, the.best of the transatlantic medical publications; and, to make a comparison nearer home, is in most respects superior to the great majority of European works ofthe same description.—The London Lancet. We need scarcely refer our esteemed and highly eminent contemporary (The American Journal ofthe Medical Sciences) from whom we quote, to our critical remarks ofthe opinions of our own countrymen, or to the principles which influence us in the discharge of our editorial duties. Our copious extracts from his unequalled publication, unnoticing multitudes of others which come be- fore us, are the best proof of the esteem which we entertain for his talents and abilities.—London Medical and Surgical Journal. The American Journal of the Medical Sciences is one of the most complete and best edited of the numerous periodical publications ofthe United States.—Bulletin des Sciences Medicates. We fully agree with the committee in awarding to the American Journal of Medical Sciences the first place in their journalistik. The long standing of this publication, the support which it has received from many of the best writers in different parts ofthe country, and the elevated lite- rary character and strict impartiality which have distinguished it, have rendered it the favorite organ ofthe profession. In the long list of its contributors, we observe the names of many whose reputation is well established on this side of the Atlantic. Its pages record many of those daring operations which are dwelt on with so much pride by the American surgeon, and contain numer- ous highly valuable memoirs in all the departments of medical science.—Edinburgh Monthly Journal and Retrospect ofthe Medical Sciences. This periodica] is so well known through the coantry, and a complete series of it so generally contained in public libraries, that a general index to it from the commencement would be one of the mo6t acceptable offerings which could be made to the medical reader. * * * It must be owned that the patriarchal quarterly has not fallen below its own high standard of merit, at the point where the committee takes leave of it for the present.—Dr. Holmes's Report to the American Medical Association. This is the only Medical Quarterly ofthe United States. Published originally twenty-nine years ago, and subjected to the control of different editors, it has always preserved the highest character among medical practitioners in every State of our wide-spread Union. And notwithstanding the ability with which other similar works have been conducted, and are now managed, it still retains undiminished its enviable reputation. Of the twenty medical periodicals of our country this one has the best claims to the title it has assumed. American it is by seniority, by its size, and by its worth. Indeed, if we are not mistaken in our estimation of it, this Journal merits a more extended and significant appellation. Since the lamented death of Dr. James Johnson, the able and distin- guished editor ofthe Medico-Chirurgical Review, and the discontinuance ofthe British and Foreign Medical Review, we have no hesitation to pronounce the American Journal of the Medical Sci- ences to be by far the most valuable now published in the world. The Edinburgh Medical and Surgical Journal is not at all to be compared to it. The Dublin Quarterly Journal of Medical Science we prize most of those now published in Europe ; but still we deem it inferior in the character and value of its communications, as also in its reviews and selections, to the one now under consideration. We know of no French or German, and still less Italian or Spanish medical periodical that we would exchange for the American.—Southern Med. and Surg. Journal. The American Journal of the Medical Sciences may, without disparagement to any other, be said to stand at the head of American Medical Journals, being the oldest and certainly one of the very best Under the head of Original Communications, it contains articles from eminent mem- bers of the profession in every part of this country. Its reviews and bibliographical notices are numerous and impartial ; and under the heads of Foreign and Domest.c Summaries, it sums up with ereat care whatever is new and valuable in periodical medical literature. The tone of the work from its commencement to the present time, has been uniformly elevated, dignified, and courteous In this respect we think its influence has been highly favorable upon the entire pro- fession We would recommend it to any physician.—III. und Ind. Med. and Surg. Journal. We hesitate not to pronounce the Journal which Dr. Hays has so long and ably edited, an honor to American Medicine, and one of the/our best medical periodicals, in our language, in the world. —N. Y. Annalist. 4 AMERICAN JOURNAL OP THE MEDICAL SCIENCES. To show the extent and variety of the information presented to the subscribers of the American Journal ofthe Medical Sciences, the publishers subjoin A CONDENSED SUMMARY OF THE CONTENTS OF THE NUMBER FOR OCTOBER, 1852. ORIGINAL COMMUNICATIONS. Memoirs and Cases, pp. 301-402. Art. I. Statistics of Fractures and Dislocations treated in the Pennsylvania Hospital during the ten years from 1840 to 1849 inclusive. By George W. Norris, M. D., one of the Surgeon's of the Institution. II. On Hemorrhage from the Umbilicus in New-born Infants, with an Analysis of Forty- six Cases. By Francis Minot*M. D. III. On Cell Organization. By James J. Waruig, M. D. IV. Case of Double Uterus. By Wm. Kelly, M. D., Physician to Blackwell's Island Hospitals [with three wood-cuts]. V. Extracts from the Records ofthe Boston Society for Medical Improvement. By Wm. W. Morland, M. D., Secretary. VI. On the Efficacy of Belladonna as a Remedy in Pertussis. By Hiram Corson, M. D., of Montgomery County, Pa. VII. A very large Mesenteric Tumor, simu- lating Ovarian Disease, successfully extirpated. By P. J. Buckner, M. D., of Cincinnati, O. VIII. A Case of Leucocythemia. Communicated by Addinell Hewson, M. D., Resident of Pennsylvania Hospital [with a wood-cut]. IX. Blindness in one Eye attended with Atrophy ofthe Optic Nerve and Optic Lobe. By Jeffries Wyman, M. D. [with two wood-cuts]. X. Cases of Cerebral Dis- ease. By Thomas F. Cook, one of the Visiting Physicians to Bellevue Hospital, N. Y. XI. Uri- nary Deposit of Epithelial Nuclei. By John Bacon, Jr., M. D., Chemist and Microscopist of the Mass. General Hospital.' XT I. Crystals of H&matoidin in the bloody fluid from a Tumor. By John Bacon, Jr., M. D. XIIl. On Inoculation and Vaccination. By Jesse Young, M. D., of Chester, Pa. XIV. Case of Hermaphrodism, involving the Operation of Castration, and illustrating a new principle in Juridical Medicine. By S. D. Gross, M. D., of Louisville, Ky. XV. Case of Ischuria Renalis. By James McGrath, M. D., of Pittsburgh, Pa. XVI. On the Anemia of Preg- nant Females. By George Martin, M. D. of Delaware County, Pa. XVII. On Neuralgia of the Scalp. By J. Brooks, M. D., of Pittsburgh, Pa. XVIII. Treatment of Acute Rheumatism with Lemon-Juice. By Robert H. Cummings, M. D., of Wheeling, Va. Reviews, pp. 403-460. Art. XIX. Transactions ofthe Medical Society of the State of Pennsylvania, at its Annual Ses- sion held in Philadelphia, May, 1852 : Vol. II. XX. Sketches of Brazil; including New Views on Tropical and European Fever; with Remarks on a Premature Decay of the System incident to Europeans on their Return from Hot Climates. By Robert Dundas, M. D. XXI. Du Rachitis, de la Fragilitc des Os, de l'Ostepmalacie. Par E. J. Beylard. XXII. De Adipis Concoctione et Ab- sorptione. Scripsit Ed. Lentz. De Bilis Functione ope Fistulas Vesica? Felleae indagata. Scripsit Reinhold Schellbach. XXIII. The Principles and Practice of Surgery. Illustrated by three hun- dred and sixteen engravings on wood. By William Pirrie, F. R. S. E. Edited, with Additions, by John Neill, M. D. Bibliographical Notices, pp. 461-479. Art. XXIV. A Treatise on the Practice-of Medicine. By George B. Wood, M. D. XXV. Four Repprts of Institutions for the Insane in the United States. XXVI. On the Preservation of the Health of Women at the Critical Periods of Life. By E. J. Tilt, M. D. XXVII. On he Employ- ment of Water in Surgery. By Alphonse Auguste Amussat, of Paris. Translated from the French by Frank H. Hamilton. XXVIII. An Analysis of Physiology. By John J. Reese, M. D. XXIX. Transactions ofthe Medical Society ofthe State of New York, during its Annual Session, held at Albany, February 3, 1852. QUARTERLY SUMMARY OF THE IMPROVEMENTS AND DISCOVERIES IN THE MEDICAL SCIENCES. FOREIGN INTELLIGENCE. Anatomy and Physiology, pp. 481-489. 1. On the Functions of the Membrana Tympani, the Ossicles and Muscles of the Tympanum, and ofthe Eustachian Tube in the Human Ear : with an Account ofthe Muscles ofthe Eustachian Tube, and their Action in different Classes of Animals. By Joseph Toynbee, Esq., F. R. S. 2. On the Structure, Function, and Diseases ofthe Liver; and on the Action of Cholagogue Medi- cines. By C. Handheld Jones, M. D. 3. Connection of the Recollection of Words with the An- terior Lobes of the Brain. By Dr. Alison. 4. Lateral Hermaphroditism. By Dr. Banon. 5. Ab- sence of Sternum. By Dr. Benjamin. Organic Chemistrt. pp. 4S9-491. 6. Presence of a Free Acid in the Lungs. By M. Verdeil. 7. On the Gastric Juice ofthe Jackal. By Dr. Landerer. 8. On the Action of Ozone on Miasmata. By M. Schonbein. 9. On the Fats of different Regions ofthe Body. By M. Lassaigne. AMERICAN JOURNAL OF THE MEDICAL SCIENCES. 6 Contents of No. 48, New Series, for October, 1852—(Continued.) Materia Medica and Pharmacy, pp. 491-498. 10. Physiological Action of Quinine. By Professor J. H. Bennett. 11. External Use of the Ni- trate of Lead. Dr. Ogier Ward. 12. On the Use of Manganese as an Adjuvant to Iron. By M. Petrequin. 13. Preparation of Manganese and Iron. By M. Burin-Dubuisson. 14. Absorption of Iodine from Ulcerated and Serous Surfaces. By M. Bonnet. 15. Effects of the prolonged and excessive Use of Iodine. By Mr. Langston Parker. 16. Guarana. By D. Ritchie. 17. Neat'8- foot Oil as an Occasional Substitute for Cod-liver Oil. By Dr. C. R. Hall. Medical Pathology and Therapeutics, and Practical Medicine, pp. 499-524. 18. General Treatment of Continued Fever. By Professor Bennett. 19. Treatment of Contin- ued Fever by Quinine. By Drs. Bennett, Christison, &c. 20. Treatment of Rheumatic Pericar- ditis. By J. R. Bennett, M. D. 21. Rapid Cure of Itch. By M. Hardy. 22. Treatment of Her micrania and Facial Neuralgia. By M. Cazenave. 23. Employment of Oxygenated Water in Asphyxia. By M. Ruspini. 24. Internal Administration of Chloroform in Delirium Tremens. R. H. Butcher. 25. On the Pathology and Treatment of Lencorrhcea based upon the Microscopical Anatomy ofthe Os and Cervix Uteri. By W.Tyler Smith, M. D. 26. Complications of Scarlatina. By Dr. Alex. Wood. 27. Temporary Albuminuria. By Dr. Jas. W. Begbie. 28. Hay Fever. By Wm. P. Kirkman, Esq. 29. On some of the Principal Effects resulting from the Detachment of Fibrinous Deposits from the Interior ofthe Heart, and their Mixture with the Circulating Blood. By Wm. Senhouse Kirkes, M. D. 30. On the Influence exerted by Chronic Diseases upon the Composition ofthe Blood. By MM. Becquerel and Rodier. 31. On the Protection against Small- pox afforded by Vaccination, illustrated by the Returns ofthe Army, Navy, and the Royal Military Asylum. By T. G. Balfour, M. D. 32. Smallpox. By Dr. John Webster. 33. Hereditary Trans- mission of Phthisis. By M. Guillot. 34, On the Influence of Pregnancy and the Puerperal State on the Progress of Phthisis. By MM. Grisolle and Dubreuilh. Epidemics, pp. 525-528. < 35. The Furunculoid Epidemic. By Thomas Hunt, Esq. 36. Epidemic of Carbuncular Inflam- mation of the Lip. Surgical Pathology and Therapeutics, and Operative Surgery, pp. 529-547. 37. Are Primary or Secondary Amputations to be preferred ? By G. J. Guthrie. 38. On the Surgical Operations usually adopted for Retention of Urine. By Edward Cock, Esq. 39. Treat- merit of Cancer. By Alexander Ure, Esq. 40. Excision of Cancer. By Dr. W. H. Walshe. 41. Treatment of Lup'us Exedens. By Mr. Startin. 42. Local Treatment of Ulcers of the Leg. By H T. Chapman, Esq. 43. New Method of Reducing Strangulated Hernia. By Dr. T. A. V\ ise. 44 Puncture of the Abdomen in Tympanites. By M. Labric. 45. Cicatrices of Burns. Dr. W. V Pettigrew. 46. Lunation of the Sacrum. By M. Foucher. 47. Cases of Atresia Am in the Adult, with Preternatural Anus. By Dr. Deutsch. 48. Consequences of Congenital Phimosis. BvM Fleury. 49. Supposed Aneurism of Bone. Alleged Death from Chloroform. By M. Pa- mard. 50. A form of Sanguineous Tumor ofthe Cranium. By MM. Stromeyer and Dufour. Midwifery, pp. 548-550. 51. How to form a Correct Estimate of the Dimensions of the Female Pelvis. By G. Vrolik. 52. Pregnancy reputed Anormal, and terminating Naturally. By M. Huguier. Medical Jurisprudence and Toxicology, pp. 550-560. 53. Action of the Gastric Fluid on the Stomach. By Dr. Dalton. 54 Strychnine in British Beer, Pale Ale &c Bv M. Payen. 55. Poisoning by Arsen.ate of Soda. 56. Should the Use of White Lead as a Paint be forbidden by Public Authority? By Dr. H DeCastelnau 57 Lead, Cider, Champagne. 58. Chloride of Palladium, a delicate Test for odine By M. Lassa.gne 59 ErgotP; easy Method of pulverizing and preserving it. By M. V.el. 60 A new Organic Be from Ergotin. By Dr. F. L. Winckler. 61. Combinations of Arsen.ous Ac.d and Corrosive Subli- mate w.th Albumen. 62. Ferrate of Potash as an Antidote for Arsenic. By Chattel. AMERICAN INTELLIGENCE. Original Communications, pp. 561-574. Extnordinarv Precocity in the Development ofthe Male Sexual Organs and Muscular System in ru m ^ vy, VnM Bv Robert Kin FORENSIC MEDICINE. BY WILLIAM B. CARPENTER, M. D., F. R. S., Examiner in Physiology and Anatomy in University College, London; author of "Comparative Physiology," •• Elements of Physiology," &c. FIFTH AMERICAN, FROM A NEW AND REVISED LONDON EDITION. With Notes and Additions bt F. G. SMITH. Jr., M. D., Professor of Institutes of Medicine in the Pennsylvania Medical College. In one very large and handsome octavo volume, of about eleven hundred pages. WELL AND STRONGLY BOUKD IN LEATHER, WITH RAISED BANDS. With Two Lithographic JPlates, and about Three Hundred .Eng-roe/ng-* on Wood. The great increase in the size of this work, and the thorough revision which every portion has experienced at the hands of the author, have caused the unexpected delay which has occurred in its appearance. The large amount of new and important matter introduced, and the rewriting of numerous chapters, as well as an entire change in the arrangement, render this rather a new work than a new edition. Its passage through the press has been carefully superintended by Professor Smith ; and, with a greatly improved series of illustrations, and very superior style of mechanical execution, the publishers confidently present this edition as worthy a continuance ofthe universal favor with which this work has been received as a standard text-book for the student and practitioner. We have much satisfaction in declaring our opinion that this work is the best systematic treatise on phy- siology in our own language, and the best adapted for the student existing in any language.—Medico-Chi- rurgical Review. This work as it now stands is the only Treatise on Physiology in the English language, which exhibits a clear and connected, and comprehensive view ofthe present condition of that science.—Edinburgh Monthly Med. Journal. Though the resources of the author's comprehensive mind are apparently devoted to the advancement of new beginners in study, there is a splendid exhibition ofthe powers of analysis an uncommon degree of suc- cess in making abstruse objects clear, and in forcibly impressing upon others the laws of life which he so well understands, which will give ec4al to Dr. Carpenter's reputation when he will be insensible to praise. All who can afford to have a gcod system of physiology should possess this ; and those who are able to keep pace with the progress of science should not be without it. No necessity seems to exist for extracting from lis pages, or commenting especially on any particular parts or portions of the volume, because it is presumed that all who can will avail themselves of it. Probably this improved edition does not cost more man one-third the price asked for it in England, and yet it is superior in very many respects.—Boston Med. and Surg. Journal. A NEW CLINICAL MANUAL—(Just Ready.) WHAT TO OBSERVE-AT THE BEDSIDE, PUBLISHED BY AUTHORITY OF THE LONDON MEDICAL SOCIETY OF OBSERVATION. In one neat volume, royal 12mo. The object of this little work is to furnish a guide to the practitioner in making a satisfactory diagnosis at the bedside of his patient. In a small compass, and systematically arranged, it pre- sents the various symptoms and points about which inquiries should be made, and it villbe found a very valuable assistant to the-younger physician, who may sometimes be at loss as to the direction in which his investigations should be pushed. By the arrangement adopted, the reader can imme- diately find any particular class, either of diseases or symptoms, concerning which he may be desir- ous of a guide, while the auspices under which the volume appears is a sufficient guarantee of its practical character and scientific position. SHARPEY AND QUAIN'S SYSTEM OF HTJMAN ANATOMY. HUMAN ANATOMY. BY JONAS QUAIN, M. D. FROM THE FIFTH LONDON EDITION. EDITED BY RICHARD QUAIN, F.R. S., and WILLIAM SHARPEY, M. D., F. R. S., Professors of Anatomy and Physiology in University College, London. Revised, with Notes and Additions, BY JOSEPH LEIDY, M.D. Complete in two large octavo volumes, of about thirteen hundred pages. BEAUTIFULLY ILLUSTRATED, WITH OVER FIVE HUNDRED ENGRAVINGS ON WOOD. It is indeed a work calculated to make an era in anatomical study, by placing before the student every de- partment of his science, with a view to the relative importance of each; and so skillfully have the different parts been interwoven, that no one who makes this work the basis of his studies will hereafter have any ex- cuse for neglecting or undervaluing any important particulars connected with the structure ofthe human frame; and whether the bias of his mind lead him in a more especial manner to surgery, physic, or physiolo- gy, he will find here a work at once so comprehensive and practical as to defend him from exclusi veness on the one hand, and pedantry on the other.—Monthly Journal and Retrospect ofthe Medical Sciences. ANCHARD & LEA'S LATE MEDICAL PUBLICATIONS. 11 WORKS BY CHARLES D. MEIGS, M. D., Professor of Midwifery and the Diseases of Women and Children in the Jefferson Medical College of Philadelphia, &c. OBSTETRICS. Obstetrics: the Science and the Art. Second edition, revised, with one hundred and thirty-one illustrations. In one large and handsome octavo volume, of over seven hundred and fifty pages. The rapidity with which this work has assumed the position of a standard authority renders it unnecessary lor the publishers, in presenting a new edition, to say more than that the author has endeavored to render it still more worthy of the favor with which it has been received, by very numerous additions, and a careful revision. The new matter thus added constitutes not less than one-sixth of the whole, to accommodate which the size of the page has been increased, and the volume itself enlarged by nearly a hundred pages. Among other additions may be particularized A NEW AND IMPORTANT CHAPTER ON CHILDBED FEVER. The series of illustrations has also been much improved, and the mechanical execution of the work will be found in every way superior. DISEASES OF FEMALES. Woman: her Diseases and their Remedies: a Series of Letters to his Class. Second edition, revised and enlarged. In one large and beautifully printed octavo volume, of nearly seven hundred pages. The value attached to this work by the profession is sufficiently proved by the rapid ex- haustion of the first edition, and consequent demand for a second. In preparing this, the author has availed himself of the opportunity thoroughly to revise and greatly to improve it. The work will therefore be found completely brought up to the day, and in every way worthy of the reputation which it has so immediately obtained. The merits ofthe first edition of this work were so generally appreciated, and with such a high degree of favor by the medical profession throughout the Union, that we are not surprised in seeing a second edition of it. It is a standard work on the diseases of females, and in many respects is one of the very best of its kind in the English language. Upon the appearance ofthe first edition, we gave the work a cordial recep- tion, and spoke of it in the warmest terras of commendation. Time has not changed the favorable estimate we placed upon it, but has rather increased our convictions of its superlative merits. But we do not now deem it necessary to say more than to commend this work, on the diseases of women, and the remedies for them, to the attention of those practitioners who have not supplied themselves with it. The most select library would be imperfect without it.— The Western Journal of Medicine and Surgery. There is an off-hand fervor, a glow and a warm-heartedness infecting the effort of Dr. Meigs, which is en- tirely captivating, and which absolutely hurries the reader through from beginning to end. Besides, the book teems with solid instruction, and it shows the very highest evidence of ability, viz., the clearness with which the information is presented. We know of no better test of one's understanding a subject than the evidence ofthe power of lucidly explaining it. The most elementary, as well as the obscurest subjects, un- der the pencil of Prof. Meigs, are isolated and made to stand out in such bold relief, as to produce distinct impressions upon the mind and memory ofthe reader.—The Charleston Medical Journal. DISEASES OF CHILDREN. Observations on certain of the Diseases of Young Children. In one handsome octavo volume, of two hundred and fourteen pages. It puts forth no claims as a systematic work, but contains an amount of valuable and useful matter, scarcely to be found in the same space in our home literature. It cannot but prove an acceptable offering to the profession at large.—N. Y. Journal of Medicine. We lake much pleasure in recommending this excellent little work to the attention of medical practition- ers. It deserves their attention, and after they commence its perusal, they will not willingly abandon it, until they have mastered its contents. We read the work while suffering from a carbuncle, and its fasci- nating pages often beguiled us into forgetfulness of agonizing pain. May it teach others to relieve the afflic- tions ofthe young.— The Western Journal of Medicine and Surgery. MEIGS'S COLOMBAT ON FEMALES. A Treatise on the Diseases of Females, and on the Special Hygiene of their Sex. By Colombat De L'Isere, M. D. Translated, with many Notes and Additions, by C. D. Meigs, M. D. Second edition, revised and improved. In one large volume, octavo, of seven hundred and twenty pages, with numerous wood-cuts. We are satisfied it is destined to lake the front rank in this department of medical science. It is in facta complete exposition ofthe opinions and practical methods ot all the celebrated practitioners of ancient and modern times— New York Journ. of Medicine. 12 BLANCHAIID & LEA'S LATE MEDICAL PUBLICATIONS. NEW EDITIONS, RECENTLY ISSUED, OF THE FOLLOWING IMPORTANT AND VALUABLE WORKS. CHURCHILL ON FEMALES^BY CONDIE-INOW READY.) On the Diseases of Women, including those of Pregnancy and Childbed. By Fleetwood Churchill, M. D., F. C. D. & E., M. K. I. A., Ac. A new American edition, revised by the Author. With Notes and Additions by D. Francis Condie, M. D. In one large and handsome octavo volume of nearly seven hundred pages. From the Author's Preface. In reviewing this edition, at the request of my American publishers, I have inserted several new sections and chapters, and I have added, I believe, all the information we have derived from re- cent researches; in addition to which the publishers have been fortunate enough to secure the services of an able and highly esteemed editor in Dr. Condie. We know of no author who deserves tnat approbation, on " the diseases of females,*' to the same extent that Dr. Churchill does. His, indeed, is the only thorough treatise we know of on the subject, and it may be commended to practitioners and students as a masterpiece in its particular department. The former editions of this work have been commended strongly in this journal, and they have won their way to an extended, and a well-deserved popularity. This fifth edition, before lis, is well calculated to maintain Dr. Churchill's high reputation. It was -evised and enlarged by the author, for his American publishers and it seems to us that there is scarcely aa v species of desirable information on its subjects, that may not be fonnd in this work. — The Western Journa of Medicine and Surgery. BENNETT ON THE UTERUS-(NOW READY.) A Practical Treatise on Inflammation of the Uterus and its Ap- pendages, and on Ulceration and Induration of the Neck of the Uterus. By Henry Bennett, M. D., Obstetric Physician to the Western Dispensary. Third American edition. In one neat octavo volume of 350 pages, with wood-cuts. BARTLETT ON FEVERS-(NOW READY.) The History, Diagnosis, and Treatment of the Fevers of the United States. By Elisha Bartlett, 31. D., Professor of Materia Medica and Medical Jurisprudence in the College of Physicians and Surgeons, N. Y. Third edition, revised and improved. In one very neat octavo volume of 600 pages. In preparing a new edition of this standard work,the author hasavailed himself of such observa- tions and investigations as have appeared since the publication of his last revision, and he has endeavored in every way to render it worthy of a continuance ofthe very marked favor with which it has been hitherto received. The masterly and elegant treatise by Dr. Bartlett is invaluable to the American student and practitioner. — Dr. Holmes's Rrport to the Nat. Med. Association. We regard it, from the examination we have made of it, the best work on fever extant, in our language, and as such cordially recommend it to the medical public.—St. Louis Med. and Surg. Journal. CARPENTER'S ELEMENTS OF PHYSIOLOGY. Elements of Physiology, including Physiological Anatomy. Second American, from a new and revised London edition. With one hundred and ninety illustrations. In one very handsome octavo volume. In publishing the first edition of this work, its title was altered from that ofthe London volume by the substitution ofthe word " Elements" for tllat of "Manual," and, with the author's sanction, the title of" Elements" is still retained, as being more expressive ofthe scope ofthe treatise. A comparison ofthe present edition with the former one will show a material improvement, the au- thor having revised it thoroughly, with the view of rendering it completely on a level with the most advanced state of the science. By condensing the less important portions, these numerous additions have been introduced without materially increasing the bulk of the volume, and while numerous illustrations have^een added, and the general execution of the work improved, it has been kept at its former very moderate price. HORNER'S ANATOMY. Special Anatomy and Histology. By William E. Horner, M. D., Profes- sor of Anatomy in the University of Pennsylvania, &c. Eighth edition. Ex- tensively revised and modified to 1851. In two large octavo volumes, handsomely printed, with several hundred illustrations. This work has enjoyed a thorough and laborious revision on the part of the author, with the view of bringing it fully up to the existing state of knowledge on the subject of general and special anatomy. To adapt it more perfectly to the wants ofthe student, he has introduced a large number of additional wood-engravings, illustrative ofthe objects described, while the publishers have en- deavoreU to render the mechanical execution ofthe work worthy ofthe extended reputation which it has acquired. The demand which has carried it to an EIGHTH EDITION is a sufficient evidence ofthe value ofthe work, and of its adaptation to the wants ofthe student and professional reader. WORKS FOR PRIVATE AND DISTRICT LIBRARIES. 13 Lord Campbell's Biographies of the Chancellors. LIVES OF THE LORD CHANCELLORS 2lnb Keepers of tt)c (!>rcat Seal of Cnglanb, FROM THE EARLIEST TIMES TO THE REIGN OF KING GEORGE IV. BY JOHN LORD CAMPBELL, A.M., F. R. S. E. Second American, from the Third London edition. COMPLETE I.N SEVEN VERY HANDSOME CROWN OCTAVO VOLUMES, CONTAINING NEARLY Four Thousand Pages. (Just Issued.) TO BE HAD IN VARIOUS STYLES OF BINDING. This has been reprinted from the author's most recent edition, and embraces his extensive modifications and additions. It will therefore be found eminently worthy a continuance of the great favor with which it has hitherto been received. To afford some idea of the scope of the work, the publishers subjoin a list of the biographies contained in each volume. VOLUME I.—A.D. 605 to 1547.—Anglo-Saxon Chancellors—Maurice, Osmond, Arfas- tus, Baldrick, Herman, W. Giffard, Ralph Bloet, Ralph Flambard, Bishopof Salisbury, Waldric, Geoffrey, Herbert, Geoffrey Rtifus, Ranulphus, Bishopof Lincoln, Roger Pauper, Philip, Robert de Gand, Reginald, William Fitzgilbert, Thomas a Becket, John, Ralph de Warnaville, Walter de Constantiis, Geoffrey, Nigel Bishop of Ely, Walter de Bidun, William Longchamp, Eustace Bishop of Ely, Walter Hubert, Walter de Gray, Richard de Marisco, Ralph de Neville, Simon the Norman, Ranulph Briton, Silvester de Everden, John Maunsel, John de Lexington, Queen Eleanor, William de Kilkenny, Henry de Wengham, Nicholas deElv, Walter de Merton, Thomas de Cantilupe, Walter Giffard, Geoffrey Giffard, John de Chishull, Richard de Middleton, Robert Burnel, John de Langton, William de Grenefield, William de Hamilton, Ralph de Ealdock, Wal- ter Reynolds, John de Sandale, John de Hotham, John de Salmon, Robert de Baldock, Henry de Burgersch, John de Stratford, Richard de Bury, Robert de Stratford, Richard de Bynteworth, Sir Robert Bourchier, Sir Robert Parnynge, Robert de Sadyngton, John de Otfard, John de Thoresby, William de Edington, Simon de Langham, William de Wickham, Sir Robert Thorpe, Sir John Kny vet, Adam de Houghton, Lord le Scrope, Simon de Sudbury, William Courtenay, Robert de Braybrooke, Sir Michael de la Pole, Thomas de Arundel, Edmund Stafford, John Searle, Cardinal Beaufort, Thomas Loughy, Sir Thomas Beaufort, Cardinal Kemp, John Staf- ford, Neville Earl of Salisbury, Cardinal Bourchier, William Wayneflete, George Neville, Sir John Forlescue, Robert Stillington, Bourchier Earl of Essex, Laurence Booth, Thomas Rotheram, John Russell, John Alcock, Cardinal Morton, Henry Deane, Archbishop Warham, Cardinal Wolsey, Sir Thomas More, Lord Audley, Lord Wriotheslev- VOLUME II.—1547 to 1645.—Marquis of Winchester/Lord Rich, Thomas Goodrich Bishop of Ely, Bishop Gardyner, Archbishop Heath, Sir Nicholas Bacon, Sir Thomas Bromley, Sir Christopher Hatton, Sir John Puckering, Lord Ellesmere, Lord Bacon, Lord Keeper Williams, Lord Coventry, Lord Finch, Lord Littleton, Lord Lane. VOLUMIi III.—1643 to 1687.—Chancellors of the Commonwealth.—Sir Edward Her- bert, Lord Clarendon, Sir Orlando Bridgeman, Lord Shaftesbury, Lord Nottingham, Lord Keeper Guilford, Lord Jeffreys. VOLUME IV.—1687 to 1737.—Maynard, Trevor, Lord Somers, Wright, Lord Cowper, Lord Harcourt, Lord Macclesfield, Lord, King, Lord Talbot. VOLU.MK V.—1737 to 1793.—Lord Hardwicke, Lord Northington, Lord Camden, Charles Yorke, Lord Bathurst, Lord Thurlow/ VOL.1!Mb". VI.—1793 to 1807.—Lord Loughborough, Lord Erskine. VOLUME VIL—Lord Eldon. It will thus be seen that in the more remote periods, the author has contented himself with raoid "sketches of the persons brought into view, while as he approaches the present time, and his subjects become more interesting, he gradually expands his notices into finished biographies of the eminent men under consideration, the life of Lord Eldon alone constituting a volume of nearly six hundred pages. Of the solid merit of the work our judgment may we avoid the stereotyped commonplace of affirming h.-■ t w?rf fro^ what has already been said. We that no library can be complete without it, we feel wifl add thaJ f?ora 1 si "fin te fund of anecdote, constrained to afford it a higher tribute by pro- ™\ k,1 v»rietvm>f stvle the book addresses it- nouncing it entitled to a distinguished place on the and happy var e^i™. S tlie mere general reader, shelves Sf every scholar who is fortunate enough S'totiS legal trstoric'aMnTui-i and while to po»e»it,-W'. Magazine. BY THE SAME AUTHOR, TO MATCH. LIVES OF THE CHIEF JUSTICES OF ENGLAND. From the Norman Conquest to the Death of lord Mansfield. In two handsome crown octavo volumes of over nine hundred pages in various styles of binding to match the " Lives of the Chancellors." In thi- work the author has displayed the same patient investigation of historical facts, depth ofrelearcT and quick appreciation of character which have rendered hts previous vo urnes so of researcn, aiiu 4 vv ( Chancellors" embrace a long line of illustrious SS^fflnSdvSSSwith the history of England they leave something .till to be C up to complete the picture, and it is th s that the author has attempted in the present S Although it naturally presents greater interest to lawyers than to the rest of the public, ^U the va" amount of curious personal details concerning the eminent men whose biographies IInt^inT the lively sketches of interesting periods of history, and the graphic and vivid Myle f th •author render it a work of great attraction for the student of history and general reader. 14 WORKS FOR PRIVATE AND DISTRICT LIBRARIES. THE GREAT AMERICAN ENCYCLOP/EDIA, BROUGHT DOWN TO A LATE PERIOD. The Encyclopaedia Americana. A popular Dictionary of Arts, Sciences, Literature, History, Politics, Biography; including a copious collection of origi- nal articles in American Biography. On the basis of the Seventh edition of the German Conversations-Lexicon. Edited by Francis Lieber, assisted by E. Wig- glcsworth, and T. G. Bradford. With Additions by Professor Henry Vethake, of the University of Pennsylvania. In fourteen large octavo volumes, containing in all nearly 9000 large double-columned pages. To be had in various styles of binding. This work is so well and so favorably known to the public, that the publishers feel it unnecessary to adduce any ofthe encomiums which have been bestowed on it from all quarters. As a copious library for constant and ready reference, on all subjects connected with the past and present state of mankind, and on every branch of human knowledge and attainment, it presents great advantages to all who are unable to accumulate large collections of books, containing in itself, as it does, vast stores of information, on almost every topic on which information can possibly be sought, from the simplest questions of history or statistics, to the most complex points of science or criticism. The steady demand which still continues for it, notwithstanding the immense number of copies which have been circulated, sufficiently proves the necessity of such a work for all educated men, and the thorough satisfaction which it continues to give to all who consult its pages; and shows that the publishers have not miscalculated in bringing the work up to a late period, with notices of con- temporary events and people, while reducing the price to about one-half of the original subscription. THE ILLUSTRATED GEOGRAPHICAL ENCYCLOP/EDI A. The Encyclopaedia of Geography. Comprising a complete Description of the Earth, Physical, Statistical, Civil, and Political. Exhibiting its Relation to the Heavenly Bodies, its Physical Structure, the Natural History of each Country, and the Industry, Commerce, Political Institutions, and Civil and Social State of all Nations. By Hugh Murray, F. R. S. E., &c. Assisted in Botany, by Professor Hooker—Zoology, &c, by W. W. Swainson—Astronomy, &c, by. Professor Wallace—Geology, &c, by Professor Jameson. Revised, with Additions, by Thomas G. Bradford. In three large octavo volumes, in various styles of binding, containing about 1900 large imperial pages, and illustrated by eighty-two small maps, and a colored Map of the United States after Tanner's* together with about 1100 wood-cuts executed in the best style. SKINNER'S COMPLETE EDITION OF YOUATT ON THE HORSE. A BOOK FOR EVERY FARMER AND COUNTRY GENTLEMAN. The Horse. By William Youatt. A new Edition, with numerous Illustrations. Together with a General History of the Horse * a Dissertation on the American Trotting Horse* how Trained and Jockeyed; an Account of his Remarkable Performances* and an Essay on the Ass and the Mule. By J. S. Skinner, Assistant Postmaster-General, and Editor of the Turf Register. In one octavo volume, of nearly 450 large pages, with numerous illustrations. One ofthe most useful books which the impulse given to agricultural knowledge within a few years has produced. A new edition was lately published in London, and this we are happy to say has been republished by Blanchard & Lea, in a beautiful style, and at a cheap rate. But the principal additional value of this new American edition, is a thorough revision, to adapt it the more exactly to the circumstances of this country, and a most valuable ntroduction, by J. S. Skinner, well known for his labors in the cause of agriculture, and editor of the Turf Register. The Introduction shows Mr. Skinner to be a thorough mas- ter of his subject, and the mass of information he has brought together on the history of the horse, the improvement, character, and performances of that noble animal, is such as could have been collected only by one who understood and appreciated the subject of which he was treating. He has also added a valu- able Essay on the Ass and the Mule. The improvement of animals, or the. science of crosses, we consider as but in comparative infancy ; and we hail with pleasure a work like the " Introduction," calculated still further to advance this great interest. We thank Mr. Skinner for this volume, and the labor he has be- stowed upon it; it will prove a most acceptable present, we cannot doubt, to the public, and should be in the hands of every one who keeps a horse.—Albany Cultivator. YOUATT Oj\l_THE DOG. The Dog. By William Youatt, author of "The Horse," &c. &c. Edited, with Additions, by E. J. Lewis, M.D. With numerous very handsome plates and wood-cuts. In one very handsome volume, crown octavo, done up in beautiful crimson cloth, gilt stamps. This volume will be found to contain a vast amount of information, nowhere else accessible, and of the utmost interest and importance to all who keep dogs. The anatomy, diseases, treatment, breeding, and breaking of that animal are described fully and clearly, together with the peculiari- ties, ofthe various races and varieties; the whole illustrated in the finest style, and presented at a remarkably low price. BLANCHARD & LEA'S EDUCATIONAL PUBLICATIONS. 15 EDUCATIONAL WORKS. The following works, and those on pp. 16, 17, and 18, will be found of much practical value as Text-Books for Schools and Colleges. Gentlemen who are interested in the progress of education will much oblige the publishers by handing this list to Collegiate Professors, Teachers, Phvsicians, or School Directors of their acquaintance. Detailed Catalogues of Blanchard & Lea's Miscellane- ous, Scientific, and Educational Publications will be furnished, by mail or otherwise, on applica- tion. A few of their publications are presented on pages 13, 14, 19, and 20, some of which will be found very useful for District, School, and other public and private Libraries. A NEW TEXT-BOOK ON NATURAL PHILOSOPHY. HANDBOOKS OF NATURAL PHILOSOPHY AND ASTRONOMY. BY DIONYSIUS LARDNER, LL. D., ETC. FIRST COURSE, containing Mechanics, Hydrostatics, Hydraulics, Pneumatics, Sound, and Optics. In one large royal 12mo. volume of seven hundred and fifty pages, strongly bound in leather, with over 400 wood-cuts.—(Just Issued.) THE SECOND COURSE, embracing ILEAT, MAGNETISM, ELECTRICITY, AND GALVANISM, Of over four hundred and fifty pages, and illustrated with about 250 cuts, is now ready. THE THIRD COURSE, constituting A COMPLETE TREATISE ON ASTRONOMY AND METEOROLOGY, THOROUGHLY ILLUSTRATED, IS IN PREPARATION FOR SPEEDY PUBLICATION. The intenlion of the author has been to prepare a work which should embrace the principles of Natural Philosophy, in their latest state of scientific development, divested of the abslruseness which renders them unfilled for the younger student, and at the same time illustrated by numerous practical applications in every branch of art and science. Dr. Lardner's extensive acquirements in all departments of human knowledge, and his well-known skill in popularizing his subject, have thus enabled him to present a text-book which, though strictly scientific in its groundwork, is yet easily mastered by the student, while calculated to inter- est the min III. ELEMENTARY GRAMMAR AND EXERCISES. By Dr. Leonhard Schmitz, F.R.S.E., Rector ofthe High School, Edinburgh, &c. In one handsome royal 18mo. volume of 246 pages, extra cloth, price 50 cents. (Just issued.) PREPARING FOR SPEEDY PUBLICATION. LATIN READING AND EXERCISE BOOK, 1 vol., royal 18mo. A SCHOOL CLASSICAL DICTIONARY, 1 vol. royal 18mo. It will thus be seen that this series is now very nearly complete, embracing nine prominent Latin authors, and requiring but two more elementary works to render it sufficient in itself for a thorough course of study, and these latter are now preparing for early publication. During the suc- cessive appearance of the volumes, the plan and execution ofthe whole have been received with marked approbation, and the fact that it supplies a want not hitherto provided for, is evinced by the adoption of these works in a very large number of the best academies and seminaries through- out the country, and by many hundred testimonials to their merits with which the publishers have been favored by eminent scholars and practical teachers. BLANCHARD & LEA'S EDUCATIONAL PUBLICATIONS. 17 UNIFORM WITH SCIUilTZ & ZUMPT'S CLASSICAL SERIES—(Now Ready.) THE CLASSICAL MANUAL; A? J£JT0ME 0F ANCIENT GEOGRAPHY, GREEK AND ROMAN MYTHO- LOGY, ANTIQUITIES, AND CHRONOLOGY. Chiefly intended for the use of Schools. By Ja jies S. S. Baird, T. C. D., Assistant Classical Master, King's School, Gloucester. In one neat volume, royal 18mo., extra cloth, price 50 cents, or strongly half bound, price 55 cents. This little volume has been prepared to meet the recognized want of an Epilome which, within the corn- pas? ot a single small volume, should contain the information requisite to elucidate the Greek and Roman authors most commonly read in our schools. The aim of (he author has been lo embody in it such details as are important or necessary for the junior student in a form and space capable of rendering them easily mastered and retained, and lie has consequently not incumbered U with a mass of learning which, though highly valuable to the advanced student, is merely perplexing to the beginner. In the amount of informa- tion presented, and the manner in which his conveyed, as well as its convenient size and exceedingly low price, it is therefore admirably adapted for the younger classes of our numerous classical schools. From Mr. B. F. Stem, Fredericksburg, Va., July 30,1852. The Clas5ical Manual I have perused with delight, and shall at once introduce in my school. It is a book thai has long been needed, and I know of none where so much varied matter can be found in so small a space. From Mr. C. Hammond, Monson, Mass., Aug. 6,1852. I shall introduce it into my school at once. It is just what we have needed for a long, long time. From Prof. Trimble, Kenyan College, O., Aug. 30,1852. It must recommend itself to the teachers in all the classical institutions within the Union, not only on ac- count of its cheapness, but also for its excellent arrangement; and it will be a sine qua non compendious class-book for every student wishing to enter our colleges. THE BOOK OF NATURE—(Nearly Ready.) THE BOOK OF NATURE; AN ELEMENTARY INTRODUCTION TO THE SCIENCES OF Physics, Astronomy, Chemistry, Mineralogy, Geology, Botany, Zoology, and Physiology. BY FREDERICK SCHOEDLER, Ph. D., Professor ofthe Natural Sciences at Worms. Prepared By HENRY MEDLOCK, F.C.S., &c. WITH ALTERATIONS AND ADDITIONS BY THE AMERICAN EDITOR. And an Index of 5 000 References. In one thick volume, small octavo, with over six hundred illustrations on wood. The rapid progress of the Natural Sciences at the present day, and their continually increasing applications to the practical wants and purposes of life, render some acquaintance with them ne- cessary to every one. Consequently, our systems of education are every day becoming more adapted to the recognition of the truth that a knowledge of facts is more important than a knowledge of words. It is in view of this that the publishers have prepared an edition of" The Book of Nature," convinced that it presents in a moderate space and at a very low price, a body of information adapted either to the wants of schools or to those ofthe private reader, who is continually feeling the necessity of some acquaintance with the laws and facts of the material world around him. The very great success ofthe work in Germany, where five editions have been rapidly exhausted, and the reputation which it immediately acquired in England, are sufficient guarantees of its com- pleteness and accuracy, while the careful supervision of a competent editor will render it equally adapted to the student in this country. A HISTORY OF GREEK CLASSICAL LITERATURE. By The REV. R. W. BROWNE, M.A., Professor of Classical Literature in King's College, London. In one very neat volume, crown 8vo., extra cloth. TO BE SHORTLY FOLLOWED BY A SIMILAR VOLUME ON ROMAN LITERATURE. From Prof. J. A. Spencer, New York, March 19,1852. It is an admirable volume, sufficiently full and copious in detail, clear and precise in style, very scholar- like in its execution, genial in its criticism, and altogether displaying a mind well stored with the learning, genius, wisdom, and exquisite taste of the ancient Greeks. It is in advance of everything we have, and it may be considered indispensable to the classical scholar and student. Mr. Browne's present publication has great merit. His selection of materials is judiciously adapted to the purpose of conveying within a moderate compass some definite idea of the leading characteristics of the great classical authors and their works. » * » * Mr. Browne has the happy art of conveying information in a most agreeable manner. It is impossible to miss his meaning, or be insensible to the charms of his polished style. Suffice it to say, that he has. in a very readable volume, presented much that is useful to the classical reader. Besides biographical information in reference to all the classical Greek authors, he has furnished critical remarks on their intellectual peculiarities, and an analysis of their works when they are of sufficient importance to deserve it.—London Athencrum. This book will be of great value to the student.—Examiner. GEOGRAPHIA CLASSICA. OR, THE APPLICATION OF ANCIENT GEOGRAPHY TO THE CLASSICS. By Samuel Butler, gp late Lord Bishopof Litchfield. Revised by his Son. Sixth American, from the last London Edition, with Questions on the Maps, by John Frost, LL. D. In one neat volume, royal 12mo., half bound. AN ATLAS OF ANCIENT GEOGRAPHY. By Samwkl Butler, D. D , late Lord Bishop of Litchfield. In one octavo volume, half bound, containing twenty-one quarto colored Maps, and an accentuated Index. 13 BLANCHARD & LEA'S EDUCATIONAL PUBLICATIONS. NEW AND IMPROVED EDITION-NOW READY. Outlines of English Literature. By Thomas B. Shaw, Profe.ssor of English Literature in the Imperial Alexander Lyceum. Second American edi- tion. With a Sketch of American Literature. By Henry T. Tuckerman. In one large and handsome volume, royal 12mo., extra cloth, of about 500 pages. The object of this work is to present to the student a history of the progress of English Litera- ture. To accomplish this, the author has followed its course from the earliest times to the present age, seizing upon the more prominent " Schools of Writing," tracing their causes and effects, and selecting the more celebrated authors as subjects for brief biographical and critical sketches, ana- lyzing their best works, and thus presenting to the student a definite view of the development of the language and literature, with succinct descriptions of those books and men of which no edu- cated person should be ignorant. He has thus not only supplied the acknowledged want of a manual on this subject, but by the liveliness and power of his style, the thorough knowledge he displays of his topic, and the variety of his subjects, he has succeeded in producing a most agree- able reading-book, which will captivate the mind ofthe scholar, and relieve the monotony of drier studies. This_ work having attracted much attention, and been introduced into a large number of our best academies and colleges, the publishers, in answering the call for a new edition, have endeavored to render it still more appropriate for the student of this country, by adding to it a sketch of American literature. This has been prepared by Mr. Tuckerman, on the plan adopted by Mr. Shaw, and the volume is again presented with full confidence that it will be found of great utility as a text-book, wherever this subject forms part of the educational course; or as an introduction to a systematic plan of reading. NEW AND IMPROVED EDITION-NOW READY. Outlines of Astronomy. By Sir John F. W. Herschel, F. R. S., &c. A new American, from the fourth London edition. In one very neat crown octavo volume, extra cloth, with six plates, and numerous wood-cuts. This edition will be found thoroughly brought up to the present state of astronomical science, with the most recent investigations and discoveries fully discussed and explained. We now take leave of this remarkable work ; which we hold to be, beyond a doubt, the greatest and most remarkable ofthe works in which ihe laws of astronomy and the appearance of the heavens are described to those who are not mathematicians nor observers, and recalled to those who are. It is the reward of men who can descend from the advancement of knowledge, to care for its diffusion, that their works are essen- tial to all, that they become the manuals ofthe proficient as well as the text-books ofthe learner.—Athenmum. There is perhaps no book in the English language on the subject, which, whilst it contains so many of the facts of Astronomy (which it attempts to explain with as little technical language as possible), is so attractive in its st\le, and so clear and forcible in its illustrations — Evangelical Review. Probably no book ever written upon any science, embraces within so small a compass an entire epitome of everything known within all its various departments; practical, theoretical, and physical.— Examiner. SOMERVILLE'S PHYSICAL GEOGRAPHY. Physical Geography. By Mary Somerville. Second American, from the Second and Revised London edition. With American Notes, Glossary, etc. In one neat royal 12mo. volume, extra cloth, of over five hundred and fifty pages. Our praise comes lagging in the rear, and is wellnigh superfluous. But we are anxious to recommend to our youth the enlarged method of.studying geography which her present work demonstrates to be as capti- vating as it is instructive. We hold such presents as M rs. Somerville has bestowed upon the public to be of incalculable value, disseminating more sound information than all the literary and scientific institutions will accomplish m a whole cycle of their existence.—BlackwoodAs Magazine. From Thomas Sherwin, High School, Boston. I hold it in the highest estimation, and am confident that it will prove a very efficient aid in the education ofthe young, and a source of much interest and instruction to the adult reader. From Erastus Everett, High School, New Orleans. I have examined it with a good deal of care, and am glad to find that it supplies an important desideratum. The whole work is a masterpiece. Whether we examine the importance of the subjects treated, or the ele- gant and attractive style in which they are presented, this work leaves nothing to desire. I have introduced it into my school for the use of an advanced class in geography, and they are greatly interested in it. I have no doubt that it will be used in most of our higher seminaries BOLMAR'S FRENCH SERIES. New editions ofthe following works, by A. Bolmar, forming, in connection with "Bolmar's Levizac," a complete series for the acquisition ofthe French language :— A SELECTION OF ONE HUNDRED PERRIN'8 FABLES, accompanied bv a Key,containing the text, a literal and free translation, arranged in such a manneras to point out the difference between the French and English idiom, &c. in one vol 12mo. A COLLECTION OF COLLOQUIAL PHRASES, on every topic wecessary to maintain conversa- tion. Arranged under different heads, with numerous remarks on the peculiar pronunciation and us>es of various words; the whole so disposed as considerably to facilitate the acquisition of a correct pronuncia- tion ofthe French In one vol. ISino ' LES AVENTURE3 DE TELEMAQUE, PAR FENELON, in one vol. 12mo , accompanied by a Key to the first eight books, in one vol. 12mo.. containing, like the Fables, the text, a literal aim free translation, intended as a sequel to the Fables. Either volume sold separately. ALL THE FRENCH VERBS, both regular and irregular, in a small volume. j WORKS FOR PRIVATE AND DISTRICT LIBRARIES. 19 THE GEOLOGIST'S MANUAL—(Just Issued.) THE GEOLOGICAL OBSERVER, BY SIR HENRY T. DE LA BECHE, C. B., F. R. S., Director-General of the Geological Survey of Great Britain, &c. WIT^H OVER THREE HUNDRED WOOD-CUTS. In one very large and handsome octavo volume, of seven hundred pages, DONE UP IN EXTRA CLOTH. The object which the author has proposed to himself in this work has been to afford a general view of the chief points ofthe science, such as existing observations would lead us to infer were established, to show how the correctness of such observations may be tested, and to sketch the .direction in which they may apparently be extended. To accomplish this, he has entered into a minute detail of the results of geological investigations throughout the earth's surface, and, without confining himself to a mere detail of facts, he has endeavored to explain the causes, as well as the results of geological action. The assistance of numerous diagrams and illustrations has also been resorted to, to make manifest to the student the various forms of geological pheno- mena, and to guide him in the observations which he may desire to make for himself. To exem- plify the manner in which this plan has been carried out, a very brief summary of the contents is subjoined. I. Introduction. II. Decomposition of Rocks. III. Removal ofthe Parts of Rocks by Water. IV. Lacustrine Deposits. V. Action of the Sea on Coasts. VI. Distribution and Deposit of Sediment in Tideless Seas. VII. Distribution and Deposit of Sediment in Tidal Seas. VIII. Chemical Deposits in Seas. IX. Preservation of the Remains of existing Life in Mineral Matter. X. Transportation of Mineral Matter by Ice. XI. Ossiferous Caves and Osseous Breccia. XII. Volcanoes and their Products. XIIL Salses, or Mud Volcanoes. XIV. Earthquakes. XV. Quiet Rise and Subsidence of Land. XVI. Sunk (Submarine) Forests, and Raised Beaches. XVII. Temperature of the Earth. XVIII. Mode of Accumulation of Detrital and Fossiliferous Rocks. XIX. Igneous Products of Earlier Date than those of Modern Volcanoes. XX. Consolidation and Adjustment of the Component Parts of Rocks. XXI. Bending, Contortion, and Fracture of Bedded Rocks. XXII. Filling of Fissures and other Cavities with Mineral Matter. XXIII. Partial Removal and Denudation of Rocks^ XXIV. Geological Maps and Sections. Additional Notices. JOHNSTON'S PHYSICAL ATLAS. THE PHYSICAL ATLAS OF NATURAL PHENOMENA. FOR THE USE OP COLLEGES, ACADEMIES, AND FAMILIES. BY ALEXANDER KEITH JOHNSTON, F. R. Gt. S., F. G.S. In one large volume, imperial quarto, handsomely and strongly bound, With Twenty-six Plates, Engraved and Colored in th'e best style. Together with 112 pages of Descriptive Letterpress, and a very copious Index. m, , , ■ r ' „•» in ohm-t a p-rarjhic encvclopffidia ofthe sciences—an atlas of human knowledge The book before.usis,,m short agraphic e^'°P es_that he who runs may read. The Thermal done into maps. It exempimes ine irum «•"<-■ h f Europe. the abstract researches Laws of Leslie it enunciate., by^^bei l^^^^.fC^ ^tion of the'globe ; a formula of La- of Gauss it embodies •n.^f«waPJhr^^ez^,%Gowi a problem of the transclndental analysis, which place it melts (,?^n,lofia. ltt.le,^ ^,° .^ake^ plain to the eye by a little stippling and hatching on a given covers pages;wiUii definite ^^Xtio^Wa^Ld ?pace, heat and cold, wet and dry frost and degree ofJ°"gi'7degtor^1cP1^ent and tide, plant and beast, race and religion, attraction and repulsion, gla- snow, volcano ana storm,, current umx <■ >*... mountain, mine and forest, air and cloud, and sea and cier and avalanche fossil and mX^aVlndOT ™e earth"'a™d above the earth, that the heart of man sky-all in the .ear h ™*™fj ^e earth »jd °n «he e«th, & ^^^ lnicr'ocown alld planted on has conceived or his head understooa are uiu' b s ' T h t we have a summary these little sheets of paper thus ma"""*,^.^^.^^^anrt aIl the answers of Nature herself set down of all the cross-questiousof Nature for twenty ce.™ ai i JohMton iswell known as a geo- and -Peaking £ ^^^^^^a ch; and " s'ermin that this work will add to his reputation; for FftaSfifuU? engra^dj and aecompanied with explanatory and tabular letterpress of great value.- London Athtnaum. , 20 WORKS FOR PRIVATE AND DISTRICT LIBRARIES. NIEBUHR'S ANCIENT HISTORY—(A New "Work. Now Ready.) LECTURES ON ANCIENT HISTORY: FROM THE EARLIEST TIMES TO THE TAKING OF ALEXANDRIA BY OCTAVIANUS. CONTAINING The History of the Asiatic Nations, the Egyptians, Greeks, Macedonians, and Carthaginians. BY B. G. NIEBUHR. Translated from the German Edition of DR. MARCUS NIEBUHR, BY DR. LEONHARD SCHMITZ, F.R. S.E., WITH ADDITIONS AND CORRECTIONS FROM HIS OWN MS. NOTES. In three very handsome volumes, crown octavo, extra cloth, containing about 1500 pagea. From the Translator's Preface. " The Lectures on Ancient History here presented to the English public, embrace the history of the ancient world, with the exception of that of Rome, down to the time when all the other na- tions and states of classical antiquity were absorbed by the empire of Rome, and when its history became, in point of fact, the history ofthe world. Hence the present course of Lectures, together with that on the History of Rome, form a complete course, embracing the whole of ancient his- tory. * * * * We here catch a glimpse, as it were, of the working of the great mind of th« Historian, which imparts to his narrative a degree of freshness and suggestiveness that richly com- pensates for a more calm and sober exposition. The extraordinary familiarity of Niebuhr with th« literatures of all nations, his profound knowledge of all political and human affairs, derived not only from books, but from practical life, and his brilliant powers of combination, present to us in these Lectures, as in those on Roman history, such an abundance of new ideas, startling concep- tions and opinions, aa are rarely to be met with in any other work. They are of the highest im- portance and interest to all who are engaged in the study, not only of antiquity, but of any period in the history of man." The value of this work as a book of reference is greatly increased by a very extensive Index of about fifty closely printed pages, prepared by John Robson, B. A., and containing nearly ten thou- sand references; in addition to which each volume has a very complete Table of Contents. STRICKLAND'S QUEENS OP ENGLAND. COMPLETE LIBRARY EDITION. LIVES OF THE QUEERS OF ENGLAND, FROM THE NORMAN CONQUEST: WITH ANECDOTES OF THEIR COURTS. Now first published from Official Records, and other Authentic Documents, Private as well as Publk. NEW EDITION, WITH ADDITIONS AND CORRECTIONS. BY AGNES STRICKLAND. Complete in six handsome crown octavo volumes, containing nearly foue thousand pages, and done up in various styles of binding. These volumes have the fascination of a romance united to the integrity of history.__Times. This is the twelfth and last volume of this delightful series. Miss Strickland has brought her suc- cessful task to a close with the reign of Queen Anne, and has shown her usual judgment and taste in so doing, as an attempt to trace the Brunswick succession of Queens would have been attended with obvious difficulties. The series is now before the public, therefore, as a complete work, and we do not hesitate to say. that, as a whole, few historical works exhibit a more earnest love for truth, or greater anxiety to record facts and not theories. The work is, indeed, alike characterized by industry and impartiality, and will reflect lasting credit upon the author.—New Monthly Magazine, May, 1848. Miss Strickland, through the intervention of M. Guizot, has had access to a variety of unpublished docu- ments, deposited in the secret archives of France, and some exceedingly curious details, obviously ner*r intended for the world, have thus been brought to light.—Court Journal. We must pronounce Miss Strickland, beyond all comparison, the most entertaining historian in the English language. She is certainly a woman of powerful and active mind, as well as of scrupulous jus- tice and honesty of purpose. And, as we before remarked, the considerable number of new document* to which she has had access, and the curious nature of some of these documents, impart to her production a character of which it would be hard to determine whether the utility or the entertainment predomi- nated.—Morning Post. A most valuable and entertaining work. There is certainly no lady of our day who has devoted her pen to so beneficial a purpose as Miss Strickland. Nor is there any other whose works possess a deeper or more enduring interest. Miss Strickland is, to our mind, the first literary lady of the age.—Chroniflt. A valuable contribution to historical knowledge. It contains a mass of every kind of historical matter of interest, which industry and research could collect. We have derived much entertainment and in- struction from the work.—Athenaum. This interesting and well-written work, in which the severe truth of history takes almost the wildness of romance, will constitute a valuable addition to our biographical literature.—Morning Herald. Miss Strickland has made a very judicious use of many authentic MS. authorities not previously col- lected, and the result is a most interesting addition to ouf biographical library—Quarterly Review. ✓ BLA.NCHARD & LEA'S LATE MEDICAL PUBLICATIONS. 21 NEW AND ENLARGED EDITION OF NEILL & SMITH'S COM PEN DI U M—(NOW READY.) AN ANALYTICAL COMPENDIUM OF THE VARIOUS BRANCHES OF MEDICAL SCIENCE, FOR THE USE AND EXAMINATION OF STUDENTS. BY JOHN NEILL; M. D., Demonstrator of Anatomy in the University of Pennsylvania ; Surgeon to the Pennsylvania Hospital: and FRANCIS GURNEY SMITH, M.D., Professor of Institutes of Medicine in the Pennsylvania Medical College, &c. Second Edition, Revised and Improved. In one large royal 12mo. volume, of 1000 pages, with 350 illustrations. CONTENTS. ANATOMY, 192 pp., 159 illustrations. PHYSIOLOGY, 144 pp., 43 illustrations. SURGERY, 134 pp., 50 illustrations. OBSTETRICS, 124 pp., 41 illustrations. MATERIA MEDICA and THERAPEUTICS, 130 pp., 29 illustrations. CHEMISTRY, 106 pp., 19 illustrations. PRACTICE OF MEDICINE, 172 pp., 3 illus- trations. The increased size of this edition is sufficient evidence that it is not a mere reprint. Stimulated by the approbation of the profession, as evinced by the rapid exhaustion of the first impression, the authors have" thoroughly revised it in every part, introducing such improvements as the progress of science and the practical use of the work have suggested, and rewriting many portions. It is therefore now presented, with some confidence, as worthy of the very favorable reception which has been accorded to it. The mechanical execution of the work will be found to have undergone a like improvement, and as the price has not been increased, it may be regarded as one of the cheapest works before the profession. In the rapid course of lectures, where work for the student is heavy, and review necessary for an exami- nation, a compend is not only valuable, but it is almost a sine qua non. The one before us is. in most of the divisions, the most unexceptionable of all books of the kind ihai we know of. The newest and soundest doctrines and the latest improvements and discoveries are explicitly, though concisely, laid before the stu- dent. Of course it is useless for us to recommend it to all last courf e students, but there is a class to whom we very sincerely commend this cheap book as worth its weight in silver—that class is the graduates in medicine of more than ten years'standing, who have not studied medicine since. They will perhaps find out from it that the science is not exactly now what it was when they left it off.— The Stethoscope. Having made free use of this volume in our examinations of pupils, we can speak from experience in re- commending it as an admirable compend for students, and as especially useful to preceptors who examine their pupils, It will save the teacher much labor by enabling him readily to recall all of the points upon which his pupils should be examined. A work of this sort should be in the hands of every one who takes pupils into his office with a view of examining them; and lhis is unquestionably the best of its class. Let every praciitioner who has pupils provide himself with it, and he will find the labor of refreshing his^know- ledge so much facilitated that he will be able to do justice to his pupils at very little cost of time or trouble to himself.— Transylvania Med. Journal. JVJEW EMTIOJV OF It.iJlSliOTllJl.il OJV PARTURITIOJW THE PRINCIPLES AND PRACTICE OF 0BSTETEIC MEDICINE AND SURGERY, In reference to the Process of Parturition, BY FRANCIS H. RAMSBOTHAM, M. D., Physician to the Royal Maternity Charity, Sec. tec. SIXTH AMERICAN, FROM THE LAST LONDON EDITION. Illustrated with One Hundred and Forty-eight Figures on Fifty-five Lithographic Plates. In one large and handsomely printed volume, imperial octavo, with 520 pages. In this edition the plates have all been redrawn, and the text carefully read and corrected. It is therefore presented as in every way worthy the favor with which it has so long been received. 22^ BLANCHARD & LEA'S LATE MEDICAL PUBLICATIONS. NEW AND IMPORTANT TEXT-BOOK ON SURGERY—(Just Issued.) THE PRINCIPLES MD PRACTICE OF SURGERY, Illustrated by numerous Engravings on Wood. BY WILLIAM PIRRIE, F. R. S. E., Regius Professor of Surgery in the Mareschal College and University of Aberdeen; Surgeon to the Royal Infirmary, &c. Edited, with Notes, By JOHN" NEILL, M. D., Demonstrator of Anatomy in the University of Pennsylvania; Lecturer on Anatomy in the Medical Institute of Philadelphia ; Surgeon to the Pennsylvania Hospital. In one large and very handsome octavo volume, of nearly eight hundred pages, with three hun- dred and sixteen beautiful illustrations. This work, although just introduced to the notice of the profession, has already acquired a high reputation for the fulness of its details and the soundness of its precepts ; and has been introduced as a text-book in many ofthe medical colleges. A few notices with which it has been honored by the press are subjoined. However well it may be adapted for a text-book (and in this respect it may compete with the best of them) of this much our reading has convinced us, that as a systematic treatise, it is carefully and ably written, and can hardly fail to command a prominent position in the library of practitioners; though not complete in the fullest sense ofthe word, it nevertheless furnishes the student and practitioner with as chaste and concise a work as exists in our language. The additions to the volume by Dr. Neill, are judicious; and while they render it more complete, greatly enhance its practical value, as a work for practitioners and students.—JV. Y. Journal of Medicine. We know of no other surgical book of a reasonable size, wherein there is so much theory and practice, or where subjects are more soundly or clearly taught.— The Stethoscope. There is scarcely a disease ofthe bone or soft parts, fracture, or dislocation, that is not illustrated by accu- rate wood-engravings. Then again every instrument employed by the surgeon is thus represented. These engravings are not only correct, but really beautiful, showing the astonishing degree of perfection to which the art of wood-engraving has arrived. Prof. Pirrie in the work before us has elaborately discussed the principles of surgery, and a safe and effectual practice predicated upon them. Perhaps no work upon this subject heretofore issued is so full upon the science of the art of surgery.—Nashville Journal of Medicine and Surgery. We have made ourselves more intimately acquainted with its details, and can now pronounce it to be one of the best treatises on surgery in the English language. In conclusion, we very strongly recommend this excellent work, both to the practitioner and student.— Canada Med. Journal. Our impression is, that as a manual for students, Pirrie's is the best work extant.— Western Med. and Surg. Journal. NEW AND ENLARGED EDITION, MUCH IMPROVED. PRINCIPLES OF SURGERY. BY JAMES MILLER, F. R. S. E., Professor of Surgery in the University of Edinburgh. Third American, from the Second and Revised Edinburgh Edition. Revised, with Additions, By F. W. SARGENT, M. D., Author of " Minor Surgery," &c. In one large and very beautiful octavo volume, of seven hundred and fifty-two pages, WITH TWO HUNDRED AND FORTY EXQUISITE ILLUSTRATIONS ON WOOD. The publishers have endeavored to render the present edition of this work, in every point of me- chanical execution, worthy of its very high reputation, and they confidently present it to the pro- fession as one ofthe handsomest volumes as yet issued in this country. This edition is far superior, both in the abundance and quality of its material, to any of the preceding. We hope it will be extensively read, and the sound principles which are herein taught treasured up for future application. The work takes rank with Watson's Practice of Physic; it certainly does not fall behind that great work in soundness of principle or depth of reasoning and research. No physician who values his repu- tation, or seeks the interests of his clients, can acquit himself before his God and the world wiihout making himself familiar with the sound and philosophical views developed in the foregoing book.— New Orleans Medical and Surgical Journal. Wiihout doubt the ablest exposition of the principles of that branch of the healing art in any language. This opinion, deliberately formed after a careful study of the first edition, we have had no ci^e io change on examining the second. This edition has undergone thorough revision by the author ; many (expressions have been modified, and a mass of new matter introduced. The book is got up in the fine-i -lyle, and is an evidence ofthe progress of typography in our country.— Charleston Medical Journal and Review. We recommend it to both student and practitioner, feeling assured that as it now comes to us, it presents the most satisfactory exposition of the modern doctrines of the principles of surgery to be found in any volume in any language.—N. Y. Journal of Medicine. BLANCHARD & LEA'S LATE MEl)ICAL PUBLICATIONS. 23 COOPER'S SURGICAL LECTURES—(Just Issued.) LECTURES ON THE PRINCIPLES AND PRACTICE OF SURGERY. BY BRANSBY B. COOPER, F.R.S., Senior Surgeon to Guy's Hospital. In one very large octavo volume, of seven hundred and fifty pages. For twenty five years Mr. Bransby Cooper has been surgeon to Guy's Hospital; and the volume before us may be »aid to consist of an account of the results of his surgical experience during that long period. We cordially recommend Mr. Bransby Cooper's Lectures as a most valuable addition to our surgical literature, and one which cannot fail to be of service both to students and to those who are actively engaged in the practice of their profession.— The Lancet. A good book by a good man is always welcome; and Mr. Bransby Cooper's book does no discredit to its palemity. It has reminded us, in its easy style and copious detail, more of Watson's Lectures, than any book we have seen lately, and we should not be surprised to see it occupy a similar position to that well- known work in professional estimation, it consists of seventy five lectures on the most important surgical diseases. To analyze such a work is impossible, while so interesting is every lecture, that we feel ourselves really at a loss what to select for quotation. The work is one which cannot fail to become a favorite with the profession ; and it promises to supply an hiatus which the student of surgery has often to deplore.—Medical Times. NEW r\ND IMPORTANT WORK ON PRACTICAL SURGERY—(JUST ISSUED,) OPERATIVE SURGERY, BY FREDERICK 0. SKEY, F. R. S., &c. In one very handsome octavo volume of over 650 p'ages, with about one hundred wood-cuts. In conclusion, we must express our unqualified praise of the work as a whole. The high moral tone, the liberal views, and the sound information which pervades it throughout, reflect the highest credit upon the talented author. We know of no one who has succeeded, whilst supporting operative surgery in its proper rank, in promulgating at the same, time sounder and more enlightened views upon that most important oi all subjects, the principle that should guide us in having recourse to the knife.—Medical Times. GROSS ON URINARY ORGANS—(Lately Issued.) A PRACTICAL TREATISE ON THE DISEASES AND INJURIES OF THE URINARY ORGANS. BY S. D. GROSS, M. B., &c, Professor of Surgery in the New York University. In one large and beautifully printed octavo volume, of over seven hundred pages. With numerous Illustrations. Dr. Gross has brought all his learning, experience, tact, and judgment to the task, and has produced a work worthy of his high reputation. We feel perfectly safe in recommending it to our readers as a mono- graph unequalled in interest and practical value byanyotheron the subject in our language; and we cannot help saying that we esteem it a matter of just pride, that another work so creditable toour country has been contributed to our medical literature by a Western physician.— The Western Journal of Medicine and Surgery. THE CYCLOPEDIA OF PRACTICAL MEDICINE; COMPRISING Treatises on the Nature and Treatment of Diseases, Materia Medica, and Thera- peutics, Diseases of Women and Children, Medical Jurisprudence, &c. &c. EDITED BY JOHN FORBES, M. D., F. R. S., ALEXANDER TWEEDIE, M.D., F.R. S., AND JOHN CONOLLY, M. D. Revised, with Additions, BY ROBLEY DUNGLISON, M. D. THIS WORK IS NOW COMPLETE, AND FORMS FOUR LARGE SUPER-ROYAL OCTAVO VOLUMES, Containing Thirty-two Hundred and Fifty-four unusually large Pages in Double Columns, Printed on Good Paper, with a new and clear type. TKV WHOLE WELL AND STRONOLY BOUND, WITH RAISED BANDS AND DOUBLE TITLES. This work contains no less than FOUR HUNDRED AND EIGHTEEN DISTINCT TREATISES, By Sixty-eight distinguished Physicians. The most complete work on Practical Medicine extant; or, at least, in our language.—Buffalo Medical and Surgical Journal. For reference, it is above all price to every practitioner.— Western Lancet. One of the .most valuable medical publications of the day—as a work of reference it is invaluable- Western Journal of Medicine and Surgery. It has been to us, both as learner and teacher, a work for ready and frequent reference, one in which modern English medicine is exhibited in the most advantageous light.—Medical Examiner. We reioice that this work is to be placed within the reach ofthe profession in this country, it being unques- tionably one of very great value to the practitioner. This estimate of it has not been formed from a hasty ex- amination but after an intimate acquaintance derived from frequent consultation of it during the past nine or ten vears ' The editors are practitioners of established reputation, and the list of contributors embraces many of the most eminent professors and teachers of London, Edinburgh, Dublin, and Glasgow. It is, indeed, the ^at merit of this work that the principal articles have been furnished by practitioners who have not only devoted especial attention to the diseases about which they have written, but have also enjoyed opportunities for an extensive practical acquaintance with them—and whose reputation carries the assurance of their competency justly to appreciate the opinions of others, while it stamps their own doctrines with high and just authority .—American Medical Journal. 24 BLANCHARD & LEA'S LATE MEDICAL PUBLICATIONS. A NEW BOOK ON THE HEART AND LUNGS—(Just Issued.) DISEASES OF THE HEARtTTUNGS, AND APPENDAGES; THEIR SYMPTOMS AND TREATMENT. BY W. H. WALSHE, M.D., Professor of the Principles and Practice of Medicine in University College, London, Sec. In one handsome volume, large royal 12mo. of 512 pages. A boon to the practitioners of this country, and an honor to our national literature. Dr. Walshe hat managed to give every essential fact connected with the diseases of the lungs, as well as of the heart, and also to include one of the best treatises we have ever perused on the art of physical diagnosis. He lias thus fiven us one of the most practical and useful works with which we are acquainted; and we have lillLe oubt that our verdict will be re echoed by those whose daily practice will enable them to lest the value ot Dr. Walshe's instructions.—The British and Foreign Medico-Chirurg. Review. To the practitioner, the clinical teacher, and the student, this work will prove alike invaluable.—Medical Times. We can unhesitatingly recommend itas the best in the language— Medical Examiner. We consider this as the ablest work in th_e English language, on the subject of which it treats. The author being the first stelhoscopist of the day, exhibits a nice and correct appreciation ofthe value, etc. of the various morbid sounds, and of their connection with physical changes.—Charleston Medical Journal. MALGAIGNE'S SURGERY—(Just Published.) OPERATIVE" SURGERY, BASED ON NORMAL AND PATHOLOGICAL ANATOMY. BY J. F. MALGAIGNE. TRANSLATED FROM THE FRENCH, BY FREDERICK BRITTAN, A. B., M.D., M.RC.S.L. WITH NUMEROUS ILLUSTRATIONS ON WOOD. In one handsome octavo volume of nearly 600 pages. Certainly one ofthe best books published on operative surgery.—Edinburgh Med. Journal. We can strongly recommend it both to practitioners and students, not only as a safe guide in the dissect- ing-room or operaiing-theatre, but also as a concise work of reference for all that relates to operative sur- gery.—Forbes's Review. CARSON'S SYNOPSlS-(JUST ISSUED.) SYNOPSIS OF THE COURSE OF LECTURES ON MATERIA MEDICA AND PHARMACY, delivered in the University of Pennsylvania. By Joseph Carson, M. D., Professor of Materia Medica and Pharmacy in the University of Pennsylvania. In one very neat octavo volume, of two hundred and eight pages. ESSAYS ON LIFE, SLEEP, PAIN, INTELLECTION, HYGIENE, AND DEATH. By Samuel Henry Dickson, M. D. Professor of the Institutes and Practice of Medicine in the Charleston Medical College. In one very handsome volume, royal 12mo. (Just Issued.) SIJHOJ\^>8 PATHOLOGY—KJYou> Heady.) GENERAL PATHOLOGY, AS CONDUCIVE TO The Establishment of Rational Principles for the Diagnosis and Treatment of Disease; A Course of Lectures, delivered at St. Thomas's Hospital, during the Summer Session of 1850. BY JOHN SIMON, F. R. S., One ofthe Surgical Staff of that Hospital, and Officer of Health to the City of London. In one neat octavo volume, extra cloth. NEARLY_READY. AN ATLAS OF PATHOLOGICAL HISTOLOGY. BY GOTTLIEB GLUGE, M. D., Professor of Physiology and Pathological Anatomy in the University of Brussels. Translated, with Notes and Additions, by JOSEPH LEIDY, M. D. In one volume, very large imperial quarto, WITH THREE HUNDRED AND TWENTY FIGURES, PLAIN AND COLORED, ON TWELVE PLATES. The great ami increasing interest with which this important subject is now regarded by the profession, and the rapid advances which it is making by the aid of the microscope, have induced the publishers to pre- sent this volume, which contains all the most recent observations and results of European investigations. The text contains an exposition of the present state of microscopical pathology, while the plates are considered as among the most truthful and accurate representations which have been made of the pathologi- cal conditions ofthe tissues, and the volume as a whole may be regarded asabeautiful specimen of mecbaa- ical execution, presented at a very reasonable pribe. BLANCHARD & LEA'S LATE MEDICAL PUBLICATIONS. 25 NEW AND IMPROVED EDITION-(Now Ready.) DISEASES OF THE SKIN, BY ERASMUS WILSON, F. R. S., Consulting Surgeon to the St. Pancras Infirmary, author of a " Treatise on Human Anatomy," '■ Portraits of Skin Diseases," &c. &c. THIRD AMERICAN PROM THE THIRD LONDON EDITION. In one neat octavo volume, extra cloth, 480 pages. Alto, to be had with Fifteen beautiful Steel Plates, of which Eight are exquisitely colored; representing the normal and pathological anatomy of the skin, together with accurately colored delineations of more than sixty varieties of disease, most of them the size of nature. ALSO, THE PLATES SOLD SEPARATE, IN BOARDS. The increased si^e of this edition is sufficient evidence that the author has not been content with a mere republication, but has endeavored to maintain the high character of his work as the standard text-book on this interesting and difficult class of diseases. He has thjis introduced such new matter as the experience of the last three or four years has suggested, and has made such alterations as the* progress of scientific investigation has rendered expedient. The illustrations have also been materially augmented, the number of plates being increased from eight to sixteen. The "Diseases of the Skin," by Mr. Erasmus Wilson, may now be regarded as the standard work in that department of medical literature. The plates by which this edition is accompanied leave nothing to be de- sired, so far as excellence of delineation and perfect accuracy of illustration are concerned.— Medico-Chi- rurgical Review. As a practical guide to the classification, diagnosis, and treatment of the diseases of the skin, the book is complete. We know nothing, considered in this aspect, better in our language ; it is a safe authority on all the ordinary matters which, in this range of diseases, engage the practitioner's attention, and possesses the high quality—unknown, we believe, to every older manual—of being on a level with science's high-water mark—a sound book of practice.—London Medical Times. Of these plates it is impossible to speak too highly. The representations of the various forms of cutaneous disease are singularly accurate, and the coloring exceeds almost anything we have met with in point of delicacy and finish.—British and Foreign Medical Review. BY THE SAME AUTHOR-(Now Ready.) ON CONSTITUTIONAL AND~ HEREDITARY SYPHILIS; AND ON SYPHILITIC ERUPTIONS. In one small octavo volume, beautifully printed, with four exquisite colored plates, presenting more than thirty varieties of syphilitic eruptions. Mr. Wilson's extensive experience in the treatment of this class of diseases has enabled him to present an interesting and highly practical work, embodying some novel views, and illustrated with numerous cases. We need scarcely say that Mr. Wilson's book on Syphilis commands attention. It is illustrated by some well-finished colored drawings, which are excellent representations of syphilitic affections of the integu- ment, and it is full of cases replete with interest.—Medical Times. A MANUAL ON SKIN DISEASES—(Now Ready.) A PRACTICAL TREATISE ON DISEASES OF THE SKIN. BY J. MOORE NELIGAN, M. D., M.R.I. A., Author of "Medicines, their Uses and Modes of Administration," &c. In one neat volume, royal 12mo. Wp must sav he bears off the palm for clearness, conciseness, and rigid plainness of expression. This rle enables him to compress much in a single sentence without in any degree injuring the sense, but, pa £ pontrarv making it more comprehensible and impressive. His simplification of the divisions is a stria- My the efleclivertes . "~M jj^gj"' are fuji details of treatment "and formula? given at the close of each see- peutic consiae ra"°\ * er is devoted to "those general points in therapeutics which are specially applicabte riou, but an enure <-p n T^e present work forms a favorable contrast to the voluminous and disputed lo this class otaiieo "'edecessors and will, we feel assured.be admirably conducive to facilitating the d6,dy oftkTstudent,and improving the practice of the practitioner.-DK&fcn Quarterly Journ. of Med. Seienee. 26 BLANCHARD & LEA'S LATE MEDICAL PUBLICATIONS. PEREIRA'S MATERIA MEDICA. NEW EDITION, GREATLY IMPROVED AND ENLARGED. THE ELEMUNTS OF MATERIA MEDICA AND THERAPEUTICS, BY JONATHAN PEREIRA, M. D., F. R. S. and L. S. THIRD AMERICAN EDITION, ENLARGED AND IMPROVED BY THE AUTHOR, INCLUDING NOTICES OF MOST OF THE MEDICINAL SUB- STANCES IN USE IN THE CIVILIZED WORLD, AND FORMING AN ENCYCLOPEDIA OF * MATERIA MEDICA. EDITED BY JOSEPII CARSON, M. D., ' Professor of Materia Medica and Pharmacy in the University o( Pennsylvania. Vol. I.—Just issued, large octavo, of near 850 closely printed pages, with 145 wood-engravings. Vol. II.—In press, and undergoing important revisions from both author and editor, may be Bhortly expected, in large 8vo., of about 900 pages, with several hundred illustrations. The present edition of this favorite and standard work, will be found far superior to its prede- cessors. Besides very large additions and alterations which were made in the last London edition, the work has undergone a thorough revision on the part of the author expressly for this country ; and has further received numerous additions from the editor. It is thus greatly increased in size, and most completely brought up to the present state of our knowledge on this important subject. A similar improvement will be found in its mechanical execution, being printed with new type on fine white paper, with a greatly extended series of illustrations, engraved in the highest style of art. The work, in its present shape, and so far as can be judged from the portion before the public, forms the most comprehensive and complete treatise on materia medica extant in the English language. Dr. Pereira has been at great pains to introduce into his work, not only all the information on the natural, chemical, anil commercial history of medicines, which might be serviceable to the physician and surgeon, but whatever might enable his readers to understand thoroughly the mode of preparing and manufacturing various arti- cles employ d either for preparing medicines, or for certain purposes in the arts connected with materia medica and the practice of medicine. The accounts ofthe physiological and therapeutic effects of remedies are given with great clearness and accuracy, and in a manner calculated to interest as well as instruct the reader.— The Edinburgh Medical and Surgical Journal. GRJIUJiJI'S CHEMISTRY, .Vtw and Enlarged Edition. ELEMENTS OF CHEMISTRY; INCLUDING THE APPLICATIONS OF THE SCIENCE IN THE ARTS. BY THOMAS GRAHAM, F. R. S., &c. Professor of Chemistry in University College, London, &c. Second American, from an entirely Revised and greatly Enlarged English Edition. WITH NUMEROUS WOOD ENGRAVINGS. Edited, with Notes, BY ROBERT BRIDGES, M. D., Professor of Chemistry in the Philadelphia College of Pharmacy, &c. TO BE COMPLETED IN TWO PARTS, FORMING ONE VERY LARGE OCTAVO VOLUME. PART I. now ready, of 430 large pages, with 185 engravings. PART II. preparing for early publication. From the Editor's Preface. The " Elements of Chemistry," of which a second edition is now presented, attained, on its first appearance, an immediate and deserved reputation. The copious selection of facts from all reliable sources, and their judicious arrangement, render it a safe guide for the beginner, while the clear exposition of theoretical points, and frequent references to- special treatises, make ita valuable assistant for the more advanced student. From this high character the present edition will in no way detract. The great changes which the science of Chemistry has undergone during the interval, have rendered necessary a complete revision ofthe work, and this has been most thoroughly accomplished by the author. MaBy por- tions will therefore be found essentially altered, thereby increasing greatly the size of the work, while the series of illustrations has been entirely changed in style, and nearly doubled in number. Under these circumstances but little has been left for the editor. Owing, however, to the ap- » pearance of the London edition in parts, some years have elapsed since the first portions were published, and he has therefore' found occasion to introduce the more recent investigations and discoveries in some subjects, as well as to correct such inaccuracies or misprints as had escaped the author's attention, and to make a few additional references. BLANCHARD & LEA'S LATE MEDICAL PUBLICATIONS. 27 The great Atlas of Surgical Anatomy—(Now Complete.) SURGICAL ANATOMY. BY JOSEPH MACLISE, Surgeon. IN ONE VOLUME, VERY LARGE IMPERIAL QUARTO, With. Sixty-eight large and. splendid Plates, drawn in the best style, and beautifully colored, Containing one hundred and ninety Figures, many of them the size of life. TOGETHER WITH COPIOUS EXPLANATORY LETTER-PRESS, Strongly and handsomely bound in extra cloth, being one of^the best executed and cheapest surgical works as yet issued in the country. This great work being now concluded, the publishers confidently present it to the attention of the profession as worthy in every respect of their approbation and patronage. No complete work of the kind has yet been published in the English language, and it therefore will supply a want long felt in this country of an accurate and comprehensive Atlas of Surgical Anatomy to which the student and practitioner can at all times refer, to ascertain the exact relative posi- tion of the various portions of the human frame towards each other and to the surface, as well as their abnormal deviations. The importance of such a work to the student in the absence of anatomical material, and to the practitioner when about attempting an operation, is evident, while the price of the book, notwithstanding the large size, beauty, and finish of the very nu- merous illustrations, is so low as to place it within the reach of every member ofthe profession. The publishers therefore confidently anticipate a very extended circulation for this magnificent work. Notwithstanding the short time in which this work has been before the profession, it has received the unanimous approbation of all who have examined it. From among a very large number of commendatory notices with which they have been favored, the publishers select the following:— From Prof. B. Gilbert, Philadelphia. Allow me to say, gentlemen, that the thanks of the profession at large, in this country are due to you for the republication of this admirable work of Maclise. The precise relationship of the organs in the regions displayed is so perfect, that even those who have daily access to the dissecting-room may, by consulting this work, enliven and confirm their anatomical knowledge prior to an operation. But it is to the thousands of practitioners of our country who cannot enjoy these advantages that the perusal of those plates, with their concise and accurate descriptions, will prove of infinite value, These have supplied a desideratum, which will enable them to refresh their knowledge of the im- portant structures involved in their surgical cases, thus establishing their self-confidence, and ena- bling them to undertake operative procedures with every assurance of success. And as all the practi- cal departments in medicine rest upon the same basis, and are enriched from the same sources, I need hardly add that this work should be found in the library of every practitioner in the land. From Prof. Gibson, Richmond, Va. Excellent as are the previous numbers, the pre- sent one far surpasses them, and indeed is superior to anything of the kind I have ever seen. The plates illustrating the anatomy of the Urethra and Bladder are superb. From Prof. McClintock, Philadelphia. I regard it as the best book on the subject ever published in this country. I have recommended it to the gentlemen of our classes, many of whom, after procuring it, have thanked me for the advice. From Prof. Bethune, Trinity College, Toronto. The work is exceedingly well brought out, and reflects the highest credit upon your establishment It will afford me great pleasure to recommend it to all my professional friends and pupils. From Prof. Kimball, Pittsfield, Mass. I have examined these numbers with the great- est SSi, and feel bound to say that they Tre altogether the most perfect and satisfactory plates ofthe kind that I have ever seen. From Prof. Richardson, University of Toronto. No commendation is necessary from me to secure for it a wide circulation, for it has obtained, both in Britain and America, the most marked approba- tion: and upon examination it will commend itself to all for the clearness, fidelity, and beauty of the plates, and the able descriptions of the letter-press. From Prof. Brainard, Chicago, III. The work is extremely well adapted to the use both of students and practitioners, being sufficiently extensive for practicaj purposes, without being so expensive as to place it beyond their reach. Such a work was a desideratum in this country, and I shall not fail to recommend it to those within the sphere of my acquaintance. From Prof. P. F. Eve, Augusta, Ga. I consider this work a great acquisition to my library, and shall take pleasure in recommending it on all suitable occasions. From Prof. Peaslee, Brunswick, Me. The second part more than fulfils the promise held out by the first, so far as the beauty of the il- lustrations is concerned ; and, respecting my opin- ion of the value of the work, so far as it has advanced, I need add nothing to What I have pre- viously expressed to you. From Prof. Gunn, Ann Arbor, Mich. The plates in your edition of Maclise answer, in an eminent degree, the purpose for which they are intended. I shall take pleasure in exhibiting it and recommending it to my class. From Prof. Rivers, Providence, R. I. The plates illustrative of Hernia are the most satisfactory I have ever met with. From Prof. S. D. Gross, Louisville, Ky. The work, as far as it has progressed, is most admirable, and cannot fail, when completed, to form a most valuable contribution to the literature of our profession. It will afford megreatpleasure to recommend it to the pupils of the Unifersity of Louisville. 28 BLANCHARD & LEA'S LATE MEDICAL PUBLICATIONS. Maclise's Surgical Anatomy—(Continued.) From Prof. R. L. Howard, Columbus Ohio. In all respects, the first number is the beginning of a most excellent work, filling completely what might be considered hitherto a vacuum in surgical literature. For myself, in behalf of the medical profession, I wish to express to you my thanks for this truly elegant and meritorious work. I am confident that it will meet with a ready and ex- tensive sale. I have spoken of it in the highest terms to rhy class and my professional brethren. From Prof. Granville S. Pattison. N. Y. The profession, in my opinion, owe you many thanks for the publication of this beautiful work— a work which, in the correctness of its exhibitions of Surgical Anatomy, is not surpassed by any with which I am acquainted; and the admirable manner in which the lithographic plates have been executed and colored is alike honorable to your house and to the arts in the United States. From Prof. J. F. May, Washington, D. C. Having examined the work I am pleased to add my testimony to its correctness, and to its value as a work of reference by the surgeon. From Prof. Alden Marsh, Albany, N. Y. From what I have seen of it, I think the design and execution of the work admirable, and, at the & roper time in my course of lectures, I shall ex- ibit it to the class, and give it a recommendation worthy of its great merit. From H. H. Smith, M.D., Philadelphia. Permit me to express my gratification at the execution of Maclise's Surgical Anatomy. The plates are, in my opinion, the best lithographs that I have seen of a medical character, and the color- ing of this number cannot, I think, be improved. Estimating highly the contents of the work. I shall continue to recommend it to my class as I have heretofore done. From Prof. J. M. Bush, Lexington, Ky. I am delighted with both the plan and execution of the work, and shall take all occasions to recom- mend it to my private prfpils and public classes. This is by far the ablest work on Surgical Ana- tomy that has come under our observation. We know of no other work that would justify a stu- dent in any degree, for neglect of actual dissec- tion.' A careful study of these plates, and of the commentaries on them, would almost make an anatomist of a diligent student. And to one who has studied anatomy by dissection, this work is invaluable as a perpetual remembrancer, in mat- ters of knowledge that may slip from the memory. The practitioner can scarcely consider himself equipped for the duties of his profession without such a work as this, and this has no rival, in his library. In those sudden emergencies that so often arise, aud which require the instantaneous command of minute anatomical knowledge, a work of this kind keeps the details of the dissecting-room perpetually fregh in the memory. We appeal to our readers, whether any one can justifiably un- dertake the practice of medicine who is not pre- pared to give all needful assistance, in all matters demanding immediate relief. We repeat that no medical library, however large, can be complete without Maclise's Surgical Anatomy. The Ame- rican edition is well entitled to the confidence of the profession, and should command, among them, an extensive sale. The investment of the amount of the cost of this work will prove to be a very profitable one, and if practitioners would qualify themselves thoroughly with such important know- ledge as is contained in works of this kind, there would be fewer of them sighing for employment. The medical profession should spring towards such an opportunity as is presented in this republica- tion, to encourage frequent repetitions of American enterprise of this kind.—The Western Journal of Medicine and Surgery. One of the greatest artistic triumphs ofthe age in Surgical Anatomy.—British American Medical Journal. A, One of the most useful and elegant practical works on anatomy ever published. --London Lancet. Too much cannot be said in its praise; indeed, we have not language to do it justice.—Ohio Medi- cal and Surgical Journal. The most admirable surgical atlas we have seen. To the practitioner deprived of demonstra- tive dissections upon the human subject, it is an invaluable companion.—N. J. Medical Reporter. The most accurately engraved and beautifully colored plates we have ever seen in an American book—one of the best and cheapest surgical woiki ever published.—Buffalo Medical Journal. It is very rare that so elegantly printed, so well illustrated, and so useful a work, is offered at so moderate a pried.—Charleston Medical Journal. Its plates can boast a superiority which places them almost beyond the reach of competition.— Medical Examiner. Every practitioner, we think, should have'a work of this kind within reach.—Southern Medical and Surgical Journal. No such lithographic illustrations of surgical regions have hitherto, we think, been given.— Boston Medical and Surgical Journal. As a surgical anatomist, Mr. Maclise has proba- bly no superior.—British and Foreign Medico- Chirurgical Review. Of great value to the student engaged in dissect- ing, and to the surgeon at a distance from the means of keeping up his anatomical knowledge.— Medical Times. All that can be desired or expected.—American Medical Journal. The mechanical execution cannot be excelled.— Transylvania Medical Journal. A work which has no parallel in point of accu racy and cheapness in the English language.— N. Y. Journal of Medicine. To all engaged in the study or practice of their profession, such a work is almost indispensable.— Dublin Quarterly Medical Journal. No practitioner whose means will admit should fail to possess it.—Ranking's Abstract. Country practitioners will find these plates of immense value.—N. Y. Medical Gazette. We are extremely gratified to announce to the profession the completion of this truly magnificent work, which, as a whole, certainly stands unri- valled, both for accuracy of drawing, beauty of coloring, and all the requisite explanations of the subject in hand. To the publishers, the profession in America is deeply indebted for placing such a valuable, such a useful work, at its disposal, and at such a moderate price. It is one of the most finished and complete pictures of Surgical Anato- my ever offered to the profession of America. With these plates before them, the student and practitioner can never be at a loss, under the most desperate circumstances. We do not intend these for commonplace compliments. We are sincere; because we know the work will be found invalua- ble to the young, no less than the old, surgeon. We have not space to point out its beauties, and its merits ; but we speak of it en masse, as a whole, and strongly urge—especially those, who, from their position, may be debarred the privilege iind opportunity of inspecting the fresh subject, to furnish themselves with the entire work__The New Orleans Medical and Surgical Journal. BLANCHARD & LEA'S MEDICAL PUBLICATIONS. 29 WATSON'S PRACTICE OF M EOICI N E-N EW EDITION. Lectures on the Principles and Practice of Physic. By Thomas Watson, M. D., &c. &c. Third American' from the last London Edition. Re- vised, with Additions, by D. Francis Condie, M. D., author of ** A Treatise on the Diseases of Children," &c. In one octavo volume, of nearly eleven hundred large pages, strongly bound, with raised bands. To say that it is the very best work on the subject now extant, is but to echo the sentiment of the medical press throughout the country.— N. O. Medical Journal. Regarded on all hands as one of the very best, if not the very best, systematic treatise on practical medi- cine extant— St. Louis Med. Journal. As a text-book it has no equal; as a compendium of pathology and practice no superior.— N. Y. Annalist. We know of no work better calculated for being placed in the hands of the student, and for a textbook; on every important point the author seems to have'posted up his knowledge to the day.—Amer. Med. Journal. One ofthe most practically useful books that ever was presented to the student.—A*. Y. Med. Journal. CHURCHILL'S M I D vf I FERY, BY CONDIE. NEW AND IMPROVED EDITION—JUST ISSUED. On the Theory and Practice of Midwifery. By Fleetwood Churchill, M. D., &c. A new American, from the last and improved English edition. Edited, with Notes and Additions, by D. Francis Condie, M. D., author of a ••Practical Treatise on the Diseases of Children," &c. With one hundred and thirty-nine illustrations. In one very handsome octavo volume. To bestow praise on a book that has received such marked approbation would be superfluous. We need only say, therefore, thai if the first edition was thought worthy of a favorable reception by the medical pub- lic, we can confidently affirm that this will be found much more so. The lecturer, the practitioner, and the student, may all have recourse to its pages, and derive from their perusal much interest and instruction in everything relating to theoretical and practical midwifery.—Dublin Quarterly Journal of Medical Science. A work of very great merit, and such as we can confidently recommend to the study of every obstetric practitioner.—London Medical Gazelle. This is certainly the most perfect system extant. It is the best adapted for the purposes of a text-book, and that which he whose necessities confine him to one book, should select in preference to all others.—Southern Medical and Surgical Journal. The most popular work on Midwifery ever issued from the American press —Charleston Medical Journal. Certainly, in our opinion, the very best work on the subject which exists.—N. Y. Annalist. Were we reduced to the necessity of havingbut one work on Midwifery, andpermiltedtochoose,vre would unhesitatingly take Churchill.— Western Medical and Surgical Journal. It is impossible to conceive a more useful and elegant Manual than Dr. Churchill's Practice of Midwifery. — Provincial Medical Journal. No work holds a higher position, or is more deserving of being placed in the hands of the tyro,the advanced student, or the practitioner.—Medical Examiner. THE STUDENT'S TEXT-BOOK OF SURGERY. The Principles and Practice of Modern Surgery. By Robert Druitt, Fellow of the Royal College of Surgeons. A new American, from the last and improved London edition. Edited by F. W. Sargent, M. D., author of " Minor Surgery," &c. Illustrated with one hundred and ninety-three wood-engravings. In one very handsomely printed octavo volume of 576 large pages. From Professor Brainard, of Chicago, Illinois. I think it the best work of its size, on that subject, in the language. From Professor Rivers, of Providence, Rhode Island. I have been acquainted with it since it^ first republication in this country, and the universal praise it has received I think well merited. ___ From Professor May, of Washington, D. C. Permit me to express my satisfaction at the republication in so improved a form of this most valuable work. I believe it to be one of the very best text-books ever issued. t From Professor McCook, of Baltimore. I cannot withhold my approval of its merits, or the expression that no work is better suited to the wants of the student. I shall commend it to my class, and make it my chief text-book. THE STUDENT'S TEXT-BOOK OF ANATOMY. NEW AND IMPROVED EDITION—JUST ISSUED. A System of Human Anatomy, General and Special. By Erasmus Wilson M. D. Fourth American, from the last English edition. Edited, with a new chapter on Histology, by Paul B. Goddard, A. M., M. D. With two hundred and fifty illustrations. Beautifully printed, in one large octavo volume of nearly six hundred pages. in ma n v if not all the Colleges ofthe Union, it has become a standard text-book. Th is, of itselfis sufficiently in many ,i va)ue a. work very desirable to the student; one, the possession of which will greatly ?.XJ!m^p his nro«e*s in the study of Practical Anatomy.—New York Journal of Medicn,. r = u.i7hor ranks with the highest on Anatomy.—Southern Medical and Surgical Journal. i!«flirRiftilie -tudent all the assistance that can be expected from such a work— Medical Examiner. -rhJ"mostcomplete and convenientmanual forlhe student we possess— American Journal of Med. Science. In every respect this work, as an anatomical guide for the student and practitioner, merits our warmest and most decided praise.—London Medical Gazette. MEDICAL AND SURGICAL WORKS PUBLISHED BY BLANCHARD & LEA, PHILADELPHIA. The following works on medical and other sciences, published by us, may be had of all the principal Booksellers throughout the Union, who can in all cases procure, with but little delay, any books inquired for, which they may not have on hand. Physicians ^lroughout the country will therefore find no difiiculty in ob- taining any of our publications, by ordering them at the nearest bookstore. Par- ticulars respecting prices, &c, furnished on application. Catalogues of our Miscellaneous Publications will be sent by mail, if requested. BLANCHARD & LEA. Philadelphia, January 1, 1853. DICTIONARIES &. JOURNALS. AMERICAN JOURNAL OF THE MEDICAL SCIENCES, quarterly, at $5 a year. CYCLOPAEDIA OF PRACTICAL MEDICINE. by Forbes, Tweedie.&c, edited by DtjnglisonJ in 4 royal Svo. vols., 3154 double columned pages. DUNGLISON'S MEDICAL DICTIONARY, 8th ed., 1 vol. large octavo, 928 pages. HOBLYN'S DICTIONARY OF MEDICAL TERMS, by Hays, 1vol. large 12mo.,402 pages. NEILL AND SMITH'S COMPENDIUM OF THE MEDICAL, SCIENCES, 2d ed., enlarged, 1 vol., large 12mo., 1000 pages, 350 cuts. MEDICAL NEWS AND LIBRARY, monthly, at $1 a year. ANATOMY. ANATOMICAL ATLAS, by Smith and Horner, imp. 8vo., 650 figs. New and cheaper edition. HORNER'S SPECIAL ANATOMY AND HIS- TOLOGY, new edition, 2 vols. 8vo., many cuts. HORNER'S UNITED STATES DISSECTOR, 1 vol. large royal 12mo., many cuts, 444 pages. MACLISE'S SURGICAL ANATOMY, now complete in 1 large imp.4to. vol., strongly bound, with 68 magnificent colored plates. SHARPEY AND QUAIN'S* ANATOMY, by Leidy, 2 vols. 8vo., 1300 pages, 511 wood-cuts. WILSONS HUMAN ANATOMY, by Goddard, 4th ed., 1 vol. 8vo., 252 wood-cuts, 580 pp. WILSON'S DISSECTOR, by Goddard. New edition, with cuts, 1 vol. 12mo., 458 pages. PHYSIOLOGY. CARPENTER'S PRINCIPLES OF HUMAN PHYSIOLOGY, 1 large vol. 8vo., many illus- trations, new and improved edition, by F. G. Smith, M.D., (now ready.) CARPENTER'S ELEMENTS, OR MANUAL OF PHYSIOLOGY, new and improved edition, 1 vol. 8vo., 566 pages. (Just Issued.) CARPENTER'S COMPARATIVE PHYSIOL- OGY, 1 vol. 8vo., new edition, (preparing.) DUNGLISON'S HUMAN PHYSIOLOGY, 7th edition, 2 vols. 8vo., 1428 pages, and 472 cuts. HARRISON ON THE NERVES, I vol. 8vo., 292 pages. KIRKKS AND PAGET'S PHYSIOLOGY, 2d edition, 1 vol. 12mo., many cuts, (now ready.) LONGET'S PHYSIOLOGY. Translated by F. G. Smith, 2 vols. 8vo., many cuts, (preparing.) MATTEUCCI ON THE PHYSICAL PHENO- MENA OF LIVING BEINGS, 1 vol. ]2mo., 388 pages, cuts. SOLLY ON THE BRAIN, 1 vol. 8vo., 496 pp., 118 cuts. TODD AND BOWMAN'S PHYSIOLOGICAL ANATOMY AND PHYSIOLOGY OF MAN. Parts I II. and III., 1 vol. 8vo., 156 wood-cuts. Part IV. nearly ready. PATHOLOGY. ABERCROMBIE ON THE BRAIN, 1vol. 8vo., 324 pages. BLAKISTON ON DISEASES OF THE CHEST, 1 vol., 384 pages. BLOOD AND URINE MANUALS, by Reese, Griffith, and Markwick, 1 vol. 12mo., with plates. 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VOGEL'S PATHOLOGICAL ANATOMY OF THE HUMAN BODY, I vol. 8vo., 536 pages. colored plates. WILSON ON THE SKIN, 1 vol. 8vo., 3d edition enlarged, 480 pages, (now ready.) Same work, with 15 plates. WILSON ON SVPHILIS, 1 vol. 8vo., beautiful colored plates (now ready.) WHITEHEAD ON STERILITY AND ABOR TION, 1 vol.8 vo, 368 pages. n WILLIAMS'S PRINCIPLES OF MEDICINE by Clymer, 2d edition, 440 pages, 1 vol. 8vo. ' WILLIAMS ON THE RESPIRATORY OR GANS, by Clymer, 1 vol. 8vo., 500 pages. BLANCHARD & LEA'S MEDICAL PUBLICATIONS. 31 PRACTICE OF MEDICINE. ASHWELL ON FEMALES, 2d ed., 1 vol. 8vo., 520 pages BARLOW'S PRACTICE OF MEDICINE, (pre- paring.) , 'VF BENNET ON THE UTERUS, 3d and enlarged edition, 1 vol. 8vo., 350 pages, (now ready.) BARTLETT ON FEVERS, 3d edition improved, 1 vol. 8vo., (now ready.) BENEDICT'S COMPENDIUM OF CHAP- MAN'S LECTURES, 1 vol. 8vo., 258 pages. CHAPMAN ON FEVERS, GOUT, DROPSY, ice. &c, 1 vol. 8vo., 450 pages. 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BLANCHARD & LEA have now ready a Catalogue of their Medical and Surgical Publications, containing descriptions of the works, with Notices of the Press and speci- mens of the Illustrations, making a pamphlet of forty-eight large octavo pages. It has been prepared with great care, and without regard to expense, forming one of the most beautiful specimens of typographical execution as yet issued in this country. Copies sent by mail, free of postage, to Physicians, on application to the Publishers. NLM032067127