THE HUMAN BODY. Illustrated Eibrary of Wonders. published by Jltessrs. (Efjmfcs SciiGner Co., 654 BROADWAY, NEW YORK. Each one volume 12mo. Price per volume, $1.50. Wonders of Glass-Making, .... 49 Wonders of Italian Art, . . . . .28 The Sun, bt A. Guillemin, . . . . 88 * The Moon, by A. Guillemin, . . . .60 Wonders of Optics, . ... 70 TnUNDER AND LIGHTNING, . .... 89 Wonders of Heat, .... 90 Intelligence of Animals, . . . . , 64 Great Hunts, . .... 22 Egypt 3,300 Years Ago, . . . . .40 Wonders of Pompeii, ..... 30 Sublime in Nature, ... . . 60 » Bottom of the Ocean, .... .93 * WONDERS OF THE HEAVENS, . . . .48 * Wonders of Architecture, ... .60 * Acoustics, ....... n4 Wonders of the Human Body, ... 45 * Lighthouses, ...... * Subterranean World, .... 27 Titles of Books. No. of Illustrations * In Press for early publication. The above works sent to any address, post-paid, upon receipt of the wrtca by the publishers. THE MAJORS KNAPP ENG.MFG& LrTH.CO.71 BROADWAY N.Y. WONDERS OF THE HUMAN BODY. FROM THE FRENCH OF A. LE PILEUR, DOCTOR OF MEDICINE. ILLUSTRATED BY FORTY-FIVE ENGRAVINGS BY LEVEILLE. NEW YORK: CHARLES SCRIBNER AND CO. 1870. PUBLISHERS’ PREFACE. There is an increasing tendency in the present day to make common property of special knowledge. Even such infor- mation as formerly belonged to certain professions alone is, at least in its rudiments, becoming more generally diffused; and on the part even of those professions the tendency is recognized as within reasonable bounds deserving of encour- agement. To take “the human body” as an illustration, medical men find that the useful feature of their art is facilitated by the dissemination of information regarding its structure and functions. On the other hand, the public daily see more and more clearly that “prevention is better than cure,” and that to prevent derangements of the wonderful machine, with the guidance of which each individual is intrusted, more ac- quaintance with its mechanism and laws of normal action is indispensable. Apart from its utility, a knowledge of anatomy and physiology is gradually becoming a necessary part of a liberal education. To meet these requirements the Publishers now present this translation from the French of a book which, in the original, has attained to great popularity. While sufficiently VI PREFACE. minute in anatomical and physiological details to satisfy those who desire to go deeper into such studies than many may deem necessary, this work is nevertheless written so that it may form part of the domestic library. Mothers and daughters may read it without being repelled or shocked; and the young will find their interest sustained by incidental digressions to more attractive matters. Such are the pages referring to phrenology and to music, which accompany the anatomical description of the skull and of the organs of voice; and the chapter on artistic expression which closes the book. Attention may also be directed to the numerous accurate and also simple engravings, which have been introduced in the hope of elucidating the verbal descriptions in the text. CONTENTS. Introduction.—Opinions of the ancients concerning the human body.—Summary of general anatomy.—Substance of the body or organized matter.—Anatomical elements.—Nutrition.—Fluids. —Tissues, I CHAPTER I. PAGE Form of the body.—Its beauty.—The master-pieces which it has inspired.—Description of the skin—its functions, 13 CHAPTER II. CHAPTER III. Structure of the body.—Bones, cartilages, joints.—Muscles, ten- dons, aponeuroses, 25 CHAPTER IV. Spinal column.—Thorax.—Upper limb; shoulder, arm, fore-arm, hand.—Lower limb; hip, thigh, leg, foot, 41 CHAPTER V. Motion.—Effort.—Locomotion; standing, walking, running, jump- ing, swimming, 57 CHAPTER VI. The head.—The skull, bones of the skull, sutures, arch of the skull, base of the skull.—Measurement of the skull; facial angle, angle of Daubenton; comparison of the superficies of the skull and of the face.—System of Gall.—The face, bones of the face, upper jaw, lower jaw, ............. r 6y Digestion.—Waste of the organism repaired by alimentation.—- Hunger.—Thirst.—Organs of digestion; abdominal cavity, peri- toneum. — Digestive apparatus. — Mouth, lips, cheeks, teeth, palate, soft palate, tongue.—Pharynx.—CEsophagus.—Stomach. •—Intestinal canal; small intestine, large intestine, intestinal con? CHAPTER VII. viii CONTENTS. volutions, mesentery, omentum.—Mucous membrane.—Liver.— Pancreas.—Spleen.—Kidneys.—Mechanism of digestion.—Di- gestion of the stomach, gastric juice, peristaltic movement, chyme. —Intestinal digestion, bile, pancreatic juice, chyle.—Absorption; endosmosis, exosmosis, functions of the veins and lymphatic vessels in absorption, rapidity of absorption, 73 PAGE CHAPTER VIII. Respiration.—Thoracic cavity; pleura.—Organs of respiration: lungs, trachea, bronchia.—Respiration; influence of respiration on the blood, Lavoisier’s theory, theory of catalytic phenomena; mechanism of respiration, respiratory sounds, frequency of re- spiration; capacity of the lungs; modification of the air in the lungs.—Influence of atmospheric pressure on respiration; moun- tain-sickness, ........ 89 CHAPTER IX. Circulation.—Organs of the circulation; heart, pericardium; arteries, capillaries, principal arteries; veins, principal veins; portal sys- tem; lymphatic vessels and ganglia.—Mechanism of the circula- tion; discovery of the circulation, action and sounds of the heart, arterial circulation, pulse, capillary circulation; venous circula- tion, valves of the veins; discharge of chyle and lymph into the veins. Sanguification; circulation in the pulmonary artery, capillaries, and pulmonary veins.—Influences which accelerate or retard the beating of the heart, . 102 CPIAPTER X. Nervous system.—Cerebro-spinal nervous centre. — Cerebrum.— Cerebellum.—Isthmus of the encephalon.—Medulla oblongata.— Spinal cord.—Membranes; dura mater, arachnoid, pia mater.— Nerves; cranial nerves, spinal nerves, great sympathetic.—Func- tions of the nervous system; functions of the spinal nerves of motion and of sensation; function of the cranial nerves; functions of the spinal marrow.—Functions of the encephalon; medulla oblongata, pons Varolii, peduncles of the cerebrum and cere- bellum, corpora quadrigemina, pineal gland, optic thalami, cerebrum and cerebellum.—Functions of the great sympathetic. —Reflex power.—Nerve force.—Memory, 119 Sense of sight.—Organ of vision.—Globe of the eye; sclerotic; cornea; choroid ; ciliary ring; ciliary body; ciliary process; iris; Eupil; uvea; pigment; retina; vitreous body; hyaloid mem- rane; crystalline; anterior and posterior chambers; aqueous tumour.—Muscles of the eye.—Conjunctiva.—Eyelids, eyelashes, CHAPTER XI. CONTENTS. PAGE IX —Lachrymal apparatus.—Vision ; functions of the retina, re- versed images; functions of the iris; optic centre, visual angle, visual impressions, single or mixed, adaptation of the eye to dis- tances, myopia, presbyopia; achromatism; single and double vision with two eyes, stereoscope; alternation in the action of the eyes; persistence of impressions on the retina; accidental images; irradiation; accidental aureola; Daltonism; apparent motion of objects.—Optic nerve.—Movements of the eye.—Ex- tent of vision, 152 CHAPTER XII. Sense of hearing.—Organ of hearing.—External ear; pavilion of the ear, auditory canal.—Middle ear; tympanum, drum, or membrana tympani, fenestra ovalis, fenestra rotunda, Eustachian tube, the small bones of the ear, muscles and movements of the small bones.—Internal ear; labyrinth, vestibule, semicircular canals, cochlea, membranous labyrinth.—Auditory nerve.— Noises and sounds; duration, pitch, intensity and quality of sound; passage of sound through air, water, solid bodies; gravity, sharpness of sound.—Mechanism of hearing; functions of different parts of the ear; movement of sounds in the ear; propagation of sounds to the auditory apparatus by the vibrations of the bones of the skull.—Opinions of physiologists on the functions of different portions of the labyrinth; theory of Helm- holtz.—Fineness and delicacy of hearing.—Correctness of the ear.—Estimation of the intensity, the distance, and the direction of sounds; ventriloquism.—Duration of auditory impressions.— Sensations having an internal origin.—Parallel between the eye and ear, 182 CHAPTER XIII. Sense of smell. Olfactory organs.—Nose; nasal fossae, turbinated bones, pituitary membrane. — Olfactory nerve. Odoriferous principles; their development, their action on the nervous sys- tem.—Smell,—its seat; duration of olfactory impressions.—Uses, and acuteness of smell, 203 CHAPTER XIV. Sense of taste.—Organ of taste.—Special nerves of the organ.— Flavours.—Taste, 210 CHAPTER XV. Sense of touch.—Difference between touch and feeling.—Tactile sensibility and general sensibility.—Organ of touch. Sensation of contact; difference in the sensibility of different regions of the body; simple contact, shock, vibration.—Sensation of pressure; X CONTENTS. relative aptitude of different regions in appreciating it; variable sensation according to the form of the body and the extent of its surface.—Sensation of temperature, variable according to the temperature of the skin, the density of bodies, and the surface in contact; identical sensation from contact with a body very hot and very cold; relative sensibility of different regions to tem- perature.—The touch; its delicacy.—The touch compared with the other senses; illusions of touch; persistence of tactile impres- sions, sensations from internal or subjective causes; causes which modify feeling, 217 PAGE Voice and speech.—Organ of voice; larynx, cavity of the larynx, glottis, vocal cords; the larynx at different ages and in different sexes.—Physiology of the larynx; mechanism of the voice; opinions as to the formation of the voice.—Galen, Fabricius Acquapendente, Dodart, Ferrein, Biot, Muller, Savart, Masson, and Longet.—Theories founded on laryngoscopic observations.— Formation of sounds in whistling.—Voice; speaking voice, mechanism of articulate sounds, vowels, consonants, timbre of the vowels; the tongue as an organ of pronunciation.—Singing; chest voice, falsetto voice, mixed voice; different theories on the formation of the falsetto: Muller, M. Segond, M. Longet, M. Fournie, M. Bataille, M. Mandl.—Timbres of the voice: high pitch, grave pitch.—Compass of voices: bass, baritone, tenor, contralto, mezzo-soprano, soprano.—Ventriloquy, 228 CHAPTER XVI. Physiognomy; study of it in works of art.—Movements of expres- sion, their seat.—Colouring of the skin; paleness, redness.—Ex- pression of the muscles; effort, muscles of the face.—Physiognomy of the senses.—Expression of the eyes, vision, easy or difficult, blindness.—Expression in the act of hearing, easy or difficult, hearing of an orator, musical hearing.—Expressions of smell and taste.—Expressions relating to the touch, 247 CHAPTER XVII. LIST OF ILLUSTRATIONS. FIG. PAGE 1. Blood seen under the microscope, 4 2. Bony tissue as seen with the naked eye, 8 3. Osseous and cartilaginous tissues as seen through the micro- scope, 8 4. Laminated fibres in the first stage of development, .... 9 5. Stripped muscular tissue as seen under the microscope, . . 10 6. Nervous tissue seen under the microscope, 11 7. A nerve and its ramifications seen by the naked eye, ... 12 8. Apollo Belvedere, 15 9. The Venus of Milo, 17 10. The Skin, 21 11. Skeleton, 27 12. Elbow-joint, 33 13. Biceps muscle of the arm, 35 14. Lower portion of the leg, 37 15. The hand, palmar aspect, 46 16. The hand, dorsal aspect, 46 17. Knee-joint, 52 18. Skeleton of the foot, 54 19. The foot, 55 20. The leg in standing, 61 21. Section of the trunk and its cavities in the median line, . . 74 22. Section in the median line through the inferior portion of the nasal fossae, the mouth, pharynx, larynx, oesophagus, and trachea, 76 23. Transverse section of the thoracic and abdominal cavities, . 81 24. Lungs and heart, 91 xii LIST OF ILLUSTRATIONS. FIG. PAGE 25. Section showing the ramifications of the bronchi in the lungs, 93 26. Heart and principal arterial and venous trunks, 103 27. Transverse section of the heart, 105 28. Imaginary diagram of the course of the blood in the circula- tion, 116 29. Cerebro-spinal nervous centre, 120 30. Nervous system, 121 31. Upper surface of the brain, 123 32. Lower surface of the brain, 124 33. Section of the encephalon in the median line, 126 34. Vertical section of the eye on the median line, 153 35. Rods of Jacob under the microscope, 156 36. Diagram illustrating “ blind point ” in retina, 161 37. Course of the luminous rays in the eye, 162 38. Diagram illustrating the visual angle, 164 39. Accommodation of the eye to different distances, . . . . 167 40. Diagram illustrating single vision with two eyes, . . . . 170 41. Irradiation, 176 42. Section showing the different parts of the ear, 183 43. Experiment on the sensations of touch, . 226 44. Section of larynx in the median line, 229 45. The glottis and vocal cords, 242 THE HUMAN BODY. CHAPTER I. INTRODUCTION. Opinions of the ancients concerning the human body.—Summary of general anatomy.—Substance of the body or organized matter.—Anatomical elements. —Nutrition. —Fluids. — Tissues. It has been said with truth, that the human mind, which can survey the heavens and calculate the motion and density of the stars, finds itself confounded when, returning from these distant journeyings, it enters its own proper dwelling- place. Man’s own organization is still among those mysteries of nature which he is least able to penetrate, in spite of his incessant efforts to lift the veil which hides it. In all ages he has sought to know himself; in all times he has studied the relations between his own existence and that of the world; and those universal influences which, though evident to him, are nearly all inexplicable in their action upon living beings. Carried by their imagination into this way of comparing the human body with the rest of creation, Aristotle and some other philosophers saw in man an epitome of the wonders of the universe. He was for them the microcosm, the dimi- nutive and summary of the entire world. Paracelsus and the astrological doctors developed from their stand-point the ideas of the Greek philosophers, and pushed to its extreme limits the doctrine of sidereal influence 1 2 THE HUMAN BODY. upon man. According to them, the body had, like the earth, an axis and two poles; the head, the seat of the soul, corres- ponded to the heavens where divinity resided, &c. Since that time, and especially in our own day, the ima- gination has given way to a rigorous method of study and to positive ideas. But whether we venturously follow Aris- totle and Paracelsus, or whether we prefer the exact results of science to their poetic theories, we shall always see in the human body the highest and most perfect creation of nature among living beings, and we shall admire the efforts and the discoveries which the study of its organization has enabled the mind to make from the time of the masters of antiquity down to our own day. In the human body, as in animals and in the vegetable kingdom, the organized matter is composed of what are termed proximate (or immediate) principles and anatomical elements. Of these proximate principles some are of mineral origin, as oxygen, water, the carbonates, the chlorides, the phosphates, &c. They penetrate the organism, and there furnish the materials, by the aid of which other principles of a different order are formed. These last essentially consti- tute the body, hence the name organic substances is specially applied to them. There is nothing in the mineral kingdom analogous to these organic substances, though they borrow their original elements from it. They are solid or semi-solid (globuline, musculine), liquid or semi-liquid (fibrine, albu- men, caseine), colouring or coloured (hematosine, biliver- dine). They decompose where they are formed, and give birth to another class of proximate principles. These last are of very different natures, and possess different attributes; they are acids, salts, alkaloids, fatty bodies; they are urea, creatine, stearine, cholesterine, and the sugar of the milk and of the liver, lactic acid, uric acid, &c. This double and continuous movement of combination and resolution of proximate principles results in the forma- tion of the anatomical elements. This is the term applied to very minute bodies, free or attached, which present special geometrical, physical, and chemical characters, as well as a structure which has no analogy to that of minerals.—They NUTRITION—HUMOURS. are the smallest organic subdivisions of which the tissues and fluids are capable by anatomical analysis. Their reunion and combination form the solids and liquids of the organism. By assimilation they borrow their substance from the molecules of the proximate principles, while at the same time and in equal proportions they abandon other molecules of these same principles by a process of separation. This assemblage of phenomena is termed nutrition. In this manner water, carbon, lime, phosphorus, iron, and the other principles, co-operate in forming globuline, fibrine, musculine, and the other organic substances, which by their combination constitute the anatomical elements of the blood, the muscles, the bones, the nerves, the body in a word; this is assimilation. 3 At the same time other molecules of the same principles, in equal proportions, abandon by a separatory process the substance of the organism, and unite to form the milk, saliva, tears, bile, and the other secretions, which are to be completely excreted as improper for nutrition, or partially thrown off and partially returned to the system. As to the anatomical elements, some of them have a form which may be described, as globule, fibre, tube, and cell; others are amorphous, and serve to fill the spaces between those first-named. We see therefore that the immediate or proximate prin- ciples and the anatomical elements constitute all organized matter whether solid or fluid. The fluid portions of the human body greatly exceed the solid; they are computed at nine-tenths of the whole weight. Water enters largely into the composition of these fluids, a portion of which only is contained in the vessels or reservoirs specially set apart for each of them, while the remainder penetrates the solid parts and forms part of their substance. The term humours—fluids—is applied to the liquid or semi-liquid portions of the organism formed by the mingling and dissolution of immediate principles, and they ordinarily hold the anatomical elements in suspension. The solid portions are called tissues. 4 THE HUMAN BODY. These fluids are classed, according to the part they play in the human economy, into constituent fluids, secreted fluids or secretions, excretions, and intermediate products, which partake of the nature of the other three. The constituent fluids are three in number—the blood, chyle, and lymph. The blood is the nutritive fluid of the body; it contains all the immediate principles that are found in its organism. In- cessantly renewed by digestion and respiration, it supplies to each organ assimilable matter, and to the special labora- tories the materials for the secretions, and carries off the results of disassimilation which are to be thrown out of the organism. It is therefore at once a reparative and a purify- ing fluid. The term “ fluid flesh,” which has been applied Fig. 1.—Blood seen under the microscope. to it, is incomplete, for it contains not only the muscular tissue, but the essential elements of all the other tissues are found in its mass. The blood is heavier than water, its specific gravity being 1052 to 1057, while that of water is 1000. In the blood- vessels the blood is composed of—1st. anatomical elements, red and white corpuscles. 2d. Of a fluid, of which 779 parts in weight in 1000 are water in men, and in women 791 parts in xooo. This fluid is the plasma, the plastic substance, the nourishing juice in which are found all the immediate BLOOD. 5 principles of the blood. Among these principles are lime, ammonia, soda, potash, phosphorus, magnesia, iron and other metals in the form of salts; chlorides, sulphates, carbonates, phosphates, &c.; and mingled with these are the principles of the secretions and organic substances, of which the most important, from their quantity, are—fibrine, 2'5 parts in 1000, and albumen 69 to 70 in 1000. The blood owes its colour to the red corpuscles, which are themselves coloured by a substance which De Blainville has named hematosine, and which contains 7 parts in 100 of iron. These corpuscles are round flattened disks of ’006 to ‘007 of a millimetre in diameter, and a thickness of ’002 milli- metre. Under the microscope they appear grouped together without order, or piled one upon another like pieces of money, and are of a red colour in reflected light. The white corpuscles are smooth, spherical, of a yellowish-white colour in a reflected light, and from -oo8 to ’014 of a millimetre in diameter. The colour of the blood is a beautiful crimson red in the arteries, but of a darker colour in the veins. We shall have occasion to examine it from this point of view in treating of the circulation. When blood which has been drawn is allowed to stand in the vessel, it separates into two distinct parts: the one, semi- solid, is called the crassamentum—the clot; the other fluid, is called serum. The clot is the coagulated fibrine which carries with it the red globules which were held in suspension in the blood. When the coagulation is delayed, these glob- ules, being heavier than the other portions of the blood, fall toward the lower part of the vessel; and the fibrine, freed from them, coagulates and retains its own proper colour, and the clot is composed of two layers—the superficial layer is of a grayish or white colour and semi-transparent, and is termed the “buffy coat.” It is formed of pure fibrine mingled with the white globules; the other is composed of fibrine and of the red globules which give it its colour. The serum is a transparent, greenish-yellow fluid, sometimes a little whitened by minute fatty specks; from which circumstance, and from some other points of analogy between them, it has 6 THE HUMAN BODY. been called the whey. It is a little less dense than the clot, and contains among other principles a great deal of albumen. The serum is the plasma without the fibrine. The chyle is a white opaque fluid closely resembling milk, which is separated from the food during the process of diges- tion, and is drawn by the chyliferous vessels from the surface of the smaller intestine, and serves .to fonn the blood. As it advances toward the point where it mingles with the blood, it resembles this fluid more and more in its composition; it takes a roseate tint, and, if left to itself, it separates into fibrinous clot and albuminous serum. The lymph is a clear, transparent fluid, slightly tinted with green or yellow. Drawn from the organs by the lymph- atic vessels, and especially from the skin and the surface of the mucous and serous membranes, the lymph is poured into the mass of blood by two principal canals. Like the chyle it contains white globules and minute specks of fat. When extracted from the lymphatic vessels, it also separates into fibrinous clot and serum, containing a little albumen. We see therefore that chyle and lymph are imperfect blood. The chyle leaves the digestive apparatus in a crude state, and goes to the blood-making laboratories for its perfection. The lymph comes from the extreme limits of the organs to these same laboratories, and, uniting with the chyle, is poured into the blood—the constituent fluid par excellence. The secreted fluids or secretions are produced by special apparatus from the materials furnished by the constituent fluids. They differ from these last in being only a medium for the elements which they hold in suspension, these elements not being essential to them, as the globules are to the blood, for example. They all contain one or several organic fluid substances, to the nature of which the secreted fluid owes its essential properties. These humours are very numerous, and play a very distinct part in the human economy. They are normal or morbid, as they owe their origin to the regular function of the organs or are modified by the action of disease. We shall mention only milk, which resembles the blood by being composed largely of serum, and which cannot be CHYME—TISSUES. 7 replaced by any substance for the alimentation in the first stages of infancy;—the aqueous and vitreous humours of the eye, the synovia which bathes and lubricates articulated sur- faces, the tears, and the saliva, which we shall see later takes a part in digestion, and in which Mons. Longet has shown the existence of minute and therefore harmless proportions of sulpho-cyanide of potassium, one of the most virulent poisons. In popular language the term humour is applied exclusively to the purulent fluids, morbid products which differ in some particulars according to the conditions under and the organs in which they are formed. It is unfortunate that they should monopolize a term which belongs to all the organic fluids. We shall merely point out the intermediate products, among which figures the chyme, a semi-fluid substance formed in the stomach during digestion, and the excretions which the system rejects, after having separated from them nearly all assimil- able principles. The tissues are the solid parts of the body, formed of anatomical elements either bound together or simply in juxtaposition. The tissues are classed according to the elements peculiar to them, according to their texture, that is to say the mode in which these elements are arranged; and according to their essential properties, which are either physico-chemical, such as consistence, extensibility, retrac- tility, elasticity, and hygrometricity, or organic, like the properties of absorption, of secretion, of development, of regeneration, of contractility, and of innervation. These properties are variable according to the tissues, which are more or less tenacious, more or less extensible, and so forth. Or they are peculiar to certain tissues, and independent, for a tissue may be retractile and not extensible or elastic, and vice versd. Constituent tissues are those which, composed of the fundamental elements, fibre, cell, and tube, form the essential organism. Produced tissues are those which eman- ate from the first, and may be detached from them without destroying them, and are only accessory or complementary parts. These products are normal or morbid, according to their nature and substance. THE HUMAN BODY. Among the numerous tissues which exist in the economy we cite the following:— Fig. 2.—Bony tissue as seen with the naked eye. Fig. 3.—Osseous and cartilaginous tissues as seen through the microscope. A, Cells of cartilaginous tissue. B, Section of a canal of Havers, showing the disposition of the starry cells in the substance of a bone. C, Starry cells magnified. Osseous or bony tissue, which is composed principally of an anatomical element called osteoplasm. It is compact in CELLULAR, ADIPOSE, MUSCULAR TISSUE. 9 some parts of the bones, and spongy in others. This tissue is traversed by infinitely ramified conduits, called the canals of Havers, which contain the blood-vessels and the medullary substance or marrow. Cartilaginous and fbro-cartilaginous tissue. Cellular or connective tissue, more exactly named laminated tissue, formed of laminated fibres, long, flattened, undulated filaments in bundles, and of fibres appertaining to elastic tissue. In nearly every part of the body this substance fills the spaces between the tissues or between the bundles of the fibres of which they are made up: on the surface of the body and of its cavities, and around the organs, it is disposed in enveloping membranes. Adipose tissue is formed of cells or vesicles containing fat. It is never found except in the cellular tissue and at the points where this last is least dense. These two tissues united are com- monly designated by the term fat, or fatty layer, but they are distinct notwithstanding, and neither wasting nor increase of fat causes any change in the mass of the cellular tissue, but only in the quantity of fat contained in the cells of the adipose tissue. Epithelial tissue has for its ana- tomical elements, cells or free nuclei, which form by juxta- position either a very thin single layer, or several superposed layers. It is of this tissue that the epidermis and the epithelium, a kind of internal epidermis, are essentially com- posed. Muscular tissue. This constitutes the muscles, or the flesh, properly speaking. It is composed of elements called muscular fibres, which are of two sorts, the smooth, formed of fibre-cells, and the striped, formed of bundles of fibrils. The fibrils are the fundamental element of the muscular tissue; their primitive microscopic bundles unite in secon- dary bundles visible to the naked eye, and are known in T ...... ... first stage of development. THE HUMAN BODY. descriptive anatomy under the name of fibres of the muscles. The fibrils are contractile but not elastic, and their primitive bundles have a homogeneous envelope of elastic but not contractile tissue called sarcolemma. Fibrous tissue has the same ele- ments as the cellular tissue, united in compact bundles visible to the naked eye, strongly adherent among themselves, and interlaced in every direction. Fibrous tissue is found especially in the articulating and inter- osseous ligaments and in certain en- veloping membranes, as the sclerotic, for example, which forms the white of the eye. Tendinous and aponeurotic tissue is made up of a variety of very thin laminated fibres, with puckered edges, undulated and adhering directly at one extremity to the sarcolemma of the striped muscular fascicles, and to the osseous substance at the other. These fibres unite in little flattened polyhedral bundles, from ‘ooi to ‘002 of a millimetre in breadth, from which the tendons and aponeuroses, which are of a tendinous nature, are formed. Tendinous tissue is in extensible lengthwise, and inelastic. Nervous tissue is essentially formed of tubes, which are large and small. They have homogeneous, thin, trans- parent walls, and contain a viscous, fatty fluid, which is the medullary substance or the white substance of Schwann, in which there is a sort of stem—the axis-cylinder. In the spinal marrow and in the brain the walls of the tube are wanting, and only the medullary sub- stance and the axis-cylinder remain. As we approach the outside of the body we find, on the contrary, that the tubes Fig. 5.—Striped muscular tis- sue as seen under the microscope. A, Fibril deprived of the sar- colemma, to show the disks of which it is composed. A', One of these disks. B, Severalfibres less magni- fied. NERVE-TISSUE. 11 become more homogeneous in structure, until at their ex- tremity they are reduced to a filament in which the walls, the a b, Spherical nerve-cells. c, Bi-polar cell, f M\ulti-polar cells. h, Cells of the ganglia, and nerve-fibres. i, Nerz’e-tube and axis-cylinder. k, Termination of a nerve-fibre in an organ. Fig. 6.—Nervous tissue seen under the microscope. cylindrical axis, and medullary substance are not distinguish- able. At certain points of the nervous system the tubes differ anatomically, according as they belong to the nerves of sensation or the nerves of motion. Other elements also are found in the nervous tissue—the ganglionic cells or corpuscles, and the fibres of Remak. The ganglionic corpuscles, so called because they are found in the substance of the ganglia, receive the sensitive tubes as they come from the brain or spinal marrow. These tubes unite with the walls of the corpuscle at one of the points or poles of its periphery, and emerge from it at the opposite pole. 12 THE HUMAN BODY. The ganglionic corpuscles are divided into bi-polar or multi-polar, according as they receive one or several tubes. Fig. 7.—A nerve and its ramifications seen by the naked eye. The fibres of Remak appear to be one of the constituent elements of the filaments of the nerves of motion. CHAPTER II. Form of the body—its beauty.— The master-pieces which it has inspired.— Description of the skin—its functions. Nature, in modelling animals, has marvellously adapted their forms to the functions and to the mode of life to which she has destined them; but no creature has received in the same degree as man, that mingling of strength and of elegance in contour, of grandeur and delicacy in the lines, and in no other has she taken such care to distinguish the two sexes in bestowing upon them her most precious gifts. It is of the human race alone that Buffon could say: “Man has strength and majesty; beauty and the graces are the dowry of the other sex.” The fabulist, using the poet’s privilege, makes the lion say— “Lions might hold the upper hand, If they but had the art to paint.” Doubtless in comparing himself with certain animals, man cannot ignore his inferiority in muscular strength and in the arms which nature has given him; but what matters it? He feels his superiority to these beings, though they are stronger and better armed than he. He knows how to avoid their attacks and to triumph over their brute force. He constrains them to his service, and disposes of their lives and of their bodies, by obeying not a blind instinct but the voice of reason. If he believes himself first among the dwellers on his planet, it is not his vanity which persuades, but his intelligence that proves it to him, and gives him the right to treat all other creatures as their master. We admire the majestic bearing of a tree, the elegance of 14 THE HUMAN BODY. a flower, the plumage and flight of a bird, the stately tread of some huge mammal, but nothing impresses us so much as the human form. It is not from sympathy with beings of our own species that we find them more beautiful; the judgment that we pronounce upon their beauty is not due to the inclination of one sex to the other; this sympathy and this inclination are common to most of the superior animals, but man alone appreciates the difference between individuals as between species; it belongs to him only to class them according to their merits, and to distinguish perfection from deformity; he alone possesses the sentiment of the beautiful, that faculty which permits him to admire the Creator in his works, and gives him the right to place himself in the first rank of animated beings. The plastic arts receive their most elevated inspirations from the human form, and it is to the efforts of painters and sculptors to reproduce it in its perfection that we owe the treasures of our museums.- It is often said of these master-pieces that they are the ideal of beauty, but we are not to understand from that something superior to nature itself. The artist may appreciate the relative beauty of the models which offer themselves to his eyes, but in ceasing to follow nature and in endeavouring to become her superior, he could only bring forth an imaginary product, a monstrosity. Ana- tomy should be his first study; if he forgets its precepts he becomes incorrect, like the musician who offends against the laws of harmony. The ideal is not therefore a form more perfect, it is the perfection of the natural form itself which the artist strives to attain, either by drawing inspiration from a single model, or by uniting in a single figure all the details which he has borrowed from different individuals. Far from seeking to surpass nature he feels that his hand is powerless to render completely the impression which his practised eye receives. Within certain limits he may nevertheless exaggerate or weaken some detail of form, and that too without ceasing to imitate nature, who shows him in this manner how he may embody the character and the physiognomy. The painter and the sculptor therefore may rightly allow themselves a certain latitude in lines and proportions; it is a poetical Fig. 8.—Apollo Belvedere. Fig- 9.—The Venus of Milo. THE HUMAN FORM—SKIN. license, analogous to that which allows a musician to obtain grand effects by momentary discords. To us then it seems that in questions of this nature the critic should proceed with a great deal of reserve. The right of the anatomist to point out an irregularity cannot be contested, and the artist should be warned that to genius alone can such be permitted; but even if we admit that all the criticisms addressed to painting or to sculpture in the name of the natural sciences are well founded, who could, in the presence of a master-piece, obstinately dwell upon a fault of detail? As regards the inspiration drawn from the human form, the beauty of Raphael’s Madonnas and the admirable paintings of the Venetians impress us perhaps still more than statuary. Under the pencil of the great masters it is man himself that we see. What is more beautiful than the “Vierge & la Chaise,” or than that “ Violante” painted by Giorgione, of which Venice formerly possessed the glowing figure? In sculpture the form alone is seen, painting adds the illusion of colour and the transparency of tone; the figures of the statuary have exactness in movement and flexibility of form, the painter vitalizes his creations, gives light and life to the eye, and makes the blood circulate through the skin, which he seems to steal from the living model. The skin is a membraneous tissue, resistant and flexible, varying in density and thickness according to locality, which covers the whole body and completes the form by softening the contours. It adheres to, and is intimately united with, the subcutaneous cellular tissue by fibrous prolongations. At some points it receives aponeurotic insertions, as in the palm of the hand and the sole of the foot; at others, as on the neck, for instance, the muscular fibres are attached to the skin, and mingle with the fibres of its deeper layer. There are folds in the skin, sometimes temporary and at others constant, which result from the flexion of the parts or from the contraction of the muscles, becoming more marked with age, and more or less numerous and profound as the subject is inclined to leanness or to obesity. The skin slides over the organs within certain variable 20 THE HUMAN BODY. limits, according as the cellular tissue which it carries with it is more or less relaxed, and as it is itself thick or thin. Thus it is movable on the back of the hand and top of the foot, on the front of the neck and on the surface of the joints; it is almost immovable on the cranium, on the palm of the hand, and on the sole of the foot. Elastic, very extensible, and very resistant, it sustains, without being torn, violent shocks and great compression; as in certain wounds by firearms, for instance, the projectile will penetrate the clothing to the skin, and injure the organs which it covers without itself being broken. The skin is the organ of feeling, its surface is endowed with a sensibility which becomes extremely delicate at several points. Being constantly in more or less intimate contact with the atmosphere, it transmits to the economy the influ- ence of external agents; and it is partly by its tissues that the fluids and gases are eliminated, which have done their office, and are to be thrown off as the ultimate and abandoned products of nutrition. This function of continual exhalation makes the skin the regulator of the temperature of the body. When the tem- perature of the organism is elevated either by motion or any other internal or external cause, the sweat immediately appears, and the cooling or loss of heat caused by its evapo- ration reduces the temperature to its normal standard. Lavoisier was the first who clearly explained this function, so important from its utility, and from the serious conse- quences which result from its disturbance. Almost entirely deprived of the covering which nature has given to animals, the colour of the human skin exhibits the richest and greatest variety of shades. This colour is inces- santly modified by the sensations, the movements, by moral or physical emotions; and the transparency of its tissues give as much delicacy as vigour to the tones which animate it; it is not, as in the plumage of birds or in the shells of molluscs, an assemblage of brilliant colours, often without transition, but it is a blending at once the most harmonious and the most striking; it is light in its softest changes, in its most dazzling splendour. THE SKIN EPIDERMIS. 21 On examining the thickness of the skin, we first find on the surface a thin transparent membrane, a sort of organic varnish, designed to receive the contact of the air and of external objects. This is the epidermis. Elastic and very Fig. io.—The Skin. A. Section of skin under the microscope. it b. Superficial and deep layers of epidermis. c. Dermis—true skin. d. Fatty areas of the deeper portions of the dermis, d. Muscular layer subjacent to the skin. e e'. Sweat glands and ducts, f. Hair-follicle and sebaceous gland. B. Hair seen under the microscope. flexible, it lends itself to every movement of the skin, pro- tecting its exquisite sensibility and modifying its property of rapidly absorbing gases and soluble bodies. Although this membrane is so thin, we can discover a superficial or horny layer and two deeper layers. The first, the true epidermis, thickens and becomes callous under the influence of rubbing or pressure, as for instance on the heel. The other two layers are the mucous network of Malpighi and the pigmentary layer. It is in the substance of this last especially that the pigment, the colouring matter of the skin, is developed. 22 THE HUMAN BODY. It is a black or brownish substance, more or less abundant according to the region of the body, individual, or race, but constantly existing in normal conditions, alike in Europeans and in the people of Soudan and Australia. The presence of this pigment and its unequal distribution contribute to the variety of complexion exhibited in the white race. Under the pigmentary layer is the dermis, the thickest and most resistant part of the skin; it is white, semi-transparent, and is composed of fibres of cellular tissue, fasciculated and very dense; of elastic fibres, ramified and disposed in net- work; and of contractile fibre cells. Immediately under the epidermis the surface of the dermis is covered with papillae, little conical or rounded elevations formed by the extremities of the nerves and vessels, which are divided into nervous papillae and vascular papillae. Each nervous papilla is surmounted by an organ, which from its function and its microscopic dimensions is called a tactile corpuscle or corpuscle of touch. They are much less numerous than the other papillae, and are not found everywhere on the skin. They are seen on the palm of the hand and on the lateral and palmar surfaces of the fingers, on the sole of the foot, on the tongue, the lips, and some other points. The epidermis follows exactly the shape of these papillae, and thus forms, in tracing the furrows which separate them, those graceful meandering lines and elegant curves which we see especially on the palm of the hand. Very dense at its thickest portion, the structure of the dermis grows more relaxed on approaching its lower face, and forms spaces or areolae in which adipose tissue is developed, and at last it intimately unites itself to the subcutaneous cellular tissue, from which the dermis receives, and to which it sends, fibrous prolonga- tions. Gratiolet is inclined to admit that these so-called nervous papillae are almost entirely wanting in nerves. He compares them to little keys, so to speak, pressing lightly on a very sensitive surface, and leaving there only very limited impres- sions. Other connections also exist between the tegument and the subcutaneous cellular tissue: these are the nerves and SWEAT-FOLLICLES SEBACEOUS GLANDS. 23 the lymphatics and blood-vessels, which arise from the skin or terminate in it; and the follicles or glands, which are situated in the substance of the dermis, according to most authors, but in the subcutaneous adipose tissue, according to Robin. These send the product of their secretions by special ducts to the epidermis. These ducts traverse the substance of the skin sometimes in straight and sometimes in twisted lines, and give passage, some to hairs, to the beard and to products of this nature which are formed in the bulb of the hair-follicles; and others, to the secretions of the sweat-follicles and the sebaceous glands. The orifices of the sweat-follicles, situated at the base of the papillae, exhale the secretion in the form of insensible perspiration, or in the form of little drops on the surface of the skin. Those of the sebaceous glands open, some into the hair-ducts, and others on the surface of the epidermis, and furnish to that membrane and its dependencies a fatty substance which seems to be designed to preserve the softness of the skin, and to protect it from injury or change from the sweat; we find them therefore in the greatest abundance at those points where the transpiration is most active. Of these glands and follicles of which the microscope shows us the details, some attain the size of a grain of millet, but most of them hardly reach a millimetre in diameter. Their orifices are on the surface of the epidermis, a point long disputed, but now admitted by anatomists. But these orifices are not what were formerly denominated pores. It was supposed that there were gaps or spaces in the skin analogous to those in a sieve, and that the cutaneous secre- tions issued from these gaps; but neither in the epidermis nor in the skin are there any such gaps, and it will be seen from the preceding description wherein the doctrines of the ancients differ from, and wherein they resemble, those of our own day. The epidermis is regarded by anatomists as impermeable, and yet experiment proves that even the perfect skin allows gases and fluids to penetrate the organism. If we do not admit that this absorption takes place through orifices at the surface of the. epidermis, and if we suppose it to take 24 THE HUMAN BODY. place by imbibition or endosmosis, it is plain that the skin is permeable, at least under certain conditions. But it is not equally so throughout its whole extent; the thicker the epidermis the slower and more difficult is the absorption; in short, the skin, like all the other tissues, absorbs certain sub- stances to the exclusion of others. We shall have occasion to discuss these phenomena in treating of absorption. After enveloping the body, the skin folds back upon the openings which give access to its cavities, and modifying its nature, becomes, under the name of the mucous membrane, an internal skin, analogous, as we shall see further on, to the external skin in its structure, its functions, and in the intimate connection which is established by their reciprocal influence and unity. CHAPTER III. Structure of the body.—Bones, cartilages, joints—Muscles, tendons, aponeuroses. Bones.—The bones are the framework of the human body. They are formed of a hard and extremely resistant tissue, and they surround more or less completely with solid walls the cavities containing delicate organs; they provide attachments and support for the soft parts, and furnish a fulcrum for the movements of the body; and lastly, by their resistance they permanently maintain the propor- tions between its different parts. The osseous substance is composed of calcareous salts— phosphate or carbonate of lime—intimately combined with organic principles, the decomposition of which produces gelatine. If the bone is immersed for a length of time in hydro- chloric acid, the calcareous matter will be dissolved, and the isolated gelatine will retain perfectly the form of the bone; and in the same manner if the gelatine be destroyed by combustion, the lime which remains will show the normal form and dimensions of the bone. In a gelatinous state the bone is soft and flexible; in the calcareous state it is hard, rigid, and brittle; in a normal condition each of these con- stituent substances serves as a corrective to the other; and their properties united give to bone its solidity and its elastic resistance. In the osseous tissues, as in all those of the body, we re- cognize a movement of composition and of decomposition, of molecules assimilated and again rejected after a certain time; but in none of the organs so well as in the bones has it 26 THE HUMAN BODY. been possible to demonstrate this double movement of nutri- tion. If we mingle madder with the food of an animal, the bones soon become red, and they regain their original colour when the colouring matter ceases to form part of the food. Or, more conclusive still, if the madder be given for a while and then omitted, and after a time be again given, the bones show a white layer between two red ones, which proves that they grow from the circumference toward the centre, by the ossification of the deepest layers of the periosteum. The bones are divided according to their form into long, flat, and short bones. The long bones, which are first and most rapidly developed, are more dense in the middle or body of the bone than at their extremities. This body is formed principally of a compact bark or rind of ivory-like tissue, and is pierced throughout its length by the medullary canal; the extremities are composed of spongy tissue en- veloped by a thin layer of ivory tissue. The long bones combine to form the limbs and the thorax; designed to serve as levers or columns, they are twisted on their axes or bent so as to offer the greatest possible resistance in exert- ing a force or supporting a weight. The flat bones form the walls of the cavities of the cranium, of the chest, and of the pelvis; they are thinner in the middle than at the edges, and are composed of two leaves or tables of ivory tissue resting upon and confounded with each other at some points, and separated at others by a layer of spongy tissue. The short bones are very irregular in form and difficult to describe; very spongy in texture and relatively light. They develop later and more slowly than the others, and they are placed in groups in parts of the body where the bony frame must possess a limited power of motion, and yet be very firm, as in the foot, in the hand, and in the spinal column. There are 198 bones in the human skeleton when it has reached its perfect development. On the surface of the bones, and especially at the extremities of the long ones, there are prolongations of different forms, designed either to join the bones together, or to serve for the attachment and insertion of muscles or ligaments. These prolongations are Fig. ii.—Skeleton, EPIPHYSIS—PERIOSTEUM—CARTILAGE. 29 the apophyses, which are distinguished by anatomists by names suggested by their position, by their use, or borrowed from objects of which they recall more or less exactly the form. The body of the long bones and the central part of the large bones are developed before the extremities and the edges. The extremities of the long bones are cartilaginous in early life, their articulating surfaces are formed of cartilage adherent to, but not continuous with, the bone to which it belongs. This is the epiphysis, which afterward becomes ossified, but is not perfectly united to the bone till about the age of twenty. Some of the large bones also present epiphyses on their edges or borders. A white fibrous membrane, resistant in youth and reduced to a thin layer of cellular tissue in the adult and aged, which is called the periosteum, envelops every part of the bones, except where they are covered with cartilage and where the tendons and ligaments are attached. The periosteum adheres closely to the bone, and distributes a network of vessels through its substance. Recent surgical investigations have shown that the periosteum plays an important part in the partial reproduction of the bone after certain operations. Cartilage.—To the bony system belong the cartilages, which are formed of what might be termed tissue in a state of transition between fibrous and bony substance. This tissue, homogeneous in true cartilage, mingled with fibrous substance in the fibro-cartilaginous parts, is elastic and flexible, and in colour either yellowish or pearl-white. The cartilages unite the bones at those points where, as in the chest, the bony frame must yield to expansive movements; they furnish a flexible skeleton to certain organs, as the external ear, for example, the nose, the eyelids, and the larynx; and lastly, they play an important part in the joints. No part of the organism shows more clearly than the bony system the care which nature has taken to provide during infancy the gifts of which she is so prodigal in maturity, and which she withdraws little by little in old age. During in- fancy, when protected by maternal care and when the growth should be rapid, the gelatine predominates in the bones; they are flexible and have only a resistant power propor- tionate to the movements and efforts of infancy; it is the branch full of sap, but of which the woody portion is not yet developed. In youth, as the muscular power augments, the bones gradually become more solid; the extremities, at first cartilaginous, become ossified; the epiphyses unite with the body of the bone; and the articulating cartilages gain more consistence. In the adult at last the bones are complete. They are able to resist the muscular efforts of maturity, and perform their functions perfectly, like all other parts of the organism which are fully developed. But age approaches, the strength decreases, nutrition falls off, the bones become more solid, their power of resistance lessens, the medullary canal enlarges, the proportion of calcareous salts in the osseous substance augments, the bones are harder but they are also more brittle. Thus, as each phenomenon of life is linked with every other, we find the bones of a child quickly and easily restored if broken; in the adult the process may be longer, but is generally easy and complete; in the old man the reunion of the fragments takes place slowly, and sometimes cannot be effected at all. The deli- cate twig, which afterwards became a vigorous branch, is now dry and destined to speedy decomposition. Joints.— The bones are attached to each other, either by their extremities or their sides, in such a manner as to per- mit freedom of motion to a greater or less extent between the different parts of the skeleton and of the body. Held together by a sort of cog-wheel system, by the fitting of a projection into an appropriate cavity, or by juxtaposition, they are maintained in connection either by the reciprocal attachments of these projections, or by envelopes—the articular capsules—and by ligaments, constant in their nature, but varying in form and disposition, according to the dif- ferent movements which they are designed to permit and insure. THE HUMAN BODY. This assemblage, this connection of the bones, is termed a joint. Joints are classed according to the form of the articulating surfaces, and according to the extent and variety of the movements produced by them. The bones of the SUTURES—VARIETY OF FORM IN JOINTS. 31 skull are attached by the notches on their edges; these are termed the sutures of the skull. They ossify with age, and may be considered temporary joints, or rather a transition between the separation of the bones and their unification. The other joints, on the contrary, are permanent, and de- signed to leave to the bones which they unite a mobility which continues during life. In some of the joints the surfaces are nearly plane or flat; others present projections with corresponding depressions; sometimes there is a segment of a spheroid upon which the cavity which receives it moulds itself; sometimes a cylinder which turns upon its axis in a ring, or a pulley-groove around which slides an apophysis, or a mortise in which a tenon is set. Here, as in all the works of nature, we admire the inex- haustible variety of form and of mechanism. Doubtless there exists between certain articulations resemblances which per- mit them to be classed together; but all are as distinct as the bones which they unite, and like them present diversity of character. Separately considered they astonish us no less by the multiplicity of detail in their mechanism, whether we examine the most complex or those whose surfaces pre- sent the least irregularity. In fact we nowhere find a uniform plan, and the projections as well as the depressions are curved in the most capricious manner. These details of the general outline belong to no precise geometrical form; they are neither cubes nor spheres, neither cylinders, cones, nor pyramids, although in anatomical language these terms are applied to them. There is an assem- blage in the same apophysis, or in the same cavity, of curved surfaces borrowed from the most widely differing solids, united under angles the most varied, and modelled on sinu- osities which defy geometrical description. In addition to these distinctive characters of the joints, we may mention others which are common to them all. All the joints have cartilages covering the bones which form them; all are kept together by special ligaments, and are lined with a synovial membrane, whose functions we shall subsequently describe. 3 2 THE HUMAN BODY. The polish on the articular cartilages facilitates their sliding over each other, and lessens the friction of the bony ex- tremities, while their elasticity diminishes the pressure and deadens the shocks to which the joints are subject The thickness of these cartilages is proportioned to the motion and the pressure which they are designed to support, and it is greatest at the centre of the convexity of protuberances and on the borders of cavities. The articular cartilages never ossify, differing in this respect from those which, as in the thorax for example, maintain continuity and play the part of flexible bones. These last are ossifying cartilages. The others differing in structure, being without vessels, have been compared to the enamel on the teeth. In fact, they are composed, like that enamel and some other analogous productions, of an almost inorganic substance, and mechani- cal injuries are the only ones which they have to fear. Wherever in the organism surfaces move over each other, they are covered with a membrane which secretes a fluid, differing in quality according as there is a sliding or rubbing of the organs. In the interior of the joints the membranes are termed synovial membranes, and secrete a fluid called syfiovia, because its physical characters resemble those of the white of an egg. The synovia is to the joints what oil is to the wheels of a machine; incessantly poured out upon the surfaces, it lubricates them, and renders the movement, already so easy owing to the polish of the cartilages, still more so; it increases the suppleness and elasticity of these last, which if they wrere not supplied with this oily fluid would soon be worn out, and motion would be impossible. This sometimes results from certain diseases, and sometimes also in old age. We have said that the joints are united by ligaments. This term is applied to the bands or membranes com- posed of fibrous tissue, flexible and inextensible. The liga- ments, which are in the form of bands, are sometimes parallel and sometimes interlaced, and placed either between the articular surfaces or around them. In the latter case their internal face is covered with intimately adherent synovial membrane. The ligaments are attached to the bones at a CAPSULAR LIGAMENTS. 33 greater or less distance from the articular cartilage, and they adhere so strongly that it is easier to break the bone or the ligament than to tear it from the spot where it is planted. The membranous ligaments—capsulary ligaments or fibrous capsules—are like a circular band of which the two openings are fastened to the bones which they unite. The fibrous pads or cushions which run round the circumference of cer- tain articular cavities are also considered as ligaments. They increase the depth of these cavities, and give greater Fig. 12.—Elbow-joint. A. Humerus. B. Ulna. C. Radius. solidity to their borders, upon which the osseous extremity received there exerts considerable pressure. Such is the assemblage of apparatus comprised in the joints. The most perfect machine which man has ever been able to construct bears no comparison to the admirable mechanism of which we have just endeavoured to give a general idea, in the precision, delicacy, and variety of their organs or of their movements. Even in their most com- plicated parts, machines invented by man offer nothing but 34 THE HUMAN BODY. a simple mathematical precision, impossible to mistake, be- cause all the surfaces are conceived and traced out geometri- cally. In the joints, on the contrary, all the lines and surfaces are vague and uncertain; and when we examine an articular extremity, the inferior extremity of the humerus for example, we shall at first be tempted to believe that the unsymmetrical projections and depressions, the incomplete grooves, and the undefinable irregularity of the whole, belong to a work spoiled or modelled at hazard by a confused mind; but on seeing the action of the elbow-joint when laid open by the anatomist, we discover that it is to this very irregularity of the bony extremities, to the multiplicity of detail, to the absence of symmetry, and to the more or less limited extent of their articulating surfaces, that the variety of movement is due, and we cannot sufficiently admire this assemblage, so complex, but yet so justly calculated to give to the move- ments of the fore-arm the greatest precision, strength, and rapidity, and to combine these movements with those of the arm and the hand. And if we pass from the most mobile of these joints to those not at all or only slightly movable, the perfect coapta- tion of their surfaces, their powerful methods of union, the unity of movement of the bones, whether they take part in the motion or serve only as fulcrums, all seem to be as simple as possible in function, although the whole as well as the details presents the most delicate application of the laws of mechanics and statics. We may add that here as well as everywhere in the study of the works of nature, we see the organs develop themselves from the embryonic state to that of perfection, under the influence and in the exercise of their functions. But leaving out the inimitable results produced by life in natural creations, and considering them as inor- ganic bodies, the mechanism of the joints leaves far behind all the most ingenious productions of art or science. The distance appears to us greater still when, instead of a combination of surfaces and the method of their union, we study the action of the muscles and the transformations which are incessantly taking place in the organs of digestion and respiration. In unveiling a part of these mysteries to MUSCLES. 35 man, the progress of science only increases his admiration. What would it be if life, that force of which he is conscious, and which he shares with all organized beings, should cease to be to him an impenetrable secret! Muscles.—United by the joints, the bones of the skeleton, taken as a whole, approach the form of the body. But in order to put these bones in motion, and to bring these joints into play, we must call to our aid an external force. By itself, if we may be per- mitted a very familiar comparison, the skeleton is a puppet of which the different parts are put in motion by threads. The threads by which the skeleton is moved are the muscles. The name muscles is given to the masses of red tissue which constitute the flesh. We have already described the ele- ments of the muscular tissue; how the primitive microscopic bundles, united into secondary ones, become muscular or fleshy fibres easily dis- tinguished by the naked eye. These fibres are parallel or divergent ac- cording to the muscle, and assume different forms. Sometimes it is that of a ribbon (sartorius, sterno- hyoid, &c.); sometimes a broad web-like tissue of a texture more or less firm, like the transverse muscles of the abdomen; in one region the muscle, swollen in the centre, and drawn out like a thread at the ends, resembles a spindle in form (biceps, straight muscle of the thigh); in another it is fan-shaped (temporal, obturator), or like a ring (orbicular muscle of the lips and eyes); or the fibres converge like the radii of a circle (the diaphragm); or are disposed in parallel lines like Fig. 13.—Biceps muscle of the arm. A. Body of the muscle. B. B. Superior tendons. C. Inferior tendons. 36 THE HUMAN BODY. the feathers of a pen (extensor muscles of fingers). Lastly, certain organs, the heart for example, are nothing but muscle, or rather an assemblage of muscles intimately united. The muscles determine the form and volume of the body, and especially of the limbs. The outline depends upon their projection, and changes incessantly as they are in action or in repose. They are disposed in layers, deep or superficial, and united in groups or separated by sheaths and mem- branous partitions. Their colour varies from deep red to pale rose, according to the region of the body they occupy, age, sex, the constitution and richness of the blood. The stronger the muscle the redder it is, and it becomes still brighter under the influence of exercise. The muscles of the human body number about 350, and they are distinguished by names suggested by their form, their locality, their functions, or their attachments. Some are fixed to the skin, as several of the muscles of the face; others to muscles in their vicinity, as in the face and tongue; others still to the cartilages, but the largest number to the bones by means of the tendons or the aponeuroses, of which we proceed to speak. Tendons, aponeuroses.—In most of the muscles we can dis- tinguish a fleshy portion, which is essentially the muscle, and a fibrous portion, which is called either teiidon or aponeurosis according to its form. The tendons are fibrous cords of variable length, rounded or flattened, of a pearl-white colour, attached to the bones by one of their extremities and united to muscular fibres by the other. The aponeuroses are nothing but large thin tendons, a kind of fibrous web or band which accompanies the muscles, separating them by partitions or enveloping and uniting them in bundles. The tendinous fibres are generally developed in the substance of the fleshy part of the muscle, or on the surface, which they cover to a certain extent. In the first instance they are inclosed, as it were, by the muscle; in the second, they envelop it like a sheath. This reciprocity gives great solidity to the whole. The muscles and tendons are united together by the direct adherence of the extremities of their fibres, which takes place TENDONS, APONEUROSES. 37 in right lines; or by the insertion of the fleshy fibres at some point in the length of the tendon, at various angles, but never exceeding 45 degrees. Such is the force of this adhesion between the two tissues that rarely if ever does external violence or the greatest effort succeed in overcoming it, the tendon or the muscle breaks before separating at their points of union. We have already pointed out, in speaking of the articular ligaments, the remarkable fact that the adhe- sion of two organic tissues is strong- er than the cohesion of either of the respective tissues. The tendons and the aponeur- oses, though very flexible, are en- tirely inextensible, and offer there- fore great resistance to force applied to their length. This is one of the conditions necessary for the part which they play in uniting the organ of motion and the object to be moved. Like the ossifyitig cartilages, the tendons may be considered as a transition tissue. They partially ossify with age at their points of insertion into the bones, but they are never entirely transformed in the human race, as in some animals, the Gallinaceae for example, into a bony trunk. Suppleness and variety of movement would not accord with this transforma- tion; and among the differential marks which Plato might have added to his famous definition of man, this would have sufficed to prevent Diogenes from saying, as he exhibited the cock stripped of its feathers, “ Behold Plato’s man!” A relatively slender tendon suffices to transmit a motive force developed by a certain amount of contractile fibre, and the fleshy portion of the muscles far surpasses in volume the tendons and the aponeuroses. If the muscular fibres attached themselves directly to the bones the surface of the bones Fig. 14.—Lower portion of the leg. A. Teitdon ofAchilles. THE HUMAN BODY. would not be sufficient to supply space for them; this direct attachment to large surfaces is confined to a few only, the others being attached by their aponeuroses or tendons to limited spaces. The muscles are at the same time contractile and exten- sible. The muscle shortens by contraction and increases in thickness at the same time that its length diminishes ; in repose it is soft and yielding to touch, in contracting it becomes hard and resistant. These successive changes are easily demonstrated by applying the hand to the course of a superficial muscle, on the front of the arm for example, on the biceps. When the fore-arm is extended it projects but slightly and yields to pressure; it swells, on the contrary, becomes resistant, and forms a marked protuberance, when contracting in order to flex the fore-arm. The contraction of a muscle may also take place without its being shortened. When, for example, the fore-arm is extended upon the arm, if the extensors oppose the flexion by contracting, the biceps and anterior brachial, both flexor- muscles, may contract without their ends approaching each other. Glisson, Borelli, and other anatomists have supposed that the muscle increases in volume during contraction; but further experiment, confirmed also by those of Prevost and Dumas, has demonstrated that it gains in thickness only what it loses in length, and that there is no change in the absolute volume. In contracting, the muscular fibres become tortuous and wavy, -wrinkles are formed on the surface, a sort of trembling pervades the whole mass, and its temperature is raised. Becquerel and Breschet have observed this increase to reach half a degree centigrade. To the contraction of certain muscles must correspond the inertia or even lengthening of the antagonistic muscles, as for instance when the fore-arm is flexed upon the arm or the leg upon the thigh, the extensors of the fore-arm and of the leg take part in the movement and lengthen by means of their extensibility. In like manner the muscular texture which forms the walls of certain organs, as of the stomach and intestines, is expanded by the fluids and the aliments, or by MUSCLES, THEIR ACTION. 39 the gases which are developed in them. The flute-player of antiquity kept his cheeks distended by means of a leather strap. Thus there is a constant struggle between the con- tractility and the extensibility of the muscles. But if, during the contraction of certain muscles, as the flexors of the arm, the antagonistic muscles, the extensors, are relaxed and do not oppose the movement, they regulate it nevertheless by virtue of a property named muscular tonicity, which gives to their tissues even when not contracted a certain power of resistance. Thus when a group of muscles is paralyzed, the antagonistic muscles cause by their contraction a jerking movement which has no regularity. In contracting, the muscles act like levers upon the bones, and therefore just so much less powerfully as they are placed obliquely to the bone. Notwithstanding the larger part of the muscles are attached to the bones at an acute angle, and their direction is very oblique in regard to the lever they are to move. The result is a great loss of force, but this loss is compensated by an increase of volume in the muscles, that is in the number of fibres of which they are composed. Most of the muscles are subject also to deviations or reflections around the joints. Some even take a direction perpendicular to their original one in turning round bony hooks or in the grooves of the pulleys. The apophyses, or the protuberances to which they are attached, permit them to move at a greater angle and a more favourable one than the initial angle, and this angle gradually increases as the bone obeys the force applied to it; and lastly, the relative direction of the muscle as regards the bone varies according to the attitude. These dispositions of the muscles are always adapted to the kind of movement to be executed, to the extent or rapidity required, or to the force demanded; and they are always so combined as to produce the maximum of useful result. So in flexing the fore-arm, in elevating the arm, the bones act as levers of the third order. The biceps, anterior brachial, and deltoid muscles act as very short levers upon the arm, and their initial direction is almost parallel to the bone, but it soon becomes almost perpen- dicular to it. In this case extent and rapidity of movement 40 THE HUMAN BODY. are important, force is only a secondary consideration. If we wish to raise the body on the toes, motion is more limited but a great amount of force is necessary. The gastrocnemius and soleus muscles, which form the calf of the leg, are inserted by the tendon of Achilles—the largest in the body—to the posterior extremity of the calcaneum (or heel-bone), and perpendicular to its axis; the posterior tibial muscle and the flexors of the toes pass behind the internal malleolus under the calcaneum and under the astragalus, as in the groove of a pulley, and are inserted into the plantar surface of the scaphoid and to the last phalanges of the toes, and these muscles act upon the foot, which serves as a lever of the second order; that is to say, under conditions the most favourable to the power represented by the muscular con- traction. CHAPTER IV. Spinal column. — Thorax.—Upper limb ; shoulder, arm, fore-arm, hand.—Lower limb; hip, thigh, leg, foot. Spinal column.—The spinal column is the foundation to which all the other parts of the skeleton are adapted. It is composed of seven cervical vertebrae, twelve dorsal and five lumbar vertebrae, and is terminated by the sacrum and coccyx. Throughout its whole length runs the vertebral canal, which holds the spinal marrow, and communicates with the cavity of the skull. Each vertebra is composed of a body, two articular processes, two transverse processes, and a spinous process. The body, the anterior portion of the vertebra, is cylindrical, and forms a layer of the column. The articular processes, placed at the sides, serve to unite the vertebrae together; and the transverse processes give attachment to the ligaments, muscles, and in the dorsal regions to the ribs. The spinous process, the posterior portion of the verte- bra, forms that series of projections which has given to the vertebral column the name of the spine. The spinous process bifurcates into two plates which complete the ring or verte- bral orifice formed by each vertebra, and the open space in which forms a segment of the vertebral canal. Numerous and powerful ligaments combine to unite the vertebrae. Be- tween their bodies fibrous disks in the form of lentils are placed, which adhere intimately to the articular surfaces; they are formed of concentric layers, and near the centre there is a spongy substance saturated with a fluid analogous to the synovia. These disks or intervertebral ligaments, besides binding together the bodies of the vertebrae, serve 42 THE HUMAN BODY. to diminish the shocks and the pressure to which they are subjected from the weight of the parts of the trunk above them. They sink down and become thinner while the body is erect, so that there is a difference in the height between morning and evening of about '02 or '03 of a millimetre; but repose in bed restores to the fibrous disks their primi- tive thickness. Between the vertebral plates stretch the yellow ligaments, remarkable for being formed of an elastic tissue which yields to the movements of the spinal column. Other inextensible ligaments envelop the spine at every point, and give great solidity to the whole. The spinal column has three curves— two backward in the cervical and lumbar regions, and one forward in the dorsal region. The ligaments which unite its layers permit only a slight degree of flexibility in the upper dorsal region, but this is a little more extended at the neck and loins, and powerful muscles give it at need great rigidity. And lastly, to its curves, and to the complicated mechanism of its articulations, it owes its great power of vertical re- sistance. The head is balanced upon the first cervical vertebra, which is called the atlas; the manner of its articulation with the spinal column permits great extent and freedom of move- ment, while powerful ligaments and muscles give it great strength. Thorax.—The ribs are attached by the transverse pro- cesses to the dorsal vertebrae, and in front by cartilages to the sternum or breast-bone. They are twelve in number on each side. The interstices of this bony cage are filled with muscles; they cover and form with it the walls of the chest, called also the thorax or thoracic cavity, which contains the lungs and heart. The flexibility of the costal cartilages, and the mobility of the articulations of the ribs with the spinal column, allow the thorax to expand and to contract in re- spiration. Upper limb.—Near the apex of the cone formed by the chest the upper or thoracic limbs are attached. They are composed of four parts—the shoulder, arm, fore-arm, and hand. The two bones of the shoulder are the scapula, which SHOULDER-JOINT, ELBOW-JOINT. 43 is attached by muscles to the upper part of the back, and the clavicle or collar-bone, which extends, from the sternum to the scapula, embracing the top of the chest. At the angle formed by the superior border and the external edge of the scapula an articular surface, called the glenoid cavity, receives the upper extremity or head of the humerus, the bone of the arm, which articulates at the elbow with the ulna and the radius, the two bones of the fore-arm; these form with the carpus the wrist-joint, which unites the fore- arm to the hand. The deltoid, the great dorsal and great pectoral, and other less powerful muscles, combine to form the shoulder, and give motion to the humerus. The triceps and biceps of the arm, &c., which surround the humerus, flex or extend the fore-arm and turn it on its axis; and numerous muscles cover the fore-arm and move the hand. The articulation of the humerus with the scapula or the shoulder-joint is, of all joints, the one that permits the most extended movement. The shallowness of the glenoid cavity permits great freedom of motion to the rounded head of the humerus. Thus the arm, which hangs parallel with the body in a state of repose, can be raised vertically to the head, laterally forward so as almost to enfold the chest, and also backward, though in a more limited degree; it can be turned on its axis in all these positions, and in the movement of circumduction it describes a very flat cone, the base of which, especially in front, approaches the apex. The elbow-joint is one of the most complicated in the whole system. The lower extremity of the humerus, and the upper extremities of the ulna and the radius, are adapted to, and interlock with each other by a series of rounded surfaces and pulley-grooves, which permit the fore-arm to flex itself forwards upon the arm; while a protuberance of the ulna, the olecranon, which forms the projecting part of the elbow, limits the backward movement by resting in a cavity of the humerus. It is into the olecranon that the tendon of the triceps of the arm, the principal extensor of the fore-arm, is inserted, and we shall see the analogy farther on between this process and the knee-pan. The movements of the fore-arm singularly multiply by 44 THE HUMAN BODY. their application those of the arm. The radius and ulna may be placed in contact with the humerus by flexion, and again the radius turns on its own axis, without either the ulna or the humerus taking part in this movement, which is called pronation or supination, according as the palm of the hand is turned outward or inward. But what renders the thoracic limb a perfect organ, that which explains the variety and extent of its movements, and which gives them all their value, is the hand; that admirable instrument which in its perfection belongs only to the human race. The ha?id is elegant and beautiful in form. Its isolation, its contour—defined without stiffness—the delicacy of its mould, the mobility of its different parts, and the variety in their tints, make of it a being by itself in the human body, and give it an expression and a physiognomy. Completely developed even in infancy, it presents a most attractive model and an inexhaustible subject of study to the artist. Its structure has led many philosophers to think that it is to it alone that man owes his superiority to the animals, and to attribute to it the greatest influence over the intellectual faculties. But the study of man shows that we must reverse this proposition. The hand is only the instrument of the intellect, the perfection of the one is necessarily dependent upon that of the other, and the hand of man, like every other part of his being, has no equal in the animal kingdom. As for seeing in the greater or less perfection of the hand a sign of the degree of intelligence, and carrying it so far as to distinguish between the hand of a man of talent and genius, and that of a fool or a man of moderate ability—this is a theory which, speciously presented, might perhaps be entertained as a subject having curious aspects, but on no other ground. In short, if the hand of the idiot is alike badly developed with the brain—if we believe that an arrested development of the fingers, or the presence of supernumerary ones, are signs of degeneration in the race—are we to con- clude that perfection of the thoracic limbs is the rule, as has been said, in men of eminence? We need not go so far back as Esop for an example of a great mind in a deformed THE HAND—WRIST-JOINT. 45 body. Conde, Luxembourg, Pope, and other illustrious and celebrated men, were victims of rickets. They had long and knotty hands, one of the most constant signs of this malady. If men of inferior intelligence often have thick and inflexible hands, it is because they are often born under conditions which impose rough work upon them. They receive as a heritage, with the toil of their fathers, this clumsiness of form, which is the consequence of this toil. The hand of the man who is not forced by his position to manual labour is always finer and more delicate than that of the workman, and he trans- mits to his children this detail of conformation as well as the general resemblance. The delicacy of the limbs, the prin- cipal element of their elegance, is therefore a sign of race rather than of intelligence, and belongs especially to the oriental. The hand of a European cannot enter the guard of an Indian sword or poniard. Shall we conclude from that that the Anglo-Saxon or the Norman has less intelligence than the Arab or the Hindoo? De Blainville relates that Recamier attached a certain importance to the form of the hand, and was accustomed to examine those of his pupils with this idea. “Mine,” he adds, “were, like the others, sub- mitted to the inspection of the master, and the result was not unfavourable to me.” Recamier being present, confirmed the statement of the former pupil of the Hotel-Dieu, now become an eminent naturalist. But the hand of De Blain- ville was neither fine nor elegant; it was a well-made, vigorous, and muscular hand, like the body to which it belonged; equally skilful, in fact, in holding a sword, a pencil, or a scalpel. The wrist-joint, which unites the hand to the fore-arm, resembles in its mechanism that of the shoulder. Eight bones of different and very complicated forms constitute the wrist or carpus. Three of these form the articulation with the fore-arm, the others are united to the five bones of the metacarpus, the palm, or middle part of the hand, to which the fingers are attached. These are composed of two pha- langes in the thumb, three in the index, middle, ring, and little fingers. The first three bones of the carpus are grouped in such a manner as to present an ellipsoid surface on the 46 THE HUMAN BODY. side of the fore-arm; a condyle which is received by the elliptic cavity formed by the inferior extremity of the radius and ulna. The hemispheric head of the humerus turns on its axis in the glenoid cavity, but this movement is prevented in the hand by the elongated form of the condyle of the carpus. The rotation of the ulna supplies this want, and the hand turns with the bones which are attached to it in Fig. 15.—The hand, palmar aspect. A. Short abductor m uscle of the thumb, above and outside of which is seen the opposing muscle [opponenspollicis), B. Short flexor of thumb. C C. Tendons of the superficial flexor of the fingers. D. Sheath of the tendons. E E. Tendons of the deep flexor. Fig. 16.—The hand, dorsal aspect. A. A nnular ligament of the wrist. B B. Tendons of the common extensor of the fingers. C C. Tendinous expansions fastening the tendons together. supination and pronation. Further, it has a separate move- ment in flexing the hand forward, backward, or sidewise. In circumduction it describes a cone, and makes many other movements in common or singly. The numerous muscles which determine these movements form a very complicated mechanism. Their tendons are interlaced and bound together by bands and aponeurotic fibres, and from this results a more or less complete unity of action. It is sometimes difficult to make a movement with a single finger without the others taking part in it, as in executing instrumental music, for instance; but practice gives to these movements perfect independence. The mechanism of the movements of the hand has been made singularly clear by the recent experiments of M. Duchenne of Boulogne, who has succeeded in distinguishing by means of electricity, the action not only of different orders of muscles, but also of each particular one. Gerdy counts thirty-four distinct move- ments of the hand, and if we include the combinations of these different movements we shall reach a much higher number. The opposition of the thumb to the other fingers, alone or united, is of all these movements that which especially characterizes the human hand, in which alone it exists in its perfection. This action of the thumb results from its length, from the first metacarpal bone not being placed on the same plane as the other four, as is the case in the monkey, and from the action of a muscle—the long flexor of the thumb—peculiar to the human hand. This muscle completes the action of the other motor of the thumb, and permits man to hold a pen, a graver, or a needle; it gives to his hand the dexterity necessary in the execution of the most delicate work; it is the attribute of his intelli- gence. In repose the hand of man is presented in an attitude half opposed to the thumb; but it is not so in the monkey, even in the species most resembling man. It is opposable in these animals, but much less so than in man; and the five bones of the metacarpus being on the same plane, the fingers—or toes—can be placed flat upon the ground in walking, in which the four limbs always take part. Properly speaking, then, the hand belongs to man alone, and its conformation does not permit us to consider it as a nor- mal organ of locomotion. It can by turns form itself into a plane, round itself into a cylinder, hollow itself into a gutter, make the fingers spread like so many diverging rays, and form, in the words of De Blainville, a compass with five branches; it collects the fingers in the form of a cone, of a ACTIONS OF THE HAND. 47 48 THE HUMAN BODY. spheroid, &c.; and lastly, it can reach every portion of the body. The hand is essentially the organ of touch and of prehen- sion. These functions devolve principally upon its anterior or palmar face. The nervous papillae with which it is pro- vided abound specially at the ends of the fingers, where they form furrows in elegant curves under the epidermis. The tendons in it are very numerous, and bound together by multiplied connections. Strong aponeuroses and sheaths, through which the tendons slide, make the skin compact, and combine to give unity to the general movements of the dif- ferent parts of the organ, and independence to partial ones. A layer of adipose tissue, very close in texture, protects, with- out lessening its power or its delicacy, that network of muscles, vessels, and nerves, this apparatus which sometimes barely touches an object, and sometimes grasps it with such violent pressure. The hand, in fact, is either a delicate pincer or a powerful vice; it guides the burin of the en- graver, which leaves behind it the finest trace, the hatchet of the carpenter and the axe of the woodman, whose blows are given with as much strength as skill. The fingers of the sailor knot the heavy cordage, and those of the optician stretch a spider’s thread, without breaking it, across the field of an astronomical telescope. The same organ can hold a switch, a club, a sword, a hammer, or a pen. It moulds itself to a body to ascertain its form; it comes to the aid of the eye in completing or rectifying its impressions, and in some cases even supplies its place. Thus the finger of the physician perceives on the surface of an organ the slightest inequality in relief; and the hand of Michael Angelo fol- lowed with enthusiasm the contour of the antique torso, which the eyes of the great artist could no longer contem- plate. But nothing gives a more complete idea of the perfection of the mechanism of the hand, than the execution of instru- mental music. Examine an artist while he plays on a violin. His fingers rest upon the strings so as to leave them exactly of the length necessary for the tones they are to give. The half of a millimetre, more or less, greatly changes the true- ACTIONS OF THE HAND. 49 ness of the note; and a cord a millimetre out of place pro- duces a note which even the unpractised ear recognizes as false. But the fingers fall upon the strings at precisely the point required. They run over them, succeeding each other with giddy rapidity, following every imaginable combination, and yet the hand gliding over the instrument incessantly changes its position. Sometimes a single finger produces an isolated note; sometimes two or three act simultaneously to produce a concord; while a fourth, striking the string with increasing rapidity, produces a trill which rivals that of the nightingale. And even this is not all. The other hand holds the bow, and the movements of the right arm must be in correspondence with those of the left hand; the coincid- ence between the movements of one hand and that of the other must be mathematically exact. Add to these all the modifications necessary to produce the piano and the forte, to swell the sound or to let it die away—all, in a word, that constitutes musical expression, and it will be admitted that this mechanism is allied to the wonderful, and that it sur- passes the most perfect productions of human art. The agility and flexibility of the hands, the concordance and independence of their movements, is not less remarkable in the playing of the pianist. How is it possible not to ad- mire those two hands, both oftenest occupied together, and the action of which alternates or coincides with so much pre- cision and rapidity; together they produce on an average from six to eight notes at a time—separating, approaching, crossing, and mingling their fingers, which move over the keys as if each one were completely independent of all the others? A skil- ful pianist produces about 640 notes a minute in medium time, and 960 in extremely quick time. These numbers give us an idea of the rapidity of movement which can be attained by the hand of man. The devoted servant of the body, the hand which nourishes it knows also how to defend it. It has been said that man is created without arms. What then is the hand which en- ables him to construct and employ for his defence those in- genious and terrible machines, that hand which can at need itself become a formidable weapon? The poets have sung THE HUMAN BODY. the praises of Pollux defending his own life and that of his companions with the arms which nature gave him ; but if we admire Pollux battling with the Sicilian giant, we turn our eyes from the arena ensanguined by the gauntlet of Entellus. The soldier considers it an honour to employ with skill in the defence of his country the sword which she has intrusted to him; but he despises the arms and the trade of the gladiator. The principal function of the upper limb is to remove objects from the body, and to draw them to it; but it can also remove the body from a fixed point, or approach it to one. It is in this way that the sailor raises himself on the rigging, or the gymnast on the trapeze; but the weight of the body is not in proportion to the strength of the limbs which raise it, and although exercise renders this effort less difficult by increasing the power of the muscles, it is evident that here the arm performs a function which does not devolve upon it chiefly, and which belongs to a more powerful mem- ber, of which we will now speak. Lower or abdominal limb.—It is composed, like the upper limb, of four parts—the hip, thigh, leg, and foot. The two bones of the hip, or pelvic bones, articulate together and with the sacrum; this last, placed between the two like a wedge, transmits by their means the weight of the body to the lower limbs, which are the pillars of the human edifice. On the external face of each pelvic bone we see a deep, hemispheri- cal, articular cavity. This is the cotyloid cavity, which receives the head of the thigh-bone, and forms with it the articulation of the hip. The femur or thigh-bone is the longest and strongest bone in the skeleton; it is almost cylindrical, and is curved outward, which gives it greater strength. At its upper extremity we see the head of the femur, supported by a neck which is united to the body of the bone at an ob- tuse angle. This obliquity has the effect of increasing the distance between the two femurs, and in consequence be- tween the two lower extremities, thus giving to the body a larger base and greater stability. Another result is, that the weight of the body is transferred to the femur, but not directly and in a right line; the necks of the two femurs HIP-JOINT, KNEE-JOINT. form by their union part of an arch upon which rests the upper portion of the cotyloid cavity, and thus divides the force acting upon the lower limbs. The head of the femur represents nearly two-thirds of a sphere. It exactly fills the cotyloid cavity, but is not itself all inclosed in it, as the depth of the cavity does not exceed half the diameter of the sphere to which it belongs. A very elastic, circular, fibro-cartilaginous ring surrounds the edge of the cotyloid cavity, increasing its size, embracing the head of the femur; and acts as a valve and hermetically closes the articular cavity in which the head of the femur is retained by atmospheric pressure alone. In fact, if we place this articu- lation, properly prepared, under the receiver of an air-pump, we shall see, as a vacuum is produced, the head of the femur gradually slip down and leave the cotyloid cavity as far as the ligaments will permit, and when air is again ad- mitted into the receiver, it resumes its place in the cavity. This beautiful experiment of E. Weber shows in a striking manner the direct and constant influence of external agents on the functions of the organism. The inclosing of the head of the femur in the cotyloid cavity gives the articulation of the hip great solidity, which is augmented by the muscles and ligaments which hold the parts together as well as give them motion, so that it is only by the greatest violence that the head of the femur can be forced out of this cavity. This articulation, which is of the same nature as that of the shoulder, permits the movement of the lower limb in every direction, though to a less ex- tent than that of the arm. We shall again have occasion to discuss this movement. The lower extremity of the femur ends in two oblong, rounded masses, which are called the condyles of the femur, which rest in two cavities in the superior portion of the princi- pal bone of the leg, or tibia, and form with them the articula- tion of the k)iee. The semi-lunar cartilages, interposed between the two bones, diminish the pressure of the femur on the tibia, and prevent the displacement of the former by increas- ing the surface and depth of the articular cavity. In front of the knee-joint is placed the patella or knee-pan, the largest 52 THE HUMAN BODY. of the sesamoid bones, which adapts itself by two articular facets to those presented by the condyles of the femur, and gives attachment by its upper border to the tendon of the extensors of the leg, while by its lower border it is intimately united to the ligament of the knee-pan, which fastens it to the tibia. In comparing the elbow with the knee, we per- ceive the striking similarity of the knee-pan to the olecranon. The knee-pan serves as a pulley for the extensor-muscles, the action of which upon the leg is increased by the change of direction given to them, while the olecranon is a powerful lever, by means of which the fore-arm is extended. Front view. A. Femur. D, b. Condyles of femur. d. Upper extremity of fibula. C. Tibia. D. Fibula. Fig. 17.—Knee-joint. Side view. A. Femur. B. Knee-pan. C. Tibia. D. Fibula. The second bone of the leg is the fibula, which is parallel to the tibia, and with it forms the articulation of the foot. This bone, which takes no part in the articulation of the knee, yet represents the ulna, which plays so important a part in the formation of the elbow, while the tibia corre- ANKLE-JOINT. 53 sponds to the radius. Nature, by one of those transforma- tions of which she furnishes numerous examples, has united the two extremities of the ulna and radius in one, allowing the first of these bones to exist only as a rudiment in its upper portion. This blending of two organs is termed by naturalists a coalescence. The resemblance of the tibia to the radius was remarked by De Blainville, and has been demonstrated by M. Martins in his beautiful work on the pelvic and thoracic limbs. The lower extremities of the tibia and fibula united form a mortise, in which the astragalus, one of the bones of the tarsus, is received, and thus constitute the tibio-tarsal articula- tion, or articulation of the foot. The foot moves upon the leg in such a manner as to form with it a straight line when extended. The movement in an opposite direction, or flexion, is much more limited, the two malleoli which embrace the astragalus not permitting lateral movements in the foot, those which do take place being made by the articulation of the astragalus with the other parts of the tarsus, though a limited movement of circumduction can be made by the foot. It has been said that the foot is another hand —pes altera mantes—and if the hand completes the arm, so does the foot complete the leg. Without it locomotion could not be effected except by movements quite different from those of walking, and under conditions of equilibrium much less favourable, and with much greater fatigue; running, and consequently jumping, would be impossible. But if the foot and the hand are varieties of the same type of organization, they present differences in regard to their respective uses; the foot, designed to support the body, is especially remark- able for its solidity; in the hand mobility is the predomi- nating quality. The foot of man, exclusively designed for the support of the body, is not an organ of prehension, and cannot, like the foot of the monkey, take hold of objects by opposing the thumb to the other fingers; the toes, disposed upon the same plane, have neither the length of the fingers nor the extent and variety of their movements; in a word, it is a foot and not a hand, as it is in the quadrumana. 54 THE HUMAN BODY, The foot is composed of twenty-six bones, seven of which constitute the tarsus, which articulates with the leg and A. Internal malleolus, lower extrem- ity of tibia. B. Astragalus. C. Calcaneum. D. Scaphoid. Fig. 18.—Skeleton of the foot. E. Cuboid. F. First metatarsal. G. H. First and second phalanx of the great toe. corresponds to the carpus. Five bones form the metatarsus, which corresponds to the metacarpus, and articulates with the tarsus behind and with the toes in front. The foot is narrow and thick in its posterior part, thinner and broader anteriorly; it forms a right angle with the leg, and rests upon the ground at the extremities only. The middle portion is in the form of an arch, and in consequence resists shocks and supports pressure much better than it could if it were flat and touched the ground throughout its whole length. And although the parts are very firmly united together, there is sufficient mobility to give great elasticity to the whole, and this elasticity is augmented by the toes. The foot thus supports the weight of the body like an arch and spring combined, giving it in this way great advantage in resistance. And lastly, in jumping from a height it extends itself instinctively, and touches the earth first at its point only, so as to break the shock. This distribution of force, which results from the form and the elasticity of the foot, not only UPPER AND LOWER LIMBS. 55 protects its mechanism, but also avoids the grave injuries which might be produced in certain organs, such as the brain and the liver, by the rebound. Fig. 19.—The foot. If we compare the upper and the lower limbs taken as a whole, we shall remark among their principal distinguishing characteristics, that the flexion of the fore-arm upon the arm takes place in a forward direction, while that of the leg is backward. M. Martins has demonstrated that this opposi- tion in their movements, necessitated by their destination to different functions, is due to the twisting of the humerus. The femur is a straight bone and not twisted upon its axis. The humerus, on the contrary, is turned on itself i8o°, or half the circumference. This is not the result of the me- chanical action of the muscles and of the function of the upper limb; although the form of the bone does not permit this peculiarity to be anatomically recognized till about the second year, it exists virtually as soon as the bone is developed. Muscles, vessels, and nerves all follow this rotating movement indicated by the spiral disposition of the humerus, and most anatomists have pointed it out without hinting at the physiological consequences which M. Martins has shown result from it. This learned observer has shown that the humerus, artificially untwisted, corresponds in all points with the femur of the same side, and by this manoeuvre 56 THE HUMAN BODY. in an opposite direction to the work of nature, he has explained the proceeding by which she bent the articulation of the elbow forward and that of the knee backward. The articulations of the lower limb permit to it a great variety and extent of movement. Under the action of powerful muscles it folds back upon itself or becomes a rigid column, raising or lowering with rapidity and facility the body of which it supports the weight. In walking it is carried forward or backward, and by turns extended or bent; it turns on its axis or changes from the vertical in order to maintain the equilibrium by the direction of the foot or to enlarge the base of support. It can raise itself laterally almost to a right angle with the body, and in front it approaches it still more nearly. In fencing it bends or is extended, raises and lowers the body, and carries it backward and forward by movements which succeed each other almost as rapidly as those of the arms. But it is especially in the varying steps of a skilful dancer that we can admire the perfection of this mechanism, and all the suppleness, strength, and agility that exercise can give to it. CHAPTER V. Motion.—Effort.—Locomotion; standing, walking, running, jumping, swimming. Motion.—Physiologists remark several varieties of motion which may be grouped in two—voluntary and involuntary movements. Among the involuntary movements, which are also called automatic, some result from the impression pro- duced by an idea, a passion, or a scene, gay or sad, or by a movement identical with that which is produced. Such are laughing, and the motions of the face expressing sadness, anger, fear, and other moral or physical impressions; trem- bling of the limbs in consequence of deep emotion, yawning, and so forth. Others proceed from the excitement of the sensitive nerves, such as sneezing, coughing, winking, chat- tering of the teeth, or shivering after a cold bath. In certain cases, in fact, impressions transmitted from the organs to the brain, either directly by the nerves of sensa- tion or indirectly by the spinal cord, without any sensation taking place, or what amounts to the same thing, without our being conscious of any, occasion an excitement which is transmitted to the motor-nerves, and causes movements in which the will has no part. These movements are generally executed by the muscles of organic life, which are not under the control of the will; but they can also be made by those which are under its control. These are called reflex movements. Some of them are undoubtedly automatic;' as for the others, it has not been demonstrated that a sensation and an act of the will do not precede the muscular contrac- tion. Thus sneezing and coughing are independent of the 58 THE HUMAN BODY. will, it can neither prevent them nor arrest their develop- ment. It is the same with the chattering of the teeth, with shivering and winking of the eyelids on contact with the air, with the tears, or only when a foreign body menaces the eye. In this last case, although the muscular contraction is in- stantaneous and seems to be involuntary, it is evidently pre- ceded by a sensation which the eye has transmitted to the brain. This may even be considered as voluntary, since if the attention is excited, the will can oppose the instinctive movement. Other movements take place in the organism of which we have more or less perception; when a carriage threatens to overset, for example, we throw ourselves to the side opposite the inclination; or when suddenly coming on the edge of a precipice the body stiffens or is thrown backward; and when a player at ball or billiards inclines or turns in the same direc- tion in which he wishes to direct his ball. Analogous phenomena are caused by a sort of attraction or instinctive imitation. When, for example, the eyes follow the move- ment of a great waterfall into a gulf, the body very soon fol- lows the oscillations, though we do not perceive them until the motion becomes so great as to threaten to drag us into the abyss. We are indebted to M. Chevreul for the obser- vation and explanation of effects of this nature, of which charlatanism avails itself in table-turning. If the elbow be placed upon a table, and a pendulum formed of a string and a ring be held in the hand, and we fix the eyes on the ring, we shall soon see it begin to oscillate, although the arm ap- parently remains immovable; the oscillations may keep the same direction, or change according to the mental desire, and this without any bad faith or a consenting movement on the part of the person holding the pendulum. But if we place a support under the hand near the end of the fingers, or a bandage over the eyes of the experimenter, the oscilla- tions cease. They were caused by an almost imperceptible and involuntary movement of the fore-arm and hand, under the influence of the eyes looking at the ring and the direc- tion that it takes. And again it is a similar movement or series of movements which gives the impulse to the turning table; in the unconsciousness of the muscular contraction lies all the merit of this phenomenon, which loses its mar- vellous character as soon as you show the too credulous per- formers that they themselves are the involuntary movers. Voluntary movements, as their name indicates, are produced under the influence of the will, but not under its direct or immediate action. The volition of the movements of loco- motion, for example, emanate from a certain part of the brain, from the cerebral lobes; but in order that the move- ment may be executed, the muscles must contract, and this muscular contraction owes its origin to a force which ema- nates from the occipital protuberance, a different part of the brain from that which gives birth to thought. Observations on paralytics prove that the will is insufficient to produce movement. In order that movements may be executed in the order and with the unity necessary to the accomplishment of the will, they must be co-ordinate. Several physiologists, and especially Flourens, have regarded the cerebellum as the organ essential to this co-ordination of movement. A lesion of this part of the brain produces a disturbance in locomo- tion similar to that caused by drunkenness; but pathological observation has demonstrated that there is sometimes absence of co-ordination when the cerebellum is not affected. The muscles unite in the voluntary movements, some as motors, and others, antagonistic to these, as the moderators of movement. M. Duchenne (of Boulogne) has shown that in the voluntary movements of the limbs and the trunk these two systems of muscles, impulsive and modifying, are simul- taneously contracted by a double nervous excitation; one to produce the movement and the other to modify it. Without this unity of intention between the antagonistic muscles, the movements would lose their precision and their certainty. Effort.—When one or several groups of muscles contract themselves strongly in order to perform a function requiring force, or to overcome an obstacle, to draw or push away a body, the name effort has been given to this action of the muscles. There is effort in walking, climbing, running, and a great number of other functions. Whatever muscles take VOLUNTARY MOTION EFFORT. 59 THE HUMAN BODY. part in effort they must have a point of support or fulcrum, directly or indirectly upon the skeleton of the trunk, that is on the spinal column and the bones of the thorax. An effort is always preceded by an inspiration which dilates the thorax, thus rendering the bones of which it is composed immovable by the contraction of the inspiratory muscles, and furnishing a fixed point to the muscles attached to these bones. Thus, one after another, the greater part of the muscles of the system joins in a movement of which sometimes the arm or the hand only is the immediate instrument. The proof of this is the impossibility of making a movement distinct from that which is the immediate object of the effort, without this effort ceasing or diminishing. When it is at its highest point, respiration is suspended, the glottis closes or remains slightly open, according to the nature and the degree of intensity in the effort; the inspired air distends the lungs, and if a part escapes it is too small to lessen the expansion of the chest; the abdominal viscera are compressed from above by the diaphragm in front, and laterally by the muscles of the abdo- men. During certain efforts the air is expelled slowly through the glottis, and when the movement terminates suddenly with redoubled force, the expiration is accomplished rapidly and sometimes in the form of a cry. The sailor who hauls in a rope, or the baker as he with difficulty raises the dough to throw it back into the kneading-trough, accompanies the movements which he executes with a cry of which the rhythm expresses the different periods of the effort. Locomotion.—Man moves over the surface of the ground by three principal methods of progression—walking, running, and leaping; but the point of departure is always the vertical position. In this attitude, which characterizes the human race, the equilibrium of the head upon the vertebral column, and that of the trunk upon the coxo-femoral articulations, and of the thighs on the legs, is independent of all muscular contraction, the ligaments being sufficient to insure it. And farther, the muscles of the neck, of the trunk, and of the thigh maintain the rigidity of the spinal column, oppose or prevent the flexion of the knee, and restore the equilibrium when it is compromised, while the muscles of the leg prevent THE ERECT POSITION. 61 the flexion, anterior or posterior, of the tibio-tarsal articula- tion, the surfaces and ligaments of which only permit an un- stable equilibrium of the body upon the feet. Lastly, the feet, separated from each other by a distance equal to that The foot resting the toes on the ground. Fig. 20.—The leg in standing. The foot resting flat on the ground. which divides the heads of the femurs, complete the mechan- ism by which man alone, among all living beings, stands erect with his face placed vertically, and on a plane parallel to that of the body, but not turned toward heaven, as has been poetically said. In the attitude of a soldier without arms, with the heels touching each other, and the feet forming nearly a right angle, a stronger contraction of the muscles of the leg is 62 THE HUMAN BODY. necessary, and consequently fatigue is sooner induced. When resting on one foot only the body departs laterally from the vertical and leans a little backward, the leg which supports only its own weight rests on the ground, with the muscles completely relaxed, acting as a support and counterpoise. This attitude when standing is the least fatiguing, firmest, and also the most elegant; it is the one preferred by painters and sculptors, and was considered by Leonardo de Vinci as the most natural. When the body moves it is divided into two quite distinct sections: the one, comprising the head, trunk, and upper limbs, representing the mass to be transported; the lower limbs are at once the movable supports of the superior parts of the body, and the agents of propulsion which communi- cate to them the movement of translation. In all move- ments of this nature the trunk inclines forward at an angle which varies according to the quickness, from 50 7' in the slowest walk to 22° 5' in the fastest running. From this position there is a constant tendency to fall forward, which is neutralized by the moving of the lower limbs in such a direction as that the heads of the femurs shall always serve as the point of support for the body. M. Longet compares this unstable equilibrium of the body upon the femurs to that of a rod on the end of a finger, so inclined that the only means to prevent its fall is to carry the finger forward in the same direction as the inclination, more rapidly as this inclination becomes greater. By their alternate flexion and extension the lower ex- tremities give an impulsion to the trunk, they lengthen and contract in a direction inclined to the horizon, since it is forward and not vertically that they push the body; the re- sult is that the centre of gravity sinks toward the ground just in proportion to the rapidity of the mode of progression. Each extremity props itself by turns on the ground, and then the impulse being given the knee bends, the heel rises, the foot is lifted, the limb, shortened by flexion and sus- pended from the pelvis, is directed from behind forward, and is again placed upon the ground. In this movement the leg, according to the brothers 63 WALKING. Weber, represents a pendulum which bends and oscillates by its weight alone; according to M. Duchenne (of Bou- logne), it obeys the contraction of the flexor-muscles. The experiments of the Webers having demonstrated, as stated above, that the head of the femur is retained in the cotyloid cavity by atmospheric pressure alone, these skilful observers conclude that in the second movement in walking the weight of the thigh alone determines the flexion of the joints and the oscillation of the three segments of the pendulum, which is then represented by the lower extremity. Basing his opinion on pathological observation, M. Duchenne thinks that the contraction of the flexors of the thigh, leg, and foot is the real cause of the second movement of the extremity in walking, and that the action of weight contri- butes very little to it. According to M. Be'clard, the tonicity of the flexor-muscles, developed by extension, suffices for seconding the pendulum movement of the lower limb. In walking the body advances without ceasing to rest upon the ground, and by effecting a succession of move- ments, which are divided in each step into two principal ones. First,—the body rests upon the two lower limbs; the right leg, placed behind and inclined to the horizon, touches the ground at the extremity of the metatarsus and at the toes, it stretches out, and the foot is raised to an angle of forty-five degrees; now the left limb is placed forward, rest- ing on the ground on its sole, the knee is a little bent, the heel exactly under the head of the femur, and the trunk slightly inclined forward. Secondly,—the left leg alone sup- ports the weight of the body; it lengthens by extending the knee and straightening the foot; its direction inclines to the horizon, and the body pushes itself forward, while the right leg is raised from the ground by bending the knee, follows the movement of translation given to the body, executes half an oscillation, and touches the ground, first at the heel, which places itself exactly under the head of the femur, and then on the sole of the foot on which the body rests. To accelerate his movement man inclines more forward, the centre of gravity falls nearer to the earth, and the flexion of the limb placed behind is greater, the pendulum is shorter 64 THE HUMAN BODY. and its oscillation more rapid; at the same time the greater flexion gives more force to the extension, and the impulsion forward is increased; and more still, extension acts in a direc- tion still more inclined, which results in a lengthening of the step. The motion is also increased by the extension of the leg resting on the ground while the other oscillates, in such a way that when the latter touches the ground the former detaches itself in order to swing in its turn. In walking quickly the body rests upon the ground only by one foot at a time. When walking, and especially when walking rapidly, the arms accompany with their isochronous oscillations the movements of the lower limbs, and contribute to maintain the equilibrium: indeed it is next to impossible to walk quickly when the arms, from any cause whatever, cannot oscillate. According to the experiments of the brothers Weber, the speed of a man of ordinary stature is, in rapid walking, about 10,267 yards per hour. This speed could not long be main- tained, and must be considered as exceptional. In ordinary walking the speed is nearly four miles an hour, and can be kept up for a long period But exercise and a special aptitude for it enable some men to walk great distances in a relatively short space of time. Trained walkers have gone seventy-five miles in twenty hours, and walked the distance of thirty-seven miles at the rate of five miles an hour. The moun- taineers of the Alps are generally good walkers, and some of them are not less remarkable for endurance than for speed. Jacques Balmat, who was the first to reach the sum- mit of Mont Blanc, at sixteen years of age could walk from the hamlet of the Pelerins to the mountain of La Cote in two hours—a distance which the best trained travellers re- quired from five to six hours to get over. At the time of his last attempt to reach the top of Mont Blanc, this same guide, then twenty years old, passed six days and four nights without sleeping or reposing a single moment. One of his sons, Edward Balmat, left Paris to join his regiment at Genoa; he reached Chamonix the fifth day at evening, having walked 340 miles. After resting two days he set off again for Genoa, where he arrived in two days. WALKING—TROTTING. 65 Several years afterward this same man left the baths at Loueche at two o’clock in the morning, and reached Cha- monix at nine in the evening, having walked a distance equal to about seventy-five miles in nineteen hours. In 1844 an old guide of De Saussure, eighty years old, left the hamlet of Prats in the valley of Chamonix in the afternoon, and reached the Grands Mulets at ten in the evening, then after resting some hours he climbed the glacier to the vicinity of the Grand Plateau, which has an altitude of about 13,000 feet, and then returned without stopping to his village. We will cite in addition the performance of a man from Thun, who walked in September, 1867, a distance estimated at forty Swiss leagues in twenty-three hours, representing at least thirty-four hours of walking for ordinary travellers. Rimning differs from walking principally in the fact that at a given moment the body leaves the ground, and passes through space in the same manner as a projectile. The body is inclined more forward, and the centre of gravity is lower than when walking. The lower limbs execute the same alternate movements as in the first mode of progres- sion; but at the moment when the right leg leaves the ground and commences its demi-oscillation, the left, which is bent and only touches the ground at the extremity of the foot, pushes rapidly forward, and with sufficient force to throw the body upward and forward, and the two legs oscil- late together during an instant, then the one which left the ground first falls before the other on the point of the toes. The body has made a spring, and the same manoeuvre takes place alternately on each side, and the result is a succession of springs which constitute running. Trotting is running when the impulsion forward is not so strong, and the movements are less rapid, which renders it more applicable to uneven ground, where it is necessary to choose the place where the foot is to be placed at each step. The greatest attainable speed for a man is, according to the brothers Weber, seventeen miles in an hour; but if this speed has ever been maintained for one hour, which is doubtful, it could not certainly be continued much longer. The maximum of speed attained in the gymnasium of 66 THE HUMAN BODY. Amoros was twenty-five miles in two hours and forty-five minutes, that is, about nine miles an hour. Leaping is, properly speaking, nothing but a step of run- ning taken singly. A man can jump with his feet joined, that is to say, the two feet quit the ground at the same in- stant, and the body is thrown vertically upward and forward, or backward. The jump may be preceded by running seve- ral steps in order to get under way, as it is termed. In this case the speed acquired during the first steps is added to the impulse given to the body by the last one. By exercise men have succeeded in jumping vertically a height of two metres, and horizontally over a space of five or six metres. Amoros speaks of an Englishman who jumped across a ditch ten mbtres in width. Swimming.—Man can sustain himself upon the water, and traverse it for a considerable space by swimming; but this is not an instinctive method of locomotion for him—he must learn to swim, while walking and the other modes of pro- gression are natural to him, and are not acquired by study. Man walks, runs, and jumps just as an amphibious animal swims without having learned to do so; but to swim he must study the attitudes and the movements which neutralize the effect of his specific gravity, which prevent him from sinking into the water, and permit him to gain a resting-point in order to displace it. The quadruped swims as if walking in the water, that is, by making just the same movements as in walking on the ground. Man can, it is true, swim as animals walk, striking the water with his four members; but he is soon overcome by fatigue, and to swim for any length of time he must exe- cute other movements considerably complicated in their combinations. It is from that modest amphibian, the frog, from which he borrows in this case the method of progres- sion, and this loan is certainly the most inoffensive of all those which he makes from the animals. Although he seems to turn his members quite away from their normal functions, he soon attains the power of prolonging this exercise, which is eminently healthful and very precious, since he finds in it a means of saving his own life and the lives of his fellowmen. CHAPTER VI. The head. — The skull, bones of the skull, sutures, arch of the skull, base of the skull.—Measurement of the skull; facial angle, angle of Daubenton; comparison of the superficies of the skull and of the face.—System of Gall.—The face, bones of the face, upper jaw, lower jaw. The Head.—The head is the most important part of the body, and to it and to the organs which it contains our attention is most particularly attracted. The heart and lungs support life by the respiration and the circulation, the digestive apparatus nourishes the body, but the head is the seat of intelligence, the centre in which all the nervous impressions meet and from which radiates the will. In the head are united the organs of sight, of hearing, of smell, and of taste; the face, almost entirely formed by the grouping of these organs, expresses by the aid of numerous muscles the impressions transmitted to the brain, the passions, calmness or agitation of mind, and, within certain limits, the phases of thought. In other regions of the body life is unconscious, and the functions in their performance, whether healthy or diseased, are executed mechanically; the head alone perceives sensations and interprets their meaning, it is by it that man knows himself, by it he feels that he lives, and is able to say, “I think, therefore I am.” The head is formed of two distinct parts: first, the skull, a bony case which envelops the brain, and incloses in the thickness of one of the bones of which it is formed the organ of hearing; secondly, the face, in which are united the organs of sight, of smell, and of taste. The skull is composed of eight bones: the frontal or coronal, which corresponds to the forehead or sinciput; the 68 THE HUMAN BODY. occipital in the posterior part of the skull or occiput; the two parietal bones, which form the side walls of the skull, and contribute, with the frontal and occipital, to form its arch; the two temporal bones occupy, as their name shows, the region of the temples; the ethmoid, which owes its name to the sieve-like plate of its upper surface; and the sphenoid, so called because it is wedged in between all the other bones with which it articulates, and which rest upon it as upon the keystone of an inverted arch, thus forming the base of the skull on which the brain rests. The frontal, occipital, pari- etal, and temporal bones are flat, formed of two plates of ivory tissue—internal and external tables—between which is a more or less thick layer of spongy tissue. The bones of the cranium are united by means of sutures formed by the junction of the teeth of their serrated borders, almost precisely like what is termed in architecture dove- tailing. At birth the bones which form the arch of the skull are united only by a membranous tissue, and their borders overlap each other even on slight pressure in such a way as to lessen the diameter of the head; but although the sutures are not yet developed, a part of the tooth-like processes already exists in a rudimentary state. The membranous intervals are greater at the point of union of the occipital and frontal with the parietal bones; these spaces are called the fontanelles. They are soon filled with bony tissue, and at four years of age not a trace of them remains. About the end of the third year the borders of the bones are cut into fine notches or teeth, which increase in number till the period of adolescence. Before this the suture which unites the two halves of the frontal bone begins to disappear; and later still, when the brain is fully developed, the other bones gradually close together. The internal surface of the skull presents a series of depressions, portions of the arch which have been called fossce, and according to the bones which constitute them, the frontal, occipital, and temporal fossce, and which correspond to the projections which we see on the external surface. There are also a great number of projections and depressions, which to a certain extent are modelled to the surface of the THE SKULL—THE FACIAL ANGLE. 69 brain, but which form no relief on the outside of the skull. There is no opening in the arch of the skull, but there are several in its base through which the nerves and blood- vessels pass; the most important of these is the foramen magnum, which is the communication between the cavity of the skull and the vertebral canal. The skull is oval in form flattened at the base, with the larger end at the back. It is never perfectly symmetri- cal, and differs in shape and size according to age, the in- dividual, and the race. It is larger in proportion in the infant than in the man, and in the white race than in the other races. But whatever may be the varieties which it presents, they appear exclusively in the arch. Starting from the principle that the skull is modelled upon the brain, in measuring its dimensions we seek to ascertain that of the organ which it incloses. To attain this object, Camper drew two straight lines, the one starting from the first in- cisors of the upper jaw and passing over the median line of the forehead; the other starting from the auditory canal and carried horizontally till it encountered the first, formed with it an angle called the facial angle, which is from 80 to 85 degrees in the European, 75 in the Mongolian race, and 70 in the Negro. This anatomical character, considered as an expression of intelligence, did not escape the notice of the artists of antiquity. The statues which they have bequeathed to us prove this; among their gods, the facial angle of Jupiter Trophonius, for example, is 90 degrees. Daubenton proposed to measure the occipital angle to com- plete the measurement of Camper, which applied only to the anterior portion of the skull; but these angular measure- ments would not give the extent of a solid nor of a cavity; the thickness of the bones at certain points, and the varying development of the cavities or sinuses comprised between the internal and external tables, would take from these measurements much of their signification. In order to be more exact, Cuvier, dividing the head by a section from front to back, compared the area of the skull with that of the face, leaving out the lower jaw: he found that in Europeans, the area of the skull was four times that of the face, and in THE HUMAN BODY. the Negro the area of the face is greater by a fifth, that of the skull being proportionally less. This last method of measurement, even though it gives an id<*a c the relative intelligence within narrow limits only, i at v>t founded upon certain facts, and it expresses the ■r of the proportional development of the face and skull in the superior animals. And even in measuring by the facial angle the causes of error may be avoided to a certain extent, and this measurement is an expression of an incontestable anatomical fact. But this is not the case with a doctrine which was received with enthusiasm about the beginning of this century, though now almost forgotten. We speak of phrenology. Gall pro- fessed to discover the degree of development of the faculties by exploring the cranium. According to his theory, the skull is moulded upon the brain, and presents protuberances corresponding to those of that organ, and thus gives the measure of the development of the intellectual and emotional faculties. These faculties, which he localized in the ence- phalon, were composed, according to him, of a series of conoid bundles, the base of which corresponded to the sur- face of the brain and the apex to the medulla oblongata. Each one of these cones was the seat of a faculty, of which he numbered twenty-seven, placing all the intellectual faculties in the anterior portion of the brain, the animal faculties in the posterior portion, and the moral faculties in the middle portion over the ear: the first confined for the most part to a very small space, and the others distributed over larger surfaces. The pupils of Gall added eleven faculties to those which he had classed. Among the latter, the sense of right and wrong—or as they termed it, conscientiousness— did not appear. To this system it was objected that if the principal projec- tions of the exterior of the skull, the frontal and parietal protuberances, for example, correspond to the depressions or fossae of the interior, no external relief indicated the digital impressions and the small cavities which correspond to the surface of the brain; that at several points an external projection corresponded to one on the inner surface; that THE SYSTEM OF GALL THE FACE. the arch of the brow (the superciliary ridge), where six faculties are located, is more or less prominent, not from the cerebral relief, but from the development of the frontal sinuses; and that there is no resemblance between e fc'tn of the internal table and the external table in thu-~ on l region. Gall was therefore wrong in tracing upon the bn the seat of each faculty according to the elevations which he found upon the skull. It was added also, that, even admitting the localization of the faculties and the divisions of the brain, it was very irrational to unite all the faculties in corresponding portions of the cranial arch, and to attri- bute none at all to those portions of the brain which are not in contact with the skull, or which rest laterally and in front on its base. This exclusive grouping was unjustifiable, and is to be considered as purely arbitrary. Gall and his school invoked the aid of the comparative anatomy of the brain in support of his system. Leuret gave them a death-blow by showing that the study of the brain in the animal scale proves the facts to be in entire disagree- ment with the theory of the German savant, and that it dis- proves at all points the. propositions of phrenology. The face is composed of fourteen bones, which form, by their union with each other and with the bones of the skull, the cavities in which the organs of sight, of smell, and of taste are placed. Twelve of these bones are in pairs, and placed symmetrically on each side: these are the superior maxillary, the malar or cheek bones, the nasal bones, the lachrymal bones, the superior turbinated bones, and the palatine bones. Two are not paired: these are the vomer and the inferior maxillary. The superior maxillaries, with the lachrymal and malar bones, combine to form the inferior portion of the orbit; they are united to the temporal bones by the malar bones, the protuberances of which form the cheek-bones. At their alveolar border the teeth are placed, and the space included in the dental arch is called the pala- tine arch, which is prolonged backward by the palatine bones. The nasal bones form the upper portion or root of the nose; below these, and between the superior maxillaries, is the nasal cavity, which is divided into two parts by a partition, 72 THE HUMAN BODY. of which the vomer forms a portion. The superior turbinated bones articulate with the maxillaries and contribute to mul- tiply the nasal sinuses, in which are the ramifications of the olfactory nerves. The inferior maxillary is at first composed of two bones, which are early joined together at the point called the sym- physis of the chin. The branches of this bone form a right angle with its body, called the angle of the jaw, and at their superior extremity they divide into two apophyses; namely, the condyle, which articulates with the glenoid cavity of the temporal bone, and the coronoid process, where the tendon of the temporal muscle is inserted. This is one of the muscles which draw the lower jaw to the upper one in chew- ing the food. This skeleton, with its strange and imperfect outlines, this type of Death, disappears under the muscles and teguments, which cover it with an elegant envelope. The eyelids veil the orbit and protect the eye, the watchful sentinel and inves- tigator of the exernal world, the admirable instrument which enables the brain to contemplate the works of creation and to express its most vivid impressions. The nose covers the organs of smell, while it completes them by protecting their sensibility; the lips are placed before the mouth, and they are at once an organ of prehension, a docile and indefatig- able guard, a necessary instrument in articulating sounds, and one of the most expressive of the features which com- bine to form the physiognomy. The concha, or external ear, surrounds the auditory canal, and serves to collect the sonorous waves, and to give expression to the head. The hair, the eyebrows, and eyelashes protect the skull and the eye against external objects, and at the same time their dif- ferent shades, and curves, and undulations, greatly contri- bute to the beauty of the whole. Lastly, the skin of the face is animated with the most delicate tints, or is clothed in the vigorous tones and that admirable carnation which has been so well rendered by the Venetian painters. CHAPTER VII. Digestion.— Waste of the organism repaired by alimentation.—Hunger.— Thirst.—Organs of digestion ; abdominal cavity, peritoneum.—Diges- tive apparatus.—Mouth, lips, cheeks, teeth, palate, soft palate, tongue.— Pharynx.—CEsophagus.—Stomach.—Intestinal canal; small intestine, large intestine, intestinal convolutions, mesentery, omentum.—Mucous membrane. —Liver.—Pancreas. — Spleen.—Kidneys.— Mechanism of digestion.—Digestion of the stomach, gastric juice, peristaltic movement, chyme.—Intestinal digestion, bile, pancreatic juice, chyle.—Absorption; endosmosis, exosmosis, functions of the veins and lytnphatic vessels in absorption, rapidity of absorption. Digestion.—The human body loses every day through vari- ous channels, by exhalation or excretion, about 310 grains of nitrogen, an essential principle of animal matter, and lbs. of water, and burns 10 ounces of carbon in contact with the oxygen of the atmosphere. A very short time, therefore, is sufficient to exhaust the organism if it does not find in the alimentation the new elements by which it is reconstructed. Of this unceasing necessity of repairing the loss which the organs sustain by the action of life, man is imperiously reminded by hunger and thirst; hard condi- tions of existence. He can support the first of these wants for a time, which varies according to age and individual strength; it is a sensation agreeable at first, but it soon becomes a torture, a succession of atrocious pains, and moral and physi- cal destruction follow. The annals of hunger are terrible in science and in history; it has been called, with too much reason, an evil counsellor, and he who has the means to appease it each day should be thereby reminded of those less fortunate than himself. 74 THE HUMAN BODY. Thirst is a sensation painful from the first, and can be borne for a shorter time than hunger; for it necessarily im- plies the privation of all liquid aliment, and exhaustion super- venes much sooner than when a man is deprived of solid food, but is able by the aid of a little water to prolong his life for some days. The organs of digestion, of which we will give a summary idea, are, for the most part, contained in the abdomen. Abdominal cavity.—This ca- vity is the largest in the body; it is situated below the chest, from which it is separated by the dia- phragm, and extends to the lower extremity of the trunk. It is divided into several parts or re- gions, which are—ist. In the upper portion, the epigastrium, corresponding to what is called the pit of the stomach, and the two hypochonders {hypo, under; chondros, cartilage), which rise up from each side of the epigastrium, under the double arch of the diaphragm and under the car- tilages of the ribs. 2d. In the middle, the umbilical region, and the planks or sides. 3d. In the lower portion, the hypogastrium or lower belly, and the iliac fossce, inclosed by the bones of the same name. The walls of the abdomen are formed principally by muscles and apon- euroses, combined with the vertebral column and the bones of the pelvis. The lower or false ribs have only an in- direct connection with the abdominal cavity, resulting from its being set into the bottom of the chest. Fig. 21.—Section of the trunk and its cavities in the median line. A. Cavity of the chest. B. Diaphragm. C. Abdominal cavity. D. Vertebral column. E. Spinal canal. ABDOMINAL CAVITY ORGANS OF DIGESTION. 75 The abdominal cavity is lined with a serous membrane called the peritoneum. Like all the membranes of this nature, it is formed of cellular or laminated tissue and elastic fibres; its free surface is covered with an epithelium, a sort of epidermis, which resists the continual friction result- ing from the movements of the organs; and lastly, like all its congeners, it is a sac without an opening, folded on itself, and consequently with double walls. The space between these walls is empty, their corresponding surfaces rub freely against each other, and are moistened by a fluid analogous to the serum of the blood, a secretion peculiar to these membranes, and from which they derive their name. The internal wall of the sac covers all the organs which it con- tains, and the external wall is attached throughout its whole extent to the cavity which it lines. We shall, by-and-by, have occasion to return to the disposition of the peritoneum. The digestive apparatus is one of the most complex and extensive in the organism; it is accessible to our investiga- tions in all its parts, and we are able to follow the working of the functions which devolve upon it. We can observe the metamorphosis which the food undergoes; we can repro- duce in our laboratories a part of these transformations; a step farther, and, as Fontenelle has said, we should surprise nature in the very act; but this impossible step is the immense distance which separates inert matter from organized sub- stance, physical and chemical phenomena from the vital functions. The organs of digestion are the mouth, the pharynx, the oesophagus, the stomach, the liver, and the pancreas. The spleen and kidneys are appendages of the digestive apparatus, but belong rather to the circulatory or excretory. The month forms the entrance to the digestive apparatus; it contains the organ of taste, and serves in eating and in articulating sounds. Bounded above by the palatine arch, below by a muscular wall and by the tongue, on the sides and in front by the cheeks and the lips, the mouth presents in front the opening of tbe lips, behind, the isthmus of the throat by which it communicates with the pharynx and over which the soft palate falls. 76 THE HUMAN BODY. The lips form the anterior wall of the mouth, and are com- posed principally of the orbicular muscle of the lips, to whose Fig. 22.— Section in the median line through the inferior portion of the nasal fossa:, the mouth, pharynx, larynx, oesophagus, and trachea. A. Mouth. B. Soft palate. C. Tongue. D. Tonsil. E. Epiglottis. F. Thyroid cartilage. G. A rytenoid cartilage. H. Superior vocal chord. I. Inferior vocal chord. K. Ventricle of the larynx. L. Larynx. M. N. Trachea or windpipe. O. Pharynx, before which is seen the cricoid cartilage. concentric fibres are attached nearly all the muscles of the face; a very thick skin intimately united with the orbicular THE LIPS THE CHEEKS. 77 muscle, a layer of small salivary glands subjacent to it, and the mucous membrane, complete these two movable, extensible, and contractile veils. The lips are an organ of prehension and suction; they prevent, especially the under lip, the escape of saliva; they assist in the articulation of sounds and in playing upon wind-instruments; and lastly, they take an extensive part in the expression of the physiognomy. Abundantly provided with nerves and vessels, the lips are extremely sensitive, especially on their borders, where the skin grows thin, takes a carnation tint, and is insensibly transformed into mucous membrane. Although the orbicular muscle limits them in a measure, and imposes upon them certain functions and a distinct region, they are in reality only the anterior portion of the cheeks, with which they are in constant communication by movement and function. The cheeks form the sides of the face and the lateral walls of the mouth. They embody in their substance the muscles intrusted with the performance of the complex functions of the mouth. One of these muscles, peculiar to that part of the cheek which forms the buccal wall, brings the food between the jaws and reacts against the distension of the cheeks by the air. Its action in playing on wind-instru- ments has given it the name of buccinator; it contributes also to the expression by drawing the commissure of the lips backward, while the great and small zygomatic muscles raise it. The triangular muscle of the lips, on the contrary, lets it fall; and lastly, the masseter, a thick muscle of great power, brings the lower jaw against the upper one, and with the temporal muscle performs mastication. The internal face of the cheeks is covered with mucous membrane, and its whole surface is scattered over with little openings, which give pas- sage to the saliva, which is secreted by a great number of glandules analogous to those in the lips. Near the middle is the opening of the canal of Stenon, through which the saliva secreted by the parotid gland is poured into the mouth. This gland is situated, as its name indicates, in front of the ear, and is the most important of the salivary glands. The teeth are implanted in the alveolar border of the upper and lower jaw, forming two symmetrical arcades, and when the 78 THE HUMAN BODY. mouth is closed they circumscribe its limits like an internal wall. They are twenty in number in the child, and thirty-two in the adult. They are divided into eight incisors, four canine, and twenty molars. The last four molars are called the “wisdom teeth.” A tooth is composed of three distinct parts: the pulp, the ivory, and the enamel. Vessels and nerves penetrate the pulp, but do not go beyond; the ivory which envelopes the pulp constitutes the root and the crown of the teeth. That part of the tooth where the crown joins the root is called the neck. This last is covered with a layer of bony tissue. The crown commences at the neck, and is overlaid with the enamel, a tissue very poor in animal sub- stances, and almost inorganic. The teeth are not bones; though their roots have an osseous covering, they do not present either in their essential parts—the ivory and the enamel—or in their mode of development and their physio- logical conditions, any connection with the osseous system; they are considered as analogous to the epidermic productions, the hair, nails, &c., which they resemble in many respects. Palate.—The palatine arch is formed, as we have already seen, by the upper jaw-bones and the palatine bones. It is circumscribed in front and on the sides by the upper teeth. It is covered with a thick mucous membrane, very hard, and presenting transverse ridges. Behind, it is continued by a musculo-membranous partition, called the veil of the palate— the soft palate—covered anteriorly by the mucous buccal, posteriorly by the pituitary membrane. Its inferior border is free and floating, presenting on the median line an appen- dage called the uvula. Each of its lateral borders forms a continuation with the tongue and the pharynx by two folds, which are called the pillars of the soft palate, and be- tween which on either side lie the tonsils. In a state of repose the soft palate closes the back part of the mouth; but when raised prevents the food and drink, and the voice also, from passing into the nasal fossae. The tongue is a fleshy body, symmetrical, longer than it is broad, flattened from above downwards, thicker toward the middle than at its extremities, larger behind than in front, and rounded on the edges. The posterior extremity of the THE TONGUE. 79 tongue is called its root, and the anterior the point or tip. Its upper surface or back, and a part of its edges, are covered over with papilla, which are divided into conical, fungiform, and cup-shaped papillae. Its lower surface is free for about one-third of its length anteriorly: at the point of attachment we observe a mucous fold called the franum lingua or bridle of the tongue. Its two posterior thirds receive the muscles which fasten it to the neighbouring parts. The base or root of the tongue is fixed to the hyoid bone, an osseous semi- circle bifurcated at its extremities, placed between the tongue and the larynx, and bound to these two organs by muscles, which gives unity to their movements in rising and falling. The tongue is formed of muscles, some of which are proper to itself, and others attach it to the hyoid bone, to the lower jaw, and to the styloid process of the temporal bone. All these muscles interlace their fibres in an inextricable manner, especially towards the upper portion of the tongue. At the median line and in the centre they are fixed to a cartila- ginous plate, a sort of indirect prolongation of the hyoid bone, which gives greater solidity to the whole. The buccal mucous membrane covers the tongue, and is remarkably dense on its dorsal face. The complex interlacement of the muscular fibres of the tongue permits a great variety of motion. It can raise or lower itself, lengthen or shorten, shrink or expand, diminish the end to a point, bend itself upwards and downwards, hollow itself into a canal lengthwise or breadthwise, carry its point and its edges to the parts of the mouth into which mastica- tion has dispersed the food; in short, it exhibits in its move- ments and changes of form great force and the most subtle dexterity. The tongue receives three nerves; the great hypoglossal, the lingual, and glosso-pharyngeal; the first gives motion, and the last two are the sensitive nerves of taste. Under the influence of the first it takes part in the functions of diges- tion and in the articulation of sounds, and endowed by the others with a special sensibility, it is the principal organ of taste. The bottom of the buccal cavity communicates with the THE HUMAN BODY. pharynx, a canal with elastic walls formed by muscles, and lined with mucous membrane. It extends from the back of the mouth to the oesophagus, and is the vestibule of this passage, a sort of funnel, the upper part of which shares in deglutition, and adds to the resonance of the voice. The anterior wall of the oesophagus is formed by the larynx, the superior orifice of which, surmounted by the epiglottis, opens into the pharyngeal cavity, so that it is only the half of a canal completed in front by the larynx. The pharynx is continued below by the oesophagus, a tube formed by two membranes, the external muscular and the internal mucous. It is extensible and very contractile; it descends between the spinal column and the trachea, which it overlaps a little to the left, and on reaching the thorax it follows the posterior mediastinum, and at last traverses the diaphragm and opens into the stomach. The stomach.—The form of the stomach has been com- pared to that of a bagpipe. It is a large pouch, an expan- sion of the digestive tube, placed transversely across the upper portion of the abdomen. Its left extremity or great cul-de-sac, lying in the hypochondriac region, is rounded and larger than the right, which corresponds to the epigastrium. Above, it forms a concave curve—the lesser curvature; be- low, a convex curve—the greater curvature. The opening by which it communicates with the oesophagus is to the right of the great cul-de-sac, and is called the cardiac orifice; and that which opens into the intestine, the pylorus, or pyloric orifice. The walls of the stomach are formed of four membranes, which, proceeding from without inwards, are a serous—the peritoneum—a muscular, a fibrous, and a mucous membrane. The muscular membrane is composed of three layers of fibres, some longitudinal, others circular. These fibres are slender and open for the most part, but near the pylorus they are closer and stronger, and around this orifice they form a muscular ring, which has been named the pyloric valve. The intestinal canal is a continuation of the stomach; its walls, like those of that organ, are composed of four mem- THE INTESTINAL CANAL. 81 branes—a serous, muscular, fibrous, and mucous membrane. It is divided into the large and small intestines. The smaller intestine is composed of the duodenum, jejunum, and ileum. The duodenum is so named because it measures A. Heart. B. Lungs separated to show the heart. C. Diaphragm. D. Liver. Fig. 23.—Transverse section of the thoracic and abdominal cavities. E. Gall-bladder. F. Stomach. G. Small intestine. H. Transverse colo?i. nearly twelve finger-breadths in length; it extends from the stomach to the jejunum, from which no line of demarcation separates it, nor is the jejunum separated from the ileum. These names indicate a purely arbitrary distinction, drawn by the ancient anatomists between these three parts of the intestinal canal. The large intestine differs from the small one externally in size, and because it presents a series of more 82 marked enlargements. The coecum is its upper portion, of a larger calibre than the ileum, and separated from it by the ileo-coecal valve, a fold of the internal membranes designed to prevent the reflux of fluids. It opens into the ileum, not at its extremity, but by a lateral orifice; below this orifice, it forms a sort of ampulla, terminated by the appendix vermi- formis. The coecum is followed by the colon, from which it is separated only by an artificial division. It is the largest and longest portion of the large intestine; it forms a curve called the arch of the colon, and is divided into the ascending, transverse, and descending colon, to which succeeds the rectum, the extremity of the intestinal canal. The total length of the intestine is about nine yards. It occupies a large portion of the abdomen, in which it is folded in numerous convolutions. The peritoneum {peri, around; teinein, to stretch) enve- lops the intestinal canal, attaches it to the vertebral column by a double membranous fold, called the mesentery, and par- tially covers it by a floating fold or epiploon. Imagine a membrane doubled back so as to form a long broad fold. At the bottom of and within this fold lies the intestine, which we may suppose to be stretched in a straight line. The membrane adheres closely to three-quarters of the surface of the intestine, and then folds back on itself. The two leaves of this peritoneal covering are united by cellular tissue, which permits their separation by distension of the intestines. If now we pucker the fold at its root, the border which contains the intestine will form numerous sinuosities, and this is really the arrangement of the intes- tinal convolutions. In the region of the colon, the fold formed by the peritoneum is very much broader, the in- testine lies in the middle of its breadth, and the rest falls like a veil in front of the intestinal mass, and rises to the stomach, which it partially covers as well as the liver and spleen. This moving veil is the epiploon (epi, upon; pleo, I float). That part of the fold behind the intestine fastens it- self to the front of the vertebral column, and takes the name of mesentery (mesos, middle, and enteron, intestine). The mucous membrane.—This membrane is to the cavities THE HUMAN BODY. MUCOUS MEMBRANE—LIVER. 83 which it lines, what the skin is to the surface of the body. It is an internal skin, which is a continuation of the external. Like the skin, it is an organ of absorption and secretion. It is composed of a corium or true skin and a sort of epi- dermis, named the epithelium, variable in its texture and in its elements according as it is to offer more or less resistance. A peculiar fluid—mucus—is secreted by this membrane and preserves its softness. The mucous membrane is covered, throughout the digestive canal, even to the end of the small intestine, with great numbers of papillae or villi, and espe- cially on the tongue. In the stomach it has numerous folds, which are effaced when the organ is distended; and through- out the smaller intestine it forms the valvulce connivetitcs, wrinkles or folds designed to increase the extent of absorbing surface. The liver is an organ of a glandular nature, and, like all the glands, is designed to secrete a peculiar fluid. It separates from the blood the elements which constitute bile. Situated in the right hypochonder, it enters the arch of the diaphragm; and it occupies also a portion of the epigastrium, and then comes in contact with the stomach, the arch of the colon, &c.; behind, it corresponds to the vertebral column, the aorta, and the descending vena cava; in front to the base of the chest. It is held in its place by ligamentous folds of the peritoneum; the most important of these is the suspen- sory ligament. The form of the liver is difficult to describe: its upper surface is convex, its lower slightly concave. It is divided into the right and left lobes; to the latter is attached an appendage named lobus Spigelii or Spigel’s lobe. The under surface of the liver is marked by the longitudinal and transverse fissures. Through this last the portal vein enters. Examined en masse, the liver is of a reddish-brown colour. Its substance is yellowish, granular, and contained in an envelope of cellular tissue called Glisson's capsule. Several kinds of vessels are found in it: the hepatic artery, which carries the blood which nourishes the organ; the portal vein, which carries the blood to the liver which is to be purified; the hepatic vein, which transmits to the descending vena cava the blood elaborated by the gland; and lastly, the bile-ducts, 84 THE HUB1AN BODY. which secrete or transport the fluids extracted from the blood by the liver to the gall-bladder, situated under the right lobe. The tissue proper of the liver is essentially constituted by the secretory canals of the bile, each one of which ter- minates in an acinus or lobule; a net-work of capillaries of the portal vein surrounds these lobules, which by their union in clusters form the liver, and which are so many diminu- tives of that gland. The secretory ducts are continuous with the hepatic ducts, and the capillaries of the portal vein with those of the hepatic veins, which transmit to the inferior vena cava the blood from which the bile has been separated. The liver secretes sugar also, which, formed in this gland at the expense of the blood from the portal vein, is immediately decomposed, and in health disappears in the process of nutrition. Pancreas.—This is an elongated gland situated behind the stomach: it secretes the pancreatic juice—a fluid analogous to the saliva, and which the pancreatic canal pours into the ductus cholcdochus, near its orifice in the duodenum. Spleen.-—This is a spongy vascular body situated in the left hypochonder, between the stomach and the false ribs: it serves as a reservoir in over-fulness of the portal vein. Its special use and purpose are unknown. The kidneys are two in number, and are placed on the right and left of the lumbar vertebrae in the lowest part of the hypochonders. They are glands of a peculiar and very complicated structure. They separate the urea from the blood, and transmit to the bladder the urinary secretion by two canals called ureters. The upper portion of the kidneys is covered by the supra-re7ial capsules, the use of which is not known. Mechanism of digestion.—This function consists in the decomposition, liquefaction, and absorption of alimentary substances; it prepares the nutriment by separating the assimilable portions which are to be mingled with the blood from those which are not fit to enter into the organism. The aliments undergo in the mouth the first change neces- sary to their introduction into the digestive canal, which is also no less important in relation to their chemical trans- DIGESTION IN THE STOMACH AND INTESTINES. 85 formation. They are here mixed with the saliva, which penetrates them thoroughly, softens and dissolves them in part, and thus renders their mastication, taste, and degluti- tion more easy. The saliva also transforms the amylaceous substances contained in the food first into dextrine and then into glycose or sugar; it reduces a portion of the fatty bodies to an emulsion—that is to say, it separates them into particles held in suspension in the salivary fluid, and begins the decomposition which is completed in the digestive canal. Digestion in the stomach.—From the mouth the alimentary mass descends through the pharynx and oesophagus to the stomach, where it mingles with the gastric juice, one of the most powerful agents of digestion. The gastric juice is secreted by glandular tubes situated in the mucous mem- brane of the stomach. It is a colourless fluid, saltish as well as acid to the taste. It contains, among other elements, alkaline chlorides, lactic acid, and an organic substance called pepsine, which is peculiar to it. The gastric juice pours into the stomach in considerable quantities when food is introduced into it, mingles there with the mass, softens it, and induces a fermentation which results in their ultimate liquefaction. During digestion a characteristic movement takes place in the stomach and intestinal canal—the circular fibres of the muscular membrane contract successively from above downwards, and push the alimentary substances in the same direction. Gradually as the lower fibres contract the upper ones relax in order to contract anew. This is called the peristaltic movement. Under its influence the contents of the stomach are kept incessantly in motion, mixed with the gastric juice, and directed toward the pylorus. This orifice is so named because it is like a door-keeper to the stomach, allowing the aliments which have been sufficiently elaborated to pass out while the others are retained in the organ. After a time, which varies from three to five hours in dif- ferent individuals and at different ages, the alimentary mass is converted into a grayish paste, acid, and almost fluid; it then takes the name of chyme, and the function of the stomach, chymijication, is accomplished. Intestinal digestion.—In proportion as the chyme reaches 86 THE HUMAN BODY. the duodenum through the pyloric orifice, the bile and the pancreatic juice mingle with it, as the gastric juice does in the stomach. They both aid in liquefying the chyme by the water which they contain, and by their special action upon the substances of which it is composed: the pancreatic juice continues with even more activity than the saliva to trans- form the amylaceous matter into glycose. The bile assists the digestion of the animal matter by reducing the fatty bodies to an emulsion, and it appears also to act as an excitant to the function of the intestine; and lastly, a fluid secreted by the mucous membrane of the intestine, as the gastric juice is by the stomach, co-operates with the biliary and pancreatic secretions. Under the influence of these agents, of the fermentation induced by the pepsine and of the peristaltic movement, the chyme is liquefied during its advance through the smaller intestine, and is transformed into a white milky fluid—the chyle—which the chyliferous vessels draw from the surface of the mucous membrane, and carry to the thoracic duct, from whence it goes to be mixed with the blood. Absorption.—The moment chyle is formed digestion proper may be considered as accomplished, though on this function also depends the absorption of the chyle, which must still be perfected in its course through the smaller intestine and the veins before it mingles with the blood. The mechanism of absorption is still unknown. It has been explained as taking place by endosmosis—a phenomenon dis- covered by Dutrochet, which results from the property which tissues possess, under certain conditions, of permitting fluid or gaseous bodies to pass through their capillary canals. If, for example, two fluids which may be mixed, though they may be of different natures and different densities, are separ- ated by a membrane, two currents are established through this membrane in opposite directions, and of unequal force, tending to mix the two fluids, the stronger current is gener- ally produced by the fluid the least dense; and this is called endosmosis—the feebler current exosmosis. In this experi- ment the substances mingle without changing their nature; but it is not so in absorption. The substances absorbed by ABSORPTION. 87 the organic tissues change incessantly during their progress, borrowing or lending elements to each one of the molecules through which they pass. And farther, the different tissues absorb more or less of the same substance by virtue of pro- perties which are unknown. In this way a poison which remains inert on the mucous membrane of the stomach is rapidly absorbed by the lungs. The mucous membranes absorb more rapidly than the skin, and this tissue is more or less permeable according to its thickness, its density, as the epidermis which covers it is thick or thin. Absorption is therefore very rapid in inocula- tion—that is, when the substance to be absorbed is intro- duced into the substance of the tissues. Wherever the point of absorption may be, it takes place by the lymphatic vessels, and especially by the veins. The veins absorb a greater number of substances than the lymphatics, and carry them more quickly into the circulation; they charge themselves especially with the materials which are to be rejected from the economy, while the lymphatics absorb from preference those that can still be assimilated. The veins and the chyliferous vessels, which are a variety of the lymphatics, draw from the mucous membrane of the intestine the useful products of digestion; but the lymphatics take possession of fats, while the veins prefer fluids, albumen, sugar, and salts. It is well known with what rapidity certain substances taken into the alimentary canal, or into the lungs, pass into the other organs, and exhale, or are eliminated. Thus the presence of the ferro-cyanide of potassium has been recog- nized in the urine within one minute after its ingestion into the stomach. Indigo, gallic acid, and other colouring matters, or those possessing a characteristic odour, pass in the course of fifteen or twenty minutes through all the wind- ings of the circulation. As has already been stated, absorption takes place much more rapidly by the skin when it has been deprived of its epidermis. Five or six minutes are generally a sufficient time for the alkaloids of opium or belladonna to manifest their action on the nervous system, and in some cases this action is produced in a few seconds. Other substances, especially 88 THE HUMAN BODY. sulphate of copper, are almost as rapid in their effect o*n the stomach as chloroform and several gases when placed in contact with the mucous membrane of the lungs; they pro- duce phenomena which develop themselves with terrible rapidity. Medicine derives great assistance from this ab- sorbent property of the tissues; thanks to which, humanity is daily spared a vast amount of suffering. CHAPTER VIII. Respiration.—Thoracic cavity; pleura.—Organs of respiration: lungs, trachea, bronchia.—Respiration; influence of respiration on the blood, Lavoisier's theory, theory of catalytic phenomena; mechanism of respira- tion, respiratory sounds, frequency of respiration; capacity of the lungs; modification of the air in the lungs.—Influence of atmospheric pressure on respiration; mountain-sichness. Thoracic cavity.—The thorax or chest, as we have already- seen, is formed by the vertebral column, the ribs, and the sternum. The shoulder-blades and collar-bones belong to the arm, which is an appendix of the thorax. The thorax resembles a bony cage (fig. n, p. 27), the interstices of which are filled with the muscles; the interior of this cage is the thoracic cavity (fig. 21, p. 74). It is the second cavity in point of size in the body; it has the form of a cone, slightly flattened from before backwards, with the base turned down- ward, and hollowed out in front. It is bounded at its apex by the sternum, the clavicles, the first rib on the right and left, and the seventh cervical vertebra; at its circumference by the sternum, the ribs, and the dorsal vertebrae; at its base by the false ribs, the costal cartilages, and the xyphoid car- tilage. The diaphragm corresponds to this base (fig. 21, p. 74); this is a muscular partition, the fibres of which radiate from a central aponeurosis; it closes the chest at the bottom, into which it rises like an arch, a little depressed in the centre. The diaphragm is attached to the cartilaginous border of the false ribs, to the xyphoid process, and to the lumbar vertebra. This last attachment is effected by mus- cular fasciculi, which are called the pillars of the diaphragm. The central aponeurosis of this muscle is in the form of a 90 THE HUMAN BODY. clover leaf; it was considered a nervous centre by the ancients, perhaps because of the pain and the peculiar sen- sations induced in the epigastrium by strong emotions, or because they confounded the tendinous fibres with the nervous tissue. Pleura.—The cavity of the chest is lined with a serous membrane, called the pleiwa, which forms in each half of this cavity a sac without an opening. There are therefore two pleurae, a right and a left. Proceeding from the edges of the sternum and the costal cartilages, the pleurae cover the lateral walls of the chest and a portion of the body of the vertebrae. They then approach each other, leaving a space between them called the posterior mediastinum. On reaching the root of the lungs, they turn from within outward, covering a portion of the pericardium and of the internal surface of the lungs, their posterior borders and external surface; they then penetrate the interlobular fissures, and fold back upon the anterior border of the lungs and upon their internal surface quite to their roots; then turning again forward, they cover the sides of the pericardium, in front of which they turn back to back, and then separating anew, they reach the borders of the sternum from whence they sprang. The space left between the pleurae behind the sternum is the anterior medi- astinum, separated, as is seen, from the posterior mediastinum by the heart and the root of the lungs. At the top of the chest the pleurae form a conical cavity, which receives the apex of the lung; at the bottom they cover the superior surface of the diaphragm. In the posterior mediastinum are the oesophagus, the aorta, the azygos vein, the thoracic duct, and the lower portion of the trachea. In the anterior mediastinum are the pericardium—the envelope of the heart—and the thymus gland, an organ whose uses are unknown. That part of the pleurae which envelops the organs of the chest, and that which lines the walls of this cavity, are thus in contact with each other without adhering, in a normal condition, and they allow the expansion and contraction of the lungs and the walls of the chest. The serous nature of the pleurae insures freedom of movement, and prevents all roughness in the constant friction of the surfaces. LUNGS. Organs of respiration. Lungs.—As their name indicates (pneumon, from pneo, I breathe), the lungs are the essential organs of respiration. They are two in number, though they Fig. 24.—Lungs and heart. A. Lungs with the anterior edges turned back to show the heart and bronchia. B. Heart. C. Aorta. D. Pulmonary artery. E. A scending vena cava. F. Trachea. G, G. Bronchia. H, H. Carotid arteries, I, I. Jugular veins. J, J. Subclavian arteries, K, K. Subclavian veins. P, P. Costal cartilages. Q. Anterior cardiac artery. R. Right auricle. receive the air by one canal and the blood by a single vessel; they may be considered as the terminal expansion of the rami- fications of the trachea, or as the two heads of a single tree. Placed in the chest, of which they occupy the larger part, 92 THE HUMAN BODY. and to the shape of which they are moulded (fig. 23, p. 81), they represent two irregular cones, resting their bases on the diaphragm, filling with their apices the two conical spaces lined by the pleura at the top of the chest, and separated by the heart and the mediastinum. The right lung is divided in its length into three lobes by two oblique clefts, and is shorter and larger than the left, which has but two lobes. The internal face of the lungs is concave; about the middle the bronchia unite with the pulmonary vessels to form the root of the lungs; their base takes the form of the convexity of the diaphragm; their edges, thin in front and at the bottom, thick and rounded behind, partially cover the heart, and fill the space which separates the diaphragm from the walls of the thorax, as well as the groove between the ribs and the vertebrae. The entire surface of the lungs is smooth and moistened with serous secretion. The tissue proper of the lungs, or pulmonary parenchyma, is of a grayish rose colour, soft, spongy, elastic, crepitating under pressure in consequence of the air it contains. It is divided into polyhedral lobules, very variable in form and in the disposition of their facets, which permit exact juxtaposi- tion without intervals; and they are separated by partitions of cellular tissue, independent and without communication with each other. Each one of these lobules is formed of a cluster of little cavities called pulmonary vesicles, constituting a cul- de-sac, and receiving the air from the bronchial ramifications of which they are the terminal expansions. The diameter of these pulmonary vesicles is from one-seventieth to one hun- dred and fiftieth of an inch; from this we can judge of the tenuity of their walls, in the substance of which notwithstand- ing ramify the capillary vessels. Each lobule represents a little lung, a diminutive of the entire organ. A bronchial twig and minute artery run into it, veins and lymphatic vessels leave it. On the surface the lobules appear bounded by their interme- diate partitions, and they form a mosaic of which the mottled colouring varies from rose to black. These black particles are principally composed of a carboniferous substance which penetrates the lung either with the air or with the blood, and which is called pulmonary carbon. LARYNX TRACHEA. 93 The lungs are supplied with air through the larynx, trachea, and bronchia. The larynx, the organ of the voice, of which we shall speak later, is continuous below with the trachea. This is a cylindrical tube flattened behind; it is composed of a series of cartilaginous rings united by a fibrous membrane, Fig. 25.—Section showing the ramifications of the bronchi in the lungs. A. Trachea. B, C. Bronchi. D, D. Bronchial tubes. and lined with a mucous membrane; it is placed in the an- terior portion of the neck, and passes vertically from above downward. The rings of the trachea do not extend quite round it; interrupted in their circuit towards the posterior fourth of the tube, they are, properly speaking, only segments of a circle, They number from sixteen to twenty, and pro- duce a corresponding number of protuberances on the surface of the trachea, which is thereby rendered rough and wavy to the touch. It is from this circumstance that it derives its 94 THE HUMAN BODY. name (trachys, rough). Formerly it was confounded with the arterial vessels, which were supposed also to be designed to contain air. At the height of the third dorsal vertebra, the trachea divides into two portions, which are called bronchi, which on reaching the root of the lungs divide into numerous rami- fications designated bronchia or bronchial tubes, and be- coming more and more slender. Of the two principal bronchi, the right is larger than the left, and the left is twice the length of the right. They are both, as well as their rami- fications, up to a certain limit, composed of fibrous membrane and incomplete cartilaginous rings. When their diameter has decreased to less than one-fiftieth of an inch, they no longer have the cartilaginous rings, and the mucous membrane cannot be separated from their walls. They continue to subdivide, and terminate, as already stated, in the pulmonary vesicles, the agglomeration of which in clusters forms the lobules of the lung. Independently of the artery and pulmonary veins by which the venous blood reaches the lung, and, transformed into arterial blood, is returned to the heart—that is, besides those which serve for the sanguification and circulation—the bronchial veins and arteries carry the blood through the lungs which is destined to nourish the organ itself, and it is probable that the tissue proper of the lung uses for itself part of the red blood formed in its cavities. Numerous lymphatic vessels are also found in the lungs. The nerves which are distributed through the lungs come from the pneumogastric and the ganglionic nervous system. Respiration.—Respiration is a function by which the oxygen of the air is introduced into the blood, and by which part of the useless and hurtful materials are expelled, in a gaseous form, from the organism. It is divided into two parts: inspiration, during which the atmospheric air penetrates the pulmonary cells; and expiration, which expels the air which has been changed during its stay in the lungs. On reaching the cells of the lungs, the blood is separated from the air by their walls and those of the capillaries, which ramify over them. However thin these membranes may be, they suffice to confine the air and the blood in distinct cavities; but like the other organic tissues, they have the property of allowing themselves to be penetrated by endos- mosis and exosmosis. The oxygen of the air therefore passes through them in order to combine with the blood; while those gases contained in this fluid, which should be eliminated, separate from it and mingle with the air, which carries them away with it during expiration. It is an interchange of gases between the air and the blood, the air giving up oxygen to the blood, and receiving from it other gaseous fluids, among which carbonic acid gas predominates in volume. This being in excess in the venous blood is exhaled from the lungs, while the oxygen of the air combines with the blood which is carried to the heart by the veins, which has been deprived of a part of its nutritive elements, and has become unfit to support life. On coming in contact with the oxygen, the venous blood loses its dark colour, becomes a brilliant red, and returns to the heart transformed into arte- rial blood. This group of phenomena is called sanguifi- cation. On the one hand the oxygen of the atmosphere burns carbon in the lung, on the other the lung exhales carbonic acid gas, nitrogen, and the vapour of water. From whence are these gases and this water derived? The carbonic acid gas is not produced in the lungs alone. The venous blood reaches the organ of respiration poor in oxygen, and charged relatively with the carbonic acid gas which it has received in its course from all the tissues; everywhere this acid has been produced by the combination of the carbon with the oxygen, which in the lung is borrowed from the air, but everywhere else it comes from the arterial blood. In a word, the oxygen combined with the blood by respiration, is separated from it little by little in the capillaries throughout the whole body in order to produce numerous products, among others car- bonic acid gas. On leaving the heart and in the arteries, the blood contains 24 parts of oxygen per 1000, in the veins it contains only 11 per 1000. As for the nitrogen and the vapour of water, one is disengaged, and the other produced during this same process of nutrition, and both are drawn RESPIRATION. 95 96 THE HUMAN BODY. from the principles in the organism which are introduced into it by digestion or respiration. Lavoisier was the first to demonstrate the absorption of oxygen by respiration, and to show by experiment the analogy existing between combustion and respiration. “ Respiration,” said he, “ is nothing but a slow combustion of carbon and hydrogen, which resembles, in every respect, that which takes place in a lamp. ... In respiration, as in combustion, it is the atmosphere that furnishes the oxygen. . . . But since, in respiration, it is the substance of the animal itself, it is the blood which furnishes the combustible, if animals do not regularly repair by alimentation that which they lose by respiration the oil in the lamp will soon be wanting, and the animal will perish as the lamp will go out for the want of nourishment.” Most physiologists have admitted Lavoisier’s theory, and they consider respiration a slow combustion of the materials of the blood by the oxygen of the atmosphere, and as the source of animal heat. We have just seen that this combustion takes place, not only in the lungs, but through- out the whole extent of the organs where the arterial blood carries the oxygen which presides over the phenomena of nutrition, that is, over the assimilation of the elements of which the blood is formed, and over the decomposition of some of these principles of which certain parts only remain in the system, while others return to be burned in the capillaries of the lungs, or to be exhaled in the form of gas or vapour of water. Some authors again do not admit that combustion takes place in respiration, the phenomena of which, of quite a dif- ferent order according to them, may be attributed to a reac- tion induced by the contact of organized substances. The decomposition and disassimilation of these are due to a series of acts of which very little is known, and which are compared to what has been termed by Berzelius 11 catalytic phenomena." But we confine ourselves to a mention only of this doctrine, which is not generally accepted. Mechanism of respiration.—We have seen that respiration is divided into two movements—inspiration and expiration. In inspiration, the diaphragm contracts and sinks down, push- MECHANISM OF RESPIRATION. 97 ing the abdominal organs downward. The ribs rise by the contraction of numerous muscles; at the same time with the sternum, which is carried forward, the intercostal spaces en- large, and the chest is developed in all its dimensions, verti- cally, antero-posteriorly, and transversely. In expiration, the inspiratory muscles relax, and others, especially those of the abdomen, lower the ribs and the sternum by contracting the chest; while the lungs, distended by the air inspired, collapse under the pressure of the thoracic walls and their own proper elasticity. The experiments of Duchenne of Boulogne tend to prove that this contraction of the lungs is due to the muscular fibres which accompany the bronchia down to their minutest ramifications. Nearly all the inspirations are effected by the movements of the diaphragm and the inferior ribs only. From time to time a deeper and more complete inspiration causes the thorax to rise, not simultaneously but successively at the base, then at the apex. In the first case the respiration is dia- phragmatic; when the lower and middle ribs are raised it is termed lateral; and lastly, when the first rib and clavicle take part in the movement, it is costo-superior or clavicular. In diaphragmatic respiration, as M. Mandl has observed, the larynx is immovable, the inspiration is easy, without effort, and permits exertion in singing or in gymnastics for a long time and without fatigue. On the contrary, persons who respire principally by the upper ribs are easily fatigued, and very soon out of breath. This is seen in women when the corset compresses the base of the chest, and in singers who adopt, on erroneous principles, the bad habit of clavicular respiration. In this last method of inspiration the larynx is drawn down by the contraction of the external muscles, and its action becomes painful. The effort of the inspiratory muscles rapidly induces fatigue, and the inspiration, always incomplete, becomes also more frequent. Diaphragmatic respiration is practised by mountaineers, gymnasts, and skilful singers—-a habit induced either by instinct, or a well-directed education. The respiratory movements are not completely under the control of the will. It is not possible long to suppress the 98 THE HUMAN BODY. contrary movement after an inspiration, and when expiration has taken place the need of inspiration soon makes itself im- periously felt. It is impossible, in fact, to retain the breath except for a very short space of time, two or three minutes at the longest: the most thoroughly trained divers not being able to exceed this limit. Respiratory sounds. — In a normal condition, and when awake, respiration takes place without noise when the move- ment is moderate; but when inspiration and expiration are strong and deep, it is accompanied by a noise caused by the air passing through the nasal passages or the mouth. During sleep the column of air breaks against the soft palate and produces snoring. Besides these sounds, which are exterior to the chest, there are others produced by the passage of the air through the bronchial tubes; and when the ear is applied to the chest of a person in good health, a soft and regular murmur is heard in rhythm with the respiration; this is called the vesicular murmur. Several morbid causes change the nature of this murmur, suppress it, or produce others. These are so many signs which enable the physician to determine the condition of the respiratory organs. Frequency of respiration.—In an adult in a condition of repose, respiration takes place about eighteen times a minute, in the infant it is more frequent. As is well known, it be- comes very active under the influence of bodily exertion, or under excitement from any cause whether physical or moral. When, on the other hand, the attention is fixed on a laborious effort, the breath is held so that it very soon becomes necessary to take long and deep inspirations to compensate for the insufficiency of those which preceded. This result of hard work or great strain of mind should be guarded against in children, as their constitution suffers greatly under the influence of incomplete respiration. Capacity of the lungs.—It is estimated that the lungs of a man from thirty-five to forty years old will contain about 225 cubic inches of air; it is less before that age, and falls to a little less than 200 cubic inches at sixty years of age. The capacity is smaller in women, and varies also according to the individual. It is only possible to obtain approximate CHANGES ON THE AIR IN THE LUNGS. 99 experimental results, as the lungs are not completely emptied at each expiration, and the cells always retain a quantity of air, and this quantity is greater in proportion as the respiration is calm and shallow. Changes on the air in the lungs.—It is clear from the fore- going, that the air which is expired has neither the same volume nor the same proportion of constituent elements as the air which is inspired. In fact, an adult man absorbs by- respiration from 450 to 550 grains of oxygen in an hour. He exhales in the same time 632 grains of carbonic acid; a less quantity of nitrogen, amounting to about a hundredth of the oxygen absorbed; and lastly, about 9720 grains of water in the form of vapour. This exhalation of water by the lungs constitutes the pulmonary perspiration, a function analogous to the perspiration of the skin. The expired air, as already stated, is deprived of a portion of its oxygen, and is charged with carbonic acid gas. The proportion of this gas is about 4 parts in 100. From 350 to 400 cubic feet of air are taken into the lungs in 24 hours, and rapidly changed, and the gravest consequences result from placing a man under condi- tions in which the air cannot be renewed. During the Eng- lish war in India in the last century, one hundred and forty- six prisoners were shut up in a room scarcely large enough to hold them, into which the air could only enter by two narrow windows; and at the end of eight hours only twenty-three remained alive, and these were in a most deplorable condi- tion. Percy relates that after the battle of Austerlitz, three hundred Russian prisoners were confined in a cavern, and two hundred and sixty of these unfortunates perished in a few hours from asphyxia. Influence of the pressure of the atmosphere on respiration. Mountain-sickness.—It is well known that the density of the air diminishes with the atmospheric pressure, that is, in the lower regions of the air, on the sea-coast for example, the air is denser than in elevated regions. Thus in order to absorb the quantity of oxygen necessary for sanguification, it is necessary to respire oftener upon high mountains than when on plains, but this acceleration of respiration is perceptible only when the height is considerable and the THE HUMAN BODY. distance rapidly passed over. Gay-Lussac, who in his balloon ascension rose to a height of 22,956 feet in six hours, found his respiration disturbed, and greatly accelerated; and having made no movement requiring exertion, he could only attribute this condition to the diminution of the pressure of the atmosphere. But in climbing mountains the move- ment and efforts of walking are added to the influence of the height; and when the difference in altitude in one day amounts to 6560 feet, a notable acceleration of respiration and quickening of the pulse is observed, which in many instances is accompanied by a peculiar sense of uneasiness, which has been termed mountain-sickness. The most remark- able symptoms are fatigue or rather partial paralysis of the muscular system, and especially of the muscles of locomotion. This paralysis of the legs increases with every step until, having gone a certain distance with increasing difficulty, it is impossible to take another step. A rest of a few seconds is sufficient for the muscles to regain their power, and it seems as if the traveller could go on without fear of a recurrence of the difficulty; but very soon it returns, and a fresh halt is necessary. The higher one goes the shorter the distance that can be passed without resting—from one hundred and fifty steps the distance falls off to one hundred—to fifty—and at last to twenty or thirty. Inclination to sleep, oppression of the heart, and loss of spirit are sometimes added to this periodic exhaustion of strength, and in some persons mountain- sickness is closely analogous to sea-sickness. In others the symptoms are such as are always induced in the respiration, circulation, and in consequence in the muscular system, by violent exercise. Thirty steps in climbing a high mountain cause as much fatigue as a forced march or run on a plain. Respiration, quickened by motion and disturbed by succes- sive efforts, is no longer sufficient for sanguification; the pro- portion between the venous and the arterial blood is no longer normal; and, above all, sanguineous congestion, which is inseparable from violent exertion, takes place in the lungs, in the brain, and other organs. But as soon as the muscles have relaxed for a few moments, two or three full in- spirations rapidly relieve the congestion, while a flood of MOUNTAIN - SICKNESS. arterial blood proceeds from the heart to revive the whole organism. 101 Up to a height of 16,400 feet, man can easily acclima- tize himself to the rarefied air. Baron Humboldt saw Peru- vians cultivating the land at Antisana, situated 13,454 feet above the level of the sea; and agricultural labour requires the development of an amount of force incompatible with mountain-sickness, even though an energy like that of our European cultivators may not be found. Jacquemont visited villages in Thibet at a height of 16,400 feet. La Paz is situated on the Andes at a height of 12,195 feet> but the inhabitants suffer no inconvenience from the rarity of the atmosphere; though strangers can walk only a short distance without stopping, and they are specially uncomfortable if the young Peruvian ladies mischievously invite them to a few turns in a waltz. It is hardly necessary to remark that these symptoms are not equally urgent in all those who expose themselves to this rarefied air. Some individuals scarcely feel them, and are soon acclimatized, while others suffer greatly for a long period. A host of circumstances and special conditions contribute also to render these symptoms more or less marked, and mountaineers themselves some- times experience them as well as the inhabitants of less ele- vated countries. CHAPTER IX. Circulation.—Organs of the circulation; heart, pericardium; arteries, capillaries, principal arteries; veins, principal veins; portal system; lymphatic vessels and ganglia.—Mechanism of the circulation; dis- covery of the circulation, action and sounds of the heart, arterial circu- lation, pulse, capillary circulation; venous circulation, valves of the veins; discharge of chyle and lymph into the veins. Sanguification; circulation in the pulmonary artery, capillaries, and pulmonary veins. —Influences which accelerate or retard the beating of the heart. Circulation.—The blood is carried by the arteries from the heart to all the organs, and it returns by the veins from all the organs to the heart. This movement of the blood to and from every portion of the body, from the heart as the point of departure, is called the circulation. The transportation of chyle and lymph by the lymphatic vessels, which are the tributaries and purveyors of the sanguiferous system, is con- nected also with the circulation. Organs of the circulation.—The heart is a hollow muscular organ, nearly in the form of a cone, of which the base is equal to the height, and about the size of the fist in the adult. It is situated towards the middle of the chest, a little to the left (fig. 24, p. 91), and between the pleurae, which contribute to form its covering. Its apex is directed down- ward, forward, and towards the left, at about the level of the fifth rib; its base looks upward, and slightly backward, and is protected by the sternum. Its anterior face, turned upward and to the right, is marked by a longitudinal furrow, as is also its posterior face, which is turned downward and to the left. Internally the heart is divided by a muscular par- tition into two nearly equal halves, placed back to back, and THE HEART. these are each again divided laterally into two cavities, the superior called the auricle, and the inferior the ventricle. The auricles take their name from a flattened appendage which Fig. 26.—Heart and principal arterial and venous trunks. A. Right ventricle. B. Lift ventricle. C. Right auricle. D. Left auricle. E. Aorta. F. Pulmonary artery. G. Brachio-cephalic trunk. H. Carotid, right and left. I, I. Subclavian arteries. K. Superior vena cava. L. Pulmonary veins. falls down upon their external face. The right auricle com- municates with the right ventricle, and the left auricle with the left ventricle. There is no communication between the ven- tricles, but before birth the two auricles communicate by an orifice, which is obliterated during the first months of life, 104 THE HUMAN BODY. leaving as the only trace of its existence a depression called the fossa ovalis. The superior and inferior vena cava open into the right auricle, and at the orifice of the latter is the Eustachian valve. The orifices of the right and left pulmonary veins are in the left auricle. The opening by which the auricles and ventricles commu- nicate with each other is called the auriculo-ventricular opening. These orifices are furnished with valves; that on the right is called the tricuspid valve, from the three angles which are formed by its leaves; and that on the left is called the mitral valve, from the slight resemblance which it bears to a bishop’s mitre. The cavities of the heart are lined by the endocardium, a very fine, smooth membrane, which has been compared to the serous membranes. These cavities present numerous inequalities, which result from the projection of the bundles of muscular fibre which point in every direction. In the ven- tricles these fascicles form fleshy columns (columnce carnece), disposed in a net-work running from one point of the walls to another, and several which take part in the movement of the valves, send out to these valves a crowd of little tendons. The walls of the left ventricle are much thicker and more resistant than those of the right ventricle. Pericardium.—This is the term applied to the covering which envelops the heart; it is a sac composed of two layers, a fibrous membrane on the outside, and a serous membrane on the inside. This last covers the external surface of the heart, and is reflected back upon itself in order to form, like all the membranes of this nature, a sac without an opening. The heart is thus covered by the pericardial sac, but not contained inside its cavity. A correct idea may be formed of the disposition of the pericardium around the heart by recalling a very common and very convenient, though now discarded head-dress, the cotton night-cap. The pericardium incloses the heart exactly as this cap covered our forefathers’ heads. Arteries.—The vessels which carry the blood from the right ventricle to the lungs, and from the left ventricle to the ARTERIES. whole system, are called arteries. The first-named, the rami- fications of the pulmonary artery, contain the dark blood which is carried to the lungs to be oxygenized by contact with the air. It is on the contrary red blood which runs in the aorta, the original trunk of all the arteries distributed Fig. 27.—Transverse section of the heart. A. Right ventricle. B. Left ventricle. C Right auricle. D. I.eft auricle. E. Right auricula-ventricular orifice and tricuspid valve. F. Left anriculo-ventricular orifice and mitral valve. G. Origin of the pulmonary artery and sigmoid valves. H. Origin of the aorta, and valves. I. Orifice of inferior vena cava. K. Superior vena cava. L, L. Orifice of the pulmonary veins. through the body. There are two classes of arteries, one pertaining to the pulmonary system or lesser circulation, and the other to the aortic or general circulation. We will first consider the last-named. The ancient anatomists, finding the arteries empty after death, believed that they were designed to contain air, and from this circumstance they derive their name (aer, air, and 106 THE HUMAN BODY. tcrein, to contain). For the same reason, and with more accuracy, they named the tube which conveys the air to the lungs the trachea-artery. Galen discovered the presence of blood in the arteries, but he retained the name, and others have continued it, although it does not accord with their functions. The walls of the arteries are composed of three superposed coats. The outer one is fibro-cellular, vascular, and very resistant; the middle one, the membrane proper or elastic, is less resistant, and changes its texture under the influence of age or other causes. The inner is extremely thin, and is analogous in texture to the endocardium. When a ligature is applied to an artery, the internal and middle coats are broken through by the pressure, but the external one resists it. The arteries communicate with each other in their course through the body, and especially toward the extremities by numerous anastomoses—that is, they join each other either by means of branches, or by forming a net-work, the meshes of which, rounded and in arches, are closer in proportion as the twigs are smaller. They terminate in innumerable microscopic ramifications, called the capillary vessels, which are intermediate between the ends of the arteries and the veins. The walls of the arteries are nourished, like all other parts of the body, by the vasa vasorum, or vessels of the vessels. And lastly, the arteries are enveloped in their course by numerous nervous filaments from the great sympathetic nerve, and by lymphatic vessels. The arteries wdiich penetrate the substance of muscles, like those of the thigh and leg, are protected by an aponeu- rotic sheath, and by fibrous rings which prevent them from being pulled out of place or compressed during the contrac- tion of the muscles which surround them. Principal arteries.—The aorta, which is the main trunk of the arterial system which carries the red blood, is the largest artery in the system. It commences at the upper portion of the left ventricle, not far from the ventriculo-aortic orifice; it has three valves, called the sigmoid or semi-lunar valves, PRINCIPAL ARTERIES. 107 which serve to prevent the reflux of the blood, and which completely close the vessel when expanded. The aorta runs upward and to the right, and is here the ascending aorta; then it turns to the left, passing in front of the spinal column, and taking a new turn downward, it forms the arch of the aorta; it runs along and to the left of the spine through the posterior mediastinum, and is called the descending aorta, and passes through the opening in the dia- phragm. On reaching the abdomen it becomes the abdo- minal aorta, up to about the fourth lumbar vertebrae, where it bifurcates and forms the two primitive iliac arteries. From its upper portion the aorta throws off important branches, of which the principal are the followingThe brachio-cephalic or innominate artery, which springs from the arch, and is its representative on the right side of the chest. This trunk gives off the right common carotid and subclavian; the left common carotid and subclavian spring directly from the arch of the aorta. The common carotid arteries run upward along the outside of the neck on a level with the upper border of the thyroid cartilage, and each divides into the external and internal carotid. The external carotid gives off the superior thyroid, the facial, lingual, and occipital arteries.. At the level of the con- dyle of the jaw it divides into the temporal and internal maxillary. The internal carotid runs upward along the cervical ver- tebrae, enters the skull, gives off the ophthalmic artery, and is distributed through the brain. The subclavian runs outside, behind and below the clavicle, as its name indicates, and gives off, among other branches, the vertebral artery, and the internal mammary; and on reaching the arm-pit (axilla) it takes the name of the axillary artery, and gives off important vessels to the shoulder and chest; and then descending along the humerus under the name of the brachial artery, it divides below the elbow, and forms the radial and ulnar arteries, which furnish the vessels of the fore-arm and those of the hand. Among the arteries arising from the descending aorta we 108 THE HUMAN BODY. will mention only the coeliac trunk, which divides into three branches, destined to the liver, the stomach, and the spleen; the superior and inferior mesenteric, which go to the mesentery and intestines; and the renal or emulgent arteries. Iliac arteries.—The common iliac arteries, formed by the bifurcation of the aorta, run obliquely downward to the right and left. After attaining a length of about two and a half inches, each one divides into the mternal iliac, which ramifies on the inside and on the outside of the pelvic cavity, and the external iliac, which at the point where it leaves the pelvis gives off the epigastric artery. This artery runs upward behind the anterior wall of the abdomen, and unites by anastomosis with the lower extremity of the internal mammary artery. On leaving the pelvis the external iliac takes the name of the femoral artery, gives off large branches to the muscles of the thigh, and on reaching the lower third of this region, becomes the popliteal artery, or artery of the ham. This last gives off the anterior tibial, and then divides into the posterior tibial and the peroneal artery. The anterior tibial at the point of the articulation of the foot with the leg takes the name of dorsal artery of the foot, and ramifies over the upper surface of the foot; while the peroneal and posterior tibial, after having, like the anterior tibial, distributed branches to the leg, terminate in the plantar region, or sole of the foot. Veins.—The veins carry the blood from the extremities to the heart. They are divided like the arteries into two classes, according as, filled with red blood, they run from the capil- laries of the lungs to the trunks of the pulmonary veins— which is the lesser circulation; or as they carry the black blood to the venae cavae—which is the general circulation. The veins of the liver and their principal trunk, the portal vein, have sometimes been considered as also a separate system; and this distinction has also been extended to those of the kidneys and other organs. The walls of the veins are much thinner than those of the arteries, and are formed of four tunics, of which the fourth or internal one is like that of the arteries; the others are formed of elastic or cellular fibres, longitudinal in the third, circular in the second, in such a manner as to present the PRINCIPAL VEINS. 109 greatest resistance. The third and fourth coats form folds, which when extended partially close the vessel. These valves are disposed in such a manner as that when the blood moves toward the heart it presses them close to the walls of the veins, and they are no obstacle to its course; while, if it moves in the contrary direction, they close and prevent its return toward the extremities. The veins are disposed in two planes. Some are deeply placed, and accompany the arteries, of which they are called the companions (pence comites arteriarumj, others are superficial, and creep along under the skin without any coincidence with the direction of the arterial vessels. Springing from the capillaries, by means of which they com- municate with the arteries, the venous radicles unite more rapidly than those of the arteries into considerable branches, superior in numbers and total capacity to the arterial trunks. Many of the arteries, in fact, are accompanied by two veins as satellites, of at least equal calibre; and the superficial veins show still greater disproportion. In the interior of the cranium the veins are transformed into sinuses or canals formed by the dura mater, which receive the venous branches of the brain. The veins are enveloped in their course by numerous lymphatic vessels. Principal veins.—The superior and inferior vena cava are to the venous system what the aorta is to the arterial system. The superior vena cava receives the blood from the head, neck, the upper extremities, and the walls of the chest; it opens into the right auricle of the heart. It is formed by the two brachio-cephalic trunks and the azygos vein. Each of these brachio-cephalic venous trunks unites, like the arterial trunks of the same name, all the principal veins of the head and the arms, which are the two jugulars, internal and ex- ternal, and the subclavian. The internal jugular corresponds to the carotid artery; it receives the blood from the sinuses of the dura mater, from the veins of the head, of the neck, and part of the shoulder. The external jugular carries the blood from a part of the superficial veins of the head to the subclavian vein. The subclavian vein corresponds to the artery of the same name, and receives the companion veins, and veins corre- THE HUMAN BODY. sponding in name to the arteries of the upper limb; it is also the common trunk of the superficial veins of the hand, fore- arm, and arm, the principal of which are the cephalic and basilic. This last vein crosses the radial artery in the bend of the elbow, and is separated from it by a tendinous expan- sion of the biceps muscle. The cephalic and basilic veins are those most commonly opened in blood-letting; this operation is rendered delicate by the situation of the basilic, which ex- poses the artery to the danger of being wounded. The azygos vein (azygos, without a fellow) forms the com- munication between the superior and inferior vena cava. It rises vertically in the posterior mediastinum and to the right of the spine, and about the level of the seventh rib it receives the lesser vena azygos, which comes from the abdomen. The inferior vena cava opens into the right auricle under the superior vena cava. It is the common trunk of all the veins coming from the parts below the diaphragm, and is formed by the union of the two iliac trunks, companions of the iliac arteries; it runs up vertically to the right of the spine as companion vein to the aorta, and receives the veins of the abdomen. Its primitive branches, the iliac trunks, are formed by the union of the veins of the pelvic cavity and of the lower extremities, companions of the arteries of the same name. Among the superficial series of veins, which are also tributaries to the main iliacs, are the external and internal saphenous veins, which run from the foot to the top of the thigh. These two veins are plainly visible on the front of the ankle and on the calf. Portal system.—An arrangement of veins peculiar to the abdomen, and especially to the liver, is designated by this term. The portal vei?i is formed by the union of the veins of the mesentery, spleen, stomach, and intestine; it trans- mits the blood from these organs to the liver, from whence it is poured into the inferior vena cava. Lymphatic vessels and ganglia.—This is the name given to a special circulatory apparatus composed of very delicate vessels with transparent walls and of ganglia or glands, which appear to be formed by these vessels, some of which ter- minate in and others spring from them. MECHANISM OF THE CIRCULATION. 111 The lymphatic vessels have a very irregular course, and exhibit numerous swellings which are owing to valves. They exist in every part of the body, and transport the chyle and the lymph, drawn by their microscopical roots from the surface of the mucous membrame of the intestines, or from the tissues of the organs. They accompany the blood-vessels in their course, especially the veins, and they are also found in great numbers at the surface of the body in regions abounding in subcutaneous veins, as in the limbs, face, and neck. They are very numerous in the mesentery and around the intes- tines; they unite in two principal trunks or reservoirs, one of which is the thoracic duct, which rises through the chest at the left of the spine, and opens into the left subclavian vein, the other is called the great right lymphatic vessel (ductus lymphaticus dexter), which runs parallel with the first, and opens into the right subclavian vein. Mechanism of the circulation.—Galen was the first to dis- cover that the arteries contained blood and that they com- municated with the veins, but he went no farther than this. In 1553 Michael Servetus, guessing, so to speak, the pheno- mena of the pulmonary circulation, indicated very exactly the course of the blood and its elaboration in the lungs by contact with the air. But the doctrine of Servetus rested neither upon proof nor experiment, it resulted from a sort of intuitive perception of the facts, and he was not aware either of the impulsive force of the heart or the action of its valves. Other physiologists, like Servetus, had glimpses of the truth and added new discoveries to his; in fact, most of the phenomena of the circulation had been suspected or indi- cated at the commencement of the seventeenth century, but all the knowledge on the subject was but a chaos of facts and reasonings without unity, and often contradictory. It required the genius of Harvey to extract from this chaos a simple and irrefutably demonstrated system. Movements and sounds of the heart.—The heart, the prin- cipal agent of the circulation, is the source of movements which are not under the control of the will, but which are constantly influenced by moral impressions and by sensations. These movements consist in the alternate contraction and relaxa- THE HUMAN BODY. tion of the walls of the heart, that is in the opening and shutting of its cavities. The ventricles contract simultane- ously, then to this contraction succeeds a period of relaxa- tion, during which the auricles in their turn contract, to relax during a new contraction of the ventricles. The dilating movement is called the diastole, and the contracting the systole. During the diastole the blood flows into the cavities of the heart, to be expelled by the systole; the contraction of the auricles forces it into the ventricles, that of the ventricles throws it into the aorta and the pulmonary artery. The contraction of the ventricles modifies the form of the heart. Its transverse circumference is ellipsoid during the diastole, and becomes circular during the systole; the antero-posterior diameter being thus greater, the point of the heart strikes the anterior wall of the chest, and if the ear be applied to this point, a dull sound will be heard at the moment of the shock, and about half a second after, a clearer sound is heard, coincident with the relaxation or the diastole of the ventricles. The mechanism of these sounds has been variously explained; they seem to be owing, the first to the sudden closing of the tricuspid and mitral valves at the moment when the ventricular systole throws the blood into the aorta and pulmonary artery; the second to the closing of the sigmoid valves during the ventricular diastole, under the influence of the elasticity of the arteries, which tends to cause a reflux of the column of blood. The alternation of the systole and diastole constitute the rhythm and regularly marked beating of the heart which makes itself heard and felt through the walls of the chest. We will follow these movements in their evolution and the blood in its course. Arterial circulation.—The left ventricle, in contracting, pushes the red blood which it contains in the direction of the auriculo-ventricular orifice and toward the orifice of the aorta,—but the mitral valve is so placed that it closes under the impulse of the moving blood, which is thus forced into the aorta and from thence into all the arteries, in which its motion is caused by the triple action of ventricular contrac- tion, and of the elasticity and contractility of the arterial ARTERIAL CIRCULATION. walls. In vessels of a certain calibre this movement is jerk- ing and rhythmical, precisely like that of the heart, and if we place the finger on the course of an artery we feel the shock of the blood, or the pulse. The pulse and the beating of the heart are synchronous, that is, they take place simultane- ously, or rather with an interval so short as to be impercep- tible. But in proportion as the blood advances through the arterial ramifications, the numerous changes of direction which it undergoes and the friction between it and the walls of the vessels diminish the force of its impulsion; and at last, on reaching the capillary vessels it flows continuously and with- out shock. In examining, under a microscope, a vascular membrane belonging to a living animal, the circulation of the blood through the capillaries is plainly visible. The largest of these canals allow the column of blood to pass rapidly, in the smallest ones its course is slow and the blood-globules can only pass one by one; they float in a transparent fluid, and sometimes a globule becomes entangled obliquely across the calibre of the vessel and stops until another comes to push it forward. Malpighi was the first to verify in this manner the accuracy of Harvey’s theory, forty years after it had been propounded by the illustrious English physiologist. The different causes, therefore, which accelerate or retard the contractions of the heart, influence the motion of the blood in the arteries; and farther, the contractility of these vessels may be influenced by local causes, and the movement of the blood is modified so as to be either retarded or quickened, as they are contracted or relaxed. In the first case the afflux of blood is not sufficient to excite the organs, which become sluggish and partially paralyzed; in the second it is so great as to cause an abnormal activity of the function. And lastly, we all know that the repose or action of the muscles has the effect of retarding or accelerating the circula- tion, general or local, which, in the course of time, results in the diminution or increase of the muscular strength. It is in the capillaries, in fact, that arterial blood yields to the tissues the elements of which it is composed, and which it delivers to them for assimilation, in order to receive in 114 THE HUMAN BODY. exchange the disassimilated particles which are to be rejected from the system or submitted to a fresh elaboration. A living and nourishing fluid, it carries to the organs life, heat, and the elements of nutrition. Venous circulation.—After passing through the capillary vessels, the blood passes into the venous radicles. At its entrance into the aorta and during its course through the arterial system, it was of a brilliant red colour, now it has become dark; the arterial or red blood is changed to venous or black blood; deprived of the greater portion of its constituent elements it returns to their source for a fresh supply. The blood moves in the veins from the impulsion received originally from the heart; this force is designated by the term vis a tergo, because it is exerted behind the fluid column. The elasticity of the veins, and their contractility also, con- tributes to urge the blood along in its return towards the heart, but it is the valves which most effectually second the cardiac impulse by opposing the reflux of the blood toward the arteries. If a moderately tight ligature be placed around the arm, the veins begin to swell because of the afflux of blood, which can neither go on toward the heart because of the ligature, nor return toward the arteries because of the valves which oppose it in that direction. If the finger be now passed lightly over the course of a vein in a direction op- posed to the circulation, the little nodules which mark the projections caused by the distended valves are easily dis- tinguished. Thanks to the play of these valves, any pressure upon the veins, from muscular contraction, or whatever cause, can only carry the blood toward the heart, while with- out them it would be impelled indiscriminately one way or the other. Therefore the valves are more numerous in the veins which are connected with the muscles; in the deep veins of the limbs, for example, than in those which creep along under the skin. Gravitation affects the movement of the venous blood, which is much less rapid than that of arterial blood. When the hands hang down for a long time as in walking, they swell so much that the flexion of the fingers is difficult, and VENOUS AND PULMONARY CIRCULATION. it is the same with the feet and legs after long-continued standing, and varicose veins appear on the limbs of persons whose profession obliges them to remain on their feet. In following the course of the blood on its return to the heart, we find a venous system belonging to the liver and intestines; the portal system—to which reference has already been made—which carries the venous blood from the diges- tive canal and from the spleen to the liver. This system is remarkable from the fact that it is ramified at both ex- tremities; at the intestinal extremity the radicles or roots, and at the hepatic the branches, are found. From this it has been inferred that the bile is secreted from the blood of the portal vein and not from the blood of the hepatic artery; but this question still remains unsettled. The inferior vena cava, after receiving the blood from the lower regions of the body, turns toward the heart like the superior vena cava, but before reaching it, the blood receives by the subclavian veins the lymph and chyle which have been brought to it by the two grand trunks of the lymphatic system; the elements of nutrition drawn from the intestine come to replace those which have just been given up for assimilation. Thus partially reconstituted, the blood pours back through the venae cavse into the right auricle of the heart, and the auricle by contracting throws it into the right ventricle. At last the blood has returned to the heart, and although it is enriched by the assimilable products of digestion, it is still incomplete, and must be transformed in order to become perfect arterial blood, while at the same time the combustion of a portion of its principles will produce the heat which is soon to be distributed to the organism. It is in the lungs that this elaboration of the blood is to take place—hematosis or sanguification. Pulmonary circulatio7i.—The right ventricle contracts, and the flood of venous blood closes the tricuspid valve, and passes into the pulmonary artery. This artery and all its ramifications contain black or venous blood, while the pul- monary veins, as we shall soon see, convey red or arterial blood; it is therefore to their direction, from the heart to the 116 THE HUMAN BODY. lungs, or from the lungs to the heart, that the vessels of the pulmonary circulation owe their names. The pulmonary artery, like the aorta, is provided at its orifice with three valves, called sigmoid or semi-lunar valves. From the right ventricle to the ramifications of the pulmonary artery the blood has but a short distance to pass, and it meets with no resistance at all comparable to that encountered in the sys- temic arterial circulation. The walls of the right ventricle therefore are much thinner than those of the left, and con- sequently have less power. In the ca- pillaries of the lungs the motion of the blood varies in quickness according as the respiration is easy, or retarded by any obstacle, or by the presence of air unfit for the performance of the respi- ratory functions. The capillaries are distributed through the substance of the lungs in such a manner that they cor- respond to the pulmonary cells. (See Respiration, p. 92.) It is in these ulti- mate divisions of the lungs that the oxy- gen of the air combines with the venous blood charged with carbonic acid, and transforms it into arterial blood. The reddish-brown globules of the venous blood take a vermilion colour from contact with the oxygen, and charged with oxygen, the blood penetrates into the radicles of the pulmonary veins, obeying the original impulse, the vis a tergo, as in the general venous system, but with greater quickness. It is now carried back to the left auricle, which immediately transmits it to the ventricle, where its circular course ends, only to commence again immediately. The circulation may be divided into two simultaneous periods, or, as has been already stated, the ima- ginary circle through which the blood passes is composed of two unequal segments described by the fluid column. The Fig. 28. •— Imaginary dia- fram of the course of the lood in the circulation. A. Course of the venous blood.. JB. Course of the arterial blood. ACCELERATION AND RETARDATION OF PULSE. 117 upper segment indicates the pulmonary or lesser circulation, the lower the general or systemic circulation. Influences which retard or accelerate the beating of the heart. —In an adult in a normal condition, the heart beats about sixty times a minute, and the pulse consequently indicates the same nilmber of pulsations, but diverse causes may augment or diminish the frequency of these movements. They become more frequent during digestion, and under the influence of alcohol, coffee, or other excitants; abstinence, on the contrary, retards them. Intellectual labour also accel- erates the action of the heart, but the heart is calmer during sleep, and shares in a measure the repose of the other organs. An unlooked for sight, a word striking the ear, or a thought crossing the mind, will cause strong and rapid pulsations. Eristratus discovered the cause of the malady which threat- ened the life of Antiochus, by placing his hand on the heart of the young prince at the moment that Stratonicea appeared before him. The pulse is accelerated also by muscular exercise, and by violent efforts. But in this case the cause is complex, for the respiration is also more frequent, and this function is one of those which have most influence on the circulation. In ordinary breathing, each inspiration gives more force to the blood in the arteries, and if the respiration becomes more hurried it is recognizable in the pulse. If, on the contrary, respiration is suspended or imperfect, the circu- lation is retarded, and the pulse beats with less force; in a word, in most physiological conditions there is a constant relation between the respiratory movements and the beating of the heart. The alternate expansion and contraction of the walls of the chest are therefore one of the principal causes which affect the circulation, by facilitating the afflux of blood to the thoracic cavity and insuring its expulsion from it. The pressure of the atmosphere also influences the be-ating of the heart, but only under certain conditions. It is not un- common to find in the high valleys among the Alps men whose pulse beats between fifty and sixty times a minute—this infre- quency is perhaps more common among mountaineers who live at an altitude of 3280 feet or more, than in less elevated THE HUMAN BODY. countries. We may consider therefore that the altitude has no influence upon persons who have long lived at a given level. But if we rise rapidly to a great height, the pulse quickens very sensibly. Aerostatic ascensions and mountain journeys furnish the proof of this. It is not to locomotion or to muscular effort that this quickening of the pulse can be attributed in the aeronaut or the traveller on horseback, but it is chiefly due to the greater frequency of respiration in an atmosphere of lesser density. The diminution of the pressure of the atmosphere conduces also to the same effect by relaxing the vessels; but the fall in temperature in pro- portion to the rise in elevation seems to neutralize this last effect by the contraction of the tissues which it induces. (See Respiration, p. 99.) The establishment of the fact, that an increase in the pressure of the atmosphere diminishes the frequency of the pulse is due to the observations of Pravaz and Tabarie. Both these authors state that the pulse falls to fifty and even to forty-five pulsations per minute when the subjects are placed in an apparatus for compressing air, and the pressure is increased to that of two atmospheres and over. Results entirely contrary were observed by M. Francois in the tubes containing compressed air which he used in building the bridge at Kehl in i860. This physician observed that the pulse invariably quickened in the labourers employed upon this work under a pressure of about two atmospheres. Other observations by M. Hermel establish the fact that the pulse is sometimes retarded, and sometimes quickened in compressed air to one hundred and fifty in a minute. The phenomena observed in men who work in compressed air seem to be due to complex causes, among which we must note the vitiation of the air from deficient renewal. We shall not here discuss the numerous causes which may, in pathological conditions, influence the circulation. CHAPTER X. Nervous system. — Cerebrospinal nervous centre. — Cerebrum. — Cere- bellum.—Isthmus of the encephalon.—Medulla oblongata.—Spinal cord. —Membranes; dura tnater, arachnoid, pia mater.—Nerves; cranial nerves, spinal nem not ourselves feel. 178 THE HUMAN BODY. Sometimes there is an apparent displacement of objects, although neither the objects nor the eyes are in motion, but in a normal condition it is always after a movement of the body that this phenomenon appears. As when the body is whirled round rapidly and then suddenly stopped, every- thing seems to turn in an inverse direction. It is probable that the illusion then depends on the impulse to movement in a certain direction imparted to the brain; in fact, if we stop after turning round, the sensation of turning persists for some moments, especially in the head; and if we refer it instinctively to external objects, it is in consequence both of the persistence of the previous sensation, and of the idea of our actual immobility. We turn still, just as after having laid down a burden we continue to feel its weight upon us. Gratiolet ascribes the apparent motion of objects under these circumstances to insensible oscillations, which displace to a limited extent the ocular axes, but he does not indicate the cause of these oscillations. Optic nerve.—The visual impressions are transmitted from the retina to the brain by means of the optic nerve, of which that membrane appears to be the expansion. The two optic nerves converge from the base of the orbit toward the centre of the base of the skull, where there is an interlacement of their fibres in such a manner, that a portion of the right nerve goes to the left side of the brain, and a part of the left nerve to the right side; this is called the chiasma, or commis- sure of the optic nerves. Physiological theories, which are no longer tenable, have been deduced from this crossing of the nerves, and nothing positive is yet known of the relation between this disposition and the visual function. Mechani- cal irritation of the nerve seems to develop luminous impres- sions as in the retina, but it causes no pain whatever. Movements of the eye.—The ocular globe is put in motion in the orbit by six muscles, grouped two by two, which raise or lower the eye, turn it inward or outward, or on its antero- posterior axis. In these movements the centre of the globe is immovable, and the eye moves around its transverse and vertical diameters. These three orders of movements are independent of each other, and may be made singly, or in MOVEMENTS OF EYE. RANGE OF VISION. 179 combination, in such a manner as to direct the pupil towards all points of the circumference of the orbit, The straight, supe- rior, inferior, external, and internal muscles move it upward, downward, inward, and outward, and their successive action gives it a movement of circumduction. The two oblique muscles turn the eye on its antero-posterior axis, in such a manner as always to maintain the horizontal position of its transverse diameter, when the head or the body inclines to the right or the left. All these muscles take a direct or indi- rect part in every movement of the eye; if looking up or down, for example, the straight, superior, or inferior acts alone; the other muscles assure the movement, and confine it to the transverse axis. Such is the perfection of this mechanism, that the cornea is raised or lowered without the least lateral deviation, like the objective of a meridian glass; and the eye perceives by this succession of movements if the image of a line on the retina deviates o-oooo2 of an inch from the vertical. The eyelids follow the movements of the globe when it is raised or lowered, obeying the action of the muscles of which they receive the aponeurotic prolongations. The movements of the two eyes are always symmetrical, and of the same kind; both are raised or lowered at once, directed to right or left, or around their axes; they can be turned inwards simultaneously to see an object very near at hand, or slightly outwards, when they turn from such a point to one in the distance. Even when one eye is closed, the globe turns in the same direction as that of the open eye. This unity and variety of movement contribute to make the eye the most important feature of the physiognomy. Extent and delicacy of vision.—As regards the distance at which man can distinguish objects, he is less gifted than many other animals; but in every other respect his visual powers are at least equal to that of inferior beings. We know very little of the sensations produced in animals by colours; it seems probable that they have a relative perception of them to a certain extent, as the sight of red irritates the bull, for example; and we know that birds of prey from a great height in the air distinguish the colour as well as the form of 180 THE HUMAN BODY. a lark or a quail hiding in the ploughed fields, although it so closely resembles that of the soil. But if we should suppose them endowed with sensitive faculties, useless within the limits of their instinct, could we find anything in animals more perfect than the organs to which man owes the prodi- gies of painting? We must, however, distinguish here between that which pertains to the visual apparatus, and that which proceeds from the intellect. The eye perceives the tints which nature offers in almost infinite variety; the mind com- pares them, and recognizes the elementary colours of which they are composed; the eye reflects in turn the model, the palette, and the picture; the mind perceives the relation of shades, and combines them in such a manner, that by mingling or contrasting them such a result is produced as conforms to the first impression; but in order that an artist may judge whether red or blue predominates in a violet tint, in order to appreciate the shade, the retina must transmit it to the brain in its purity. At the manufactory of the Gobelins, we see the wools used in the fabrication of the tapestries arranged according to their shades. The number of these shades exceeds 28,000, and yet when we compare two approximate shades we distinguish them with facility, and perceive the interval which separates them. The people who live in the country, seamen, and especially men living in a savage state, generally have sharper sight than the residents of cities. May not the habit of seeking to distinguish objects at a distance give the eyes a power which is not acquired when they always act within a limited hori- zon? Without assimilating exactly the effects of exercise on the eye to those which result from exercise of a muscle, we are justified in thinking that an almost incessant accommo- dation to great distances must influence the eye in that respect, and if, as is very probable, the accommodation takes place by the contraction of muscular fibres, the explanation of the increased range of the eye from exercise is very simple; but facts are wanting which verify and measure this increase in individuals. There is no doubt, however, that men from whom the horizon is habitually distant distinguish certain RANGE OF SIGHT. 181 objects at a point where they are confused to other persons, although within the reach of their vision. A ship appears on the horizon, a man unacquainted with the sea can hardly distinguish the sails of this white cloud springing from the waters; but a sailor will tell you that is a brig or a three-master, a war vessel or a merchant ship, and often he will even come at its tonnage, its lading, its nation- ality, and its name. The Arab and the European in the midst of the sands of Sahara see on the horizon an object, which to the European is only a black point without appre- ciable form; the Arab sees a camel distinctly, and declares that it is at such or such a distance, without ever being de- ceived. The inexperienced mountain traveller sees before him a chaos of slopes and abrupt walls, of elevations and windings, among which he can distinguish neither route nor practicable passage; but the mountaineer sees at once the accessible points, and the turns which he must take to reach the summit of the apparently impassable barrier. This proves not that the sailor, the mountaineer, or the Arab have sharper sight than the stranger to their country; but that they have learned to know the signification of such and such details of form, such a particularity of colour and the like, which are for them distinguishing marks, which seem to trace before their eyes the description which they give to their fellow-voyager of objects that are either confused or imperceptible to him. It is therefore to acquired notions, and skill in seeing objects, rather than to extent of vision, that they owe the faculty of distinguishing objects at great distances. We find also in all countries, and in all climates, men who have extraordinary powers of vision. Wrangel speaks in his voyage to the Polar seas, of a Yakoute who related having seen a great star swallow little ones, and then vomit them up again. That man, says Wrangel, had seen the eclipses of the satellites of Jupiter. Humboldt tells, in his Cosmos, of a tailor in Breslau, named Schcen, who also had seen the satellites of Jupiter with the naked eye. No examples of a greater range of vision are known. CHAPTER XII. Sense of hearing.—Organ of hearing.—External ear; pavilion of the ear, auditory canal.—Middle ear; tympanum, drum, or membrana tympani, fenestra ovalis, fenestra rotunda, Eustachian tube, the small bones of the ear, muscles atid movements of the small bones.—Internal ear; labyrinth, vestibule, semicircular canals, cochlea, membranous labyrinth.—Auditory nerve.—Noises and sounds; duration, pitch, in- tensity and quality of sound; passage of sound through air, -water, solid bodies; gravity, sharpness of sound.—Mechanism of hearing; functions of different parts of the ear; movement of sounds in the ear; propagation of sounds to the auditory apparatus by the vibrations of the bones of the skull.—Opinions ofphysiologists on the functions of different portions of the labyrinth; theory of Helmholtz.—Fineness and delicacy of hearing.— Correctness of the ear.—Estimation of the intensity, the distance, and the direction of sounds; ventriloquism.—Duration of auditory itnpres- sions.—Sensations having ati internal origin.—Parallel between the eye and ear. The ear.—The organ of hearing is not placed on the face, like those of sight, smell, and taste; but in the thickness of the base of the skull. But we may say it belongs to the face as one of the elements of the physiognomy, by its external apparatus, which contributes to the expression of the head. The ear is divided anatomically into three regions—the exter- nal, middle, and internal ear. External ear.—This is the least complicated portion of the organ; it is composed of the pavilion, or projecting part, and the auditory canal. The pavilion of the ear is similar, as the name implies, to the open portion of wind-instruments or a speaking-trumpet. It is an acoustic horn, which gathers the sonorous waves, and conducts them to the intricacies of the auditory apparatus. It consists of an elastic cartilaginous layer covered with a EXTERNAL EAR. 183 delicate skin, and is curiously modelled. Its border, rounded in its upper portion, and folded back on itself, forms the rim or helix, and terminates at the lower portion in the lobe. The concha is in the centre, and is bounded behind by the Fig. 42.—Section showing the different parts of the ear. A. Pavilion, or projecting ear. B. External auditory canal. C. Membrana tympani. D. Tympanum. E. Incus, or anvil. M. Malleus, or ha7nmer. G. Semicirctilar catial. H. Cochlea, or shell. I. Eustachian tube. antihelix, and terminates in the auditory canal. The pro- jections of the tragus .and antitragus, separated by an ellip- tical slope, protect the orifice of this canal, and a down, which might be called the lashes of the ear, sifts the air as it passes into the organ. The pavilion of the ear is directed forward, projects from the head, and its lines are in beautiful harmony with the oval of the face. 184 THE HUMAN BODY. De Blainville compares the curves and the surface of the pavilion of the ear to those of the head. According to this naturalist the curve of the superior portion of the pavilion corresponds to that of the cranium, and the free border of the rim describes a curve parallel to that which marks the temporal fossa. When the head is not prominent in k middle region, and the temporal fossae are slightly marked, the rim is absent; it is, on the contrary, broad and prominent when the arch of the skull overhangs the temporal fossae. The concha corresponds to the upper jaw, and is propor- tional to it; and the prominence of the origin of the helix represents that of the zygomatic arch; and lastly, the profile of the lobe is like that of the upper jaw. It is remarkable that this lobe exists only in man, and that man only has also a prominent and angular chin. The auditory canal, which represents the tube of the acoustic trumpet formed by the external ear, is cartilaginous next the concha, and the remaining part is excavated in the petf'ous or stony portion of the temporal bone. This canal is about one and a fifth inch in length, and its entire disposition is such that foreign bodies suspended in the air cannot pass with it to the membrana tympani. It is bent near the concha in such a manner that the air, in transmitting sound to the middle ear, does not penetrate in right lines, thus protecting the sensibility of the membrane. The middle ear.—The membrana tympani (membrane of the drum), of which the name indicates the function, is a membranous partition stretched obliquely across the bottom of the auditory canal, which it separates from the middle ear or drum. This membrane is semi-transparent and very thin, although it is composed of three layers; it vibrates under the impression of the sonorous waves, and transmits the vibratory movement to the little bones of the ear. Between the membrana tympani and the internal ear is the drum or the tympanum, a cavity hollowed out, like all those of the middle and internal ear, in the petrous portion of the bone. Among the details of its form and organization, we remark the fenestra ovalis, which communicates with the vestibule, and the fenestra rotunda, which leads to the cochlea. The drum SMALL BONES OF EAR. INTERNAL EAR. 185 also communicates with the mastoid cells, numerous sinuses which are found in the mastoid process of the temporal bone, containing air, and designed to multiply the vibratory surfaces; and lastly, it unites by a sort of funnel with the Eustachian tube, a canal about one inch and a third in length, which opens into the upper portion of the pharynx, and admits the air into the middle ear. The ossicles or small bones of the ear.—These are four in number; they are articulated together, and form a bony chain which runs from the membrana tympani to the fenestra ovalis, following a broken line. They have been named the hammer [malleus), the anvil {incus), the lenticular bone, and the stirrup (stapes), from their form or their functions. Special muscles act upon the malleus and the stapes, which are at the two extremities of the chain; the incus and the lenticular bone serving as media for the propagation of the vibrations. The motion impressed upon one of these extremities is com- municated to the other by a sort of see-saw movement of the little bones, the mechanism of which is pretty nearly repre- sented by that of a bell. One extremity of the hammer, the handle, is fitted into the membrane of the tympanum, and when the muscle of the hammer contracts, the membrane tightens, a phenomenon which will be discussed further on. The muscle of the stirrup attaches the flat part of this bone to the fenestra ovalis, and according to M. Longet prevents it from being forced in a contrary direction under the influ- ence of the muscle of the hammer, of which it is the an- tagonist. Labyrinth or internal ear.—The internal ear is that por- tion of the organ of hearing which perceives the impression of sound, and transmits it directly to the brain. It is hollowed out in the petrous bone, and is divided naturally into three distinct compartments, named the vestibule, the semicircular canals, and the cochlea or snail-shell. These divisions form together one of the most complex and delicate pieces of me- chanism in the human body. The labyrinth is composed of a bony cavity which incloses a membranous cavity in a portion of its space, and from this circumstance arises the distinction made by anatomists 186 THE HUMAN BODY. between the osseous and membranous labyrinths. We shall first consider the osseous labyrinth. The vestibule is an ovoid cavity placed in the centre of the internal ear, between the semicircular canals and the cochlea. It communicates with the drum by the fenestra ovalis, which is closed by the base of the stapes. In it are seen the open- ings of the five semicircular canals, of the vestibular stair of the cochlea, and of the vestibular canal. This latter is the opening of a vascular canal which traverses the petrous bone. Semicircular canals.—This is the name given to three curved tubes forming axes of circles, one which is horizontal and is placed between the two others, which are vertical. They are each enlarged into a bulbous cavity (ampulla) at one extremity, and communicate with the vestibule by five orifices. Cochlea (or snail-shell).—This is the name given to a conoid cavity which is separated from the semicircular canals by the vestibule, with which it communicates, and terminates at the fenestra rotunda. The cavity of the cochlea is a spiral, describing two turns and a half round its columella or axis; it is divided transversely into two portions by a partition—the lamina spiralis, throughout its entire length. That portion opening into the vestibule is called the scala vestibuli; and that opening into the fenestra rotunda the scala tympani—by which it would, if it were not for the membrane which closes it, communicate with the cavity of the tympanum. The lamina spiralis is divided lengthwise into a bony por- tion, which corresponds at its internal border to the axis; and a membranous portion, which attaches the osseous por- tion to the external wall of the cochlea. This wall is formed by the spiral plate. The cochlea is lined by a fibro-mucous membrane, which appears to be a continuation of the perios- teum of the other two cavities of the labyrinth; the mem- branous portion of the spiral plate may be considered as a prolongation of the membranous labyrinth. Lastly, the vascular canal, called the canal of the cochlea, analogous to that of the vestibule, communicates also with the cavity of the skull. The base of the cochlea rests on the bottom of MEMBRANOUS LABYRINTH. AUDITORY NERVE. 187 the internal auditory canal, by which the auditory nerve enters the organ of hearing. Membranous labyrinth.—The bony walls of the vestibule and of the semicircular canals inclose and protect a mem- branous apparatus of the same form, which is separated from them by a space filled with a limpid fluid called perilymph or liquor Cotunnii. The membranous labyrinth is therefore smaller in proportion than the osseous; the difference in size is about one-half. Its cavities contain a fluid analogous to the perilymph, and which De Blainville has compared to the vitreous humor of the eye; they also contain semi-transparent tubes and membranous sacs, the appearance of which is closely analogous to that of the retina. The membranous vestibule is composed of two distinct parts, the saccule and utricle, in which there exists a calcareous dust, which appears to represent in man and the mammifera the auditory stones or otoliths of fishes. Auditory nerve.—The auditory or acoustic nerve specially belongs to the organ of hearing, and is remarkable for the softness of its texture: it enters the ear by the internal auditory canal, and divides into two branches, one of which distributes itself to the vestibule and to the ampullar extremi- ties of the semi-circular canals; the other goes to the cochlea, and has been called the cochlear branch. Its ramifications are extremely minute; they line the surface of the modiolus and spread themselves regularly over the spiral plate, dimin- ishing in length from the base to the summit in such a manner that if we suppose the spiral plate to be placed upright, and forming a triangular plane, these filaments would resemble the strings of a harp—the longest at the base of the triangle and the shortest at the summit. They are called the fibres of Corti, from the anatomist who first described them. The microscope enables us to count more than three thousand, and we shall see later the part they are supposed to fill in audition. But before opening the physiological question, we will notice summarily some of the phenomena, the existence of which is revealed to us by the ear. Noises and sounds.—Physicists divide sounds into two 188 THE HUMAN BODY. classes—musical sound and noise. They both have the same origin, the vibrations of a body transmitted to the air. The short duration of a noise, and the lack of isochronism in its vibrations, do not permit us to appreciate its musical value, and this distinguishes it from musical sound. Thus the ex- plosion of gas or powder, the crack of a whip, or the breaking of a branch make a noise, but give no musical sound. The limit between sound and noise is otherwise in- sensible, and varies according to the individual. A noise as well as a sound may be grave or acute, feeble or intense. The difference in the duration of the sensation does not permit us to compare noise to sound, but yet the ear seizes the relation between two noises as well as between two musical sounds. A sound is called musical when its pitch can be estimated absolutely and relatively to other sounds grave or acute; or, in other words, when the number of vibrations follows a constant law and can be determined. Whatever may be the difference, however, between a noise and a musical sound, the one is only a variety or degree of the other, and both, proceeding from the same source, may be studied under the generic denomination of sound. Sound has four fundamental properties—duration, pitch, intensity, and timbre or distinctive quality. The three first named are defined by the words which express them: as for the timbre, it is the resonance peculiar to each instru- ment, to each voice, which enables us to distinguish without difficulty the notes of a violin, a clarionette, or a flute, and to recognize individuals by hearing them speak or sing. The duration of a sound is measured by the time that the body vibrates from which it proceeds; it is high and acute according to the number of vibrations, and its intensity is measured by the amplitude or range of the vibrations which cause it, and this amplitude is in proportion to the force acting on the sonorous body. The “timbre” of sounds was long an insoluble enigma to the physicist and the physiologist. J. Muller had suspected its origin in attributing it either to the isochronism of sonorous waves of different velocity, or to waves of different TIMBRE. SPEED OF SOUND. 189 length, producing a compound wave of a peculiar form, or else to a longitudinal vibration 'in the sonorous body taking place at the same time as the transverse vibration. M. Longet states, with greater precision, that the timbre of the human voice, and of wind-instruments, results from the co-existence of several sonorous waves of different tone and intensity, which modify the general form of the principal wave. But at last the beautiful experiments of M. Helmholtz have demonstrated, that the timbre of a sound depends upon the number of the harmonic notes which are produced at the same time as the fundamental note, and upon their relative intensity. When a cord of a piano giving the C, for example, is struck, that note is heard, but a little attention enables the ear to hear other simultaneous and weaker sounds; they are the result of partial vibrations which take place in the length of the cord, according to certain laws which cannot be ex- plained here. The C given by the shock impressed on the cord is the fundamental note, the other notes which are superposed upon it are the harmonics. From their fusion with the fundamental note, there results to the ear a complex sound which it decomposes instinctively into simple sounds, but they cause only a single sensation in the brain, that of a C having a special timbre. Whether the fundamental note be given by an instrument or by the human voice, the same phenomena are produced, and the timbre proves equally characteristic to the ear. The timbre is therefore the distinctive quality of the sonorous body—the form, in a certain sense, of sounds. Sound moves more rapidly in warm air than in cold; its velocity in the atmosphere is 11 i8'45 eet in a second at i6° C. (6o'&° F.) or 1086‘3 7 feet at zero, according to experiments made by the Bureau of Longitudes in 1822; and according to those of Bravais and Martins made in 1844, it is 1092'89 feet at zero (Cent.) This velocity is not modified by the varia- tions in the pressure of the atmosphere, and it is the same whether in a horizontal, vertical, or oblique direction. It is increased or diminished by the wind, according as it blows in the direction of the sound or contrary to it, though the 190 THE HUMAN BODY. velocity is not changed if the wind blows perpendicularly to this direction. Sound cannot be produced in a vacuum, and it is therefore less intense in proportion as the air is more rarefied. It is weaker, for instance, on the tops of high mountains than in the lower strata of the atmosphere, although the profound silence which reigns at times in these elevated regions permits even very feeble sounds to be heard at great distances. We were enabled to prove this with M. Martins in 1844. Near St. Cheron (Seine-et-Oise), at an elevation of 459 feet, a diapason placed on a drum could be heard in the daytime 277 yards off; while on the great plateau of Mont Blanc, at a height of 13,123 feet, the sound of the same instrument could be heard at a distance of 368 yards. On the top of Mont Blanc, we could hear our guides talk at a distance of 437 yards, and they could hear us speak also. Humboldt observes that sound is more intense and is propagated farther in the night than in the daytime, in spite of the noises and of the wind which in tropical countries increase after sunset. This diminution in sounds during the day is attributed by the illustrious observer to the unequal temperature of the strata of the atmosphere, under the influ- ence of the sun and the radiation from the earth. Sound moves much more quickly in water and in solid bodies than in the air. Colladon and Sturm found its velocity to be 4708 feet in a second in the waters of the Lake of Geneva at 8° C. (46‘40 F.) of temperature; according to the experiments of Biot, its average velocity is 10,663 feet in cast-iron pipes. This is about five times greater in water than in air, and nine times greater in the pipe. Humboldt records that sometimes volcanic detonations have been transmitted through the earth a distance of 500 to 745 miles. It is stated that the gravest sound which can be perceived by the ear is 32 vibrations in a second (16 according to Savart), and the most acute, according to Despretz, is 73,700 vibrations. A sound of 60,000 vibrations is, according to M. Martins, very feeble, difficult to hear, and of such sharp- ness as to cause a painful impression on the ear. The MECHANISM OF HEARING. sounds which are easily perceived and appreciated by the ear vary from 100 to 2000 vibrations. The gravest C of a piano of six octaves and a half counts 128, and the most acute 8192. Mechanism of hearing.—The sonorous waves penetrate directly into the auditory canal, or after they have en- countered the outer portion of the ear, the sinuosities of which they follow, and the ear itself vibrates to the shock of sounds, and these vibrations are transmitted gradually to the organ. Savart, who has demonstrated this phenomenon by experiments, observes that the very irregular surface of the ear always presents some portion at an angle most favourable to the sonorous waves, whatever may be their direction; in fact, the force with which they act upon its walls is in direct proportion to their approach to the perpendicular. If, for example, the pavilion of the right ear be covered with some substance which obliterates all the inequalities and transforms it into a plane surface, a sound cannot be heard on that side so well as on the left, when produced at an equal distance from both ears. It is to be presumed, also, that the pavilion, which increases all sounds equally, does not vibrate in unison with any one sound, nor has it, owing to the irregularities of its surface, any one peculiar to itself. And finally, the form of the pavilion, and its inclina- tion in relation to the head, seem to have a certain influence on the acuteness of hearing. Besides the vibrations which enter directly into the audi- tory canal, and those which come from the pavilion, this canal receives also those of the bones of the cranium and transmits them to the tympanum. These last and those of the pavilion reach the tympanum sooner than the first, for the reason already stated, that sounds move more rapidly in fluids and solids than in the atmosphere. It receives there- fore two orders of vibrations, but in passing to this membrane the vibrations of the air are transformed into those of a solid body; from which we may conclude with Savart and Muller, that the function of the tympanum is to serve as a medium between the air and the small bones of the ear, by changing, as we have just seen, the atmospheric vibrations. 192 THE HUMAN BODY. Sounds, augmented by the external ear, and concentrated upon the tympanum, are transmitted to the little bones, and again augmented during this transit, by a more close concentration upon the base of the stapes. We have seen that the contraction of the muscle of the hammer causes tension of the tympanum. This membrane then passes from a state of repose to a variable degree of tension, upon the effects of which physiologists are not agreed. According to Bichat, it is more tense in proportion to the feebleness of the sounds, and to the greater necessity of action of the organ in order to perceive them. Accord- ing to Muller and Savart, the tension protects the organ of hearing against too violent sounds by lessening the con- ducting power of the tympanum. According to Longet, the muscle of the malleus has no other function than to obviate variations in the tension, and especially to prevent the entire relaxation of the membrane; in a word, it is the key of the tympanum. The sonorous waves traverse the chain of little bones, and are transmitted by it to the fluid in the labyrinth, thus changing their medium without losing their intensity. If the little bones were articulated in such a manner as to form a rigid straight line, instead of an elastic broken one, the dis- tance between the tympanum and the fenestra ovalis being susceptible to variation, the result would be that in certain cases the pressure on the tympanum and on the fenestra ovalis would be too great, which the elasticity of the chain and its articulations prevent. The tympanum can only exert a limited pressure on the fenestra ovalis, and when it is at its greatest distance from it, the stapes is held in its place, in front of this opening, by its muscle. This is the theory of Savart, which was adopted and developed by M. Longet. The walls of the tympanum inclose air, which propagates the vibrations from the tympanum, and transmits them by means of the membrane of the fenestra rotunda to the fluid of the labyrinth. These vibrations lose their intensity on becoming aerial, and this fact has led to the idea that possibly they may differ in their timbre from those transmitted by the little bones. HEARING. THE MIDDLE EAR. 193 However this may be, the principal use of the air in the cavity of the tympanum is not to transmit the vibrations of that membrane; but to balance the pressure of the atmosphere on its external surface, and thus to render it completely in- dependent between two equal pressures. This is effected by means of the Eustachian tube, which conducts the air into the middle ear. The temporary obstruction of this canal induces buzzings in the ear, causing temporary deafness, which is intensified by its entire obliteration. The canal also serves as an outlet for mucus and other fluids, which may be secreted in the cavity of the tympanum. The sonorous waves enter the vestibule by the fenestra ovalis; this opening is closed by the base of the stapes, and receives the vibrations from the chain of little bones. The membrane of the fenestra rotunda transmits to the scala tympani of the cochlea the aerial vibrations of the cavity of the tympanum. This membrane, as Scarpa has remarked, is a secondary tympanum. On reaching the labyrinth the vibrations are propagated to the fluid which bathes it, and thus reach the membranous labyrinth, and the scala vestibuli of the cochlea, where finally they encounter the extremities of the ramifications of the auditory nerve. Besides the sonorous aerial waves, the ear perceives, as has already been stated, those which have been caused by an impression on the bones of the skull. Thus, when a sonorous body is held between the teeth, or against the walls of the cranium, the sound is perceived by the auditory apparatus. It is in this way that, in spite of the loss of the tympanum and the small bones of the ear, some persons can still perceive sounds of external origin. But it is indispens- able that the membranes of the fenestra ovalis and fenestra rotunda, which close the openings of the labyrinth into the cavity of the tympanum, should still remain perfect, and that the fluid of the labyrinth should still bathe its cavities. But, as may be easily conceived, hearing under these circumstances is very limited, since it can only take place when the sonor- ous body is in contact with the bones of the head. The functions of the three divisions of the labyrinth have 194 THE HUMAN BODY. been differently stated by different physiologists. According to Dugfes, the vestibule concentrates the sound, measures the intensity, and consequently judges of the distance. It has been supposed that the semicircular canals either give the idea of the direction of the sonorous waves, and of the posi- tion of the body from whence they emanate, or are simply organs for increasing the sound. De Blainville thinks that the function of the cochlea is to appreciate very acute sounds; Duges makes it the musical portion of the auditory organ, the appreciator of notes, and the special apparatus for the perception of voices and articulate sounds. Other authors have thought that the spiral plate (lamina spiralis), which narrows regularly from the base to the summit of the cochlea, corresponds to the scale of notes, from the gravest to the most acute, and that it vibrates in unison with each one of them. According to Muller and Longet, the object of the cochlea is to furnish a solid plate upon which to spread the nervous filaments, in contact with the bony walls of the labyrinth and of the head, as well as with the fluid of the labyrinth; thus being able to transmit to these filaments the vibrations com- municated to the solid or fluid portions of the auditory apparatus. And also, the spiral form of the cochlea gives in the least possible space a relatively large extent of surface for the expansion of the nervous filaments. This diversity of opinion is easily understood, the moment we pass from natural facts to physiological speculations. The auditory nerve is distributed to every portion of the labyrinth; but before entering it, while in the internal auditory canal, it divides into two branches, the smaller one running to the cochlea, and the larger to the vestibule and the semi- circular canals. If we admit that the two branches are homo- geneous, and only constitute two divisions of the auditory nerve, we must conclude that the auditory impression is per- ceived all over the labyrinth, just as the visual impression is felt on every portion of the retina. The division of the nerve, and the peculiar disposition of the ramifications in each of the labyrinthine cavities, seem to indicate a special function for each of these cavities. It seems natural to sup- HEARING. THE INTERNAL EAR. pose that apparatus so different in form, and so distinct in the different parts of the organ, should have a special object, and that they combine their functions to produce the complex sensation of hearing. Muller has demonstrated that the same aerial vibrations act with much more intensity on the fluid of the labyrinth, after having traversed the chain of small bones and the fenestra ovalis, than they do after traversing the air in the cavity of the tympanum, and the membrane of the fenestra rotunda; he thinks that the waves of the same sound transmitted through the two fenestrse differ not only in intensity, but also in their timbre up to a certain point, since those reaching the fenestra rotunda are aerial vibrations, and those reaching the fenestra ovalis, by the chain of small bones, are in the state of vibrations of solid bodies. But the cochlea also receives sonorous waves of both kinds by the scala tympani and the scala vestibuli; and farther, the cavities which form the labyrinth communi- cate with them, all being filled with a common fluid, and all united by their walls; they would seem therefore to be bound together up to a certain point as regards auditory im- pressions, and nothing demonstrates that vibrations are elec- tively directed in their movement on leaving the vestibule, either toward the cochlea or the semicircular canals. It must be admitted notwithstanding, that authors gener- ally agree in placing the principal, and indeed only seat of auditory impressions in the cochlea, and this is the doctrine now professed by M. Helmholtz, to whom we owe our know- ledge of the origin and mechanism of the timbre of sounds. We will briefly state his theory of hearing. We have already seen that the terminal filaments of the acoustic nerve spread themselves regularly side by side over the lamina spiralis of the cochlea, like the cords of a key- board; the eminent professor of Heidelberg compares these nervous filaments to the strings of a piano, and explains their functions in the following manner. If the piano be opened, and a person sings loudly above the strings any note what- ever, the sonorous waves cause the strings which respond to the harmonics of the voice, to vibrate also; each one of these strings vibrates exclusively in unison with one har- 196 THE HUMAN BODY. monic, and the note is thus decomposed by their sympathetic vibration. The same phenomenon takes place in the in- ternal ear. The fibres of Corti decompose the sounds, each one vibrating in unison with the harmonic with which it accords, and these vibrations transmitted collectively to the brain by the acoustic nerve give the sensation of the funda- mental note, and of its timbre. But here, as in every other instance, the living organ is infinitely superior to the machine constructed by man. The fibres of Corti number upwards of three thousand, and this gives four hundred sensitive cords to each octave, of which the interval or space is one sixty- sixth of a note. It is easy to understand from this how a cultivated ear can appreciate the slightest difference in sounds, as the eye perceives the least difference in the degrees of light. This theory explains one of the most mysterious parts of the mechanism of audition, it shows us the sonorous waves exciting the Eolian harp of the acoustic nerve, just as direct observation enables us to see the luminous image painted on the retina. Just as a mirror and the camera obscura repre- sent the eye, an instrument of music represents the ear- and we follow the sonorous and the luminous waves to the point where all is shrouded in mystery—to sensation, to comprehend which we must as little pretend, as to penetrate the mystery of life, or of our own intelligence. But the ingenious explanation of M. Helmholtz does not at first seem to make the phenomena of hearing as accessible as those of seeing have become by means of optical instru- ments. The convex mirror, and the productions of photo- graphy, show us magnificent monuments and vast landscapes reproduced in microscopic proportion; we have nothing like this for the ear, and we are involuntarily led to contrast the auditory organ and its fine canals with the grandeur of sounds, and of the bodies from which they emanate. Phy- sicists admit that the sonorous waves cross each other in the air in nearly the same manner as in a fluid, without modify- ing their curves, and it is thus that the distinctness of each particular sound is perceived in an accord executed by several different instruments; but, in order that this pheno- ACUTENESS AND DELICACY OF HEARING. menon of hearing may be displayed, the sonorous waves must move through the windings of the labyrinth with the same facility that they traverse space; the rush of meteors, and the immeasurable voices which nature has given to the atmosphere, to the ocean, and to mountains, must be trans- mitted to our ears in their relative proportions, as well as the sound of a falling dew-drop. How can the ear in its infinitesimal proportions perceive with equal precision the sound of the gigantic instruments which vibrate under the hand of nature, and the feeblest noise which traverses the air? Let us remember that if we get a glimpse of the details of natural phenomena, and of those movements which con- stitute life, it is not in considering them as a whole, but in analyzing them as far as our limited means will permit. In the vibrations of the globe of air which surrounds our planet, as in the undulations of the ether which fills the immensity of space, it is always by molecules which are intangible for us, put in motion by nature, always by the infinitely little, that she acts in exciting the organs of sense, and she has modelled these organs in a proportion which enables them to partake in the movement which she impresses upon the universe. She can paint with equal facility on a fraction of a line of space on the retina, the grandest landscape or the nervelets of a rose-leaf; the celestial vault on which Sirius is but a luminous point, or the sparkling dust of a butterfly’s wing: the roar of the tempest, the roll of thunder, the echo of an avalanche, find equal place in the labyrinth whose almost imperceptible cavities seem destined to receive only the most delicate sounds. Acuteness and delicacy of hearing.—It has been said that hearing is the most perfect of the senses in man. Considered as a musical instrument the ear is in fact a most admirable organ, and which man alone possesses; but here, as in the eye, we must distinguish between the apparatus of hearing and what pertains to the domain of the mind. The ear perceives sounds, but the mind estimates their regularity, measures their intervals, judges them melodious or the re- verse, determines their discord or their harmony. If the 198 THE HUMAN BODY. painter is provided with a faithful mirror, the ear is for the musician a still more infallible guide; not that it surpasses the eye in delicacy of mechanism, but that the mathematical divi- sions of sound, and of their intervals, much more minute than shades of colour, do not admit of confusion. The eye perceives a great number of tints at the same time, which may mingle upon the retina either from their vicinity, or from the rapid displacement of objects, as we see when the molecules of two colours are mixed together, and when a disk of several colours turns on its axis. On the contrary, however rapid the movement in a piece of music, each note produces a distinct sound, and when several reach it simulta- neously they always cause isolated impressions. It is thus that a musician in the midst of the accords of a large or- chestra is able to distinguish a false note and the instrument from which it proceeds. The acuteness of hearing has more influence upon the delicacy of auditory impressions, than extent of vision has upon visual impressions; acute vision is not necessary to the painter in judging exactly of colours, but the ear of the musician must have an exquisite sensibility in order that he may appreciate the truthfulness of notes and their harmonic relations; but when once this idea is acquired it is ineffaceable, and enables him to create master-pieces which his ear cannot hear. Beethoven became deaf at forty, and composed all those immortal works which for himself were never per- formed except in his mind. It is not rare to find persons w'ho distinguish musical sounds with difficulty and confound them as regards the notes. For those in whom this Daltonism of the ear is ex- treme, music has no existence; they hear only a succession of sounds more or less intense, without harmonious relation or rhythmical succession. Between this condition and that delicacy of ear which marks the leader of an orchestra or a good tuner, the degrees are infinitely varied, and absolute correctness of ear is as rare, at least, as a perfect perception of colour, although musical impressions seem to demand less effort, and to be a more common endowment than the ability to appreciate painting. MUSICAL EAR. INTENSITY OF SOUNDS. 199 It is said that a false note disturbs more than false colour- ing, but this is true only within certain limits. A mediocre amateur listening to the overture of “Der Freischiitz” at the Conservatory would be shocked, no doubt, if the horn should, by one of those accidents which it is impossible always to avoid, be out of tune; but the same amateur after having heard this same piece executed by a second-rate orchestra would be very well satisfied with the concert, and would take into account neither the false notes which might have escaped nor the want of regard to time or expression, and if he does not place the two orchestras on the same level, it will be from personal feelings. Among the crowds which visit the galleries of the Louvre every year, how many people prefer a common and inharmonious picture blazing with colour to a master-piece of Titian ! A person who sings falsely is said to have “no ear,” and often, in fact, it is to the want of exactness in the ear that the faults in the voice are due. In this case the evil is be- yond remedy, the musician who has an incorrect ear can never be sure of producing correct sounds. But if the falsity of the note is due solely to an imperfection in the vocal organ, a man who cannot sing correctly, can play the violin or violincello perfectly, because his ear judges correctly of the sounds which he produces from his instrument. Intensity, distance, and direction of sounds.—As we have seen, authors do not agree upon the functions of the different parts of the auditory apparatus in the perception of the in- tensity, the distance, and the direction of sound. The per- ception of the intensity of sound seems to depend more on the relative perfection of the whole organ than on any one of its parts. Vibrations are transmitted to every part of the ear, and even to the whole body, in loud noises and sounds. Thus thunder, the report of cannon, the grave notes of an organ or of a double-bass viol, cause a tremor in the whole body; but it is by the vibratory excitement of the auditory nerve that we judge of the intensity of sounds, as the optic nerve enables us to appreciate that of light. In regard to distance, if it is a sound with which we are familiar, that of the human voice, for example, we judge of 200 THE HUMAN BODY. it by the greater or less force of the auditory impression. As for noises of which we do not know the intensity at a given distance, as thunder, we estimate it in the same way, but with less certainty according as it is faint or loud. It is therefore to reasoning, founded on the sensation, that we owe the ability to judge of the distance as well as the intensity of sounds, and it is the same as to their direction. When we hear a sound more distinctly with one ear than with the other, we judge that it comes from the side on which the impression is strongest, and the ability of the organ to seize slight degrees in the intensity enables us to tell in what position of the head the sound is most clearly perceived. We are therefore led to place it in a certain position in regard to the direction, and by this means we acquire an idea of it within certain limits. Hence, if the ears are both in the same situation relative to the sound, as when it is in front of or behind us for example, we find it impossible to distinguish in which direction it is without turning the head. This uncertainty which we always feel in regard to the exact distance and direction of sounds enables the ventrilo- quist to produce what are wrongly supposed to be illusions of hearing, but which are simply errors of judgment guided by the imagination. The hollow, feeble voice of the ven- triloquist seems to come from a great distance, from above or from a certain depth below us, the sense of the words, the expression of the voice, the varied tones and mimicry of the juggler, do the rest. Duration of auditory impressions.—Savart has demonstrated that the duration of acoustic impressions is about the tenth of a second. Thus when the vibrations of a body do not exceed nine in a second, the ear perceives a series of distinct impressions, but beyond ten or twelve the sensation becomes continuous. Sensations of internal origin.—As the eye may be the seat of luminous impressions produced by other means than light, so sounds and noises may be heard, without the ears having been excited by sonorous waves. Ringing and humming sensations may be produced in or imparted to them, under PARALLEL BETWEEN THE EAR AND EYE. 201 abnormal conditions into which we shall not inquire; and of which the mechanism is obscure or unknown. A pro- longed shock to the auditory nerve by a loud sound or noise will cause a persistent confused sensation, which is felt by everyone after a long journey by railway, or after being near a great waterfall or in a mill for a length of time. Parallel between the ear and the eye.—The eye and the ear present many analogies, both in regard to their functions and their anatomy. The pavilion of the ear has been com- pared to the eyelids, the auditory canal to the anterior chamber of the eye, the tympanum to the iris, the cavity of the tympanum to the posterior chamber, the small bones to the crystalline, and the liquor Cotunnii to the vitreous body. These organs differ in their nature, like the exciting agents which pass through them. Sound and light both originate in vibrations, but transparency is the essential condition of the organ through which light passes, while sounds are pro- pagated through all bodies, solid, fluid, or gaseous. The sense of light enables man to contemplate the admir- able spectacle of the universe, but for the eye nature is mute; to it motion alone denotes life; hearing completes our impressions, everything is animated by it, and man takes part in the life of the external world, and shares the thoughts of his fellows. The perfection of these two senses enables us the better to appreciate the connection between the functions, and the unity of our organs. The sight speaks more directly to the intelligence, it enlarges the field of thought, it gives birth to precise notions of light, of form, of extent; and it permits the communication of thought by conventional signs. Hearing is a necessary condition of articulate language; without it man lives alone, affection and confidence lose their most precious forms of expression, and friendship cannot exist. Auditory sensations act upon the nervous system with more force than visual sensations. We are carried away by rhythm, or it adapts itself to our ideas and our passions; music plunges us into an ideal world, and holds us by an in- definable charm; in a word, if sight speaks more especially to the intellect, hearing addresses itself to the affections. 202 THE HUMAN BODY. Sight is certainly more necessary to man than hearing, but still the blind are generally gay and communicative, while the deaf seem inclined to melancholy. As to the relative influence of these two senses on the development of the intellect, we know that the education of the deaf is slow but may be complete, while that of the blind is, on the contrary, rather rapid, but is almost always very limited; many ideas cannot be acquired by them, and, as has been remarked by M. Longet, their minds rarely attain maturity. CHAPTER XIII. Sense of smell. Olfactory organs.—Nose; nasal fossce, turbinated bones, pituitary membrane.—Olfactory nerve.—Odoriferous principles; their de- velopment, their action on the nervous system.—Smell,—its seat; dura- tion of olfactory impressions.—Uses, and acuteness of smell. Olfactory organs.—The smelling apparatus is situated in the middle of the face, between the orbital cavities and the palatine arch. Placed thus above the organ of taste, which it resembles in many respects, it forms the entrance to the respiratory passages, and controls to a certain extent the purity of the air which enters them. It is composed of the nose and the nasal fossae. The nose.—Two thin, flattened bones, slightly curved in their breadth, form the superior portion of the nose. They are articulated by their internal border in the median line; at their external border they are united to the ascending processes of the upper jaw, and they are attached at the root of the nose by sutures to the frontal bone. Their inferior borders are attached to the cartilages which complete the nasal walls. The arch formed by the nasal bones is sup- ported by a bony partition, to which is attached a cartila- ginous plate, which divides the nasal cavity into two symmet- rical halves, and separates the nostrils. A delicate skin envelops the nose and covers its little muscles, which are more important from a physiognomical point of view than from their organic functions. Nasal fossce.—This is the name applied to two irregular cavities which are continuous with the nasal cavities; they rest against each other on the median line, and are bounded below by the palatine arch, and above by the cribriform 204 THE HUMAN BODY. plate (cribrum, a sieve, being perforated with numerous holes) of the ethmoid bone. They open posteriorly just above the throat. A partition formed by the perpendicular plate of the ethmoid, the vomer (a ploughshare), and a cartilage separates the nasal fossae on the line; the prolongation of this cartilage separates the nasal cavity into two parts, as we have already seen. On the external walls of the nasal fossae there are bony folds, which are called upper, middle, and lower spongy bones, and are separated from each other by corre- sponding passages. The nasal fossae communicate with numerous sinuses in the substance of the bones of the face and skull. The whole internal surface of the olfactory apparatus is lined with a mucous membrane called the pituitary ?nem- brane, this is the immediate organ of smell. This membrane dips into the numerous inequalities of the spongy bones and the passages, thus presenting a larger surface to olfactory impressions. The olfactory nerve is ramified in the pituitary membrane. It penetrates the nasal fossae through the cribri- form plate of the ethmoid, but is distributed over the upper portion only. In the lower portion of the fossae the pituitary membrane receives only nervous filaments from the fifth pair, a circumstance to be noted in reference to the mechan- ism and seat of smell. Odours.—The philosopher calculates the velocity and in- tensity of light, he can analyze it, he knows from what sub- stance a given colour emanates, and if this substance exists in the star, the rays of which he is observing; he demon- strates in the vibrations of bodies the origin of the sonorous waves, and sees in light as in sound, not particles of matter traversing space, but a movement excited in the surrounding media. Some learned men have thought that odours also result from a vibratory movement transmitted to the ambient air by the molecules of odoriferous substances, but Fourcroy demonstrated the origin of odoriferous emanations in the volatility of the immediate materials of vegetables; and odours are now generally considered as bodies existing by themselves, and not as a purely physical result comparable to sonorous or luminous waves; they are extremely minute MINUTENESS OF ODORIFEROUS PARTICLES. 205 material particles, volatilized in the atmosphere. But here matter seems to become intangible. The chemist can ex- tract from a body the essential oil which gives it its odour, but he cannot separate the odoriferous principle from the oil itself, and he can only recognize its presence by the special impression received by the olfactory nerve. Nothing gives us a more exact idea of the divisibility of matter than the diffusion of odours. Three-quarters of a grain of musk placed in a room cause a very powerful smell for a considerable length of time without any sensible diminution in weight, and the box in which musk has been placed retains the perfume for an almost indefinite period. Haller relates that some papers which had been perfumed by a grain of ambergris, were still very odoriferous after a lapse of forty years. Odours are transported by the air to a considerable dis- tance. A dog recognizes his master’s approach by smell even when he is far away; and we are assured by navigators that the winds bring the delicious odours of the balmy forests of Ceylon to a distance of ten leagues from the coast. Simple experiments prove that odoriferous bodies emit a stream of particles so small as to seem to be immaterial. When a morsel of camphor or a small body saturated with ether, or minute portions of benzoic acid, are thrown upon water, they are animated by a peculiar movement, which is due to the propulsion produced by the invisible vapour which emanates from these substances. Heat, light, and other influences modify the production of odours, and their transmission in space. Certain plants are odoriferous only at night, and it is especially in the morning and evening, when the dew is scanty, that flower-gardens perfume the atmosphere. Rain destroys the perfume of flowers, probably by its mechanical action, and by lowering their temperature. It is remarkable also that animal or vegetable odours are feebler, as the countries are colder in which the plants or animals live from which they emanate. Hence perfumes come principally from tropical countries. It has been stated that substances absorb and retain odours according to their colour. Thus, the experiments of Stark 206 THE HUMAN BODY. tend to prove that black garments are more quickly impreg- nated with an odour, and retain it longer, than light-coloured garments. On the other hand, A. Dumeril assures us he has ascertained that white stuffs absorb odours as quickly as others, but that the odoriferous particles are sooner evapor- ated from them. There must consequently be in this respect a difference in odours like that in luminous rays, but the first of these phenomena has not been at all so clearly demon- strated as the latter. Under the influence of a shock, or from friction, certain vegetable and mineral bodies emit odours more or less power- ful. Such are several varieties of wood, especially lilac and Saint Lucy, the leaves of mint, lemon verbena, and southern- wood, and certain calcareous or silicious rocks. Other plants, on the contrary, lose their aroma on being bruised, like the mignonette, the violet, &c. The contact of water, or of vapour, also develops odours in argillaceous rocks and several vegetable substances. Odours have a very marked effect on the nervous system; but some persons are far more impressible in this respect than others. There is no doubt that certain odours may cause grave disturbance in the nervous system; but the ima- gination sometimes plays a prominent part in the discomfort produced by a bouquet of roses or violets; the sight of artifi- cial flowers is sometimes sufficient to excite persons painfully who believe them to be natural. People often ascribe to this influence of odours on the brain, what is really due to the effects of carbonic acid gas, or of poisonous emanations ab- sorbed by the lungs; and how many persons there are who do not believe the open combustion of charcoal is innocuous, because it does not emit so much smell as coal. But even after making due allowance for the effects of the imagination, it is certain that odours act as an excitant on the brain, which may be dangerous when long continued. They are especially dreaded by the Roman women. It is well known that in ancient times the women of Rome in- dulged in a most immoderate use of baths and perfumes; but those of our times have nothing in common with them in this respect; and the words of a lady are quoted, who said on SMELL, 207 admiring an artificial rose, “It is all the more beautiful that it has no smell.” We are warned by the proverb not to discuss colours or tastes, and we may add odours also. Men and nations differ singularly in this respect. The Laplander and the Esquimaux find the smell of fish-oil delicious. Wrangel says his compatriots, the Russians, are very fond of the odour of pickled cabbage, which forms an important part of their food; and assafoetida is, it is said, used as a condiment in Persia, and, in spite of its name, there are persons who do not find its odour disagreeable any more than that of valerian. Smell.—The air which enters the organ of smell deposits on the surface of the pituitary membrane the odoriferous principles with which it is charged, it becomes impregnated with them, and it is in its tissues that these principles come in contact with the terminal fibres of the olfactory nerve. We have already stated that this nerve is only distributed over the upper portion of the nasal fossae; in order to produce the sensation of odours, therefore, the air inspired must reach not only the inferior but also the superior parts of these cavities. The nose is contracted at the root like a funnel, and tends to guide the odoriferous effluvia towards the point where the impression is to be perceived; and the stronger the inspiration the higher up the column of air is carried, and the more it excites the filaments of the special nerve. Some physiologists have thought, with Magendie, that the nerves of the fifth pair, which ramify over the lower portion of the pituitary membrane, were designed to serve the purpose of smell; it seems to be clearly demonstrated that the sensa- tions caused by acid or ammoniacal vapours are not olfactory, but simply painful. The pituitary membrane in its normal condition is con- stantly humid, and the secretion with which it is bathed is one of the indispensable conditions of the function of smell; and, therefore, we remark at the commencement of a cold in the head, when this membrane becomes dry, that the sense of smell is more or less impaired. The nose, by shielding the membrane from the immediate contact of the air, pre- serves its functions, and the loss of this organ diminishes, 208 THE HUMAN BODY. or even completely destroys, the sense of smell. Smelling is ordinarily involuntary, but it may be rendered more active by the exertion of the will. The inspirations are then stronger and more frequent, in order that the odour which we wish to perceive or enjoy may be carried in greater quantity toward the nasal arch. But if, on the contrary, we wish to avoid a disagreeable odour, a sudden expiration takes place from the nose, and we breathe instinctively through the mouth, and the soft palate closes the olfactory cavities behind. It is in this way that we are able to diminish the disagreeable impression arising from the odour in drinking sulphureous waters. Whether odours reach the seat of smell by the nose, or through the posterior opening of the nasal fossae, the result is the same; it is by this means that we perceive the aroma of the food when eating with the mouth shut; but under these latter conditions the persistence of the impressions very soon blunts the sensibility. A man fasting immediately perceives it, if a man with whom he is speaking has taken the smallest quantity of alcohol, even though it was only a glass of red wine; after eating we distinguish much less easily in others the odour of the aliments of which we ourselves have partaken, and the odoriferous principles of which have already saturated the olfactory membrane. The sinuses of the bones of the skull and of the face, which are in communication with the nasal fossae, take no part in the perception of odours. It has been thought that they may contribute by their secretions to moisten the pituitary membrane, or serve as receptacles for the air, which is after- ward carried from their cavities to the organ of smell. Duration of olfactory impressions. —When we have inspired a strong and penetrating odour, the sensation is prolonged for a certain time, sometimes for several hours. It is pro- bable that in this case the impression is not single, but is in- cessantly renewed by the odoriferous particles with which the mucus of the pituitary membrane is impregnated, or which is confined in the air in the sinuses. Sometimes also the odour has penetrated the garments, or is attached to the skin or the hair, and from thence continues its impressions. ACUTENESS OF SMELL. 209 Any vigorous exercise, or eating, by exciting the secretions, generally causes the sensation to disappear, the persistence of which might be exceedingly inconvenient. Gerdy makes the sense of smell the counsellor of the stomach. When the appetite is excited the smell of food is agreeable; but it is repugnant, on the contrary, when hunger is appeased, and the sense of smell warns us to take no more food. We may say, with reason perhaps, that this sense completes that of taste, by enabling us to appreciate the aroma, without which food and drink would cause only a gross sensation, or one at least entirely devoid of all delicacy. When the sense of smell is lost, or even enfeebled, the taste, perceiving flavours only, seems almost extinguished, existing alone. The sense of smell is very unequally developed in indivi- duals, but it is said to be of extreme delicacy in some races of men, and especially among savages. The stories recounted of individuals following game by tracking, and of negroes who could distinguish by smell the tracks of a negro from those of a white man, seem to indicate a faculty quite as nearly related to the sense of sight as to the one under con- sideration; and it must be admitted also that individual ex- perience and careful attention to particular circumstances produce the same results when applied to the sense of smell, as to sight or to hearing. CHAPTER XIV. Sense of taste.—Organ of taste.—Special nerves of the organ.—Flavours. —Taste. Organ of taste.—In describing the mouth as a part of the digestive apparatus, the functions of its several parts were explained, as well as of the organs which surround or fill its cavity. It is only requisite here to repeat that the tongue receives three nerves, of which one, the great hypoglossal, gives it motion; and the two others, the lingual and the glosso-pharyngeal, give it gustatory sensibility. The tongue participates by its movements in the digestive functions, and in the articulation of sounds; but it has besides a special sensibility—it is the principal organ of taste. Flavours, taste.—The cause and intimate nature of tastes are no better understood than those of odours. It is by volatilization that the intangible particles of the odoriferous principles reach us; it is by a solution more or less complete that substances impart their flavour, that inherent property which taste alone reveals to us. We recognize in this way their acidity or saltness, whether they are sweet or bitter, &c.; but nothing in the nature of bodies, in their texture, or in their constituent elements, has ever yet explained their sapidity. Flavours elude analysis and defy classification, even that which divides them into agreeable and disagreeable, for the taste of individuals and of nations singularly differs in this respect. The Laplander and the Esquimaux drink great quantities of train-oil, which for them is a greatly esteemed article of food, and is most admirably adapted to the exigen- cies of a Polar climate; the Abyssinians eat raw flesh, and find its flavour excellent, while the inhabitant of the West FLAVOURS. 2 11 partakes of it with the greatest repugnance, and only as a medicine. Oysters, which are so generally esteemed in our country, are to some persons disagreeable and nauseous; and truffles, the delight of the gourmand, are rejected by the uninitiated on account of their flavour and their perfume. It is the same with almost all alimentary substances; they are eagerly sought after by some, and despised or abhorred by others. Let us remember the proverb, and not dispute in regard to tastes; each is suited to its own country, and goodly numbers acclimatize themselves, to the great advantage of peoples, among whom at first they seem exceedingly strange. Man should control his taste, and habituate it to all whole- some aliment; this neither excludes choice, nor blunts the delicacy of the sense; and while we resist its seductions, we should give timely heed to its instincts and its counsels, for they are often invaluable. Among the substances which we taste, there are few which address themselves solely to that sense, and not at the same time to the sense of smell. This mingling together in the same substance of flavours and odours, and the simultaneous action of the senses which perceive them, has induced some authors to consider them as forming but one. They are, notwithstanding, quite distinct in their seat and in their function; the mixed sensation resulting from the union of their impressions differs entirely from that which they cause singly; we may say that the sense of smell is the necessary complement of taste, for the latter is reduced to very trifling importance when it acts alone. However much flavours may vary, they are all referable to a very few types, to the mixtures and shades of which we are quite indifferent when they do not offend us. The taste solely judges whether a substance is salt or sweet, acid or astringent, and so forth; but when our food does not awaken any other sensations, we are tempted, in spite of its flavour, to pronounce it insipid; vanilla cream and coffee cream, or ices with rum or with maraschino, do not differ in taste when the nostrils are closed. If, instead of olive-oil and wine-vinegar, bleached oil and acetic acid diluted with water be used to season a salad, we shall have the sensation of taste without 212 THE HUMAN BODY. that of smell. We must not then confound with natural taste that which smell adds to it, and it is to supply the lack in this respect of what is wanting in our food and in our blunted senses that we make use of condiments. We must also distinguish the bodies the action of which is confined to the sense of touch exercised by the tongue, and many impressions reputed to be those of taste ought rather to be considered as purely tactile, such as astringency, tartness, the irritating or caustic action of certain sub- stances, &c. On this principle M. Chevreul has divided substances into four classes according to the impression which they produce in the mouth: ist, bodies acting on the sense of touch in the tongue, such as rock-crystal, ice, and so forth; 2d, bodies acting on the sense of touch and of smell, such as aromatic metals, tin and copper for example; 3d, bodies acting upon feeling and taste, as sugar-candy, common salt, &c.; 4th, bodies acting on the touch, taste, and smell, as mint-lozenges, chocolate, or volatile oils. All alimentary substances figure necessarily in the latter class. Authors do not agree upon the seat of taste; several be- lieve it extends over nearly the whole surface of the tongue, to the pillars of the fauces, and to the upper surface of the soft palate, to the tonsils, and to the pharynx. It is now generally believed to be located at the tip, at the base, and on the edges of the tongue, and at a certain limited space on the anterior surface of the soft palate. According to M. Longet, the back of the tongue and the pillars of the fauces are not entirely destitute of gustatory sensibility. Savoury substances do not produce the same impression upon all parts of the tongue, many salts on the tip of the tongue have an acid, salt, sharp, or styptic, at the base a bitter or metallic taste; others, on the contrary, have the same flavour on every part. In general, acidity is best per- ceived at the tip, and on the edges of the tongue, saline or metallic flavours are developed at the posterior portion. In order to perceive the flavour, the savoury molecules must be bathed in saliva, and partially dissolved, so as to be SEAT OF TASTE. 213 placed in more immediate contact with the surface of the tongue. To further insure this contact, the tongue applies itself to the palatine arch, and presses the food against its surface. It is then that the gustatory impression is produced in its full force, and from this it has been inferred that the palate is the principal seat of taste. The action of the palate, however, is purely mechanical, and is limited, as we have stated, to securing immediate contact between the savoury bodies and the tongue. This is demonstrated by covering the palatine arch with a thin pellicle which is itself insipid and impermeable; the taste is just as acute under these conditions, but if the tongue is covered with this same pellicle, and the palate uncovered, no taste is perceived. The cheeks and lips also contribute to taste by carrying the particles of food which may have fallen outside the dental arch during mastication back to the tongue. Taste acts not less delicately in deglutition, when the contents of the mouth descend between the base of the tongue and the soft palate on its way through the throat. Food and drink must re- main for a certain time in the mouth in order that their full flavour may be perceived; thus the gourmand takes care to retain them, and exhaust, as it were, their aromas, before send- ing them to the stomach. For this reason, also, wine-tasters hold the wine in their mouth when they wish to judge of its quality, but they avoid swallowing this mouthful of wine after it is thus robbed of its bouquet; they reject it after thoroughly moistening the surface of the tongue, and they can then decide as to the vineyard and the year of the vintage. If they drank the wine which they taste, the smell, which here plays the principal part, would very soon become dulled. The papillse of the tongue, it is generally considered, are endowed with gustatory sensibility, and this sensibility is principally attributed to the fungiform papillae. According to M. Longet they are rather tactile organs, and the learned physiologist supports his opinion by the fact that, on the point of the tongue the taste is no less perfect where the parts are destitute of papillae, while the feeling there is much less delicate than on the papillae themselves. 214 THE HUMAN BODY. The impressions of taste are quite persistent according to some authors, but this persistence is due to the presence of savoury particles on the tongue, and is more correctly the constant renewal of the impression. Experience shows how difficult it is to get rid of certain flavours, and it is easy to understand that when dissolved, and retained by the saliva in what may be called the papillary fleece of the tongue, the particles remain, and furnish for a considerable time the materials for the sensation. It is a mechanism analogous to that which produces the persistent smell of creosote and dextrine from the hands several hours after contact with the disgusting perfume. Taste is but slightly developed in infancy, and, although it acquires some delicacy in youth, it is especially in mature age that it reaches its perfection. Far from growing feeble with the lapse of years, it retains all its acuteness, and con- soles the aged for the irreparable injuries of time. It is per- fected by exercise, and attains in some individuals remarkable delicacy, as in professional tasters, for example; but the pro- longed use of highly seasoned food, the abuse of alcoholic liquors, and above all of tobacco, enfeebles and blunts it in what may be termed its olfactory portion. The question has been raised whether taste is developed by civilization. This is admitted by several physiologists, but perhaps it would be necessary to establish a distinction between the natural sensibility of the organ and its aptitude in judging of a great number of flavours. In this last respect there is no doubt of the superiority of civilized nations, but there is great difference between them notwithstanding, and if we were to measure the civilization of nations by the deli- cacy of their taste, we might arrive at very flattering con- clusions for some, it is true, but at very painful ones for many others. We will content ourselves with saying that, in Europe, the taste is generally more developed in the south than in the north. In conclusion, it furnishes very little material to the intellect. Its scientific use is limited to in- dicating to the chemist the sapidity and species of flavour of substances. Its functions, in relation to nutrition, dispose to gaiety and POSITION OF TASTE AMONG THE SENSES. good humour, and nothing except labour produces a more powerful diversion for the mind of a person a prey to chagrin or melancholy. Stationed at the entrance to the digestive passages, it guides us in the choice of food, and controls its nature and quality; it warns us against repletion by its indif- ference to the flavours the most appreciated at the beginning of the repast, and compensates by agreeable sensations for hunger—the hard necessity of our organization. Taste is therefore a useful servant, but on the whole we see that of all our senses, it is not the farthest removed from matter, and what is worse still, it has much to be pardoned for. The stomach reproaches it with not being so virtuous as physiologists seem to believe, and accuses it of being dangerously seductive, and the worst enemy of those who should regulate their diet; and though it sometimes gives timely warning by disgust, it is often in the wrong in reject- ing wholesome food under the pretext that it is new or that its prejudices condemn it. The taste retorts by throwing the blame on those who have taught it to be fastidious; it pro- fesses, and with truth, to be docile to training, and that the prejudices come from the master of the house; and it adds that, though perfectly competent to judge of the merits of a cook, it is very little acquainted with questions of hygiene, and that the enemy of the stomach is gluttony and not taste. Some persons affect a contempt for this sense, explicable, no doubt to a certain extent, but which tempts us to be- lieve that they speak of it only from hearsay. “The mind should take precedence of the body,” as Belisus emphatically declares; but the good Chrysalus, was he wrong in saying, “Yes! my body is myself, and I will take care of it?” May we not remember in proper time and place that “man lives on good soup, and not on fine wordsbesides, one does no harm to the other, and to want even the most modest sense is to be imperfect after all. The'nard, speaking of cooking before a crowded audience at the Sorbonne, called it “ that important part of chemistry.” We may think what we please of the taste, but it has always in all ages been the endowment of men of genius. THE HUMAN BODY. In reading Brillat-Savarin, we feel disposed to believe that the mind and the gastronomic senses are inseparable. But these are delicate questions; and as we would not toss an apple of discord between nations, neither shall we between individuals, but rather prudently refer the reader to the Physiology of Taste. CHAPTER XV. Sense of touch —Difference between touch and feeling.— Tactile sensibility and general sensibility.—Organ of touch. Sensation of contact; dif- ference in the sensibility of different regions of the body ; simple contact, shock, vibration.—Sensation of pressure; relative aptitude of different regions in appreciating it; variable sensation according to the form of the body and the extent of its surface.—Sensation of temperature, variable according to the temperature of the skin, the density of bodies, and the surface in contact; identical sensation from contact 'with a body very hot and very cold; relative sensibility of different regions to temperature.— The touch; its delicacy.—The touch compared with the other senses; illusions of touch; persistence of tactile impressions, sensations from in- ternal or subjective causes; causes which modify feeling. Touch and feeling.—Tactile sensations, like all others, are more or less complete according as the attention is, or is not, directed to them. The contact of a foreign body with any sensitive portion of the organism is revealed to us by feeling, and it is by touch .that we discover the form, resistance, and temperature of this body. Feeling maybe involuntary, touch is an act of the will; there is therefore the same difference between feeling and touch that there is between seeing and looking, between hearing and listening, scenting an odour and smelling it, perceiving a flavour and tasting it. We must also distinguish between impressions due to general sensibility and tactile sensations proper; thus, if we knock the elbow we feel an acute pain along the course of the ulnar nerve, but the impression produced on the skin is perfectly distinct from this deeper suffering when not entirely masked by it. It is the same in sensations resulting from a shock to the right hypochonder which produces a pain in the liver. All the tissues which receive nerves of sensation may THE HUMAN BODY. be the seat of impressions which may be referred to the general sensibility, and which are for the most part painful; impressions on the sense of touch are only produced in certain tissues specially endowed with this sense. General and tactile sensibility are independent of each other, and they are not developed proportionally; as, for instance, the palmar surface of the fingers is endowed with an exquisite sense of feeling, but it is almost insensible to a blow which would be very painful to the cheek, in which this sense is much less developed. Organ of touch.—Touch has its seat in the skin throughout its whole extent, and in some of the mucous membranes. It is by the nervous papillae containing the tactile corpuscles that the impression is perceived, and the tactile sensibility of any region is in proportion to the number of nervous papillae existing in it. We receive three distinct impressions at a time by the sense of touch—that of contact from a foreign body, that of the pressure which it exercises on the skin, and that of its relative temperature. The sensation of contact is not equally distinct and precise in all parts of the body, and the reason of this we will endeavour to explain. If we apply simultaneously the two points of a compass to the skin, they must be more or less separated according to the region experimented on, in order that their contact may cause one or two distinct sensations, and we may in this way measure the delicacy of the sense at any given point on the skin. It is evident that the less sensitive the skin is, the more widely we must separate the points of the compass to produce a double sensation. E. Weber after many experiments classes the regions in the order of their sensibility as follows:—The tip of the tongue gives a double sensation when the feet of the compass are separated about half a line; the palmar surface of the ends of the fingers, one line; the red surface of the lips and the surface of the second joint of the fingers, two lines; the end of the nose and the palm of the hand near the fingers, three lines; the back and edges of the tongue at about an inch from the tip, and the skin of the lips, four lines; the palm RELATIVE ACUTENESS OF SENSE OF TOUCH. 219 of the hand, the cheek, and the eyelids, five lines; the palate, six lines; the prominence of the cheek, and the sole of the foot near the great toe, seven lines; the back of the hand near the fingers, eight lines; the gums, nine lines; the lower portion of the forehead, ten lines; the lower part of the occiput, twelve lines; the back of the hand, fourteen lines; the throat under the jaw, fifteen lines; the shoulder, fore-arm, and knee, eighteen lines; the chest over the sternum, twenty lines; the loins, the upper part of the back, and the neck on the line of the spine, twenty-four lines; the middle of the back, of the neck, of the arm, and of the thigh, thirty lines. Gratiolet found by oft-repeated experiments that the dis- tances recognized by the pulp of the fingers might be very much less. By touching two points on the same papillary ridge on the pulp of the last joint of the middle finger, sepa- rated only by the orifice of a sudoriferous duct, the two sen- sations were plainly distinguished at the distance of less than one quarter of a line. The experiments of Valentin, on the other hand, prove that tactile sensibility varies from single to double in cor- responding regions in different individuals; we can only accept the measurements of Weber, therefore, as indicating the relative sensibility. And lastly, we are indebted to M. Belfield-Lefevre for the experiments which led him to the following conclusions. The distance between two points of contact is better appreciated, if these points are placed on a line transverse to the axis of the body, than when on a line parallel to it or longitudinal. According to Weber, on the ends of the fingers, and on the tip of the tongue, the distance is better appreciated on a longitudinal than on a transverse line. The distance between two points of contact, distinct and simultaneous, is greater in proportion to the delicacy of feeling in the region experimented on; it seems to be greater also when the contact takes place successively in the two points, than when it takes place simultaneously, and greater also if the two contacts are separated by a longer interval of time. If the two points of contact are separated by the median line, the distance between them seems greater than 220 THE HUMAN BODY. if they are placed on the same side of the body.—If two points are touched, which are subject to variation from func- tional displacement, the eyelids or the lips for example, the distance is greater than if the two contacts take place on one eyelid, or one lip.—This sense is also increasingly developed on the surface of the limbs in proportion to the distance from the body. The sensation of contact varies according as it results from a simple application of a foreign body to the skin, or from a shock, or a succession of shocks repeated at short intervals, like that which produces vibration in a body. In the latter case the region of contact receives a shock in proportion to the intensity of the vibrations; as when we touch the skin with a tuning instrument while vibrating, or if we grasp a vibrating metallic body or wooden rod, or close the lips against the reed of a basoon while it is being blown into, it produces on the surface in contact an impression, varying from a painful shock to a simple tickling or pleasurable sen- sation. It is a sensation of the same nature, though diffused through the whole body, that we feel from the vibrations im- pressed on the atmosphere by the explosion of artillery, the roll of thunder, or the ringing of a great bell. The sense of touch then gives us an idea of the sonorous waves which excite the auditory nerve, and furnishes us with the proof, that the same cause acts differently on the special nerves of the different senses. In fact, the nervous papillae of touch transmit a sensation of motion and of shock; the tympanum perceives neither tickling nor shock, the impression which it transmits to the auditory nerve is not that of a vibratory movement, but of the sound which results from it. The sensation of pressure is distinctly perceived by touch; but we must distinguish between the pressure of a body against the skin, and the resistance which this body offers to a muscular effort tending to displace it If when the hand is supported, and a weight placed in it, no effort is made to raise it, and the muscles remain inactive, we feel a sensation of pressure, the force of which may be judged of with more or less exactness; but the moment we endeavour to appre- ciate the weight the sensation becomes complex, and we SENSATION OF PRESSURE. 221 have the idea of pressure, and that of the muscular effort which we oppose to it; and great attention is necessary to prevent an instinctive contraction of the muscles of the hand to resist the weight with which it is charged. We must also take into account habit and the relative strength of the hands; as the right, which is generally more used than the left; may be less sensitive to pressure, and appreciate its degree less exactly. Those portions of the skin where the touch is most acute, and where two points of contact are perceptible at slight distances, are, according to Belfield-Lefevre, those which estimate most correctly the degree of pressure; as the lips, the palmar surface of the fingers, the under surface of the toes, and the skin of the forehead, are better endowed in this respect than the rest of the body. But neither touch nor pressure alone can give an exact notion of the weight, we must support the body on which the experiment is made by muscular effort; the inequality of the two hands in this respect is so well known, that we use one and the other alternately in order to ascertain correctly the weight of the object. It is estimated that pressure alone will not enable us to appreciate more than an eighth of difference between two weights, but by lifting we can appreciate a sixteenth. The form of bodies also influences the sensation of pres- sure; when an object with only a small surface is applied to the skin the pressure seems greater than when it is spread over a greater extent; and it may even become painful when supported on a restricted point; thus, the weight which we carry with ease on the whole breadth of the shoulder, is in- tolerable when resting only on one of its angles. A truncated cone laid on the forehead seems heavy or light according as it rests on its smaller or larger base. Soldiers and travellers know very well that they cannot with impunity exchange the broad bands of their knapsacks for narrow straps or cords. It is unnecessary to remark, that if the weight be distributed over a large surface, each point of that surface supports but a fraction of the entire weight; the whole mass, on the con- trary, presses on a limited space. Sensation of temperature.—We recognize by contact with a 222 THE HUMAN BODY. body whether its temperature is the same, or whether it is higher or lower than the point of skin which touches it; in other words, touch gives us an idea of the relative tempera- ture of bodies. But the sensation may change in a few moments, as the object in contact with the skin rapidly im- parts or borrows heat; and if it is warmer or colder than the skin, an equilibrium is soon established when the difference is inconsiderable. And the same body may produce a sensa- tion of cold or heat successively without change of tempera- ture, according as the surface of the skin at the moment of contact is warm or cold; thus, if we take a bath in water cooler than the air, the temperature of the air, which seemed low on entering the bath, appears warm when we come out a few minutes after. It is for the same reason that we find the air of a cellar cool in summer, and warm in winter, although it has not varied. The sensation is marked in proportion to the conducting quality of the object in contact with the skin. Air seems warmer than water at the same temperature, because the air being a worse conductor of heat takes less from the skin in a given time. Air in motion, by exciting evaporation, causes a very sensible loss of heat, as every one knows; and the atmosphere also, which seems very cold when the wind blows, grows warmer apparently when the wind ceases, or when we are sheltered from it. The contrary effect from that caused by pressure is here seen; the sensation is marked in proportion to the extent of surface. The whole hand appreciates the temperature better than a single finger; and a body of a given temperature, applied over a large surface, will give a sensation of more intense heat than a warmer body which touches only a small portion of skin. We can easily understand that the skin absorbs in a given time more heat by a surface four inches square, than by one only one inch square, and the impression transmitted to the brain in this experiment represents rather the sum of the heat absorbed from all parts of the surface in contact, than the temperature of the body with which the experiment is made. When we touch a body of a lower temperature, the same SENSATION OF TEMPERATURE. 223 sensation is produced as when we touch one at a high tem- perature. Contact with a ball of frozen mercury causes a burning sensation, the same as that of iron heated to ioo° C. (2120 F.), though we know that mercury freezes at —40° C. (—40° F.) Voyagers in the Polar regions are com- pelled to envelop the metallic portions of their instruments in non-conducting substances, so as to be able to handle them with impunity. The skin and the mucous membranes do not appreciate differences of temperature with equal nicety in every portion of their surface, and the regions which are most sensitive to contact are not those which best indicate the temperature. The palmar surface of the fingers, the tongue, and the lips, are less impressionable in this respect than the skin of the cheeks, eyelids, elbow, and the pituitary membrane. We may perhaps attribute this relative insensibility in the hand, and the mucous membrane of the cheeks, to the habit of contact with warm bodies. The hand becomes rapidly inured to hold objects hot enough to cause a painful sensa- tion to persons unaccustomed to it. We see this in chemists, blacksmiths, and others. The skin need not necessarily be thickened, although this condition also decreases the sensi- bility. We often see persons of mature age bear without pain the contact of food so hot that younger people could not swallow it. The mucous membranes of the oesophagus and the stomach are more sensitive in this respect than that of the mouth; but when the food is held immovable for a few seconds between the palate and the tongue, the heat is absorbed, and the food or drink may be swallowed with impunity. It is clear from the preceding remarks that the sense of touch is an unreliable thermometer; it is sufficient, however, to guide us in matters relating to health, and in regard to external objects, especially when we permit its full develop- ment by touch. The hand is the principal means of exercising the touch. The organization of this admirable instrument, its numerous articulations, the freedom and variety of its movements, the tactile sensibility which is so fully developed in the palmar 224 THE HUMAN BODY. surface of the fingers enables us to obtain, by means of it, ideas of the form and relative situation of objects, of their motion, their resistance, their weight, their solid or fluid con- dition, of their temperature, &c. The hand grasps objects, moves over their surface, follows their outline, measures their distance and their extent, as far as the length of the lever of which it forms the extremity will permit. By the aid of this lever it raises bodies, estimates their weight, their firm- ness, and their elasticity. In touching them with the ends of the fingers it perceives the details of their form and their relative value. We have seen of how great importance deli- cacy of touch is to the artist, it is no less precious to the physician, and it renders him service which he asks in vain of any other sense. It is by the touch that he arrives at a knowledge of the state of the circulation, the existence of fluids in the tissues, and their normal or morbid consistence. By exercise the touch attains extreme delicacy. The blind learn to read with facility from letters printed in relief, and to execute certain work with tools. Saunderson, pro- fessor of mathematics in the university of Cambridge, was blind from his cradle, but he had attained to such exquisite perfection of touch, that in a set of medals he could dis- tinguish the genuine from the counterfeit pieces, though the latter were so well executed as to deceive a connoisseur judging by sight. He felt, by the impression of the air on his face, when he was passing near a tree. It is said that Jean Gonnelli, a blind sculptor, could model in clay an exact copy of a statue the outline of which he had studied by touch, but doubtless we must take this anecdote with some allowance for exaggeration. However this may be, the touch has been from the earliest antiquity an object of the most enthusiastic admiration to naturalists. It has been considered as the most exact and the most infallible of the senses, able to control their testimony and rectify their errors. It has been placed in the front rank, and held up as a type of which the others are only the modifications. Buffon says, “It is by the touch alone that we acquire complete and accurate knowledge; it is this sense which rectifies all the other senses, which might only delude COMPARISON BETWEEN TOUCH AND OTHER SENSES. 225 us and make us err, if it did not guide our judgment.” But Buffon thought that “the difference between our senses results only from the more or less external position of the nerves, and from their greater or less number in the parts which constitute the organs.” The illustrious naturalist did not recognize the special functions of the sensitive nerves; the sensations of colours, of odours, of flavours, and of sounds, were for him only tactile impressions. How could we admit that feeling could guide us in judging of the colour of objects, of their taste, their odour, or their sound! Even while ad- mitting that we can compare the excitation of the skin by contact to that of the retina by the luminous waves, it is not the less impossible to establish the least analogy between touch and sight, since the retina is insensible to contact, and as well as the optic nerve, conveys, not a tactile, but a luminous impression to the brain. As for the other senses, if air in vibration comes in contact with the tympanum of the deaf man he perceives no sound, though he is sensible of contact from foreign bodies on the tympanum; if odoriferous or savoury bodies come in contact with the pituitary mem- brane or with the tongue of a man who has lost the sense of smell or taste, he perceives neither odours nor flavours, al- though he is perfectly aware of the presence of a foreign body in the nose or mouth. The touch therefore cannot replace the other senses, though it sometimes corrects their impressions, but it needs to be constantly controlled and completed in the sensations which it produces in us. If it enables us to learn form, it is the eye which tells us of colour, and often perfects or corrects our notions of distance, extent, and even of form; as for instance, we distinguish less easily with the touch than with the eye a sphere from an ellipsoid which is nearly spherical. And besides it is when the touch has been exer- cised under the control of the sight that it furnishes us with the most exact ideas, for its results are then confirmed by those which we possess already in regard to time, motion, space, and the normal position of bodies, &c. Yet even in these conditions the sense of feeling may be the source of error. Muller says, and rightly too, that by touch we feel not 226 THE HUMAN BODY. the object which touches us, but that part of the tegument where the contact takes place and the impressions which it receives. The idea of external objects given by touch then is, when completely analyzed, the possibility of distin- guishing the different parts of the body as occupying a different place in space. The result is, that if the parts of our bodies are momentarily in an abnormal condition, we receive, notwithstanding, the sensation in the relative order that the regions from which these sensations emanate pre- serve in a normal condition. If, for example, we cause a ball to revolve between two fingers of the same hand, we have the sensation of a single body touching these two fingers; but if we cross the fingers and place the ball between Fig. 43- their extremities, the sensation is that of two balls, each one rolling in contact with one of the fingers. The sensations of touch are somewhat persistent, especially when the tactile impression is joined to that of general sensi- bility. Thus when we have carried a burden on the shoulder, or when any part of the body has been subjected to great and prolonged pressure, we still perceive the sensation some- time after the weight is removed and the pressure has ceased, but in such cases the tissues subjacent to the skin take part in the sensation as well as the skin itself. The organ of touch may also be the seat of impressions which are subjective, or which arise from internal causes, physical or moral. The sight of a striking spectacle or the emotion caused by a narrative produces in some persons a MODIFICATIONS OF FEELING. 227 marked sensation of cold; the idea of shivering causes an im- pression which resembles it, and the fear of tickling is suffi- cient to produce its effects. Feeling is modified by various influences; cold, or san- guineous congestion resulting from violent exercise, diminishes or suppresses for a time the sensibility of the skin; certain occupations, by thickening the epidermis, destroy the delicacy of the touch; and lastly, age diminishes the cutaneous per- spiration, the epidermis dries up, and the skin no longer has the suppleness and elasticity which renders the touch so delicate in youth. Tactile sensibility is often intensified by disease, and some- times modified, suspended, or destroyed. We see this in trances which supervene after, or are provoked under, the in- fluence of certain nervous affections. Charlatanism, even in our day, avails itself of this phenomenon, which we confine ourselves to simply mentioning here. CHAPTER XVI. Voice and speech.—Organ of voice; larynx, cavity of the larynx, glottis, vocal cords ; the larynx at different ages and in different sexes. — Physiology of the larynx; mechanism of the voice; opinions as to the formation of the, voice. —Galen, Fabricius Acqnapendente, Dodart, Ferrein, Biot, Midler, Savart, Masson, and Longet.—Theories founded on laryngoscopic observations.—Formation of sounds in whistling.— Voice; speaking voice, mechanism of articulate sounds, vowels, con- sonants, timbre of the vowels; the tongue as an organ of pronunciation. —Singing; chest voice, falsetto voice, mixed voice; different theories on the formation of the falsetto: Midler, AI. Segohd, M. Longet, M. Fotirnie, M. Bataille, M. Mandl.—Timbres of the voice: high pitch, grave pitch. —Compass of voices: bass, baritone, tenor, contralto, mezzo-soprano, soprano.— Ventriloquy. The larynx.—The organ of the voice is a sort of a cartilagin- ous tube composed of movable pieces articulated together, per- fectly symmetrical, wider and triangular at its upper portion, which opens into the pharynx, cylindrical at its lower portion, where it is continuous with the trachea. It is placed in the anterior and middle portion of the neck and below the hyoid bone, to which it is united by muscles and ligaments, and in consequence it follows the movements of the hyoid bone and the tongue, rising and falling with them. Its movements are connected with deglutition, the acuteness and gravity of sounds emitted, and with respiration according as it is diaphragmatic or clavicular (see Respiration, p. 97). Five cartilages form the skeleton of the larynx; they are 1. The cricoid cartilage (cricos, a ring); it is situated at the base of the organ, and is attached to the first ring of the trachea. 2. The thyroid cartilage (thyreos, a buckler), which is com- posed of two quadrilateral plates, joined together in front THE LARYNX. 229 and on the median line. This cartilage protects, as its name indicates, the organ of the voice. In front a ligament attaches its lower border to the cricoid cartilage, with which it is articulated behind; its anterior surface presents at the Fig. 44.—Section of larynx in the median line. A. Epiglottis, in front 0/ which the hyoid bone and base of the tongue are seen. B. Thyroid cartilage. C. Arytenoid cartilage. D. Posterior portion of cricoid cartilage. E. Anterior portion of cricoid cartilage. F. Vocal cord of right side. G. Ventricle of the larynx. H. Rings of the trachea. I. Trachea. top an angular sloping protuberance, which is more marked in man than in woman. It forms the projection on the front of the neck which is called “Adam’s apple.” The upper border is united to the hyoid bone by a membrane and ligaments. 3. The two arytenoid cartilages (arutaina, a funnel); they 230 THE HUMAN BODY. form the posterior and superior wall of the larynx, and come together behind in the shape of the lip of a ewer; they arti- culate with the cricoid cartilage, and are united to the thyroid by muscles and ligaments. 4. The epiglottis (epi, added to, glotta, the tongue) is a sort of cartilaginous valve, very elastic and mobile, situated a little below the base of the tongue, and attached to the supe- rior border of the thyroid cartilage. Its function is to cover exactly the superior opening of the larynx during deglutition, so as to prevent the introduction of the food into the air- passages. When the tongue is brought well forward, and the base depressed, in some individuals the summit of the epiglottis is visible. Numerous muscles attach the larynx to the sternum, to the hyoid bone, and by this last to the shoulder-blade, to the tongue, and to the lower jaw; these muscles are called ex- trinsic, and move the larynx as one piece. Others, called intrinsic muscles of the larynx, combine to form its walls, and to modify its diameter by acting on the cartilages, and assist in the functions of the glottis. Lastly, the arytenoid cartilages are united by ligaments to the epiglottis, or to the thyroid cartilage; these last, the thyro-arytenoid ligaments form, with the muscles of the same name and with the mucous membrane, the vocal cords, of which we proceed to speak. The cavity of the larynx, or its internal surface, does not correspond in form and dimensions with the external surface; it is cylindrical at the bottom, triangular at the top; the dimensions of the lower part are invariable, while those of the upper portion, on the contrary, are variable in form, from the mobility of the epiglottis, of the arytenoid cartilages, &c. About the middle of its height the laryngeal cavity presents on each side a fold formed by the thyro-arytenoid muscles and lower ligaments of the same name, and the mucous mem- brane; these resemble two ribbons of a white colour tinged with rose, running horizontally from front to back, attached by their external border and their extremities to the wall of the larynx, free on the surface and internal border, leaving an opening between them which is linear, elliptic, or trian- gular, according to the moment when it is observed, and GLOTTIS. VOCAL CORDS. 231 whether we see the whole or only the two anterior thirds. This opening permits the passage of the air into and out of the chest, it is called the glottis, the folds which circumscribe it have been called the vocal cords. About one-third of an inch higher up there are two other similar but less prominent folds, they are formed by the superior thyro-arytenoid liga- ments, and are designated by this name, or by that of the sicperior vocal cords (see fig. 44, p. 229). The space between them has been called the superior glottis, it is larger than the glottis proper, and does not resemble it in form when exam- ined by the aid of the laryngoscope. Before this instrument was invented the larynx was described by anatomists as they saw it in the dissecting-room, hence the name of superior glottis, and the likening of this orifice to that of the glottis. Between the vocal cords proper and the superior thyro- arytenoid ligaments there is on each side a depression; these are the ventricles of the larynx; and lastly, a little above these ligaments is the superior opening of the larynx, surmounted in front by the epiglottis, which is lowered upon, and covers it completely during deglutition. The space comprised between the glottis and the superior opening of the larynx is called the vestibule of the glottis. Formerly authors were divided in opinion in regard to the larynx; some gave the name of glottis to all the region between the level of the inferior and that of the superior vocal cords, others applied it to the superior glottis, and others again to the inferior glottis only. This last opinion, which has been commonly received since the investigations of Bichat and Boyer, has been confirmed by the laryngoscope, which demonstrates the existence of a single glottis, and a single pair of vocal cords. The internal walls of the larynx are lined with a fibrous membrane, constituted in part by yellow elastic tissue. This membrane, which forms the thyro-arytenoid and aryteno-epi- glottic ligaments, is covered throughout its whole extent by a mucous membrane, which on the free border of the vocal cords is very thin and transparent, slightly adherent, and covered with an epithelium different from that found on the rest of its surface. 232 THE HUMAN BODY. The larynx is but slightly developed in early infancy, and does not differ in its dimensions in the two sexes; and the characteristics of the voice are the same also. From the third to the twelfth year this organ remains nearly stationary; but about the fourteenth year it almost doubles in size in the boy, and the voice takes a masculine character. This evolu- tion is rapid, and is nearly accomplished in the course of a year, though the larynx is not perfectly developed till the twenty-fifth year. In girls it augments about a third in size. The larynx, therefore, of an adult woman is smaller than that of man, its angles are less prominent, and the glottis is smaller. These differences are related to the characteristic pitch, compass, and power, which distinguish the voice of man from that of woman. In diaphragmatic respiration the larynx is immovable; but when the expansion of the chest extends to the upper ribs, the sternum, and the clavicle, two of the extrinsic muscles of the larynx assisting in the elevation of the sternum, cause by their contraction the descent of the larynx, to which they are attached by their upper extremities. (See Respiration, P- 97-) . Physiology of the larynx, mechanism of the voice.—Like most physiological questions, that of the emission of the voice is differently explained by writers on that subject. In order to explain its functions, the larynx has been compared to dif- ferent musical instruments. Gerdy thought ‘‘that we should do better to endeavour to show that this instrument in man has no resemblance to any one formed by art.” This, doubt- less, is true; the human larynx is as inimitable in its perfec- tion as it is admirable in the results it produces; but, in comparing the most ingenious machines of this character that man has ever constructed, with the larynx, we do pre- cisely what Gerdy recommends, for this is the surest means of establishing its evident superiority. The analogy is besides incontestable, in spite of the distance which separates an inert mechanical production from a living organic apparatus, and it is only by studying the formation of sounds in instru- ments that we can, if not explain, at least seek to comprehend their formation in the larynx. MECHANISM OF VOICE. 233 The vocal apparatus of man is composed of the lungs, acting as a bellows; the trachea, which conducts the air from the lungs to the larynx, where the sound is formed; and of the pharynx, the buccal, and nasal cavities, which increase the sounds and modify their character. The air driven through the glottis by the lungs causes a vibration of the vocal cords, and sound is produced; it is increased by passing through the upper part of the larynx, the mouth, and nasal fossae; it acquires more or less volume, and its character varies according as these cavities are more or less open and free; but it does not change its nature as regards the tone. If, for example, the glottis emits a C, it may be heard as a muffled, a natural, or a nasal sound, according to the condition in which the cavities are through which it passes; but the tone does not change, it is always a C. Savants have held different opinions on the formation of sounds in the larynx, and upon the functions of the constitu- ent parts of the vocal organs. It being impossible to con- sider all these opinions, or the many experiments which have been made, the physical laws upon which they were founded, or which were opposed to them, we shall confine ourselves to a summary explanation of a few of them. We may be permitted, however, first to quote from the Magasin Pittoresque an anecdote which very well illustrates this point of our subject:— In 1798 Cuvier, in reading an essay on the voices of birds before the Academy of Sciences, remarked that some phy- siologists considered the larynx as a stringed instrument, others as a wind-instrument. An academician spoke and denied this distinction, affirming that everybody knew that the larynx was a wind-instrument. “You are in error,” im- mediately exclaimed another member, “it is a stringed in- strument.” These two theories have long divided philosophers. Galen looked upon the glottis as a reed; Fabricius Acqua- pendente gave a remarkable description of the larynx in the sixteenth century; he recognized the glottis as the essential organ of the voice, and compared its action to that of an 234 THE HUMAN BODY. organ-pipe; the air in breaking against it produced the sound, the glottis being less open for acute than for grave sounds. Dodart at the end of the seventeenth century, after hesi- tating between the vibration of the air or the vibration of the vocal cords as the origin of sound, compares the glottis to the mouth-piece of a hautboy. This great physiologist, in giving successive explanations, differing as widely as possible from each other, of the phenomena of the voice, has advanced or hinted at most of the theories which have been projected since his time. In 1741 Ferrein compared the vocal cords to the strings of a violin, the air acting as the bow. Biot could see nothing in the glottis which resembled a vibrating cord. “The simplest principles of acoustics,” said this illustrious physicist, “are sufficient to make us reject this strange opinion.” Muller advocated the theory of Ferrein against that of Biot, and yet he admits with him and with Magendie, Cagniard de la Tour, G. Weber, and other learned men, that the glottis is a reed with two membranous lips vibrating under the action of the air, and producing the sound by their vibrations. Savart compared the human glottis to a bird-catcher’s whistle surmounted by a supply-pipe, the cavities of the whistle being represented by the ventricles of the larynx, the openings by the interval between the vocal cords. The air vibrated, he thought, in traversing the inferior glottis, and divided into two columns against the superior vocal cords, which act as the stop in an organ-pipe, one of these columns of air in vibrating causes the resonance of the air in the ventricles, the other causes the vibration of the air in the vocal tube. In this last hypothesis it is not the vibration of the vocal cords, but that of the air which produces the sound. The theory of Savart on this latter point has been admitted by Longet and Masson. They believe the sound is pro- duced at the orifice of the inferior glottis the same as at the mouth-piece of wind-instruments, by the periodically variable passage of the air, which becomes the seat of a vibratory movement. The inferior vocal cords and the ventricles are MECHANISM OF VOICE. necessary for voice; the superior vocal cords should be con- sidered simply as a means of perfection in regard to the variation and modulation of sounds. Haller thought the epiglottis had no influence on voice, but that it permitted the swelling of the sounds into grave or acute without changing the tone, as did also Magendie and Biot. Longet thinks that it assists in the expulsion of the air by the nasal fossae in the production of very acute sounds, and that it may contribute to the timbre of the voice. The part of the pharyngeal, buccal, and nasal cavities in the production and modification of sound is differently stated by different authors. Savart thought that they regulated the height of vocal sounds; they have been considered as sup- plementary apparatus, and that it is to their peculiar reson- ance that the quality of the voice is due. The invention of the laryngoscope, by enabling us to see the interior of the larynx, has given us exact notions of its function. It enables us to verify the changes of form, the appearance of the glottis at different ages, and during the emission of the voice. This method of studying the larynx has resulted in late years in works of the greatest interest. M. Fournie considers the larynx as a membranous reed- instrument, and the mechanism of the voice, according to this learned observer, is as follows:—The vocal cords pro- duce the sound by their vibration, but do not vibrate in their totality. Fixed in front and at the back, at the level of their free border, they may be separated by the air, but not caused to vibrate in their entire thickness, while the mucous mem- brane which covers their free border, and which adheres only very slightly, detaches itself under the influence of the passing air, and thus forms the free vibrating portion of the reed. On this part only of the larynx the epithelium of the mucous membrane is of the same nature as that of the membranes in the other parts of the organism which are subjected to constant friction, as those of the articulations for example, and this gives it the power of resisting the friction of the air and of the vibrations which it causes. In the emission of the voice the vocal cords are stretched lengthwise and breadthwise. By producing mechanically this double tension 236 THE HUMAN BODY. of»the vocal cords in the larynx after death, M. Foumie obtained all the notes comprised between two octaves. The ventricles of the larynx are contracted and almost effaced during the emission of the voice; their function seems to be to moisten the vocal cords with a mucous fluid, and to aid in their movements, as well as those of the walls of the vestibule and glottis. The superior thyro-arytenoid ligaments adapt the tube formed by the vestibule of the glottis to the sounds emitted by the vocal cords. During the emission of sound their borders are never on the same line as the opening of the glottis; sometimes they approach the vocal cords, sometimes they almost disappear, or, on the contrary, enlarge into the vestibule of the glottis so as almost to fill it. By experiments on the dead subject, M. Fournie has proved that if these ligaments are drawn apart during the emission of a note by the larynx, the sound is lower by one tone; if only one is drawn aside it falls a semitone. The same result is produced in all the notes comprised in an octave. The epiglottis descends and nearly closes the superior opening of the larynx in grave sounds, and rises more and more as the sound becomes more acute. In the grave notes the soft palate permits the sounds to pass through the mouth and the nasal fossae, and in proportion as the voice is elevated it rises toward the posterior orifice of the nasal fossae, so as to prevent the echoing of the sound in these cavities, The nasal fossae give exit to the air when the disposition of the vocal tube is such, in the formation of certain letters, as more or less to hinder its passage through the mouth. The isthmus of the throat and the mouth have no influence on the note, but they perfect and modify its character, The trachea and bronchia, as well as the vocal tube, resound like a harmonic table, of which each part corresponds to one of the notes of the voice; and lastly, the intensity of the sound is in direct proportion to the force of the impulsion of the air, to the extent of the vocal cords put in vibration, and tq their tension. Formation of sounds in whistling.—The study of the for* WHISTLING. 237 mation of sounds in the glottis includes that faculty which man possesses of producing the sounds of whistling. This is certainly a much less important and less elevated function; but it is nevertheless very interesting to the physiologist, as it evidently nearly resembles that of the voice in its me- chanism. In order to produce the sound of whistling, the lips form a real glottis, which Dodart has named the labial glottis. The opening between the lips varies in form; in the grave tones it is nearly round in shape, and at its maximum in diameter; in the acute sounds it becomes elliptic, and is reduced to a narrow slit; the tongue regulates the intonation, by approach- ing more or less to the lower front teeth, touching them in the acute sounds, and withdrawing itself in the grave sounds. The space which separates the lips from the teeth varies also, in the same relative degree, for the same reason. The tongue sharpens the notes as in flute-playing; the grave sounds may be produced in drawing in the air, as in breathing; in short, the sound is acute or intense in proportion to the impulsion of the air by the lungs. If a disk of cork be placed between the lips, about one- fifth of an inch in thickness, with a hole about one line in diameter in the centre, the sound of whistling can be pro- duced through this aperture, and modulated the same as with the lips. Cagniard de la Tour, to whom we are in- debted for this experiment, concludes from it that the sound does not proceed from the vibrations of the lips; but has its origin in those of the air, excited by an intermittent friction against their walls. Longet and Masson compare the appar- atus for whistling in man to the whistle of a bird-catcher, and they find a close analogy between the labial and the laryngeal glottis. Fournie rejects this theory, and supposes the sound of whistling to be produced by mechanism analogous to that of an organ-pipe, the air breaking against the stop, which is represented by the upper incisors. Whichever doctrine we may accept, it is certain that the lips, or the perforated disk which replaces them, play an important part in the produc- tion and modification of sound in ordinary whistling, for 238 THE HUMAN BODY. when these sounds are made wfithout the aid of the lips, by a peculiar disposition of the tongue, it is only a single sound. It is the same in whistling through the teeth with the lips drawn apart, or when the tongue being doubled, and the fingers placed in the mouth, we produce an intensely acute sound, but which cannot be modulated. In the apparatus for whistling, as in that of the voice, the functional disposition, and its modifications in relation to the sounds emitted, takes place by movements under the control of the will, although they are, so to speak, instinctive. The changes in the dimensions of the orifices and of the buccal tube, in the tension of the walls of the mouth, the impulsion of the air, &c., are all effected instantaneously, and in such a manner as to produce all the notes. No instrument of music equals the perfection of this apparatus. Voice.—Voice is a sound produced in the throat by the passage of the air through the glottis, as it is expelled from the lungs. It is grave and strong in man, soft and higher in woman; it varies according to age, and is developed simul- taneously with the larynx, as has already been stated. It is alike in both sexes in infancy, but is modified in youth; then the voice is said to “change.” In the young woman it de- scends a note or two, and becomes stronger. In the young man the change is much more strongly marked. At the fourteenth or fifteenth year the voice loses its regularity, be- comes harsh and unequal, the high notes cannot be sounded, while the grave ones make their appearance, and the mascu- line character of the voice is established. A year is gene- rally sufficient for this change to be complete, and the voice of the child gives place to that of the man. Exercise of the voice in singing should be very moderate, if not entirely sus- pended, while this change is going on. Speaking voice.—Voice is divided into singing and speaking voice. One differs from the other almost as much as noises do from musical sounds. In speaking, the sounds are too short to be easily appreciable, and are not separated by fixed and regular intervals, like those of singing; they are linked together generally by insensible transitions; they are not united by the fixed relations of the gamut, and can only be noted with MECHANISM .OF ARTICULATE SOUNDS. 239 difficulty. That it is the short duration of speaking sounds which distinguishes them from those of singing, is proved by this, that if we prolong the intonation of a syllable, or utter it like a note, the musical sound becomes evident. And if we pronounce all the syllables of a phrase in the same tone, the speaking voice closely resembles psalm-singing. Every one must have noticed this in hearing school-boys recite or read in a monotone, and the analogy is complete when the last two or three syllables are pronounced in a different tone. Spoken voice is moreover always a chant more or less marked, according to the individual and the sentiment which the words express. The accentuation peculiar to certain lan- guages also gives the speech the character of a chant: to a French ear an Italian preacher seems always to sing. It is a chant also which is caused by all those inflections of the voice, which express our sentiments and our passions, and which vary with every thought. They extend from the feeble murmur, which the ear scarcely perceives, to the piercing cry of pain. Affectionate, sympathetic, imperious, or hostile, they sometimes charm, sometimes irritate, and always move us. It is related of Gretry, that he amused himself by noting as exactly as possible the “Bonjour, mon- sieur!” (Good day, sir!) of the persons who visited him; and these words expressed by their intonation, in fact, the most opposite sentiments, in spite of the constant identity of the literal sense. Baron, the comedian, moved his audience to tears by his recitation of the stanzas of the song, “Si le roi m'avait dotme Paris sa grand'ville"—If the king had given me Paris his great city. Mechanism of articulate sounds.—Writers are not in accord in explaining the pronunciation of letters, that is, the me- chanism of articulate sounds; but, whether grammarians or physiologists, they all class the letters according to the parts of the vocal apparatus which co-operate in their pronuncia- tion, as labials, dentals, gutterals, &c. The division of the signs of the alphabet into vowels and consonants expresses the universal idea that a vowel is a voice, a sound perfect in itself, while a consonant cannot be sounded without the help of a vowel associated with it. The consonants, indeed, do 240 THE HUMAN BODY. not make even a noise, a murmur; but they give a peculiar character to a vowel sound. We find something in the playing of an instrument analogous to this function of a con- sonant. If we pinch the string of a violin, or strike a bell with a hammer, a sound is produced which we imitate with the voice by prefixing a t or d, as dinn, tinn; if the string or the bell be made to vibrate with the bow, the sound as re- produced by the vocal organ is preceded by the letters cr, whence the imitative French word C7'in-crin. The hammer and bow are the consonants, the note of the bell or the violin is the vowel. Helmholtz has demonstrated, as we have already observed in speaking of hearing, that the timbre of sounds is deter- mined by the harmonics. He was able by means of ingeni- ous instruments to decompose the sounds which only produce a single sensation, and which seem to us simple, though they are really composed of elementary sounds more or less numerous. This analysis enabled him to discover the laws under which the quality of the sounds is constituted which are emitted by the glottis, and resound in the vocal tube under the form of vowels. Among the elementary sounds composing the sound emitted by the glottis, the vocal tube exalts a particular one by preference, and it is this one which gives to the vowel its characteristic timbre. The vocal tube disposes itself in a special form for each vowel. It lengthens or shortens, dilates or contracts; it places itself, in a word, in conditions essential to the strengthening of the sound which determines the timbre. Each vowel is there- fore characterized by a note, but each one has a particular affinity for certain notes; it is sometimes difficult, or even impossible, to give such a note on another vowel than that with which it corresponds, and thus singers are sometimes forced to substitute one vowel for another. In seeking in the different qualities of the voice, and especially in the vowels, for the seat of the resonance of sounds in the buccal tube, and the parts which co-operate in this resonance, Fournie has made a classification of the letters, which he claims to have rendered more exact and more anatomical than any of his predecessors. The tongue, THE VOWELS. THE TONGUE IN SPEECH. 241 the teeth, the lips, and the throat, are the parts by which most of the letters are formed. To these Fournie adds the palate for some of them, and the glottis for the h, which, until recently, was classed among the gutturals. It is un- necessary to remark that in the study of the vowels in their relation to the mechanism of articulate sounds, the laryngo- scope has given invaluable aid. The manner of forming the vowels differs from that of the consonants in this respect: the parts which co-operate in the formation of the vowels must be fixed during the utterance of the vowel, while the articulation of the consonants is effected by a movement of the parts essential to their forma- tion. Thus is enunciated by suddenly opening the lips which have been previously closed; and in the same way the other consonants are pronounced by some movement; and this movement is in accordance with the disposition of the parts necessary to the utterance of the vowel which precedes or follows the consonant. Of all the parts which serve for the articulation of sounds, the tongue is the one which plays the principal part, and therefore it gives its name to the whole group of modulations of the voice which constitute language, or as we sometimes say, a tongue. And yet observation teaches us that the volume of the tongue may be greatly diminished, or may even exist only in a rudimentary state, without its being im- possible to speak. De Jussieu relates that he saw a girl fifteen years old, in Lisbon, who was born without a tongue, and yet she spoke so distinctly as not to excite the slightest suspicion of the ab- sence of that organ. The Transactions of the Royal Society of London (1742) contain a report of the commission which was appointed to investigate a case of a similar nature. It was a woman who had not the slightest vestige of a tongue, but who could, notwithstanding, drink, eat, and speak as well and as dis- tinctly as any one, and even articulate the words in singing. Other instances have been known where individuals, after losing a portion of the tongue by accident or disease, have again been able to speak after a longer or shorter time. 242 THE HUMAN BODY. Singing.—We generally recognize two series of sounds in the voice in singing, one comprising the grave and semi-acute notes, and the other the high notes; this is called the register of the voice, one is the chest register or voice, and the other the head register or voice, or falsetto. Some writers admit a third series or mixed voice, which resembles a diminutive chest-voice, in quality and in the disposition of the glottis when it is produced. We have indicated already the principal physiological theories on the formation of the voice in general: there is no less diversity in opinion in regard to the falsetto. Accord- ing to Muller, it results from the vibrations of the edge only of the vocal cords; other authors incline to the notion that the glottis no longer vibrates like a reed, but like the mouth- piece of a flute. M. Segond makes the falsetto voice to come from the superior glottis exclusively, that is to say, from the vibration of the superior thyro-arytenoid ligaments. This opinion has been refuted by the experiments of M. Longet. And lastly, Weber and Longet attribute the origin of the falsetto notes to the harmonics of the vocal cords. The laryngoscope enables us to study the glottis during the emission of the chest-notes, and even of the falsetto notes, but observers are not agreed upon the phenomena which they have observed. According to Fournie, the chest, the falsetto, and the mixed Fig. 45.—The glottis and vocal cords. A, B. Glottis in the chest-voice. •C. Glottis in the falsetto voice. voice, are all produced by the vibration of the mucous fold which covers the free border of the vocal cords. CHEST-VOICE. FALSETTO VOICE. 24 3 In the chest-voice the larynx descends very low and the vocal cords are horizontal and stretched simultaneously in length and thickness; the superior thyro-arytenoid ligaments project, and partly hide the external border of the vocal cords; the epiglottis is slightly inclined over the opening of the larynx; the transverse diameter of the glottis is very small and linear, and the edges of the vocal cords are very thick and rigid. The larynx rises in proportion as the tone grows higher, the epiglottis straightens again little by little; the plane of the vocal cords inclines; the orifice of the glottis shuts progressively from behind forward, and consequently the vibrating portions diminish in length, while at the same time the tension increases. In the falsetto, the larynx is carried upward and backward against the spinal column, the soft palate rises, and its posterior pillars approach each other, the ventricles of the larynx are obliterated, the vocal cords are wholly visible, and their borders are in contact for half their length at least. The glottis is therefore closed behind, and its orifice, very much smaller than it was during the utterance of the chest- notes, diminishes progressively as the notes grow higher. In the mixed voice the glottis is open throughout its whole length, and its transverse diameter is greater than for the other registers. According to M. Battaille, in the chest-voice the cords vibrate throughout their extent, the opening of the glottis is rectilinear, there is less tension in the walls of the vestibule and glottis, and on the contrary more in the vocal cords, than in the falsetto voice. In the falsetto voice, the arytenoid cartilages embrace each other by a sort of reversion in the two upper thirds of their internal surface, the glottis then being ellipsoid in form and more open behind than in the chest-voice. This form of the glottis, which is attributed by the eminent artist to the falsetto voice, is precisely the same that M. Fournie has seen in the mixed voice, which requires less effort. M. Battaille is the only author who notes the joining of the arytenoid cartilages by their internal surface: others 244 THE HUMAN BODY. admit that they approach each other at their borders only so as to close the hollow which separates them behind, and to cause the vocal cords simultaneously to face each other through part of their length. M. Mandl has kindly communicated to us the result of his numerous observations on this subject; according to his opinion, in producing the chest-voice the arytenoid cartilages are separated behind; in the falsetto, in a normal condition, they approach and join each other on their posterior border, which causes the vocal cords to face each other—as M. Fournie also says—behind, while they remain separated in front by the slit of the glottis, which has become elliptic and much shorter; in certain persons, however, we observe something analogous to the joining of the arytenoid cartilages which M. Battaille describes, and which belongs to the normal condi- tion of the larynx. In fact, when one of these cartilages is anchylosed at its point of union with the cricoid, and does not move to meet its congener, the latter supplies the defect and covers it by a sort of overlapping. Timbres (the distinctive quality of voices).—Besides that quality which is peculiar to each individual, the voice may have several others, some of which, as purity, are due to the perfection of the entire vocal apparatus, and others, as the hoarse nasal or guttural quality, arise either from the unskil- fulness of the singer or from some change in the organ. There are two forms, however, remarkable because they may be produced at the will of the artist, these are the muffled voice and the clear voice. Their names indicate their nature. In the muffled, the sound is rounder, more velvety, and re- sembles less the sound of a reed; the pronunciation of the letters is less distinct and sharp, and the noisy vowels, like the a and e, incline to the timbre of o and u. In the clear voice the sound is piercing, somewhat noisy, and less agree- able to the ear. This high key is more common among the northern nations of Europe, while the graver one is ordinarily adopted by the singers of the south. It is generally admitted that the muffled voice is caused principally by the immobility of the larynx when as low as possible, and in fact the larynx is usually in that position in DIAPASON OF VOICES. 245 singing in this tone: though M. Segond has occasionally seen the larynx as high as possible when this voice was produced. This voice seems to depend on the narrowing of the buccal orifice and the isthmus of the throat, coincident with as great a dilatation of the mouth as possible, a disposition which muffles and veils the resonance of the sound in the cavities of the pharynx and vocal tube. If in singing the letter a, with the mouth wide open, the lips be made slowly to approach each other, and pressing them together without extending them, the sound passes from the clear to the muffled tone, and the vowel a sounds like o. This move- ment of the lips was very apparent in Mademoiselle Giulia Grisi in certain high notes, but even her admirable voice was insufficient to make us pardon her for thus marring features worthy the pencil of Raphael. Diapason of voices.—Male voices are divided into bass, baritone, or singing bass, and tenor. The voices of women are the contralto, which corresponds to the baritone, mezzo- soprano, and soprano. The extreme limits of these voices are, for the base the G below the CC; for the soprano, the F in alt. or the F cf the last octave but one of the piano. Mozart heard a singer at Parma who gave the C above. Ordinary voices do not go beyond two octaves, but celebrated artists have compassed three and even three and a half octaves. Fortunately the prodigious compass of-such a voice is not necessary to entrance a real lover of music. The artist is always sure to triumph when to correct intonation he joins sympathetic quality, and, what is rare, that good taste which will not permit him to sacrifice the expression and the charac- ter of the music to a desire to shine. Instrumental music awakens in us the most profound emotions; we are transported by Baillot’s violin or the orchestra of the Conservatory, but no instrument can equal the impression produced by a beautiful voice; no instrument can pretend to those sounds, soft or sharp, passionate or purely peaceful; none has that variety in quality, those accents which fascinate us and plunge us into ecstasy. In- struments and their voices are prodigies of art, but the human 246 THE HUMAN BODY. voice is living sound, as the glance of the human eye is animated light. Ventriloquy.—Those who created the word ventriloquy evidently believed in a voice produced by some other organ than the larynx. But in these days every one knows that what is called ventriloquy consists in concealing the origin and nature of the voice. The ventriloquist speaks with his lips nearly closed, and he so modifies the sound of his voice as to make it seem like that of a child, or a woman; he makes us believe that it comes from a chimney or a cavern, from the far distance, from the sky, or from the bowels of the earth. In the last century the French Academy of Sciences appointed a commission to study the phenomena of ven- triloquy in a man exceedingly skilful in the art, but acting in good faith and making no mystery of his power. It is to the uncertainty as to the direction of the sounds, and to the errors into which we are easily led by the organ of hearing, more than to anything else, that the ventriloquist owes his success. They may deceive ignorant and credulous people, but they are generally content to amuse their auditory, and in that they succeed. CHAPTER XVII. Physiognomy; study of it in works of art.—Movetnents of expression, their seat.—Colouring of the skin; paleness, redness.—Expression of the muscles; effort, muscles of the face.—Physiognomy of the senses.—Ex- pression of the eyes, vision, easy or difficidt, blindness.—Expression in the act of hearing, easy or difficult, hearing of an orator, musical hear- ing.—Expressions of smell and taste.—Expressions relating to the touch. Physiognomy is generally considered as the expression of the features of the face, but it is not so limited in its elements. Attitude, repose or action, fulness or slenderness of form, proportion, bold or graceful relief, and lastly, health or disease have, in the entire contour of the body, a significa- tion which completes that of the face. Physiognomy, there- fore, is the expression which form and motion give to the body. In the Caryatides of the temple of Erectheus, we admire the calmness and grandeur, the majesty of the draperies, the simple and grave lines of the figures which support without effort the marble that seems not to weigh upon them. In the Caryatides of Puget at Toulon, we see the display of power in the violently contracted muscles, in the arms which seek to relieve the head from the burden, under which the whole body stiffens, and is about to succumb! Compare a Silenus to the Farnese Hercules. In the old friend of Bacchus, the form is heavy, obese, and flaccid; it is the abjectness of drunkenness; in the other, the powerful muscles, the firm proud attitude, the noble bearing, declare the tamer of monsters and of vices. The Diana Huntress, with her sure and rapid step, is the enemy of idleness and repose; her manner is severe, and human passion has never 248 THE HUMAN BODY. throbbed in her virgin breast. The Venus Anadyomene, graceful, timid, uncertain in manner, shows much more of feeble humanity. It is to this profound sense of physiognomy in the great artists that we owe the lively emotion which the sight of their master-pieces produces, and the ancients do not, in our judg- ment, merit the reproach cast upon them for the want of expression in their heads. The Greeks, for whom statuary was especially a monu- mental art, gave to their faces the calm and dignity of gods, rather than human passions; therefore the action was quiet, the lines simple, and the expression of the head in harmony with that of the body; but when they turned to dramatic subjects, the few examples which remain enable us to judge that they were not less admirable in works of this nature. They no doubt guarded against empty grimaces, and it was principally in action that they placed the expression; but can we not read disdainful anger on Apollo’s lip? and is not pride stamped on the features of the Venus of Milo? does not watchfulness careless of danger look from the eyes of the Gladiator, and love, almost paternal, rest on the simple, spiritual head of the Faun and Child? Do we not feel a mother’s pain in the Niobe, see the suffering and the prayer in the look of the Laocoon? The sculptors of the Renais- sance imposed the same rule upon themselves before the works of antiquity were revealed to them. They were fol- lowed also by the painters, although for them these rules were less inflexible, and yielded more to details in an art more nearly allied to living nature. The artist finds in anatomical physiology, and in physi- ognomy, useful hints and precise principles; but he rightly abstains from a rigorous and servile application of them, for though the physician may find it important to know the exact function of a certain muscle, the sculptor and the painter must confine himself to the true but not realistic expression caused by its contraction. To go beyond this, which is very easy, is to arrive at that repugnant reality which certain masters of the Spanish school have not hesitated to adopt. MOVEMENTS OF EXPRESSION. 249 Caught from nature by photography, physiological expres- sion belongs to science, and is invaluable to it; but the artist, like the poet, remembers that his task is to suggest only, leaving that to be divined which could not be said or de- lineated without revolting the spectator. The movements from which the physiognomy results are always harmonious, and it is to their unity and concordance that our impressions are due. The least negligence in this respect shocks us in a picture like a false note in an orchestra, while our admiration is unbounded for a work of art in which nothing is forgotten. Lethiere paints Brutus at the execution of his sons; the face and attitude of the consul express only merciless severity, the folds of the toga are faultless, but the contracted hands reveal the agony of the father under the inflexibility of the judge. David represents him to us at the moment when the bodies of his sons are brought to him. The expression of the head is fierce, the feet, the left hand, and the whole body are strongly contracted; the right hand alone is carelessly bent, and takes no part in this convulsive state. Movements of expression.—Gratiolet, in his treatise on physiognomy, groups under this term all the modifications of form, of colour, &c., which manifest themselves on the sur- face of the body, under the influence of the most widely dif- ferent causes. These movements are direct, sympathetic, or symbolic. In looking at an object, the action of the eyes, and the animation which they give to the expression, are direct move- ments; but if we fix the attention, the body takes part in the action of the eyes, inclines forward, and seems to wish to move toward the object observed; these are sympathetic movements, and when thinking of extreme cold we shiver, this is a symbolic movement. The limbs, the trunk, and the head, that is to say, the gestures and attitude, contribute greatly to complete the physiognomy, as has already been remarked; the cavities, on the contrary, take no part in it, the seat of expression is in the skin, the muscles, and the eyes. Colour of the integuments.—The skin, particularly on the 250 THE HUMAN BODY. face, takes the greatest variety of tints, from a violet red to a livid pallor, under the influence of physical or moral causes, which quicken or retard the circulation of the blood; but besides the colouring of the face, it is the movement of the muscles, and the expression of the eyes, which gives it a definite signification. In a feeble man the motion of the heart is retarded, or sometimes hurried, as if to make up in the number of its beats for their want of energy; the blood is not sent to the surface in sufficient quantity, and the face is pale; but the languor of form and look denote the cause of the pallor. Cold causes contraction of the tissues, the circulation is impeded on the surface of the body, the features seem pinched, the lips, nose, and cheeks take a livid leaden hue; chills sometimes shake the limbs and the lower jaw; on the face, as well as over the whole body, the integument is the seat of a painful constriction, but the eyes only express suf- fering. When an assassin reproached Bailly with being afraid, he replied, “No, my friend, I am cold.” Violent exercise, joy, confusion, fury, all quicken the action of the heart, and precipitate the movement of the blood through the teguments, which relax or yield to the impulsion of the fluid; but the open mouth, the dilated nostrils, the heaving chest, the strong and rapid respiration, express, as well as the features, an agitation purely physical, and we are not tempted to assign a moral cause for the flush which follows muscular effort. The serenity and expansion of the features, the smile, the brightness and happiness ex- pressed in the eye when the face is flushed with joy, have nothing in common with the downcast eyes, the falling lip, the muscular weakness, and embarrassed manner of the man who reddens with confusion. We easily recognize also the haggard and threatening eyes, the knitted brow, the com- pressed lips, and the violently contracted or strongly agitated muscles of a man who is a prey to anger, and in whom the blood, at first impeded in its course, now in its reaction forcibly injects the integuments. We see by these few examples that the colouring of the skin, varying under the influence of the most diverse causes, EXPRESSION OF THE MUSCLES. is an important element in physiognomy, though its significa- tion is doubtful, and must be completed by the expression of all the other features, or of the body. Expression of the muscles.—The action of the muscles and the movements resulting from it, have, on the contrary, a special character, whether taken as a whole or individually, in certain muscles of the face. In making an effort, these movements embrace the whole muscular system, and the expression which results is more characteristic. When re- produced by the plastic arts, it strongly impresses the spec- tator, who feels a sort of sympathetic contraction, but which soon fatigues and irritates like all inconstant attitudes. The muscles of the face by their single or combined con- traction cause the most widely differing expressions, and correspond to all the sentiments, whether simple or complex. Thus, the muscle of the forehead raises the brow in attention, admiration, or astonishment; that of the eyebrow contracts it with pain; the great zygomatic raises the angle of the lips in laughing; the triangular muscle of the lips draws them downward in weeping; other muscles co-operate in expres- sing combativeness, fear, anger, irony, &c., in short, the slightest phase of feeling is reproduced in the features, by the slight or energetic contractions of the muscles, wrhich carry with them the skin to which they are intimately united, wrinkling or distending it. An eminent physiologist, M. Duchenne of Boulogne, particularized the action of these muscles in expressive movements. But though some of them may play a distinct part in the mimicry of the face, others always join in the movements when the sentiment or sensation acquires a certain vivacity; thus the muscle of the eyebrow alone may express a certain degree of suffering, but when it becomes intense the eyelids close, the nostrils dilate, and other signs beside prove the simultaneous action of the different muscles. For the physiologist and the physician, rigorously exact facts of this sort have the greatest value; but they are of less consequence to the artist, who must repre- sent not only the muscle but the whole of the parts, near or distant, to which its action extends. If it is necessary for him to understand anatomy and the function of the muscles 252 THE HUMAN BODY. in order to reproduce exactly their projection during move- ments of the body and limbs, it is much more the study of the living model which guides him when endeavouring to render the expression of the features; and if he fails in this, it is less from ignorance of anatomy than from lack of senti- ment or incapacity. It is remarkable also how much opinion varies in regard to works of art. Each individual brings to their examination the predisposition of his studies; and if the naturalist may sometimes criticize justly, sometimes also in his judgments the artistic sentiment is replaced by the rigorous formulas and exact notions of science; he does not consider that the artist should avoid being as exact as a Chinese copy, and that a profound artistic sentiment should be completed in its expression by its counterpart in the spectator. And lastly, a savant may be a man of genius, and still lack all artistic sentiment. Gratiolet, that fine and noble mind, could see nothing in Raphael’s “Creation” but a “deplorable work—a furious old man striving with feet and hands to separate two thick clouds.” The man who criticized one of the most admirable master-pieces of art in these terms, was a scholar of the first order, a great physiologist, and has left a work on physiognomy itself marked by the most delicate percep- tions and the most profound study. Physiognoj?iy of the senses.—The more the mind predomin- ates over matter, and separates itself from it, the more elevated will be the expression of the physiognomy. Faith and prayer transport man into an order of ideas purely intellec- tual, and give to the features a character in which sense has no part. Resignation attaches itself to the terrestrial affec- tions, and mingles with them an element of pain which, whether moral or physical, is always expressed by the marks of suffering. The recital of a dishonourable action adds a shade of disgust to indignation, and the moral impression seems to affect our organs as they are affected by material impressions. This indirect and, as it were, figurative action of the senses on the physiognomy, mingles incessantly with movements of another order, and often expresses itself with as much energy EXPRESSION OF THE EYE. 253 as the real sensations. When these latter are acute they govern the expression almost as completely as the most violent passions, and may, like them, impress upon the features the sign of an infirmity, a fault, or a vice. Our senses, as has been already stated, are united by the constant relations of complementary or sympathetic functions, as the sight and the touch, the sight and the hearing, the taste and the smell frequently control or complete each other by their simultaneous action, and often all the senses are in action at once. This coincidence of the sensations reflected by the physiognomy is a source of varied and complex expres- sions, as much so as the nervous impressions transmitted to the brain can be, and to describe the physiognomy of any one sense it is necessary almost to draw all the features of each of the other senses. The eye gives an expression of intelligence to the physiog- nomy, and reflects the thought more than any other organ of the senses. It is especially through the eye that the passions reveal themselves—that joy or sorrow, courage or fear, envy, love, or hate, frankness or duplicity, are expressed on the features; therefore, says one, if you would know a man’s sentiments, read them in his eyes. The movements of the globe of the eye, its fixity, and the contraction or dilatation of the pupil, infinitely vary the ex- pression of the face, and give to the whole of the features a decided meaning; but to the mimic language of the globe the eyelids bring an important and often decisive addition. When sight is good, attention is expressed without effort: the face is calm; the eyelids, moderately open, show the globe of the eye, which fixes itself on the object, follows it in space, and acts, in short, as do all the organs in a normal condi- tion, without any consciousness; but if, on the contrary, it is necessary to distinguish an object which is perceived with difficulty, the eyelids approach each other, the eyes twinkle, and the immobility of the body, the suspended respiration, denote more marked attention; the brow contracts, and the features wear an expression of pain, which sometimes gives short-sighted persons a forbidding character. The face of a blind man is rarely sad, but the immobility 254 THE HUMAN BODY. of the features, which are so animated by vision, produces a painful contrast. In hearing the attention is also more or less characteristic. If we wish to distinguish a distant noise, or perceive a sound, the head inclines and turns in such a manner as to present the external ear in the direction of the sound, at the same time the eyes are fixed and partially closed. The movement of the lips of his interlocutor is the usual means by which the deaf man supplies the want of hearing; the eyes and the entire head, from its position, have a peculiar and painful expression of attention. In looking at the portrait of La Condamine it was easily recognized as that of a deaf person. Even when hearing is perfect the eyes act sometimes as auxiliaries to it; in order to understand an orator perfectly, it seems necessary to see him—the gestures and the expres- sion of the face seem to add to the clearness of the words. The lesson of a teacher cannot be well understood if any obstacle is interposed between him and the eyes of the listen- ing pupil. That species of intoxication which we term ecstasy is ex- pressed on the features of a musical amateur on hearing a master-piece; all the powers of attention are concentrated on one organ; the features are slightly contracted by the smile or other expression in accordance with the character of the music; the eyes are half shut or closed, though sometimes they are fixed agonizingly on the singer in some difficult pas- sage, or enthusiastically on some leader, like Habeneck, leading his orchestra with a passionate gesture. If a piercing, harsh, or discordant sound strikes the ear, the eyes close, and at the same time the lips, the nose, and the whole face contract as if the other senses were combining to protect the hearing from the pain it endures, and against which its immovable organ cannot defend it. It is impatient suffering, and no longer the charm of a delicious sensation. Under the influence of the smell and the taste the expres- sion of the physiognomy is extremely varied, and reflects perfectly the delicacy or the force of the sensation, the degree of pleasure which accompanies it, or the horror and repugnance which it excites in us. Here, as in hearing, EXPRESSION OF TOUCH. 255 sympathetic movements are combined with the direct move- ments produced in the affected organs. When taste is con- cerned, it is very rare that they are not confounded, for almost always the aroma is combined with the taste, and either perfects its excellence or renders it still more insup- portable. But whether it expresses satisfaction or antipathy, the play of the physiognomy in sensations of this nature has nothing elevated in it, rather it unveils a certain abasement of the individual; hearing and sight are in immediate con- nection with the most precious faculties of the mind, while taste and smell appeal specially and directly to our material appetites. But we must not therefore judge too severely the elation of a gourmand seated at a well-spread table. The best compliment he can offer to his host is to show a worthy appreciation of an exquisite repast. We shall see the spirit of our guest, vivified by the sweet influence, shine from his eyes with a light which will easily enable us to pardon what little of sensuality there is in his mouth. It is by the sense of touch that we acquire clear ideas of the form of bodies, of the distance, resistance, weight, tempera- ture, &c. It confirms the testimony of our eyes, and joins its impressions to those of sight often in an effective manner, and always through the mind. The touch produces expressive movements in us then, in connection with our tactile or visual sensations; and these movements are sometimes direct, as in effort, and sometimes sympathetic and an indication of the impressions produced on the skin. Lastly, touch is the origin of symbolical move- ments by which we express the thought of bringing an ob- ject near, or putting it away from us. To this sense are re- lated the gestures which accompany our words. We affirm a fact by so placing the hand as if we would rest it firmly on a body; we deny by a gesture putting the false or erroneous proposition away from us; we express doubt by holding the hand suspended, as if hesitating whether to take or reject. When we part from dear friends, or greet them again after long absence, the hand extends towards them as if to retain, or to bring them sooner to us. If a recital or a proposition is revolting, we reject it energetically in gesture as in thought. 256 THE HUMAN BODY. In a friendly adieu we wave our good wishes through space to him who is the object of them; but when it expresses enmity, by a brusque movement we sever every tie. The open hand is carried backward to express fear or horror, as well as to avoid contact; it goes forward to meet the hand of friendship; it is raised suppliantly in prayer toward Him from whom we hope for help; it caresses lovingly the downy cheek of the infant, and rests on its head invoking the bless- ing of Heaven; in a word, the touch, real or imaginary, is constantly adding a feature to the physiognomy. THE END. €bucationol tet - Uoohc AND of FOR THE fe of £ totals in Skoals, gcataus, and Colleges PUBLISHED BY (Jljarlfps $rrii&ner %• (Jo., 654 BROADWAY, NEW YORK. Messrs. Charles Scribner & Co. invite the attention of Instruc- tors and of Students in Schools, Academies, and Colleges to the following selection from their list of publications, comprising numer- ous standard Text-Books, adapted for use in institutions of learning of all grades, as well as works indispensable for purposes of refer- ence. Very many of the text-books named are already in use in Yale, Harvard, Princeton, Williams, and other of our leading Colleges. Of those published more recently, special attention is called to Prof. Porter’s Mental Science, Prest. 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Ethical philosophy engaged his mind for at least threescore years, and was his favorite study. During nearly forty years he leCtured on the subjeCt at Princeton, and these leCtures were the basis of this succinCt manual. The treatise is elementary in its character. It is intended to lay foundations and elucidate principles ; in other words, it is upon the Philosophy of Morals The great simplicity and clearness of the author’s style will commend it as a suitable text-book for colleges, theological seminaries, and other institu- tions of learning, for which purpose indeed it has for many years been widely used. ©xterrrpore .Speaking. 13 AUTAIN, PROF.—Art of Extempore Speaking (The). Hints for the Pulpit, the Senate, and the Bar. By M. Bautain, Vicar-General and Professor at the Sorbonne. Edited by a Member of the New York Bar. With Additions, Rules of Debate, etc. One volume, i2mo, cloth . . . . $1.50 Himself one of the most eloquent of Frenchmen, Prof. Bautain in this manual lays down the rules and principles which must guide those who expert to gain distinction as ready speakers and debaters. The treatise is divided into two parts. In the first part, the “ exposition of the subject,” the qualifications necessary for public speaking, “ the mental aptitudes ” for it, and “ the physical qualities of the orator, natural and acquired,” are discussed. In the second part, M. Bautain treats at length of “ the divi- sion of the subjeCt,” “ its conception,” “ the final preparation before speak- ing,” both intellectual, moral, and physical, and of the discourse itself, with its exordium, peroration, etc., etc. The translator of the volume, a distin- guished member of the New York Bar, has admirably adapted it to the use of the American public by adding several chapters, giving some practical directions regarding the use of the voice in public speaking, and summarizing the more important rules of order and debate. The treatise is popular in style, and direCt in its treatment of the important subjeCt which it discusses. The American editor very justly remarks in the preface that his work “ has no counterpart or rival in the English language, so prolific of treatises upon rhetoric and the separate portions of the arts of composition and deliv- ery.” Charles Scribner & Co. s Text-Book r, etc. 3 ©nglish rSLarxQuetge. /'""‘LARK (N. G.).—An Outline of the Elements of the English Language, for the Use of Students. By N. G. Clark, Professor of Rhetoric and English Literature in Union College. One volume, i2mo, cloth $i 25 Originally prepared as a manual for the use of students in the college with which its author is connected, this volume, from its method, will attrad 'he interest of the general reader. It is peculiar in aiming to bring out more folly than has hitherto been done the language and the physical and intellectual elements of English character. The influence of the Celtic and Roman, the Anglo-Saxon, Danish, and Norman elements respectively, are traced succinctly, and the modifications through which the language has passed are clearly sketched. The volume closes with a number of extracts from the authors of the different periods, which serve as specimens to illustrate the changes of the language under the influences referred to. EBooks. /^OLLIER.—A Bibliographical and Critical Ac- — count of the Rarest Books in the English Language (alpha- betically arranged) which during the last fifty years have come under the observation of J. Payne Collier, F.S.A. In four volumes, cloth $1200 These volumes are the result, or rather they are one of the results, of fifty years’ untiring labor, by one of the most conscientious, industrious, and per- severing of English bibliographers. In the preface Mr. Collier states that during his whole life—and he was nearly eighty years of age when this work was produced—he has been a diligent reader of all works connected with early English literature, and that it has been his custom to lighten his severer labors by making extracts from and criticisms upon these productions whether they may have been in prose or verse. These volumes have been mainly derived from the immense mass of material accumulated in this way. The student of English literature can nowhere else find such a remarkable collodion as this of the interesting, the curious, and the rare. *** The remainder of the edition of this valuable work, having passed en- tirely under the control of Messrs. Charles Scribner & Co., is now offered at a price much lower than that originally fixed. CRITICAL NOTICES. “To the historian of literature a pioneer like Mr. Collier is of the greatest use. Such ati historian would look through Mr. Collier’s collection and see at once from his account wind books would be useful for his purpose, and what would not.”—London Saturday Rcvuw. Vie now moormiii unt* ;»et repaDiisned in tlus eouncrv — Koutui Tihn 4 Charles Scribner & Cols Text-Books, ett. ant) ©Herm^irg. Y'-'OOKE.—Religion and Chemistry ; or, Proofs op God’s Plan in the Atmosphere and its Elements. De.ivered at the Brooklyn Institute, Brooklyn, N. Y., on the Graham Foundation. By Josiah P. Cooke, Jr., Irving Professor of Chemistry and Mineralogy in Harvard University. One volume, crown 8vo, cloth $2 50 The chief aim of these ledures is to show that “ there is abundant evidence of design in the properties of the chemical elements alone, arid hence that the great arguments of natural theology rest upon a basis which no theories of organic development can shake.” It will be seen, therefore, that they diredly refute the Darwinian theory as to the origin of species, at least from one point of view. The arguments advanced are some of them novel, and all exceedingly forcible. In consequence of the large popular de- mand for the work, a new and revised edition, in cheaper form than that in which it originally appeared, has been issued. “Viewed as a scientific book alone, on its special subject, we know of none that can come in competition with ‘Religion and Chemistry,’while the polished and elegant style of the author, and his earnest conviction, everywhere apparent, that the truths he explains owe their chief value to the glimpses they afford us of the Divine economy of creation, impart to it a peculiar and signal value.”—New York Times. CRITICAL NOTICES. QPhilosojrhg. /'-''OOLEY.—A Text-Book of Natural Philosophy. An accurate, modern, and systematic explanation of the Elemen- tary principles of the Science, adapted to use in High Schools and Academies. By Le Roy C. Cooley, A. M., Professor of Natural Science in the New York State Normal School. One volume, i2mo| with over 150 illustrations $1 50 In dealing with the various problems coming within the range of the science which he expounds, Prof. Cooley uniformly proceeds from the cause to the effed, thus pursuing the only natural method, and that which is me simplest In form the work is stridly logical, and in matter it is concise, dear, and distind, while it is brought down to the latest developments of the science. CRITICAL NOTICES. “I think it will be found to be well adapted to the purpose for which it was written. Prof SCHANCK, Princeton College, New "Jersey. “ I am pleased with the work, and have recommended it to the noti:e of teachers of that department in the Maine State Seminary, connected with the Colege.”—Prof. R. C STANLliY. Bates College. Lewiston, Me. Charles Scribner & Cols Text-Books, etc. 5 ,-SLiterctfure. C~"RAIK.—A Compendious History of English Lit- erature, and of the English Language from the Not man Conquest. With numerous Specimens. By George L. Craik, LL.D., Professor of History and English Literature in Queen’s Col- lege, Belfast. Two volumes, 8vo ; half calf, $12 00; cloth . $7 50 In extent and exhaustiveness of reseat eh, in breadth of scope as well as in minuteness and accuracy of detail, Professor Craik’s great work stands without a rival among similar treatises. Prof. Craik’s method of treating this subject is peculiarly his own. Combining the history of English litera- ture with that of the English language, he takes the ground that “ in the earliest state in which it is known to us the English is both a homogeneous and a synthetic language,—homogeneous in its vocabulary, synthetic in its grammatical structure. It has since, though of course always operated upon, like everything human, by the law of gradual change, undergone only two decided revolutions; the first of which destroyed its synthetic, the second its homogeneous character. Thus, in its second form, it is still a homogeneous, but no longer a synthetic language ; in its third it is neither synthetic nor homogeneous, but has become both analytic in its grammar and composite in its vocabulary. The three forms may be conveniently designated :—the first, that of pure or simple English ; the second, that of broken or semi-English ; the third, that of mixed or compound or com- posite English. The first of the three stages through which the language has thus passed, may be considered to have come to an end in the eleventh century; the second in the thirteenth century ; the third is that in which it still is.” Prof. Craik’s treatise is devoted to this “ third form of the lan- guage,” as he defines it, and which he regards as commencing with the poetry of Chaucer, in the middle of the fourteenth century. Following down English literature from the time of Chaucer, he gives us accounts not only of writers known to all scholars, and the names of the majority of whom still live, but he furnishes specimens of the productions of a large number long since forgotten, but whose style illustrates most forcibly the transi- tions through which our language has passed. In fulness of information and in critical accuracy Prof. Craik’s work, as we have already said, sur- passes all that have preceded it in this fascinating field of investigation. CRITICAL NOTICES. “ Professor Craik’s book, going as it does through the whole history of the language, pro- perly takes a place quite by itself. We have philological books treating of our earliest literature, but we do not know of any book which, like the present, embraces both. Tht great value of the book is its thorough comprehensiveness.”—London Saturday Review. “As a record or chronicle of English literature, Mr Craik’s book is by far tlif beta that has yet been published.”—North A merican Review. 6 Charles Scribner & Cols Text-Books, etc. ctrxb QUheioric, TAAY.—Art of English Composition (The). By Prof. Henry N. Day. One volume, 121110, cloth. Pr:ce, $1 50 Art of Discourse (The). A System of Rhetoric adapted for use in Colleges and Academies, and also for private study. By Prof. Henry N. Day. One volume, i2mo, cloth. Price, $1 50 The Art of Composition and the Art of Discourse are complementary treatises designed to cover the whole field of text book instru6tion in composition and rhetoric. They are both characterized by beginning with the thought to be expressed as the vital element in all good speaking and writing, and by proceeding from that to the verbal expression. They are both unfolded in a method carefully conformed to the principles of thought, progressive and exhaustive. They, also, are both designed to train the pupil in the art of writing, and are furnished with copious exercises on each form of thought, each process of representation, and each mode of verbal expression. OPINIONS OF PRACTICAL INSTRUCTORS. “ Day’s * Art of Discourse ’ is now used as the Rhetorical Text-Book in Yale College, and 1 think no better work, for the class, has yet been published.”—CYRUS NORTHROP, Professor of Rhetoric and English Literature in Yale College. New Haven, August 2 Qth, 1868. “ Recognizing the importance of method in learning the art of composition, he begins at the simplest elements of grammar. Training, under such a system, cannot fail to produce method in thought, and to open to the student hitherto unprolific avenues to thought of which he has had no conception. In this belief, we cannot but express the hope that these works of Professor Day may come into general use in our schools and colleges.”— New Englander. “ Having for some time made use of ‘ Day’s Art of Composition ’ as a class-book, I can without hesitation affirm it to be the best book of the kind I have met with. The author has struck out a new path for himself, presenting the principles of the language on a system pe- culiarly his own. By rightly perceiving that composition is the complement to grammar, he simultaneously makes the learner acquainted with the fails and principles of the English lan- guage as it is, and, by carefully devised exercises, habituates him to the use of it as an instru- ment for the expression of thought. Grammar and composition taught in this manner be- come, instead ofahhorred and mechanically executed tasks, an exercise pleasant to the pupil, and an important means of mental training.”—HE NR Y IV. SIGL A R, Newburgh (New York) Institute. “ ‘ The Art of Composition,’ and the ‘ Art of Discourse,’ by Prof. Henry N. Day, are ex- cellent examples of text-books on the subjects of which they treat. The author’s principles ara thoroughly philosophical, and are stated with great precision and clearness, while at tha same time he brings every topic to the test of practical rules and examples. If his books ara not of the kind which may be called easy, they are yet such as command the cor fidei'<-“ of Charles Scribner & Cols Text-Books, etc. 7 the best class of teachers. They are books which afford good mental discipline, and are likely to insure sound scholarship, and to make good writers and speakers.”—JOHN 5. HA R T, Principal State Normal School, Trenton. “ 1 cannot have the slightest hesitation in pronouncing it the best work on English Gram- mar (in its own department) with which I am acquainted. The principal peculiarity of the work—the reducing language to its proper subordination to thought—is a feature that must commend itself to every intelligent mind..”—J. Q. FRENCH, Atkinson, New Hampshire. ©(emeriti of jP\AY.—Elements of Logic. Comprising the Doc- trine of Laws and Produdts of Thought and the Doctrine ol Method, together with Logical Praxis. Designed for classes and for private study. By Prof. Henry N. Day. One volume, i2mo. Price $1 50 Professor Day’s long experience as an instructor has enabled him to fully appreciate the necessities of the student and teacher, and this work with those upon the Arts of Composition and of Discourse, which supple- ment it, make a series of text books of unsurpassed practical value. The Logic is designed for learners, and the aim has been to develop the science in strift method. From the determination of the single radical principle of thought, its laws and the forms of its produdts have been methodically evolved; and the do6trine of method with the exercises is but the end and result toward which the unfolding of the dodtrine of the elements of thought have steadily tended. The exercises are prepared specially for the help of the teacher. Recognizing fully all that Sir William Hamilton and others have done for the science, Professor Day does not confine himself stridtly to any one method. Various new points are introduced which have already been approved and accepted by the numerous instrudtors who have adopted the work as a text book as valuable contributions to the advance- ment of the science. No person who studies this book can well fail to understand logic.—Dr. HORACE WEBSTER, of the College of the City of New York. A work of decided merit and well worthy a place as a text book in our higher institution* of learning.—E. J. RICE, President University of Kansas. I am most favorably impressed with its suitableness for a text book—J. W. LIND- SA Y, President of Geneva College. An excellent treatise and is well adapted for a text book in the higher institutions of learning.—C. NUTT, President Indiana State University. I have looked over Day’s Logic and am very much pleased with the method and the fulness of the author’s discussion of the subject The points which he specifies in his introductory pages give it peculiar excellence and fit it to be a text book in pure logic. • shall take great pleasure in commending it to students —The late Professor DUNS, <.v Brawn University OPINIONS OF PRACTICAL INSTRUCTORS. 8 Charles Scribner & Cols Text-Books. etc. ©relish ,-Siierctfxtrc* rAAY.—An Introduction to the Study of English Literature. By Prof. H. N. Day, of New Haven. One volume, i2mo, uniform with Day’s “ Logic" “ Art of Discourse" and “ Art of Composition.” Cloth $2.25 The distinguishing characteristic of this text-book is that it direCts the study to the literature itself as a growth, not to authorsh:p, not to history, not to criticism. It presents, in the first part, a selection of the master- pieces of our literature, most worthy of special study in themselves, while best representing the successive phases of the language and literature. These selections are accompanied by copious notes, philological, historical, and aesthetical, indicating and explaining the changes in the forms and meanings of words, the structure of the sentence, and the verse-forms in our language. It thus presents a study that can be prosecuted with as definite an aim and objeCt in each successive lesson as the ordinary study of a Greek or Latin classic. It guides the learner to what he is to learn, and the teacher to what he is to teach. Besides the concrete presentation of our literature in these representative selections, in the second part it presents, in a strict analytical method, a full detailed view of the elements of the language, and of the departments of the literature, with the leading authors in each depart- ment. To this part the notes or the selections refer throughout. The rise of language, the origin and affinities of the English tongue, its elements and characteristics, the principles of its orthography, pronunciation, word- formation, versification, etc., are here systematically treated for thorough study or for incidental reference. TYAY.—The American Speller. By Prof. H. N. Day, Author of “Logic,” “Art of Discourse,” “Art of Composi- tion,” and “ Introduction to English Literature.” In preparing this work, the entire vocabulary of the language has been ranged word by word, and distributed into classes under the orthographic principles which have determined the spelling. The pupil thus, while learning comparatively few individual words, comes unconsciously to a practical acquaintance with the classes of words, and so to the principles of the orthography. The work is of the medium size of spelling-books in use, and of the ordinary size of type. But by its compactness, its methodical arrangement in groups and classes, and its omission of foreign matter, it contains more words than ordinary spelling-books, besides a primer sufficiently ample to introduce adults to the more advanced reading lessons, and also a large selection of choice sentences for dictation exercises. Charles Scribner & Co.’s Text-Books, etc. SfceberctI x&i. TAAWSON.— The Federalist : A Collection of Essays, written in favor of the New Constitution, as agreed to by the Federal Convention, September 17, 1787. Reprinted from the original text. Under the editorial supervision of Henry B. Dawson. University edition. One volume, 8vo, cloth . $3 oa The Same ; with Bibliographical and Historical Introduction, Notes and Portraits. By Henry B. Dawson. One volume, 8vo, cloth $3 75 One of the first and most striking results of the late war was the develop- ment of an eager desire among all intelligent persons to investigate the theory and principles of our Government; and as an aid to the proper understand- ing of the great questions which these involved, there is no work in exist- ence to be compared with the Foederalist. “The text employed in this edi- tion,” as Mr. Dawson states, “ is that which the distinguished authors them- selves originally gave to the world, without addition or abridgment, or the least alteration, except where typographical errors were subsequently cor- rected by the authors themselves.” “ Mr. Dawson has performed the task with evident zealous interest in the subjedt, with a painstaking and minute thoroughness of research, which is as uncommon as it is commonda- ble, and witli unmistakable explicitness in the statement of its results.”—M. Y. Tribune. “ Mr. Dawson’s edition is the best that has been published.”—IT. Y. Independent. “ Altogether, this stands as the best edition of the Foederalist ever issued in all its particu- lars.” —Boston Post. CRITICAL NOTICES. in ©TT0li^K. T~\E VERE (PROF. M. SCHELE).—Studies in Eng- lish ; or, Glimpses into the Inner Life of our Language. By M. Schele De Vere, LL.D., Professor of Modern Languages in the University of Virginia. One volume, crown 8vo, cloth $2 50 Nearly fifty years ago Thomas Jefferson, the founder of the University of Virginia, inserted Anglo-Saxon among the subjects on which a course of lectures was to be delivered by the incumbent of the chair of modern languages. Prof. Schele De Vere, who has for many years filled the chan in question with marked ability, has gone beyond the wishes of Mr. Jeffer- son so far as to embody in this volume the results of his extensive y lilological studies and researches. The volume is written in an exceed- 10 Charles Scribner & Cols Text-Books, etc. ingly attractive style ; it is entertaining in matter, full of curious information, and forms an admirable introduction to the more profound works of Muller or Marsh, while it is in itself an admirable compend. CRITICAL NOTICES. “ No one will read it, still less will any one study and take its lessons, without finding hi9 comprehension greatly enlarged of the manifold origin, the vast variety, and the incompar- able excellences of our English language. It is withal an aid to the etymology of a multitude of words or classes of words, of which any scholar, however well-informed, will be glad to avail himself in the study of his mother tongue.”—New York Examiner. “ The work may be read to advantage by all who have any respeft for sense or conscience in the use of words, and who believe that justness of thought is closely connected with pro- priety of expression.”—New York Tribune. (olo0|3* "TYWIGHT. Modern Philology : Its Discoveries, History, and Influence. With Maps, Tabular Views, and an Index. By Benjamin W. Dwight, Author of “The Higher Christian Education.” Two volumes, 8vo, cloth . . . $6 oo The topics discussed in these volumes, the author remarks, “ spread over a wide area of the most deeply interesting and intimately related subjects.” “ Their very titles,” he adds, “ bear inspiration in them to a mind of scholar ly tastes and habits: ‘ An Historical Sketch of the Indo-European Lan- guages ‘ The History of Modern Philology‘ Etymology as a Science ‘ Comparative Phonology,’ and ‘ Comparative English Etymology in its Classical AspeCts.’ In volume first the historical, ethnographic, and biblio- graphical elements of comparative philology are presented, although brief- ly, yet, it is believed, in adequate detail; while in the second volume its more scientific and practical characteristics are offered to the view. From them both as one whole, any student of moderate classical attainments, and of but ordinary force of will, can obtain, not only a competent introduction to the treasures of the new philology, but also a sufficiently strong sense of having mastered its comprehensive array of materials and deductions to be both able and, as the author would hope, eager to pursue his studies, effectively for himself, in this most inviting field of research.” The work is one of the most scholarly, profound, philosophical, and comprehensive in the whole range of our philological literature. “ This volume is written in plain, intelligible, and unpretending language, and is the pro- duction, evidently, «f a man of very considerable learning, unremitting diligence, and large and discriminating powers of research. It is destined, if we mistake not, to enjoy the com- paratively rare merit of being at once the text-book of the student, and the hand-book of tilt philosopher.’'-—Bookseller (Londnn\. CRITICAL NOTICES. Charles Scribner & Cols Text-Books, etc. ibomcr. TYERBY.—The Iliad of Homer rendered into English Blank Verse. By Edward, Earl of Derby. From the fifth London edition. Two volumes, 8vo, on tinted paper, half calf extra, $9 ; cloth $ 5 00 The very cordial welcome extended to this translation of Homer both in Eng- land and this country is the most satisfadtory proof that could be given to its extraordinary merits. And yet in the preface to the first edition the distinguished author wrote, “Various causes, irrespective of any demerits of the work itself, forbid me to anticipate for this translation any extensive popularity.” As the ground for this apprehension he alleged a fear that taste for and appreciation of classical literature are greatly on the decline, and that the English reader who might be unacquainted with Greek “ would naturally prefer the harmonious versification and polished brf lancy of Pope’s translation ” to his own attempt to produce such a rendering of the original as “ would fairly and honestly give the sense and spirit of every passage and of every line ; omitting nothing, and expanding nothing; and adhering as closely as our language will allow even to every epithet which is capable of being translated, and which has in the particular passage any- thing of a special and distinctive character.” In the preface to the fifth edition the noble author acknowledged that the favorable reception which had been given to the work afforded a gratifying proof as to how far he had overrated the extent to which the taste for and appreciation of classical lit- erature had declined, and he might have added that the same fadt also proved that the public preferred his own translation, which is as literal as the exigencies of the English language will allow, to the paraphrase of Pope. It is certainly no exaggeration to allege that this translation of Homer will always hold a place among English classics, and that no othe' is likely to be produced which will surpass it in poetic merit joined with fidelity to the original. Whatever may be the ultimate fate of this poem—whether it take sufficient hold of tne public mind to satisfy that demand for a translation of Homer which we have alluded to, ind thus become a permanent classic of the language, or whether it give place to the still more perfect produdtion of some yet unknown poet—it must equally be considered a splen- did performance ; and for the present we have no hesitation in saying thsd it is by far the best representation of Homer’s Iliad in the English language.”—London Times. “ The merits of Lord Derby’s translation may be summed up in one word : it is eminent- ly attradlive : it is instindt with life; it may be read with fervent interest; it is immeasurably nearer than Pope to the text of the original. ... It will not only be read, but ead over again and again Lord Derby has given to England a version far more closely allied to the original, "d superior to any that has yet been attempted ill the blank verse of our language. "--EdiHi '• Review. CRITICAL NOTICES. Charles Scribner & Cols Text-Books, etc. 'Hiirxttmrieiics. T7ELTER’S First Lessons in Numbers (Illustrated). -L containing tables and tabular Exercises for pupils commencing the study of Numbers. By S. A. Felter. Prices, see Educat. Cat. Primary Arithmetic, designed for pri- mary classes, combining mental and written Arithmetic, with De- nominate Tables and U. S. Money. With and without answers. Intermediate Arithmetic. An Element ary Written Arithmetic, including the Fundamental Rules, U. S Money, and Denominate Numbers, with a short course on Frac- tions and Interest. With and without answers. Grammar School Arithmetic. This book is the highest of the Common School Series, and is intended to give the pupil all the information and pradtice he needs in any department of commercial life. With and without answers. University Arithmetic. Designed to investigate the science of Numbers, including the theory of Scales, Factors, Circulating Decimals, etc., and examines the principles relating to Exchange, Banking, Life Insurance, etc. (In prepa- ration.) Intellectual Arithmetic. Designed for advanced classes, and combines mental with blackboard exer- cises, on a new plain. Teachers’ Manual of Arithmetic. Prepared expressly for the use of teachers, and contains the best methods of oral, class, and individual instruflion. NOTE. For the convenience of Private Schools, and teachers requiring a complete Arithmetic in one volume, the “ Intermediate ” and “ Grammar School," with answers, are bound in o?ie volume, and form FELTER’S PRACTICAL ARITHMETIC. Although these books possess features which distinguish them from the many Arithmetics now before the public, they illustrate no untried theory, but are the result of a long practical experience in the class-room. Among the peculiarities and excellencies which so readily address the common- sense of educators, and which make these books such desirable aids in a school-room, are the following : I. They follow the natural order of instruc- Charles Scribner & Co.'s Text-Books, etc. tion, fadts, or the concrete, first; principles, or the abstradt, afterwards 2. They contain more than five times as many examples for practice as any rival series. 3. They are more perfectly graded and more trulj progressive than any works now before the public. 4. The several books form a series by following each other in a natural gradation, each higher book continuing the investigation of the subjedt. 5. They are truly analytic. 6. They are not overburdened with rules, remarks, and suggestions, and other superfluous matter, but require the pupils to depend upon common-sense, to use their own eyes and judgment. 7. The review of each work is such as to necessitate a thorough knowledge of each subjedt over which the class have passed, even though individual members may have been occasionally absent. 8. The “ Manual ” has been prepared ex- pressly to be used in connedtion with this series, giving the teacher model exercises, in the best methods of oral, mental, written, and class instrudtion. Copies for examination will be sent by mail, postage paid, on receipt of 30 cents each for the “ Intermediate,” “ Grammar School,” and “ Prac- tical,” and 13 cents each for the “ First Lessons,” “ Primary,” “ Intellec- tual,” and “ Manual.” “ In using my efforts for the introduction of Professor Felter’s series of Arithmetics in the schools under my supervision I have only performed the simple duty of providing them the best works I know of, and those best adapted to their wants and to the purpose had in view. These works have certain features most admirably calculated to awaken the interest and enlist the attention of our pupils ; and the study of arithmetic has taken a new start since they were introduced, and is pursued with a zest unknown before. The teachers, I believe, are universally pleased with the books, and those who were at first unfavorable to the series have become most enthusiastic in their favor.”—A. E. NEWTON, Superintendent of the Colored Schools of Washington and Georgetown. “ I am so fully convinced of the excellence of Felter’s series of Arithmetics, that I have earnestly recommended their adoption as text-books into every school in Union county. From a careful examination, and practical tests in the class-room, I am persuaded that these books possess the true ideas of teaching. They are being rapidly introduced into all the schools in the country. I would most cordially recommend teachers who have not seen them to send for a set.”—Prof. A. E. CAMPBELL, Superintendent of Public Schools, Union County, N. J. “ I look upon the work as the most natural in its gradations of any series with which I am at present acquainted, and hope to see it generally adopted in all our schools.”—JOHN CORE, Esq., Chief Clerk, Department of Public Instruction, Baltimore, Md. “ The matter is well arranged, and embraces all that is usually required in that branch of learning. The rules are plain, concise, and easily understood. The examples are well seledted, and illustrate the principles in every case. I would, therefore, recommend them to all who wish to acquire a complete knowledge of the subject.”—Prof. EDWARD McIL- DUFF, Principal of Catholic School of the A ssumption, Brooklyn, N. Y. OPINIONS OF PRACTICAL INSTRUCTORS. Catalogues containing full descriptions of Charles Scribner Co \ school text-books and appliances, with numerous testimonials from those who have practically tested them, will be sent to any ad tress on appli- cation. Charles Scribner & Co.'s Text-Books, etc. ©icetro* T^ORSYTH.—Life of Marcus Tullius Cicero. By "*■ William Forsyth, M.A., Q.C., Author of “ Hortensius,’ “ Napoleon at St. Helena,” “ Sir Hudson Lowe,” “ History of Trial by Jury,” etc., etc., and late Fellow of Trinity College, Cambridge. Twenty engravings. Two volumes, crown 8vo, tinted paper, half calf, $9; cloth $5 00 The manner in which the times of Cicero and his works have been studied has had a tendency to lead us to forget the man in the scholar or the poli- tician. Mr. Forsyth in these volumes has endeavored, and with success so complete as to make the biography one of the most charming ever written, to show us the great Roman orator as he was in his own home. In carry- ing out this design Mr. Forsyth has not only given us the most complete and well-balanced account of the life of Cicero ever published ; he has drawn for us an accurate and graphic picture of domestic life among the best classes of the Romans, one which the reader of general literature, as well as the student, may peruse with the keenest pleasure and with profit. CRITICAL NOTICES. “A scholar without pedantry, and a Christian without cant, Mr. Forsyth seems to have seized with praiseworthy tadl the precise attitude which it behooves a biographer to take when narrating the life, the personal life, of Cicero. Mr. Forsyth produces what we venture to say will become one of the classics of English biographical literature, and will be welcomed by readers of all ages and both sexes, of all professions and of no profession at all.”—London Quarterly. “ His book is a valuable contribution to our standard literature. It is a work which will aid our progress toward the truth—it lifts a corner of the veil which has hung over the scenes and adlors of times so full of ferment, and allows us to catch a glimpse of the stage upon which the great drama was played.”—North A merican Review. “ Mr. Forsyth has discreetly told his story, evenly and pleasantly supplied it with apt illus- trations from modem law, Eloquence, and history, and brought Cicero as near to the present time as the differences of age and manners warrant. * * * These volumes we heartily recommend as both a useful and agreeable guide to the writings and character of one who was next in intellectual and political rank to the foremost man of all the world, at a period when there were many to dispute with Hm the triple crown of forensic, philosophic, and political composition.”—Saturday Review. “ Mr. Forsyth has rightly aimed to set before us a portrait of Cicero in the modern style of biography, carefully gleaning from his extensive correspondence all those little traits of character and habit which marked his private and domestic life. These volumes form a very acceptable addition to the classic library. The style is that of a scholar and a man of taste.” —London Atkenceum. “The book is, in its minutest details, most emphatically a gentleman’s book, and is surf to find its way to the library-tables of all readers of taste and cultivation.”—N. Y. Times. “ We have no doubt that this edition will become a standard classic.”—N. Y. Observer Charles Scribner & Co.’s Text- Books, etc. Sftroube, T7ROUDE.—History of England from the Fall of Wolsey to the Death of Elizabeth. By James An- thony Froude, M.A., Fellow of Exeter College, Oxford. Ten volumes, crown 8vo. Price per volume, half calf, $5 ; cloth . $3 00 Mudie’s Circulating Library, the most extensive of these favorite institu- tions in London, has subscribed for a larger number of volumes of Froude’s history than it did of Macaulay’s. The fact shows how wide a popularity this work has already attained in England, and it is in every respedt fully deserved ; for to unwearied patience in research and extraordinary powers of generalization, Mr. Froude unites an eloquent and wonderfully clear and graphic style. In selecting for investigation the period covered by these volumes, Mr. Froude ventured into a field which had often been explored, but he did it with a full knowledge of the fadt that there were stores of the richest material which had been virtually untouched by previous and which were sure to reward careful examination. The Spanish archives in the castle of Simancas, and the records of the Inquisition, were thrown open to Mr. Froude by the Madrid government. He also had free access to the Imperial archives at Paris, and to the private papers of Lord Cecil at Hatfield, England. From all these sources he has derived a vast amount of material which throws a flood of light upon the personal characters of Henry the Eighth, of Mary Queen of Scots, and of Queen Elizabeth, and which at the same time illustrates very clearly the relations which these and other leading characters of the time held to the Reformation. Mr. Froude does not hesitate to express his own views because they run counter to generally received opinions, but he is always careful to sustain his assertions by refer- ence to his authorities. The first six volumes of the work extend from the fall of Wolsey, and through the reigns of Henry the Eighth, Edward the Sixth, and Mary ; and the seventh volume opens a new era in the Refor- mation with the accession of Elizabeth. So much that is new to the student is developed in these volumes that Mr. Froude’s history almost seems to be the record of a period—and that, too, one of the most important in English annals—which has never before been fully or faithfully described. “ They are a worthy continuation of a history which will hold a high place in English literature. Mr. Froude belongs to the school of Carlyle, but he is not an imitator of that great writer. He equals him in industry and profound study, but he is calmer and more natural in his tone, more thoughtful in his remarks on events, more unaffected in his narra- tive, and more simple and life-like in his portraits. In the main, he is a pictorial historian, and his skill in description and fulness of knowledge make his work abound in scenes and passages that are almost r.ew to the general reader. We close his pages with unfeigned regret, and we hid him gixxf speed in his nob'e mission of exploring the sources of English history ir. one of its most remarkable periods.’’—British Quarterly Review. CRITICAL NOTICES. 16 Charles Scribner & Cols Text-Books, etc. (S>U}ioVs (3>eo0rajrHtej3. —Primary; or, Introduction to the Stud’s of Geography. By Prof. Arnold Guyot, of Princeton College. One quarto volume, with over One Hundred elegant Illustrations. For prices, see Educational Catalogue. Elementary Geography. With Maps and Illustrations. One small 4to volume. The Intermediate Geography. In one quarto volume, elegantly Illustrated, containing Forty-five Maps, of which twelve are full-page Maps, engraved in the highest style of the art, Colored Politically and Physically, embracing Colored Dia- grams for the Construction of the Maps of each Continent, and also Colored Diagrams with full Instructions for Drawing the Maps of the separate States of the United States. Common-School Geography.—In one royal quarto volume, with numerous Illustrations. Containing Twenty-three Maps, of which five are double-page Maps, engraved in the highest style of the art, colored politically and physically, em- bracing also Diagrams for the Construction of Maps of each Con- tinent. The Same. Teachers’ Edition, with Teacher’s Guide Grammar and High-School Geography. ('In preparation.) In this series of text-books, Prof. Arnold Guyot, since the death of Carl Ritter, confessedly the greatest of geographers, unfolds that method of in- structing the science which practical experience, here as well as in Europe, has proved to be at once the most philosophical and the simplest. Instead of burdening the memory with catalogues of names having very little significance to the young student, Prof Guyot first attempts to give the pupil as correCt conceptions as possible of the leading geographical forms of land and water, with the terms by which they are distinguished, in order that he may, when employing these terms, attach a distinCl idea to each. Next he endeavors to give him an idea of the manner of representing portions of the earth’s surface by maps, thus preparing him to make the map itself a special objeCl of study; and all the time he aims to lead him on, by awakening a desire for future study, and at the same time to develop the Charles Scribner & Co.'s Text-Books, etc. powers of perception and imagination which will be constantly exercised in that study. The Elementary Geography is a class-book for study and rei i tation for Primary Scholars, containing simply that which should be firmly fixed on the memory, and omitting all merely illustrative description. It begins with lessons about home, and gradually advances in the study of limited regions which have marked characteristics, until all the leading countries of the earth are noticed. The teacher is supplied with models and methods, the result of many years of experience in geographical instruction, greatly simplifying instruction, and making the bool by far the most teach- able of its kind published. In the Intermediate Geography the leading characteristics are the study of the form of the earth and the location of the continents upon its surface ; the form of the continents and the location of their mountain ranges, rivers, lakes, and countries ; the form of countries and the location of their Physical features, cities, and towns. Constructive map-drawing and a series of ex- haustive questions upon each map serve to fix the faCts distinctly in the minds of the pupils, and in this text-book special attention is paid to the study of the United States as a whole, and to the study of the separate States. Single and double page maps, colored politically and physically, assist the scholar at each step. The Common School Geography embraces a minute and detailed study of each map ; a full description of the general physical character of each continent, its vegetable and animal life, the races of men which inhabit it, and the States into which it is divided. The physical character of each country is made the basis of the study of the country ; and all faffs regard- ing its political geography are so intimately linked with its physical char- after that it is impossible to forget them. In the arrangement of the subjeft- matter, the necessity for mechanical memorizing is entirely obviated, as each separate class of faCts is studied in connection with its immediate causes and results. Consequently the pupil is never required to commit to memory a catalogue of fafts having no connection, and therefoi e without significance. Physical Geography, heretofore so treated as to be accessible only to the mature mind, is here presented as a simple description of the physical char- after of individual continents. It is thus entirely divested of its difficulties and obscurities, and is made perfectly intelligible and attractive even to the youngest pupil. In each and all of these text-books the best artistic skill has been engaged in the production of both maps and engravings. The maps are presented in a style never before attempted in this country in school-books of this class, and the illustrations have a direft connection with the text, explaining it most pertinently and happily. The care with which these text-books were prepared has marked a new era in our educa- tional literature of this grade, and has done much to elevate and improve it. Wherever they have been put to a practical test, the result has been a 18 Charles Scribner & Co. a Text-Books, etc. cordial and emphatic approval of the principle upon which they are based, as the only one upon which geography can be taught successfully. opinions of practical instructors, and of scientific men “ Incomparably superior to anything published.”—Prof. AGASSIZ. “One of the ablest physical geographers in the world.”—Prof. J. D. DANA. “Greatly superior to any works of the kind published.”—Prof. JOSEPH HENRY. “ Thorough, systematic, and exhaustive.”—Prof. GEO. M. GAGE. “ They mark the dawn of a new era.”—Prof. W. J. ROLFE. “ We take Guyot as our guide, and use his book.”—Prof. SANBORN TENNEY. “ Philosophical and accurate ; simple and attractive.”—Rev. B. G. NOR THROP. “ It is the only system worthy of the name.”—Prof. W. H. PAINE. “ I believe in them.”—AW ANSON SMYTH. “Unquestionably the best text-books.”—Prof. THOMAS IV. HAR VEY. “No book of the kind worthy of being compared to it.”—Prof. E. A. SHELDON. “It stands the practical test of the school-room admirably.—Prof.H. B. SPRAGUE “The books have been tried with the best results.”—Prof. R. EDWARDS. “ Should be unwilling to exchange it for any other work extant.—Prof. S. H. PEARL. “Abundantly satisfactory.—Prof. EDWARD CONANT. “ The best Geography with which I am acquainted.”—Prof. J. S. CILLE V. “ I congratulate the 100,000 children of Vermont upon the adoption of these books in our schools.”—Hon. J. S. A DA MS, Sec. Board of Education, Vermont. Teachers desiring to examine Prof. Guyot’s text-books can procure them of the Publishers at the following prices: the Primary, 75 c. ; the Common School Geography, $1.50; the Intermediate Geography, $1.00 ■ or the three books will be sent together to teachers for $3.00. TS&U /'"''UYOT.—Physical and Political, and Classical Wall Maps. By Prof. Arnold Guyot, of Princeton Col- lege. Geographical Teaching : Being a com- plete Guide to the Use of Guyot’s Wall Maps for Schools, contain- ing six maps and diagrams, with full instructions for drawing the maps of the Continents, in aecordance with Guyot’s System of Con- structive Map Drawing. One volume, i2mo. . . . 75c These maps are a valuable accompaniment to the study of Prof. Guyot’s system of Geography, and they are issued in a style superior to any other maps produced in this country. There are four Series in all: the Classical, including maps of the Roman Empire, Ancient Greece, and Italia, the last named embracing a plan of Ancient Rome (6 x 8 feet in size ; $15 each, or $45 per set) ; the Large Series, in which there are nine maps (from 4x5 to 10x6 feet; $71 per set); the Intermediate Series, which include? eight maps (4x5 and 5x6 feet; $38.50 per set) ; and the Primary Series, in which there are ten maps (2 x 3 to 4 x 5 fee*; $18 per set). The Classical and Large Series are specially adapted for use in high-schools and colleges Charles Scribner & Cols Text-Books, etc. 19 and are the only ones issued in this country which deserve to be recommended for that purpose. The Intermediate and Primary Series are fully equal to the Series in all respefits, save as regards size. The different sets, in fabh combine all the essential qualities of the very best school-maps. They have the following characteristics in common : i. They are correCl. To a great extent they have been worked out anew from original documents, and are therefore fresh and original. 2. They are distinguished by clearness and simplicity. 3. Due importance is given to the physical features, which so vitally affeCI the climate, river systems, productions and eco- nomic value, animals, and even the character of the inhabitants, their civil and political conditions. Unusual care has been taken to exhibit the forms of relief, the elevations and depressions of the surface. The differ- ences in altitude of lowlands and plateaus are expressed by different tints, while the elevation and importance of the various mountain chains are indi- cated by the boldness of the topographical drawings—their depth of shading ; thus exhibiting their relative gradations and true proportions. 4. The political boundaries, the principal cities, rivers, etc., are distinctly designated, so that the maps are both physical and political. 5. Harmony has been preserved —that is, the true relative proportions of parts as found in nature. The Classical Maps have been prepared by Prof. Arnold Guyot and Prof. H. C. Cameron, with a desire of responding to the wants of an advanced scholarship, by placing within its reach the results of the most recent inves- tigations and discoveries in Ancient Geography. Classical scholars in this country have been dependent heretofore on Europe for the Geographical apparatus necessary for the higher kind of instruction which is now beginning to prevail in our classical schools and colleges. The admirable Maps of Kiepert were not only expensive, but difficult to obtain; and therefore it seemed that a series of Classical Maps, embracing all the excellences of those of Kiepert, with such additions as the present advanced state of knowledge in this department demanded, would confer a lasting benefit upon the cause of thorough education and sound classical scholarship in our country. Sci- entific Expeditions, Topographical Surveys, and the researches of modern travellers, many of w'hom were accurate classical scholars, have greatly increased our knowledge of Ancient Geography, and given definiteness and certainty to much that was previously vague and conje&ural, and these maps embody the results of all the most recent discoveries. Any maps in the different series, excepting the Primary, may be pur- chased separately. *** Messrs. Charles Scribner & Co. also furnish paper map-drawing cards, which are essential helps to the proper study of Prof. Guyot’s system. Nine in a set, are sold for 50 cents. *** Full descriptive catalogues of Guyot's text-books and maps, and all our other educational appliances, with pamphlets containing testimonials from those who have practically tested them, will be sent to any address. 20 Charles Scribner & Cols Text-Books, etc. 'HUoral TTOPKINS.—The Law of Love and Love as a Law. A Treatise on Moral Science. By Mark Hopkins D.D., LL.D., President of Williams College. One volume, iamo $i so This work is both theoretical and practical, and is specially designed for a text-book. In the theoretical part morality is made rational, both as based on ends and as involving intuitions. Obligation, in distinction from right, is made the moral idea ; the foundation of obligation is fully discussed and a reconciliation of different systems is attempted. In the practical part the Law of Love is applied in connection with the Law of Limitation, and with a classification of duties—new as respeCts its basis. “ In this work, Dr. Hopkins has given the world a clear exposition of the principles of moral science, and practical rules for their application. “ The simplicity, strength, and exactness of its style and language ; its discriminating analysis and forcible logic ; its accurate adjustments of relative truths ; its admirable blend- ing of the independence of human reason with dependence upon the Divine mind—in all these respecfts we have no hesitation in saying that its combined excellencies place the work at the head of all similar treatises. It is the most satisfactory of all works on moral science, and presents a system as far removed from adverse criticism as possible. It is rare thai thought so profound is expressed in language so concise, pure, and clear.”—Journal Albany, N. Y. “ This work is a careful, methodic, and, we believe, exhaustive essay on the subjedl of moral science, both theoretical and practical, divided and arranged in a great number of classifications, which have their logical order of sequence, and are all maintained and se' forth with a precision that makes peremptory claim on the attention of the philosophic Undent.”—IV. V. Times. " He discourses on the lofty themes of which he treats with the tranquil dignity of ; Pythagorean sage. No obscurity of thought, as in the case of Coleridge, betrays him into vague and desultory statements, dazzling the fancy of his readers with the glitter of Strang, imagery, instead of informing his mind with the coherent exposition of truth. Nor is h enticed from his firm intelledtual purpose by the vast array of ponderous erudition, witl which Sir William Hamilton so often overlays his argument and discourages his readers President Hopkins is almost master of his f'eme. He meets its difficulties manfully. Hi never shrinks before an objection, nor dodges the point of a question behind a cloud of irrelevant generalities. Even in the few instances in which he does not command oui assent to his positions, he gains our respect by the fairness and vigor of his reasoning, anc leads us to believe that could we change the point of view, there would be no difference ir our convidtions. His work will be received by the intelligent student of moral science wit! friendly welcomes, not only as the most recent production of the American mind in tha department of thought, but as, in many respects, the most complete and masterly.”—N. I'. Tribune. “ The impression produced by our cursory examination of the work is in the highesi degree favorable to its perspicuity, truth, and force.”—Boston Congregationalist. “ A complete treatise on the theory and practice of morals.”—Am. Presbyterian. CRITICAL NOTICES.