'**■■:» NATIONAL LIBRARY OF MEDICINE Washington I X JOHN DELAMATTEXl. ® S WESTERN RESERVE COLLEGE, M W m U '. S&\ TREATISE ON THE BLOOD, INFLAMMATION, AND GUN-SHOT WOUNDS, Br THE LATE . JOHN HUNTER. TO WHICH IS PREFIXED A SHORT ACCOUNT OF THE AUTHOR'S LIFE, BY HIS BROTHER-IN-LAW, EVERARD HOME. IN TWO VOLUMES, FROM THE LONDON QUARTO. Vol. I. PHILADELPHIA: Published ey THOMAS BRADFORD, printer BOOK-SELLER & ST A 'I ONER* No. 8, Sputh Fro it- Street.* I/96.^ ( 3 ) | TABLE OF CONTENTS. THE LIFE OF THE AUTHOR, page i ?! INTRODUCTION, i Sy ECT. I. OS diSeaSed a&ions, as being incompatible with each other, 3 II. OS parts SuSceptible oS particular difeaSes, 5 III. OS Sympathy, ibid ?, IV. Of mortification, 7 I PART I. * CHAPTER I. » 5? GENERAL PRINCIPLES OF THE BLOOD. 9 *} Sect. I. Of the mafs of blood, as compofed of diffe- rent parts, 13 II. Of coagulation, and its effe£t6, 15 ^ III. Of the Serum, 27 f; IV. Of the red globules, 37 V. Of the quantity of blood, and courfe of its 5 circulation, 63 * ' VI. Of the living principle of the blood, 70 VII. Some unconnected experiments reSpecting the blood, . 87 CHAPTER II. OF THE VASCULAR SYSTEM. 94 <■» y* Of the heart, jjj HOtlW 4 Table cf. contents. VI. General observations on blood-vcflels, 133 VII. Valves oS arteries, . '5° VIII. OS the diviuon or branching of arteries, 154 IX. Of the aaion oS the arteries, and the velocity of the blood's motion, I(56 X. OS veins, lT PART II. CHAPTER I. UNION BY THE FIRST INTENTION. 170 Sect. I. Of injuries in which there is no external com- munication, 182 II. OS injuries where the wound communicates externaMy, 192 III. Practical observations reSpecting union by the firft intention, 199 IV. Of Scabbing, 204 V. Accidents attended with death in a Superficial part, 209 CHAPTER II. FUNDAMENTAL PRINCIPLES CF INFLAMMATION, 211 Sect. I. Of the different cauSes which increaSe and dimi- nifh the Sufceptibility Sor inflammation, either in the whole body cr in parts, 216 II. Effects of itrength, cr weakneSs of constitu- tion, and of parts, while under inflamma- tion, 219 III. Of parts of the body moSt SuSceptible of the tnree different inflammations to be treated °f> 224 IV. Of the two parts that have the orders of in- flammation reSpecting priority inverted, 230 V. The natural cauSe oS the adhefive inflammation being limited, 2?7 VI. OS inflammation—its Stages, 237 VII. Of riie^Iindent degress, and different kindi t.f inflammation, 244 ( i ) A SHORT ACCOUNT OF THE LIFE OF THE AUTHOR. J ohn Hunter was the fon of John Agnes Hun- ter of Kilbride, in, the county of Lanerk; he was the youngeft of ten children, and was born on the fourteenth of July, 1728, at Long-Chal- derwood, a fmall eftate belonging to the family. His father was defcended from Hunter of Hunterf- ton, an old family in Ayrfhire, and his mother was the daughter of Mr. Paul, a very refpectable man, and treafurer of the city of Glafgow. He had four brothers, John, Andrew, James, and William; and five filters, Elizabeth, Janet, Agnes, Dorothea, and ISabella; of thefe, John, Andrew, Elizabeth, Agnes, and Ifabella died, while children. James was born in 1715; was brought up to the law, as a writer to the fignet in Edin- burgh, but in the year 1742 went to London on a vifit to his brother William, who was at that time a teacher of anatomy, and So much was he capti- vated by the purSuits in which he found his brother engaged, that he purpofed to follow them himfelf, and become a practitioner in phyfic. His health ■however was fo much impared by his application to anatomy, that he was obliged to return to Long. B 11 Life of the author. Calderwood, where he died of a fpitting of blood, in the twenty-eighth year or his age*. William was born on the twenty-third of May, 1718, who became unrivalled as a teacher of ana- tomy, and it was under his foftering care that his younger brother John was initiated in thefe purfuits, in which he afterwards became fo diitinguifhed. His hiltory is already in the hands of the public f. Janet married Mr. Buchanan of Glafgow, and died in 1749. Dorothea, who is (till alive, mar- ried the Rev. Doctor James Baillie, profeflbr of divinity in the univsrfity of Glafgow, by whom fhe has one Son, Matthew, doctor of phyfic, fucceffor to Dr. Hunter, as a teacher of anatomy and one of the phyficians to St. George's Hofpital, and two daughters, Agnes and Joanna. John Hunter was about ten years old at his fa- ther's death, and was left under the direction of his mother, who was particularly indulgent to this her youngeft fon. * He was fent to the grammar-School, but not hav- ing a turn for languages, nor being Sufficiently un- der controul, he neglefted his ftudies, and fpent the greateft part of his time in country amufements. About this time Mr. Buchanan, who had lately come from London to fettle at Glafgow as a cabi- net-maker, paid his addrefles to Mr. Hunter's filter * Mr. James Hunter was a young man of an unconv, monly pleafing addreSs, and oS very quick parts. The late Dr. Hunter has been heard to remark, that if he had lived to practice phyfic in London, nothing could have prevented him from nfing to the top oS his profeffion. It would have been a remarkable circumftance that three brothers inould have: acquired the firft reputation in three different branches oS the Same proSeffion. .n+Written by Dr. 8. Poart. Sin*™*, and pubUihed Life of the author. iii Janet, and having many agreeable qualities, (he was induced to marry him, although contrary to the advice of her relations. This marriage gave the family great concern ; for the qualities which had rendered Mr. Buchanan agreeable, led him in- to diffipation, and made him neglect his bufinefs. Mr. John Hunter, who was now feventeen, went to Glafgow upon a vifit to his Sifter, tor whom he had the greateft affection, to comfort her in her diftrefs, and endeavour to affift her hufband in ex- tricating himSelf from his difficulties; but finding, after fome time, all his efforts ineffectual, he re- turned to Long-Calderwood, Tired of living idle in the country he began to turn his mind to fome more active employment; and hearing much of the reputation which his bro- ther William had acquired as a teacher of anatomy, he wrote to requeft that he would allow him to come to London upon a vifit, making at the Same time an offer to be his affiftant in his anatomical refearches; or, if that propofal fhould not be ac- cepted, exprefling a wifh to go into the army. In anfwer to this letter, he received a very kind invi- tation from his brother, and immediately fet off for London, accompanied by Mr. Hamilton, a friend of the family who was going upon bufinefs; they rode up together on horfeback. Mr. Hunter arrived in London in September, 1748, about a fort-night before his brother began his courfes of lectures ; and Dr. Hunter, who was very anxious to form fome opinion of his talents for anatomy* gave him an arm to diffect for the mufcies with the neceffary directions how it was to be done; and he found the performance fuch as greatly exceeded his expectation. His firft efiay in anatomy having thus gaitied him fome credit, Mr. Hunter was now employed in a diffection of a more difficult nature; this was an B 2 iv Life of the author* arm in which all the arteries were injected, and thefe, as well as the mufcles were to be expofed and preferved; the manner in which this was per- formed, gave Dr. Hunter fo much fatisfaction, that he did not fcruple to fay, that his brother would become a good anatomift, and that he fhould not want for employment. From this period we may confider Mr. Hunter as having ferioufly engaged in anatomy and under the instructions of Dr. Hunter and his affiftant Mr. Sy- monds, he had every opportunity of Improvement, as all the diffections at this time carried on in Lon- don were confined to that fchool. In the fummer 1749, Mr. Chefelden, at the re- (Jueft of Dr. Hunter, permitted him to attend at Chelfea Hofpital, and he there learnt the firft rudi- ments of furgery. The following winter he was fo far advanced in the knowledge of human anatomy, as to inftruct the pupils in diffe&ion, to whom Dr. Hunter had very little time to pay attention. This office, there- fore, fell almofl entirely upon him, and was his conltant employment during the winter feafon. In the fummer months of 1750, Mr. Hunter at- tended the hofpital at Chelfea; in 1751,he became a pupil at St. Bartholomew's, and in the winter was prefent at operations occafionally, whenever any thing extraordinary occurred. The following fummer he went to Scotland, and brought up his filter Dorothea, and in 1753 entered as a gentle- man commoner at St. Mary Hall, Oxford. In i7?4» he became a furgeon's pupil, at St. George's Hofpital, where he continued during the fummer months, and in 1756, was appointed houfe-fur- geon. In Ae winter, 1755, Dr. Hunter admitted him to a partnerfhip m his lectures, and a certain por- non of the courfe was allotted to him, befide* Life of the author. fr which, he gave lectures when the doctor was ca!* led away to attend his patients. Making anatomical preparations was at this time a new art, and very little known; every prepara-* tion, therefore, that was fkilfully made, became an object of admiration ; many were wanting for the ufe of the lectures, and the doctor having himfelf an enthufiafm for the art, left no means untried to infufe into his brother a love for his favourite pur- suits. How well he fucceeded, the collection after- wards made by Mr. Hunter will fufficiently evince. Anatomy feems to have been a purfuit for which Mr.Hunter's mind was peculiarly fitted, and he ap- plied to it with an ardor and perfeverance of'which there is hardly any example. His labours were fo ufeful to his brother's collection, and fo gratifying to his difpofition, that although in many ether re- fpects they did not agree, this fimple'tie kept them together for many years. Mr. Hunter worked for ten years on human r.na- tomy, during which period he made himfelf matter of what was already known, as well as made fome ad- dition to that knowledge *. He traced the ramifica- tions of the olfactory nerves upon the membranes of the nofe, and discovered the courSe of fome of the branches of the fifth pair of nerves. In the gravid uterus, he traced the arteries of the uterus to their termination in the placenta. He was alfo the firft who difcovered the exiftence of the lymphatic veffels in birds. Many parts of the human body being fo com- plex, that their ftructure could not be underftood, * An account of his injecting the teftis, his deScriptioa of the defcent of that body, with observation on the hernia congenita, and his experiments in proof of the veins not being abSorbents, are publifhed in Dr. Hunter's 2&e4kxl Commentaries. ▼i Life of the author. nor their ufe afcertained, Mr. Hunter was led to examine Similar parts in other animals, in which the Structure was more Simple, and more within the reach of investigation ; this carried him into a wide field, and laid the foundation of his collection in comparative anatomy. In this new line of purfuit this active inquirer began with the more common animals, and pre- ferved fuch parts as appeared by their analogy, or in fome other way, to elucidate the human ceco- nomy. It was not his intention to make diffections of particular animals, but to inftitute an inquiry into the various organizations by which the functi- ons of life are performed, that he might thereby acquire fome knowledge of general principles. This, I believe, had never been before attempted, or certainly had never been carried far into execution. So eagerly did Mr. Hunter attach himelf to com- parative anatomy, that he fought by every means in his power the opportunities of profecuting it with advantage. He applied to the keeper of wild beads in the Tower for the bodies of thofe which died there, and he made Similar applications to the men who (hewed \:ild beafts. He purchaf- ed all rare animals which came in his way; and thefe, with fuch others as were prefented to him by his friends, he entrufled to the (howmen to keep till they died, the better to encourage them to af- fift him in his labours. His health was fo much impaired by exceflive attention to his purfuits, that in the year 1760 he was advifed to go abroad, having complaints in his breaft, which threatened to be consumptive. In October of that year, Mr. Adair, infpector-ge- neral of hofpitals, appointed him a furgeon on the Itaff; and in the following fpring he went with the army to Bellifle, leaving Mr. Hewfon to aflift his brother during his abfenee. Life of the author. Vll Mr. Hunter ferved, while the war continued, as Senior furgeon on the ftaff, both in Bellifle and Por. tugal, till the year 1763; and in that period ac- quired his knowledge of gun-fhot wounds ; a Sub- ject which makes no inconfiderable part of the prefent work. On his return to England he fettled in London; where not finding the emoluments from his half-pay and private practice fufficient to fupport him, he taught practical anatomy and operative furgery for feveral winters. lie returned alfo with unabated ardour to comparative anatomy, and his experi- ments could not be carried on in a large town, he purchai'ed, for that purpofe, about two miles from London, a piece of ground near Brompton, at a place called Earl's Court, on which he built a houfe. In the courSe of his inquiries this excellent ana- tomift afcertained the changes which animal and ve- getable fubftances undergo in the flomach when acted on by the gaftric juice; he discovered, by means of feeding young animals with madder, (which tinges growing bones red) the mode in which a bone retains its fhape during its growth ; and explained the procefs of exfoliation by which a dead piece of bene is feparated from the living. His fondnefs for animals made him keep feveral of different kinds in his houfe which by attention he rendered familiar with him, and amufed himfelf by obferving their peculiar habits, and Inftincts ; but this familiarity was attended with considerable rilk, and fpmetimes led him into Situations of dan- ger, of which the following is a remarkable in- itance. Two leopards, which were kept chained in an out-houfe, had broken from their confinement, and got into the yard among fome dogs, which they immediately attacked ; the howling this produced, viii Life of the author* alarmed the whole neighbourhood; Mr. Hunter ran into the yard to fee what was the matter, and found one of them getting up the wall to make his efcape, the other furrounded by the dogs ; he im- mediately laid hold of them both, and carried them back to their den; but as foon as they were fecur- ed, and he had time to reflect upon the rifk of his own fituation, he was fo much agitated that he was in danger of fainting. On the fifth of February, 1767, he waschofena Fellow of the Royal Society. His defire for im- provement in thofe branches of knowledge which might affift in his reSearches led him at this time to propoSe to Dr. George Fordyce and Mr. Cum- ming an eminent mechanic, that they fhould ad- journ from the meetings of the Royal Society, to fome coffee-houfe, and difcuSs fuch Subjects as were connected with fcience. This plan was no fooner eftablifhed, than they found their numbers increaf- ed ; they were joined by Sir JoSeph Banks, Dr. Solander, Dr. Mafkelyne, Sir George Shuckburgh, Sir Harry Englefield, Sir Charles Blagden, Dr. Noothe, Mr. RamSden, Mr. Watt of Birmingham, and many others. At thefe meetings difcoveries and improvements in different branches of philofo- phy were the objects of their confideration; and the works of the members were read over and criti- cifed, before they were given to the public. It was in this year that by an exertion in dan- cing, after the mufcles of the leg were fatigued, he broke his tendo achijlis. This accident and the confinement in confequence of it, led him to pay attention to the Subject of broken tendons, and to make a feries of experiments to afcertain the mode of their union. He did not, according to the com- mon practice, confine himfelf to his bed, but by compreffing the mufcles, and raifing the heel, he was enabled, with the knee being kept Straight, Life of the author. ix to walk about the third day after receiving the acci- dent. He divided the tendo achillis of Several dogs, by introducing a couching needle through the fkin at fome diftance from it, and with the edge cut through the tendon; in this way the orifice "in the fkin healed up, and made it Similar to a broken ten- don. The dogs were killed at different periods to Show the progrefs of union, which was exactly Simi- lar to that of a fractured bone when there is no wound in the fkin. In the year 1768, Dr. Hunter having completed the houfe in Wind-mill-ftreet, in which his collec- tion is at prefent deposited, and where he after- wards carried on his anatomical lectures, he gave up to Mr. Hunter the leafe of his houfe in Jermyn- ftreet, which was commodious and well Situated'for private practice. In this houfe Mr. Hunter lived ten years; the fame year too he became a member of the corporation of furgeons; and in the year Sol- lowing, through his brother's intereft, he was elected one of the furgeons of St. George's Hofpi- tal. As he was always engaged in the improvement of his profeffion, young gentlemen who came to Lon- don to finifh their education were very defirous of living in his houfe, and feveral gentlemen, very eminent in practice in different parts of the coun- try, received part of their education as his houfe- pupils. Dr. Edward Jenner of Berkley, Mr. Wil- liam Guy of Chichefter, and Mr. John Kingston, boarded in his houfe in 1770 and 1771, and lived in habits of intimacy with him '!" ]us death. In May 177 1, his Treat:fe on the natural Hiftorv of the teeth was publifhed; and in July of the fame year he was married to Mifs Home, the eldeffc daughter of Mr. Home, fargeon to iv ar^ovn-.-'? re- giment of light hone. Th- expence of hispuduits X Life of the author. had b een fo great, that it was not till feveral year* alter his firft engagement with this lady, that his affairs could be fufficiently arranged to admit ol his marrying. . In June 1772, his fon John was born, who is now an officer in the army *. In the autumn of the fame year I came to him as an apprentice. While he was paying his addreffes to my fifter Mifs Home, I was a boy at Weftminfter-fchool. During the holidays I came home, and Mr. Hun- ter who was frequently there, always Shewed me particular kindnefs ; he made my father an offer to bring me up to his profeflion ; a propofal which I readily accepted. I was ftruck with the novelty, and extent of his refearches, had the higheft re- flect and admiration for his talents, and was am- bitious to tread the paths of fcience under fo able a matter. It is a tribute which I owe to his memory to declare, that an intimate knowledge of him for one-and-twenfy years has increafed my admiration of his uncommon exertions, and my refpect for his abilities.. After finifhing my education at Weftminfter -School as a king's fcholar, and being elected off to Trini- ty College, Cambridge, I found that no advantages which could have been derived from a fcholarfhip in the Univerfity would compenfate for the time I mult have given up in keeping my terms, to the difadvantage of my chirurgical education ; I there- fore thought it prudent to forego my claims upon the Univerfiry as a king's fcholar, and inftead of going down to Cambridge, though elected, went immediately to Mr. Hunter. * He had another fon who died an infant, and tw« daughters, of which Mary Anne died while very young; and Agnes, who is Still alive, is married to Capt. Jamej Campbell, eldeft Son of Sir James, brother of the late Sir Archibald Campbell. . -*• Life of the author* xi At this time his private practice and his profeffi- onal character were advancing very faft, and his family had begun to increafe, but Still no fmall part of his time was devoted to his collection, which, as it daily became larger, was alfo attended with greater expence. The whole fuite of the belt rooms in his houfe were occupied by his preparations; and he dedicated his mornings, from fun-rife to tight o'clock, (the hour for breakfaft) entirely to his purfuits. To thefe he added Such parts of the day as were not engaged in attending his patients. The knowledge he derived from his favourite Studies he constantly applied to the improvement of the art of furgery, and omitted no opportunity of examining morbid bodies, from which he made a collection of facts which are invaluable, as they tend to explain the real caufes of Symptoms, which, during life could not be exactly afcertained, the judgment of the practioner being too frequently milled by theoretical opinions, and delufive fenfa- tions of the patients. In the practice of furgery, where cafes occured in which the operations proved inadequate to their intention, he always investigated with uncom- mon attention the caufes of that want of fuccefs, and in this way detected many fallacies, as well as made fome important discoveries in the healing art. He detected the caufe of failure, common to all the operations in ufe for the radical cure of the hy- drocele, and was enabled to propofe a mode of operating, in which that event can with certainty be avoided. He afcertained, by experiments and observations, that expofure to atmofpherical air, Simply, can neither pro luce nor increaSe inflamma- tion. He discovered in ihe blood fo many pheno- mena connected with life, and not to be referred to any other caufe, that he confidered it as alive in \ xii Life of the author* its fluid ftate. This opinion Seems to be advanced in the Old Teltament *, and, what is very extraor- nary, in the Alcoranf of Mahommed, it alfo ap-? pears to have been entertained by the celebrated Harvey \ ; but the mode in which this fubject is confidered in the following work will fufficicntly Shew that in Mr. Hunter's mind this was not an opinion adopted, but one which arofe from his own invelligation of the properties of the blood. He improved the operation for the fiftula lacry- malis, by removing a circular portion of the os unguis inftead of breaking it down with the point of a trochar. He alfo difcovered that the gaf- tric juice had a power when the ftomach was dead of diffolving it, and gave to the Royal Society a # " Ye Shall eat the blood of no manner of flefh, for " the life of ull flefh is the blood thereof. " Liviticus, chap, xvii, verfe 14. f Alcoran, chap, xxiii. intitled, " The true Belie- " ver's revealed at Mecca." « We formally created man of a finer fort of clay; af- «' terwards we placed him in the form of a feed in a fure « refceptacle; afterwards we made the feed coagulated " blood; and we formed the coagulated blood into a " piece of flefh ; then' we formed the piec? of flefh into " bones, and we cloathed thoSe bones witi flefh; then we « produced the fame by another creation, wherefore, blef- " ed be God, the moft excellent Creator." Chap. xcvi. intitled « Cc-jcaled Blood revealed at « Mecca." " Read in the name of thy Lord, who hath created all things, who hath created m^n of congealed blood." t Quinimo ex varioipr:us motu, in celeritate aut tarditate vehementia aut debilitate ct\aetera, eum et irritantis in- junam etfoventis commodum perfenticere manifeflum eft Ideoque concludimus fanguinfem per fe vivere et nutriri | GUELIEMI HARVEII, Operum, torn. ii. Exercitatio 52, Life of the author. xiii paper on this Subject, which is publifhed in the PhiloSophical Transactions *. In-the winter 1773, he formed a plan of giving a courfe of lectures on the theory and principles of furg.ry, with a view of laying before the public his own opinions upon that fubject. For two winters he read his lectures gratis to the pupils of St. George's Hofpital, and in 1775, gave a courSe for money upon the fame terms as the other teacheis in the different branches of medicine and furgery. Giving lectures was always particularly unplea- fant to him ; fo that the deiire of fubmitting his opinions to the world, and learning their general eltimation, were fcarcely fufficient to overcome his natural diflike to fpeaking in public. He never gave the firft lecture of his courfe without taking thirty drops of laudanum to take off the effects of his uneafinefs. He was fo diffident of himfelf that he trufted nothing t"> memory, and made me draw up a Short abftract of each lecture, which he read on the following evening as a recapitulation, to connect the fubject in the minds of the ltudents. It is curious that the fundamental doctrines of thefe lectures, which conftitute the principal part of the prefent work, Should be the laft of his publi- cations ; and that his anxiety to render them com- plete, fhould make him patiently revife and correct them for twenty years before he gave them to the prefs. We learn from theSe circumftances both his diffidence leSpefting himSelf, and the value which he placed upon his future reputation. Comparative anatomy may be confidered as the purfuit in which Mr. Hunter was conftantly era- ployed. No opportunity efcaped him. In the year * There are feveral preparations both in Dr. Hunter's and Mr. Hunter's collectioa illustrating this fact. C 2 xiv Life of the author* 1773, at tne requeft of his friend Mr. Walfh, he diffected the torpedo, and laid before the Royal Society an account of it's electrical organs. A young elephant which had been prefented to the Queen by Sir Robert Barker died, and the bo- dy was given to Dr. Hunter, which afforded Mr. Hunter an opportunity of examining the ftructure of that animal by affifting his brother in the diffec- tion; fince that time two other elephants died in the Queen's menagerie, both of which came under Mr. Hunter's examination. In 1774, he publifhed in the Philofophical Tranfadions an Account of certain Receptacles of Air in Birds, which communicate with the lungs, and are lodged both among the flefhy parts and hollow bones of thefe animals ; and a paper on the Gillaroo-trout, commonly called in Ireland, the Gizzard-trout. In 1775, feveral animals of that fpecies, called the gymnotus electricus of Surinam was brought alive to this country, and by their electrical pro- perties excited very much the public attention. Mr, Walfh, defirous of purfuing his inveftigations of animal electricity, made a number of experiments on the living animals ; and to give his friend Mr. Hunter an opportunity of examining them, pur- chafed thofe that died. Any anatomical account of their electrical organs was drawn up by Mr. Hunter, and published in the Philofophical Trans- actions. In the fame volume there is a paper of his, containing Experiments on Animals and Vegetables refpeding their power of producing heat. In the courfe of his purfuits, Mr. Hunter met with many parts of animals where natural appear- ances could not be preferved, and others, in which the minuter veffels could not be diftindly feen when Kept in fpirits; it was therefore neceffary to have Life of the author. XV them drawn, either at the moment, or before they were put into bottles. The expence of employ- ing profeffed draftfmen, the difficulty of procuring them, and the disadvantage which they laboured under in being ignorant of the fubjed they were to reprefent, made him defirous of having an able perfon in his houfe entirely for that purpofe. With this view he engaged an ingenious young artift to live with him for ten years; his time to be wholly employed as a draftfman, and in making anatomical preparations. This gentleman, whofe name was Bell, foon became a very good pradical anatomift, and from that knowledge was enabled to give a fpirited and accurate refemblance of the fubjeds he drew; fuch as is rarely to be met with in representations of anatomical fubjeds. By his labours Mr. Hunter's colledion is enriched with a confiderable number of very valuable drawings, and a great variety of curious and delicate anato- mical preparations ** In January 1776, Mr. Hunter was appointed Surgeon-extraordinary to his Majefty, and in the fpring he gave to the Royal Society a paper on the belt mode of recovering drowned perfons. In the autumn he was taken extremely ill, and the nature of his complaints made his friends, as well as himfelf, confider his life to be in danger. When he refleded upon his own Situation, that all his fortune had been expended in his purfuits, and that his family had no provifion but what Should ariSe from the Sale of his colledion, he became very fo- licitous to give it its full value, by leaving it in a State of arrangement. * The engravings infertcd in Mr. Hunter's Treatife on the Venereal DifeaSe, in his book upon the Animal (Eco- nomy, and moft of theSe contained in the prefent work, are taken Srom Mr. Deli's drawings, and will remain as proofs of his abilities in that particular line of drawing. XVI Life of the author* As foon as he was able to leave his room, his firt objed was to make a catalogue of his collec- tion; but his health requiring him to go to Bath, I was was employed, with the ailiftance of Mr. Bell, during his abSence, in makingdeScriptions of the preparations, leaving blanks Sor Such as I was not acquainted with. His complaints were a good deal relieved, but his impatience to return to town, made him comeback before he was well; he con- tinued, however, to amend, and very foon reco- vered. In 1778, he publifhed the fecond part of his Treatife on the Teeth, in which their difeafes, and the mode of treatment are considered.This rendered his work upon that fubjed complete. He publifhed alfo in the Philofophical Transactions a paper on the Heat of Animals and Vegetables. I had now lived fix years with Mr. Hunter, and had compleated my education; his expences had always exceeded his income, I had therefore no emolument to expedt from remaining in his houfe, which made it neceffary for me to take up fome line for my own fupport, and Admiral Ktppel's adion with the French fleet was the means of pro- curing me a very eligible Situation. The newly finifhed naval hofpital at Plymouth received the whole of the wounded men from Ad- miral Keppel's fleet, and Dr. Farquarfon, the firft commiffioner of fick and hurt, at the requeft of Mr. Adair, the prefent furgeon general to the gar- rifon of Gibraltar, gave me the appointment of af- fiftant-furgeon, with appartments to refide at the hofpital. From the circumftance of my bein"- the only furgeon en that eftablifhment, who was a member of the corporation, I was authorized by ths fick and hurt board to perform operations, and affift the furgeon in the more important parts of his duty. Life of the author. xvii In this fituation many opportunities occured to me of adding to Mr. Hunter's colledion; the Sea furnifhing curious fifh and other marine produdions, and the hofpital pradice preparations of morbid parts. Mr. Hunter was now wholly affifted by Mr. Bell. In 1779, he publifhed his Account of the Free Mar- tin in the Philofophical Tranfadions. In 1780, he laid berore the Royal Society an Ac- count of a Woman who had the Small-pox. during Pregnancy, where the difeafe feemed to have been communicated to the fetus. In 1781, he was eleded a Fellow of the Royal So- ciety of Sciences and Belles Lettres, at Gotten- burg. In 1782, he gave the Royal Society a paper on the Organ of Hearing in Fifh. Befides the papers which he prefented to that learned body, he read fix Croonion ledures upon the iubjed of Mufcular Ac- tion, forthe years 1776, 1778, 1779, 1780, 1781, and 1782. In thefe ledures he collected all his observations upon muScles, reSpeding their powers and effeds, and the ftimuli by which they are affed- ed; and to theSe he added Comparative Observa- tions upon the moving Powers of Plants. Thefe ledures were not publifhed in the Philofo- phical Tranfadions, for they were withdrawn as foon as read, not being confidcred by the author as complete difiertations, but rather as materials for fome future publication. It is much to be regretted that Mr. Hunter was fo tardy in giving his observations to the public; but fuch was his turn for inveftigation, and fo extenfive the Scale upon which he instituted his inquiries, that he always found Something more to be accom- plished, and was unwilling to publifli any thing which appeared to himSclf ununified. K:: observa- tions on the MuScular Action of the Blood-vcflels D xviii Life of the author. were laid before the Royal Society in 1780, and yet he delayed publishing them till his Obfervations on the Blood and Inflammation were arranged, and they will be found to make a part of the prefent work. In 1783, he was chofen into the Royal Society of Medicine, and Royal Academy of Surgery in Paris. In this year the Ieafe of his houfe in Jermvnftrcet having expired, and his colledion being now too large to be contained in his dwelling houfe, he pur- chafed the leaSe of a large houfe on the eaft fide of Leicefter-fquare, and the whole lot of ground ex- tending to Caltle-ftreet, on which there was another houfe. In the middle fpace between the two houfes he erected a building for his colledion. Upon this building he expended above three thou- fand pounds, and unforcunately for his family, the leaSe did not extend beyond twenty-four years. In excufe for fo inconfiderate a tranfadion, it can only be faid, that the difficulties he had met w.th in finding ground in an eligible Situation, had haraiT- ed his mind, already too much occupied, to fuch a degree, that he was glad to be relieved from that embarraiTment, and made the infereft of his family give way to his prefent accommodation. In the building formed for the colledion there was a room fifty-two feet long, by twenty-eight wide, lighted from the top and having a gallery all round, for containing his preparations. Under this were two apartments; one for his ledures, and the other, with no particular deftination at firft, but afterwards made ufe of for weekly meetings of medic: 1 friends during the winter. To this building the hou e in Caftle-ftreet was entirely uibfervient; and th_ rooms in it were ufed for the different branches of human and comparative anatomy. Life of the author* xix During the execution of this extenfive plan I re- turned to England from Jamaica, where at the clofe of the war I had been appointed Staff furgeon. Sir Archibald Campbell, the governor, coming home, gave me leave of abfence on account of my health, and allowed me to attend him. We arrived in Au« guft 1784, and I was permitted to exchange upon half pay. I found Mr. Hunter now advanced to a very con- fiderable fhare of private pradice, and a ftill greater Share of the public confidence. His colledion had increafed with his income. In this he was materi- ally affilted by the friendfhip of Sir Jofeph Banks, who not only allowed him to take any of his own Specimens, but procured him every curious animal produdionin his power, and afterwards divided be- tween him and the Briiifh Mufeum all the Specimens of animals he had colleded in his voyage round the world. To his friends the honourable Mr. Charles Greville and Mr. Walfh, he was alfo under parti- cular obligations. Drawing materials from fuch ample fources, (land- ing alone in this branch cf fciencc, and high in the public estimation, he had fo much attention paid to him, that no new animal was brought to this coun- try which was not Shewn to him ; many were given to him; and ofthofethat were for Sale he common- ly had the refufal: under thefe circumilances, his colledion made a progrefc, which would otherwise have been impoflible. In April 1785, the new room w-as compleatcd, and I devoted the whole of this fummer to the cb- jed of afhlting him in moving his prepai3tion?, and arranging them in their proper order. I/ir. Bell and Mr. Andre, a gentleman who had been the greater part of his life engaged in anatomical purfuits, were constantly employed in this bufinefs. D 2 xx Life of the author. At this period Mr. Hunter may be confidered as at the height of his chiiurgical career; his mind and body were both in their full vigor. His hands were capable of performing whatever was fuggefted by his mind ; and his judgment w is matured by former experience. Some inftances of his extra- ordinary fkill may very properly be mentioned. He removed a tumor from the fide of the head and neck of a patient at St. George's Hofpital, as large as the head to which it was attached; and by bringing the cut edges of the Skin together, the whole was nearly healed by the firft intention. He difftded out a tumor on the neck which one of the beft operating furgeons in this country had declared, rather too ftrongly, that no one but a fool or madman would attempt; and the patient got perfectly well. He difcovered a new mode of performing the o- peration for the popliteal aneurifm, by taking up the femoral artery on the anterior part of the thigh, without doing any thing to the tumor in the ham. The fafety and efficacy of this mode have been con- firmed by many fubfequent trials; and it muft be allowed to ftand very high among the modern im- provements in furgery * I believe Mr. Hunter was one of the firft. who taught, that cutting out the part was the only mode of preventing the hydrophobia; and he extended the time in which that might be done with every probability of fuccefs, beyond the period generally believed. This dodrine, in favour of cutting out the part, met with the itrongeft confirmation by two melancholy cafes, in which, from the nature of the parts and numberlefs fcratches on the fkin, it was impoffible to remove them. Though cauftic * An account of this operation is publifhed in the Tranf- adions of a Society for improving Medical and Chirurgical Knowledge. Life of the author. xxi was applied to every part that had a vifible mark, and every other precaution that could be thought of was ufed, the wounds in both inftances proved fatal. If we confider Mr. Hunter at this period of his life, it will afford us a ftrong pidure of the turn of his mind, of his defire to acquire knowledge, and his unremitting alliduity in profecuting whatever was the objed of his attention. He was engaged in a very extenfive private prac- tice; he was furgeon to St. George's Hofpital; he was giving a very long courfe of ledures in the winter; he was carrying on his enquiries in com- parative anatomy; had a School of pradical human anatomy in his houfe; and was always employed in fome experiments refpeding the animal ceconomy. He was always foiicitous for fome improvement in medical education; and, with the alfiftance of Dr. Fordyce, inftituted a medical fociety, which he allowed to meet in his ledure-rooms, and of which he was chofen one of the patrons. Th's fociety, called the Lyceum Medicum Londinenfe, under his aufpices and thofe of Dr. Fordyce, has acquired con- siderable reputation, both from the numbers and merits of its members. In the year 1786, in confequence of the death of Mr. Middleton, Mr, Hunter was appointed deputy furgeon-general to the army. He now publifhed his work upon the Venereal Difeafe, which had been long expected by the public; and, if we may judge from the rapid Sale of the firft edition, thefe expec- tations have not been difappointed. He alfo pub- lished a work entitled, Obfervations on certainParts of the Animal CEconomy. In this work he has colled* ed feveral of his papers inferted inthe Philofophical Tranfactions, which related to that fubject, having permiffion from the prefident and council of the Roy- al Society to reprint them; there are alfo Obferva- xxii Life of the author. tions upon Some other Parts of the Animal CEcono- my, which had net before been publifhed. This work met with a ready fale. It is to be confidered among the peculiarities of his charader, that he chofe to have his works printed and publifhed in his own houfe, where they were alfo fold; but find- ing this meafure to bear hard upon the bockfellers, in a way which had not been explained, and which was not intended, the fecond edition was fold by Mr. Johnfon in St. Paul's Church-yard, and Mr. Nicol in Pall-mall. In the fpring of this year he had a very fevere ili- neis, which confined him to his bed, and rendered him incapable of attending to any kind of bufinefs. In this State I was obliged to take upon m) felf the charge of his patients, as well as of his other affairs, and thefe were fo extenfive that my refidence in his houfe became absolutely neceffary. His recovery was very flow; and his health received fo fevere a Shock that he was never afterwards entirely free from complaint, or capable of his ufual bodily ex- ertions. After his recovery from this illnefs, he was fub- jed to affedions of his heart, upon every occafion which agitated his mind, or required any fudden ex- ertion of the body. In this infirm State he was un- able to attend his patients upon fudden calls in the night, or to perform operations without affiftance ; and for thefe reafons I continued to live with him till within a year of his death, and then took a houfe within a few doors, which in no reSped detatched me from his purfuits, or prevented me taking a part in his private pradice. In the ycitf 1787, he gave a paper to the Royal Society, containing an Experiment to determine the Effed of extirpating one Ovarium on the Num- ber of Young; a papsr in which the Wolfe, Jack- all and Dog, are proved to be of the fame Species; Life of the author. xxiii and a third upon the anatomy of the Whale Tribe. TheSe papers procured him the honour of receiving Sir John Copley's annual geld medal, given as a mark of diftinguifhed abilities. Thefe labours fhew that the decline of his health, although it diminifhed his exertions, by no means abated his ardour for the inquiries in which he was always engaged. In July, he was chofen a member of the Ameri- can Philofophical Society. He now applied to the Governorsof St. George's Hofpital, to be allowed on account of his health, an almtant-furgeon, which they very readily granted, and I was appointed to that office. His colledion, which had been the great objed of his life, both as a purfuit and an arnufement, was now brought into a State of arrangement ; and gave him at length the fatisfadion cf flicwing to the public a feries of anatomical fads formed into a fyf- tem, by which the ccconomy of animal life was il- luftrated. He fhewed it to his friends and acquain- tances twice a year, in October to medical gentle- men, and in May to noblemen and gentlemen, who were only in town during the fpring. This cuftom he continued to his death. Several of his friends had long been defirous of having an engraving of him, and requested him to fit for a pidure to fome painter of eminence whom they would employ. This he always declined, not choofing that it fhould be done at the expence of others; and thinking the price too high for himfelf to pay. His fcruples were, however, at length fur- mounted, by a defire to oblige Mr. Sharp, the en- graver, cf whofe works he was an admirer. This artift made a requeft that he would fit to Sir Jofhua Reynolds, who had promifVJ to take unufua! pains with the pidure; as the engraving was propofed. more xxiv Life of the author. as a reft of the artift's abilities upon which he might eftablifh a charader, than as a print for fale. This pidure, which is one of the very laft works of that eminent painter, and one of his beft, re- mains in the pofieffion of Mr. Hunter's fon; and the print which Mr. Sharp engraved from it, is con- sidered as one of the moft fpirited heads and fineft engravings, which have been produced in this country. In the year 1789, Mr. Bell, who was become a very fkillfull anatomift, and a good pradical fur- geon, received an appo'ntment as affiflant-furgecn to the ISland of Sumatra, in the Service of the Ho- nourable Eaft India Company. This appointment, procured by the friendship of Sir Jofeph Banks, he accepted with a double view, the one to improve his fortune, the other to colled fpecimens in natu- ral hiftory. In both of thefe purfuits he was fuc- ceSsful beyond his moft Sanguine expedations; he fent home fome very rare fpecimens of animals and corals, and two papers, Since printed in the Philo- fophical TranSadions, one on the double horned Rhinoceros, the other giving a delcription of an uncommonly formed Fifh ; but, unfortunately for fcience, he died of a fever, very much regretted by his friends, in the year 1792. In the year 1792, Mr. Hunter found that his courfe of ledures took up fo much of his time, that he was unable to correct his other papers. Lie therefore gave it up to me. As a previous ftep to this arrangement I had given it the two preceeding fummers. Mr. Hunter now began to prepare the prefent work for the prefs, and intended as foon as it was in the hands of the public, to give a courfe of pradical ledures in furgery, for which he had been many years colleding materials; thefe w;re fo far advanced, that another winter, had he lived, would have finifhed them. The materials of Life of the author. xxv thefe ledures having come into my hands; that they may not be entirely loft to the public, I meun to avail myfelf of them, and am preparing my arrange- ments for that purpofe. Upon the death of Mr. Adair, which happened in this year, Mr. Hunter was appointed inSpedor- generat of hofpitals, and furgeon-general of the;.*-- my. He was alfo eleded a member of the Royal College of Surgeons in Ireland. In the year 1791, he was fo much engaged in the duties of his office, as furgeon-general to the ar- my, and his private pradice, that he had little time to beftow upon his Scientific^! objeds ; but his lei- fure time, fmall as it was, he wholly devoted to them. In 179s, he was eleded an honorary member of the Chirurgo Phifical focietv of Edinburgh, and was chofen one of the vice-prefidents of the Veterinary college, then firft eftablifhed in London. Lie pub- lished in the TranSadions of the Society for the im- provement of medical and chirurgical Knowledge, of which fociety he was one of the original mem- bers and a zealous promoter, three papers, on the following fubjeds i upon the treatment of inflamed Veins, onlntrofufception, and on a mode of con- veying Food into the Stomach, in Cafes of Paraly- fis of the GEfophagus. He finifhed his observations on the CEconomy of the BeeSj and prefented them to the Royal Society. Thefe observations were made at Earl's court, and had engaged his attention for many years ; every in- quiry into the ceconomy of thefe infeds had been attended by almofl: infurmountable difficulties ; but thefe proved to him onlv an incitement, and the contrivances he made ufe of to bring the different operations of thefe indefatigable animals to view were almofl: without end. E xxvi Life of the author. Earl's Court to Mr. Hunter was a retirement from the fatigues of hisprofeffion; but in no refped a re- treat from his labours; there, on the contrary, they were carried on with lefs interruption, and with an unwearied perfeverence. From the year 1772 till his death, he made it his cullom to Sleep there du- ring the autumn months, coming to town only du- ring the hours of bufinefs in the forenoon, and re- turning to dinner. It was there he carried on his experiments on di- gestion, on exfoliation, on the tranfplanting teeth into the combs of cocks, and all his other inveftiga- tions on the animal ceconomy, as well in health as in difeafe. The common bee was not alone the fub- ject of his obfervation, but the wafp, hornet, and the lefs known kind of bees were alfo objeds of his attention. It was there he made the feries of pre- parations of the external and internal changes of the filk-worm; alfo a feries of the incubation of the egg, with a very valuable fet of drawings of the whole feries. The growth of vegetables was alfo a favourite fubjed of inquiry, and one on which he was always engaged in making experiments. In this retreat he had colleded many kinds of animals and birds, and it was to him a favourite a- mufement in his walks to attend to their adions and their habits, and to make them familiar with him. The fiercer animals were thofe to which he was moft partial, and he had feveral of the bull kind from different parts of the world. Among thefe was a beautiful fmall bull he had received from the Queen, with which he ufed to wreftle in play, and entertain himfelf with its exertions in its own defence. In one of thefe contefts the bull overpower- ed him, and got him down, and had not one of the Servants accidentally come by and frightened the animal away, this frolic would probably have coft him his life. Life of the author. xxvii The colledion of comparative anatomy which Mr. Hunter h,as left, and which may be confidered as the great objed of his life, muft be allowed to be a proof of talents, affiduity, and labour, which can- not be contemplated without furprize and admira- tion. It remains an unequivocal teft of his perfeverance and abilities, and an honour to the country in whofe fchools he was educated, and by the patronage of which he was enabled on fo extenfive a fcale to car- ry on his purfuits. In this colledion we find an attempt to expofe to view the gradations of nature, from the molt Simple ftate in which life is found to exift, up to the moft perfed and moft complex of the animal creation— man himfelf. By the powers of this art, this colledor has been. enabled fo to expofe, and preferve in fpirits or in a dried ftate, the different parts of animal bodies in- tended for Similar ufes, that the various links of the chain of perfedion are readily followed and may be clearly underftood. This colledion of anatomical fads is arranged ac- cording to the fubjeds they are intended to illuf- trate, which are placed in the following order: Firft, parts conftruded for motion. Secondly, parts ef- fential to animals refpeding their own internal ceconomy. Thirdly, parts fuperadded for purpofes conneded with external objeds. Fourthly, parts for the propagation of the fpecies and maintenance or fupport of the young. The firft clafs exhibits the fap of vegetables and blood of animals, for which fluids all the different parts of the vegetable and animal creation are form- ed, fupported, and increafed. Thefe fluids being more and more compounded, as the vegetables and animals become mora E 2 xxviii Life of the author. perfed, are coagulated and form a regular feries. The fap of many plants does not coagulate fpontaneouf- lv but is made to undergo this change by adding the extrad of Gowlard, in this refped differing from water: the fap of fuch plants is confidered as the moft Simple: in the onion there is a fpontani* ous coagulation: in inSeds the blood coagulates, but is without colour: in the amphibia, colour is fuperLdded. The moving powers of animals from the Simple Straight mufcle, to the moft complicated ftrudure of that organ, with the different applicar tions of elaStic ligaments, form a fecond feries. The growth of bone, horn, and fhell, come next in order ; and the joints which admit of their mov- ing readily on one another, finifh this fubjed. The fecond clafs begins with thofe animals of the hydatid kind, which receive nourifhment, like ve- getables, from their external furface, having no mouth. Then follow thofe which are Simply a bag or ftomach, with one opening, as the polypus, having no organs of generation, as every part of the bag is endowed with that power; but in the leech the ftrudure becomes more complex, for al- though the animal is compofed of a bag with only one opening, the organs of generation, brain, and nerves, are fuperadded, and thence a gradual feries is continued to thofe animals in which the ftomach forms only a diSLind part of the animal, for the purpofe of digeftion. The Stomachs themfelves are alfo arranged in the order of their fimplicity. Firft, the true membranous digefting ftomach, then thofe with the addition of crops, and other bags, to pre- pare the food for digeftion, as in the ruminating tribe, and, laftly, thofe with gizzards. Annexed to the ftomach, is a very complete and extenfive feries of teeth, which are varied according to the Uind of food and ftomach. After the Stomachs, are the different appearance* Life of the author. xxix of the inteftinal canal, which exhibit almoft an in- finite variety in the ftrudure of their internal fur- face from which the aliment is abforbed. The quan- tity ot furface is increafed in fome by tranfverfe folds, in fome by fpiral or longitudinal ones, and in others puts on a loculated appearance,as in the whale. To thefe are added the glands, conncded with the inteftines, as the liver, pancreas, and fpleen, which may properly be confidered as appendages. After digeftion, follows the Syftem of abforbing veffels, the fnnpleft being the roots of plants, after which are lymphatic and ladeal veffels of different animals. Thefe in the human fubjed and the ele- phant are Small, and in the turtle large and more numerous; but in the Spermaceti whale, where they are employed Sor conveying the Spermaceti, oS a Size infinitely beyond what is met with in any other animal. To thefe are annexed the thoracic duds in different animals. The natural order, in following the courfe of the aliment from the ftomach as a guide, leans from the abforbents to the heart, which in the caterpil- lar is a fimple canal or artery running along the. middle of the back of the animal, admitting of un- dulation of the blood ; from this fimple ftrudure it becomes, in different animals, by Small additions, more and more complex, till it arrives at the de- cree of perfection which is difplayed in the organi- zation of the human heart. Thefe are followed by the different Structures of valves in the arteries and veins, and the coats of thefe veffels. Then Hi- kings are fhown in all their gradations from the fimple vafcular lining of the eggfhell, which Serves as lungs for the chicken, to thofe of the more per- fed animals. In one inftance, viz. that of the fyren, both gills and lungs are feen in the fame animal. The windpipe and larynx are then frown, under all their different forms. The kidnies, which, xxx Life of the author*, feparate the fuperfluous fluids from the circulation, make the laft part of this fubjed. The third clafs takes up the moft fimple ftate of the brain, which is in the leech a fingle nerve wkh ramifications. In the fnail, the brain forms a cir- cular nerve, through the middle of which paffes the cefophagus, from which circle there are bran- ches "•oing to every part of the fkin of the animal. In the infed, the brain has a more compad form, is larger in fifh, but Still more fo in birds, gradu- ally increasing in fize as the animal is endowed with a greater degree of fagacity, till at laft it be- comes the large complex organ found in the ele- phant and in the human fubjed. The coverings of the brain, and the ganglions and peculiarities of the nerves are annexed. The organs of fenfe are arranged in the order of their fimplicity, beginning with that of touch, which is only a villous vafcular Surface, the villi very fhort where the impreffion is to be made through a thin cuticle, as in the hu- man finger ; very long where the covering is thick, as the hoot of the horfe. The organ of tafte is on- ly a modification of touch, and therefore nothing in the organization is different, but the varieties in ftrudure adapting the tongue for different pur- pofes are numerous; in many animals it anfwers the pofe of a hand, to bring the food to the mouth, as in many fhell-fifh, the ant-bear, woodpecker, and camelion. Conneded with the tongue are the fauces which in many animals have peculiarities; in the eledric eel, they have a curious carrunculated irre- gular appearance; but they are yet more extraordi- nary in the camel, which has an apparatus to moif- ten the parts, fo as to prevent the painful fenfation of thirft, thus adapting the animal to the fandv de- farts which it is deftined to inhabit; this apparatus confifts of a large bag hanging down feveral inches in the fauces, and attached to the palate, which the Life of the author* xxxi animals can at pleafure move up and down, and lu- bricate the fauces.. The organ of fmell is variously conftruded, and is more complicated in many ani- mals than in man, as in the lion, and Sea-cow. The organ of hearing in fifh confifts of three femi- circular canals; but is much more complex in land animals. The organ of feeing is different in thofe animals which are formed to fee in water, and in thofe which fee in air; it differs again in thofe which are to fee with little or with much light; all thofe peculiarities are illuftrated by preparations. The pigmentumoftheeye in fome fifh refembles poiifh'd Silver; in ruminating animals at the bottom of the eye it has a greenifh hue, in the lion and cat kind, a portion of the bottom is white; but, as a general principle, the colour of the pigmentum is the fame as the retemufcofum of the fkin of the animal, be- ing white in white animals and black in very dark ones. After the brain and fenfes are arranged the eel- lular membrane and animal oils, which are follow- ed by the external coverings. Thefe are divided in- to the different kinds, as hair, feathers, Scales, etc. with the rete mufcofum, or that membrane which is interpofed between the true fkin and the fcarf-fkin for the purpofe of giving the peculiar colour. Add- ed to thefe are the parts peculiar to different animals, for offence and defence, as fpurs, hoofs, horns, Stings, and alfo electric organs. There follow next fuch peculiar ftrudures as occur in certain tribes of animals, as the air-bladders in fifh, etc. The fourth clafs begins with thofe animals which have no diftind parts allotted for generation, that power being diftufed over the whole animal. In thefe the young grow out of the old, as in the coral and polypi; and next in order come the herma- phrodite organs both of plants, and of animals. The snale organs are then taking up as' a d'ftmd tub- xxxii Life of the author•< jed, firft in plants and then in animals, both at the' times in which they do not breed, and in the breed- ing SeaSon, to fhow their different ftates; 10 ihefe are added a number of parts which anfwer Seconda- ry purpoSes in generation, and may be confidered as appendages. The female organs are firft exhibited in the maid- en ftate, in every clafs of animals, demonstrating the fhape and length of the oviducts, the form of the uterus, the length of its horns, with the varie- ties in their ftrudure, and the inftances in which thefe horns are entirely wanting, as in fome mon- keys ; to which are added, the peculiarities refpect- ing the hymen. They are then exemplied in the impregnated ftate, beginning with the feeds of vege- tables and thoSe which have both Seeds and voung moots, as the onion. The eggs of infects follow next, with their changes, particularly of the filk worm. The Spawn of fifh, are next fhown, firft in thofe which have eggs, and then in thofe which have their eggs hatched in the oviducts, as thedog-fifh. The arrangement then proceeds to the formation and incubation of the egg in the fowl, and the pro- cefs of fcetation in the quadruped, with their pecu- liarities and the different Structures and appearances of the afterbirth. Added to thefe are the peculia- arties of the foetus, and the different modes by which the mother gives nourishment to her young. In this colledion, befides the preparations of the parts of themfelves in fpirits, in a dried ftate or cor- roded, fo-as to give the moft accurate ideas of their ftrudure, there is a confiderable number of very valuable drawings to Show the progreSs of different proceffes in the animal ceconomy, together with iuch appearances as were not capable of being pre- served. 1 his Sketch will give an idea, but a very inade- quate one, of the fyStem which is comprehendLd irt i Life of the author. xxxiii Mr. Hunter's colledion. It alfo includes a very large feries of whole animals in fpirits arranged ac- cording to their internal ftrudure, and many of the moft rare fpecimens of preferved animals in this country, as the camelopardus, guanica, hippopota- mus, tapir, argus-pheafant, etc. There is alfo a Series of Skulls of different animals to fhew their peculiarities, and fkeletons of almoft every known genius of animals, there is a large colledion of fhells and infeds ; a prodigious num- ber of calculi of different forts from the urinary and gall-bladders, the Stomach, and inteftinal canal; there are likewife the moft uncommon deviations from the natural ftrudure, both in man and in other animals, preferved in fpirits or in a dried ftate; the moft extraordinary fpecimens of this kind are a dou- ble human uterus, one of the parts pregnant, and a double human Skull perfedly formed, the one up- on the top of the other. To make this colledion more complete in everv fubjed conneded with com- parative anatomy, is added one of the largeft and moft feled colledions of extraneous foifils that can be feen in this country. The fymptons of Mr. Hunter*s complaint, for the laft twenty years of his life, may be confidered as thofe of the angina pedoris; and form one of the moft complete hiltories of that difeafe upon record. I have chofen to give this account a place by itfelf diftind from the general hiftory of his life, of which it forms aru important part, more efpecially when prefixed to a medical work. Each Symptom was defcribed at the time it occur- red, and either noted by himSelf, or didated to me, when Mr. Hunter was too ill to write; they will F xxxiv Life of the author. therefore be found more accurately detailed than la ordinary cafes *. Mr. Hunter was a very healthy man for the firft forty years of his life; and, if we except an inflam- mation of his lungs in the year 1759, occasioned moft probably by his attention to anatomical pur- fuits, he had no ccmphiint of any confequence du- ring" that period. In the Spring of 1769, in his for- ty-fir ft year, he had a regular fit of the gout, which returned the three following fprings, but not the fourth; and in the Spring of 1773, having met with fomething which very forcibly affeded his mind, he was attacked at ten o'clock in the forenoon with a pain in the ftomach, about the pylorus; it was the fenfation peculiar to thofe parts, and became fo vi- olent that he tried change of pofition to procure eale, he fat down, then walked, laid himfelf down on the carpet, then upon chairs, but could find no relief; he took a Spoonful of tincture of rhubarb, with thirty drops of laudanum, without the fmalleft benefit. While he was walking about the room he eaft his eyes on the looking-glais, and obferved his countenance to be pale, his lips white, giving the appearance of a dead man, this alarmed him, and led him to feel for his pulfe, but he found none in either arm; he now thought his complaint Serious; Several phylicians of his acquaintance were then fent for, Dr. William Hunter, Sir George Baker, Dr. * As the Statement of the following cafe ij made up Srom detached notes which were not written with a view to pub- lication, it will appear in point oS language extremely defi- cient ; it was, however, thought better to leave it in its pre- fent Sorm, lezft, by altering the language, the effed oS Some oS the expreSSions might be diminished, or miSunderftood; it was a!So believed, that an account, however crude, com- ing diredly Srom the author, would be more acceptable to the public, than one a little more finifned from any other hand. Life of the author* xxx> Huck Saunders, and Sir William Fordyce, all came but could find no pulfe; the pain ftill continued, and he found himfelf at times not breathing. Be- ing afraid of death foon taking place if he did not breathe, he produced the voluntary ad of breath- ing, by working his lungs by the power of the will; the fenfative principle, with all its effects on the ma- chine not being in the leaft affeded by the complaint. In this ftate he continued for three quarters of an hour, in which time frequent attempts were made to feel the pulfe, but in vain; however, at laft, the pain leffened, and the pulfe returned, although at firft but Saintly, and the involuntary breathing be- gan to take place; while in this ftate, he took Ma- deira, brandy, ginger, etc. but did not believe them of any fervice, as the return of health was very gra- dual; in two hours he was perfedly recovered. In this attack there was a fufpenfion oS the moft material involuntary adions, even involuntary breathing was flopped, while SenSation with its con- fequences, as thinking and ading with the will, were perfed, and all the voluntary adions were as Strong as before. Quere. What would have been the confcquence of his not having breathed by means of the volunta- ry mufcles? It.ftruck him at the time that he would have died; but we cannot fuppofe that would have been the confequence, as breathing moft probably is only neceffary for the blood while circulating, and as the circulation was flopped, no good could have arifen from breathing. From this cafe it appears that, the involuntary adions of the body are not a regular feries of adions depending abfolutely on one another, but each part can and. often does a.d independently, or leaves off ading while other adions are going on; but although F 2 xxxv i Life of the author. there is not an abfolute dependence, there is a ne- ceffary connexion among them, without which their adions cannot long continue. The ftomach was probably the feat, or origin of this ceffation of ac- tion; as we know that affedions of the ftomach have the greateft influence on every part of the body, and that affedions of every part, have the power of in- fluencing the ftomach. Mr. Hunter never had any return of thefe affec- tions of the ftomach, though frequently troubled with flight complaints both in the ftomach and bow- els, which were readily removed by fmall dofes of rhubarb. In other refpeds he enjoyed his health till the year 1776. Towards the end of the fpring he was feized with a very fevere and dangerous ill- nefs, in confequence of anxiety of mind from being obliged to pay a large fum of money for a friend, for whom he had beenfecurity, and which his circum- stances made extremely inconvenient. At two o'clock in the forenoon he eat fome coll chicken and ham, and drank a little weak punch; immediately after this he went eight miles in a poft- chaiSe. While he was on the journey he had the feel of having drank too much, but paffed the re- mainder of the day tolerably well; at twelve o'clock at night his ftomach was a little difordered, for which he took fome caraways, and went to bed; he had no fooner lain down than he felt as if fumended in the air, and foon after the room appeared to go round; the quicknefs of this motion feemed to in- creafe, and at laft was very rapid; it continued for fome time, then became Slower and flower tiil the whole was at reft; this was fucceededby vomiting, which was encouraged and gave him a good night's reft; next day he was tolerably well, but fatigued: the morning after, thinking'himfelf quite recover- ed, he went out before breakfaft, drank fome tea and eat fome bread and butter, which he was net Life of the author. xxxvti accuftomed to do. At eleven o'clock, he felt his Stomach much in the fame ftate as before; in about half an hour, the fenfation of the room appearing to turn, recommenced, and continued for fome time, but not with fuch violence as in the laft attack; he became fick and vomited; the fenfation of himfelf and every thing elfe going round continued for fome time, but not with fuch violence as in the laft at- tack ; he became fick and vomited ; the fenfation of himfelf and every thing elfe going round, went off, but that of being fufpended in the air continued, with a giddinefs; he now could hardly move his head from an horizontal pofition, and about two o'clock was brought home in his carriage, the mo- tion of which was very difngreeable, giving the fen- fation of going down, or finking *. Alter he went to bed, the giddinefs and the idea of being fufpended in the air increafed, and the leaft motion of the head upon the pillow appeared to be fo great that he hardly durSt attempt it; if he but moved his head half round, it appeared to be mov- ing to fome diftance with great velocity; the idea he had of his own Size was that of being only two feet long, and when he drew up his foot, or puthed it down, it appeared to him to be moving a vaft way. His fenfations became extremely acute or heighten- ed ; he could not bear the leaft light, fo that although the window-blinds were fhut, a curtain and blanket were obliged to be hung up againft it, the fire to have a Screen before it, and the bed curtains to be drawn; he kept his eyelids clofed,yet if a lighted can- * It is very curious that, the fenfation of finking is very uneafy to moft animals. When a perSon is toffed in a blank- et, th,e uncomfortable part is falling down; take aiiy ani- mal in the hand and rait'.- it up, it is very quiet, but bring it dow i and it will exert all its powers oS refiflance, 'evefy mufcle in the bddy is inaction; this is the cafe even with, a child as early as its birth. xxxviii Life of the author. die came acrofs the room, he could not bear it; his his hearing was alSo painfully acute, but not fo much increafed, as his fight; the fmell and tafte werealSo acute, every thing he put into his mouth being much higher flavoured than common, by which means he relifhed what he eat; his appetite at firft was very indifferent, but Soon became good; his pulSe was ge- nerally about fixty, and weak, and a Small degree of heat on the fkin, efpecially on the hands and feet; he remained in this ftate for about ten days, and was obliged to be fed as he lay; by this time he was rather better; that is, he could move his head more freely. When he was at firft attacked, the pulfe was full and eight ounces of blood were taken away, butthis did not appear to beoffervice; the day following he was cupped between the fhoulders, and had a large blilter applied upon the part; he tcok an emetic, and feveral times purging medicines, and bathed his feet in warm water, but nothing appeared to be of the leaft ufe. The purging and vomiting diftreffed him greatly, for both the ftomach and inteftines were fo irritable, that lefs than half the ufual quan- tity had the defired effed. He took fome James's powder, and drank fome white wine . whey on ac- count of the heat in the fkin, efpecially in the feet and hands, which took it off, and gave him for the firft time a comfortable feel. At the end of ten days all his ideas of bis prefent ftate became more na- tural, the ftrange deception concerning his own fize was in part correded, and the idea of fufpen- fion in the air became lefs; but for fome time after, the fire appeared of a deep purple red. When he got fo well as to be able to ft and without being gid- dy, he was unable to walk without Support, for his own feelings did not give him information refped- ing his centre of gravity, fo that he was unable to Life of the author. xxxix ballance his body, and prevent himSelf from fall- ing. He gradually recovered from this ftate, and a3 foon as he was able went to Bath, where he ftaid fome time and drank the waters, which were thought to be of fervice to him; but did not flay long enough to give them a fair trial; he returned to town much better, and in a few weeks got quite well. From this period to 1785, he had no particular indiSpofi- tion, but certainly did not enjoy perfed health, for in 1785, he appeared much altered in his looks, and gave the idea of having grown much older than could be accounted for from the number of years which had elapfed. About the beginning of April 1785, he was at- tacked with a fpafmodic complaint, which at firft was flight, but became afterwards very violent, and terminated in a fit of the gout in the ball of the great toe; this, like his other attacks, was brought on by anxiety of mind; the firft fymptom was a fenfation of the mufcles of the nofe being in adion, but whe- ther they really were, or. not, he was never able to determine; this fenfation returned at intervals for about a fortnight, attended with an unpleafant fen- fat^g^ in the left fide of the face, lowerjaw, and throat which feemed to extend into the head on that fide, and down the left arm, as low as the ball of the thumb, where it terminated all at once; thefe fenfa- tions were not conftant, but returned at irregular times; they became foon more violent, attacking the head, face, and both fides of the lower jaw, giving the idea that the face was fwelled, particularly the cheeks, and fometimes Slightly affeded the right arm. After they had continued for a fortnight they ex- tended to the fternum, producing the fame diSagree* able fen rations there, and giving the feel of the fter- num being drawn backwards toward the Spine, as well as that of opprcinon in breathing, although xl Life of the author. the adion of breathing was attended with no real difficulty; at thefe times the heart Seemed to mi's a ftroke, and upon feeling the pulfe, the artery was very much contraded, often hardly to be felt, and every now and then the pulfe was entirely ftopt; he was afterwards attacked with a pain in the back, about that part where the oefophagus paffes through the diaphragm, the fenfation being that of fome- thing Scalding hot paffing down the ceSophagus ; he was next Seized with a pain in the region of the heart itfelf, and laft of all with a fenfation in the left fide, nearly in the feat of the great end of the ftomach, attended with confiderable erudations of wind from that viScus; theSe Seemed to be rather fpaSmodic than a fimple.difcharge oS wind, a kind of mixture of hiccough and erucfation, which laft Symptoms did not accompany the former, but came on by themfelves. In every attack there was a raw fore Seel, as if the fauces were excoriated. All thefe Succeeding fymptoms (thofe in the ftomach and nole only excepted) where, in addition to the firft, for every attack began with tht firft fymptoms. The complaint appeared to be in the vafcular fyftem, for the larger arteries were fenfibly contraded, and fore to the touch, as far as they could be touted, principally in the left arm ; the urine at thofe times was in general very pale. Thefe fvmptoms increafed in violence at every return, and the attack which was the moft violent, came on one morning about the end of April, and lafted above two hours; it began as the others had done, but having continued about an hour, the pain became excruciating at the apex of the lu:art; the throat was fo fore as not to allow of an attempt to fwaliow any thing, and the left arm could not bear to be touched, the leaft preffure upon it giv- ing pain, the fenfation at the apex of the heat was that of burning or Scorching, which, by its violence, Life of the author* xK quite exhaufted him, and he funk into a fwoon or doze, which lafted about ten minutes, after which he ftarted up, without the leaft recolledion of what had pafled, or of his preceeding illnefs. I was with him during the whole of this attack, and ne- ver law any thing equal to the agonies he fuffered j and when he fainted away, I thought him dead, as the pain did not feem to abate, but to carry him off, having firft completely exhaufted him. He then fell afleep for half an hour, and awoke with a confufion in his head, and a faint recollec- tion of fomething like a delirium ; this went off in a few'days. The affedions above-defcribed were, in the be- ginning, readily brought on by cxercife, and he even conceived that if he had continued at reft, they would not have come on; but they at laft feized him when lying in bed, and in his fleep, fo as to awaken him ; affedions of the mind alfo brought them on ; but coolly thinking orreafoning did not appear to have that effed. While thefe complaints were upon him, his face was pale, and had a contraded appearance, making him look thinner than ordinary ; and after they went off his colour returned, and his face recovered its natural appearance. On the commencement of the com- plaint, he fufpeded it to be rheumatifm, and ap- plied eledricity to his arm, which took it off for the time only ; he then, for two or three nights fucceflively, took three grains of James 's powder, without any abatement of the fymptoms; he next had recourfe to the camphorated julep, both at the commencement of the fpafm, and while it was up- on him, but obtained no relief; he tried Hoffman's anodyne liquor, in the dofe of a tea-Spoonful, and and not finding it to anfwer alone, joined to it the camphorated julep, but the fpafms feemed to be more G xlii Life of the author* Violent; one night he took twenty drops of the- baic tindure, which made his head confuSed all the following day, but did not at all abate the fpafms ; the following day he took two tea-fpoonfuls of the bark, which heated him, and gave him a head-ach, thirft, and drynefs of his morith, which prevented his continuing it. At. the defire of Dr. David Pit- cairn, "" he took the powder of valerian, an ounce a day, which feemed for the firft two days to remove his fpafms, but they returned on the third with more violence than ufual, efpecially one evening at the Royal Society, which induced him to leave off the valerian, and he bathed his feet on going to bed in warm water, mixed with half a pound of flour of muftard, and took a tea-fpoonful of tinc- ture of rhubarb in ginger-tea ; alfo wore worfted ftoc'-rings all night'. On Friday morning, the twentieth of May, be- tween fix and feven o'clock, he had a violent fpafm, attended with moft violent erudations of wind from the ftomach for nearly a quarter of an hour. Dr. Pitcairn, who was fent for upon this occafion, afk- ed him, if there was any diftrefs upon his min General principles cf the blood. 13 The red colour of the blood is produced merely by fome red matter diffufed through it, but not common to all ani- mals. The blood exhibits a greater variety of changes, and admits of more experiments to determine its nature and properties than the folids. This, in fome rdegree, arifes from its fluidity, in which form it has not yet attained its ultimate ftate, and is only the Subftance that furnifhes ma- terials, out of which the folids are produced or augmented. The heat in the animal body, principally in thoSe which are called warm animals, has been commcjnly confidered as depending principally on the blood, or at leaft as being con- neded with it, as much as with any other portion oS the bodyf: as I Shall have occafion to take notice of the in- creafed heat of inflamed parts, it might be expeded, that I fhould endeavour to explain this principle in the hiftory of the blood. I profefs, however, not thoroughly to un- derstand it, and the theories hitherto brought forward, do not in the leaft fatisfy me ; as I think that none of them ac- cord perfedly with every circumftance obfervable in thef«. cafes, I. OF THE MASS OF BLOOD, AS COMPOSED OF DIFFERENT PARTS. The blood, while circulating in the veffels, appears to the eye to be a homogeneous maSs; but when it is paffing in veffels So Small as almoft to Separate its vifible parts, ancj is viewed in a microScope, there is no appearance but that of globules moving in the veffels. In fuch a Situation the other parts called the coagulable lymph, and the Serum, are not distinguishable, on account nually carrying away the land Srom one Situation, and deposit- ing it in another; taking down continents, and leaving the ocean in their place ; while at the Same time they are railing con- tinents out of the Sea. But animals work upon foreign matter, introduced from time to time into the SySlem. f From whence the expreSlion, warm blooded, or cold blood- ed animals; but the expreflicn Should rather be, the animals of a permanent heat in all atmofpherc -, and animals of a heat jariable with every atmofphere. 14 General principles of the blood. of their being tranfparent, and the globules do not, ftridly Speaking, constitute a part of the fluid, but are only dif-, fufed through it. Thefe globules being red, give this co- lour to the blood, and are called the red part, but are not always of the fame rednefs when colleded in a mafs ; this is probably owing to each globule being changed in its tint of colouring. The blood of fome animals has no fuch globules, but is perfedly tranfparent, indeed more fo than the moft tranfparent parts of the red blood, to which it is analogeous. A red colour is therefore not effential to con- stitute true blood; and I believe the Slight tinge of colour (here is in the blood, independent of the globules, arifes from the fol ;tion of various fubftances in the ferum. The blood has a peculiar tafte, being faltifh, but oS a peculiar flavour : we can always diftinguifh by the tafte when there is blood in the mouth. TheSe are the principal observations we can make on the blood when circulating, or in its fluid State ; but as one part oS it under certain circumftances changes into a Solid, or as it is commonly termed, coagulates, more oS its parts are thus expoSed; in this procefs the blood Separates into two diftind Substances, a coagulating part, and another which Separates Srom it and remains fluid ; but the coagu- lum entangles the red part, and this alone fhews the blood to be Sormed of thefe component parts. The parts of the blood fo feparated, have been named according to their ap- parent properties; the one, the coagulable lymph ; the Or ther, the ferum ; and the red part has been called the red globules; but upon a more intimate knowledge of the dif- ferent parts of this fluid, we Shall find that thofe terms arc ive-t expreffive of all their properties. The term coagulable lymph, is not expreffive of this pro- perty, as one whieh is inherent in the lymph itfelf; for ma* ::y Su'oltances are capable of being coagulated, though not Spontaneously, yet by chemical means. For inftanee ; heat coagulates the farinaceous part of vegetables, and thus forms piste; and alfo mucus. Spirits of wine coagulates many animal fubftances; acid coagulates milk, &c. the term, therefore, to be uSed reSpeding this property of the blood, fL..»uld be fuch as expreffes its inherent power of felf-coa- g-.d-ition: perhaps coagulating might be better applied to w'nc is called coagulr.bie lymph; and the epithet coagulable H'^nt hi ^Served for thofe fluids which require a chemical procefs to prcduce that effed. Of this kind is the ferum, General principles of the blood. t § for I have difcovered this fluid to be compofed of two parts, which is afcertained by means of the different cauSes of coa- gulation. To diScover all the various properties and ufes of the component parts of the blood in the machine, may be impoffible ; and to determine whether they will ad, or are employed conjundively to produce the effed, is not eaSy: but there are Some properties, discoverable whirh would incline us to believe, that particular parts oS the blood are employed to compoSe Darticular Solid parts, which are Sound to poflefs properties Similar to different parts oS the blood. II. OF COAGULATION, AND ITS EFFECTS. As coagulation is the firft change which the blood un* dergoes, when out of the veffels, and as it even coagulates while in them, under certain circumftances, we Shall consi- der this proceSs firft. Though fluidity is neceffary to ena- ble the blood to circulate, yet coagulation is no leSs neceffa- ry, when it is to be diSpoSed oS out of the circulation, even within the body, and thereSore deServes to be considered with no leSs attention. There is, I think, more to be learn- ed oS the uSe of blood in the animal ceconomy, from it? coagulation, than from its fluidity. The coagulation of the blood, when out of the circulation, would feem to be unconnected with life, yet life could not go on without it; for as all the folid parts of the body are formed Srom the blood, this could not take place, if there did not exift in it the power oS coagulating. Many diSeaSes exhibit the blood coagulated in the living body, even in the veffels themSelves, but more Srequently when extravaSated. Coagulation does not belong to the whole maSs of circulating blood; but only to the part I have called coagulating lymph, which during this adion commonly detaches itSeff Srom the other part, called the Serum. Whether the whole maSs oS the Serum be a diftind part oS the blood when circulating, is not eafily determined, as we have no mode oS Separating it Srom the coagulating lymph, while both are fluid. The Serum making a part of the whole mafs in the fluid ftate, the firft Stage in the coagulation is a Species of decomposition, forming a fepa- id General principles of the blood. ration of the ferum. But, on the other hand, there ar£ reafons for considering the coagulating lymph as diftind Srom the Serum, even when both are fluid ; Since the Serum can be Separated from the lymph, without coagulating, by many adions of the veffels, both natural, preternatural, or difeafed. Thus the liquor of the amnios, and that of dropfies, are formed ; and therefore we may conclude, that the feparation of the ferum, when the lymph is coagulated, is not an ad neceffary to the coagulation, but an effed of it. The circumftances attending the coagulation of the lymph are fubjed to great varieties. Thefe depend upon or correfpond with the State of the body at the time, of which we can beft judge by the readinefs or difficulty with which the blood coagulates, and by the firmnefs or loofnefs of the coagulum. The whole mafs of the blood being a compound, oS which the parts are in Some degree Separat- ed : the appearances upon coagulation are attended with Still more variety than the lymph alone could exhibit, or than could occur in thoSe animals which are not pofleffed oS red blood, as the red part brings to view many oS the changes in the lymph, by the difference oS its colour, as well as of its Specific gravity. The three Substances which become vifibly diftind when the lymph coagulates, differ as to gravity; the Serum is the lighteft, znd remaining fluid Swims upon the top ; the red globules which undergo no change, are the heavieft, and fink more or lefs in the lymph; but being entangled in it, add to its weight fo as to make it fink deeper in the ferum. Blood when extravafated coagulates Sooner or later, ac- cording to the quicknefs or Slownefs of its extravafation, and the quantity extravafated: it coagulates late when drawn into a bafon rapidly, and in confiderable quantity; foon, when allowed to flow Slowly, and in fmall quanti- ties. This will be better understood when I treat of the principles oS coagulation. When blood is received into a cup, and thereby expoSed, it certainly coagulates more readily than when extravaSated in the cellular membrane, or in the veffels ; and on the ex- poSed Surface it coagulates more readily than any where elfe, except round the edges of the difh in which it is con- tained. It has been obferved, that the upper furface of the Wood coagulates firft, forming a thin pellicle, as milk does, General principles of the blood. n When near boiling ; while underneath it ftill remains fluid ; but the whole gradually becoming thicker, and lofing its transparency, coagulates in about fifteen or twenty minutes into a fubftance of pretty thick confiftence. The time re- quired will vary according to the quantity of blood in one mafs, and the difpofition of the blood at the time. We may obferve the following appearances when the blood is coagulated. The coagulum is generally, but not always, Swimming in a fluid; for it Sometimes hap- pens that the lymph does not Squeeze out the Serum in the ad of coagulation, in which there is an ad of contradion. The top of the coagulum is toughelt, or firmeft; and it becomes leSs and leSs So towards the bottom, becauSe there is leSs of the coagulating lymph at the bottom, in propor- tion as the red globules fubfide m the lymph before it coa- gulates. The coagulating lymph has a degree oS toughneSs in proportion as it is free from ferum ; for while the ferum is mixed within it, though there mrey be red globules, it is not very tough; but when preffed between the Singer and thumb, fo as to Squeeze out the Serum, it becomes nearly as tough, and elaftic, as the coats of an artery, to appear- ance, becoming fibrous, and.even, forming lamina; and indeed appears to be very much the fame kind of fubftance with an artery, which gives us a clear idea how a membrane may be formed, and probably can be varied according to the impreffion made on it by the furrounding parts. This is one reafon why the lymph, which has the ftrongeft dif- pofition Sor coagulation, is the tougheft, as it parts with more oS its Serum. The lymph is transparent, but whe- ther tinged as the Serum is found to be, v/e can hardly Say, as it is Seldom poflible to catch it in a fluid State tree from red globules, and never Srom Serum, which has itfelf a tinge. When out of the body in a difh, where it is long in coagulating, and the red globules fink faft, we find it tranSparent; but, during coagulation, it becomes more muddy, till at laft it is opaque, but with a tinge oS colour. On being Steeped in water it is often rendered very white, which would not probably be the cafe if it had a tinge of its own, independent of the ferum. Blood ufually requires a confiderable time for its complete coagulation, or rather contradion ; for, if allowed to Stand Some days, the coagulated part becomes leSs and leSs, as more and more of the ferum is Squeezed out, which cannot I, 12 General principles of the blood. ariSc Srom the Serum being lighter, and iffuing out fponta- neoufly ; for without fome expelling force it would be re" hincd mechanically by the capillary attradion, as in a fponge. The blood which is longeft in coagulating, coa- gulates moft ftrongly, and produces the moft complete Sepa- ration oS its parts. In Such instances as the coagulating lymph continues longer fluid, it allows the red globules more time to Subfide, and the Serum to be more Squeezed out Srom the craflimentum. When the coagulation is flow, and of that kind which will be firm when completed, wc may flam off the fluid coagulating lymph, free from the red globules ; and the part fo taken will coagulate immedi- ately, while that in the cup remains fluid fome time longer. Many caufes have been affigned for the coagulation of the lymph, which appear to me to be ill-Sounded. It Sre- quently happens that when changes take place in matter of which the immediate cauSes are unknown, the mind refers them to Some circumstances which accompany theSe chang- es ; although, perhaps, they may have had no concern whatever in producing them, and may be only attendants. This will always be the caSe where thoSe changes ariSe out of the nature of the part itfelf. A feed put into moiSt ground grows ; but the moift ground is only a neceffary at- tendant, and not the immediate caufe. The life of the feed, Stimulated to adion by the moifture, is the immediate cauSe of its growth, aud it continues to grow becaufe its adion is always excited. All the water in the world would riot make a dead feed grow. The fame mode of diftindion is applicable to the coagulation oS the lymph. The firft observations on the blood were moft probably made on that of the more perfed animals, whofe heat is commonly greater than the heat oS the atmoSphere. Such bjood when extravaSated, was Sound to coagulate on cooling; it was thereSore natural to SuppoSe that the coagulation of tlie lymph aroSe Srom its becoming colder, as happens in jelly* ; but cold, Simply, has certainly no effed upon the coagulating lymph. IS we take a SlSh out of the fea, the heat of its body, * This term has been applied to the coagulation of the blord, but I think improperly ; Sor 1 (hould only call that jelly, which became Solid by add, and fluid again by heat ; coagulation is totally different, tor it is a new fpech-s of combination. The freezing of blood may be called, congelation. General principles of the blood. to perhaps about 6o°, and bring it into an atmoSphere oS 700, the blood, on being let out of the veffels, will immediately coagulate. This was afcertained on board of a Ship lying off Bellifle, in the fummer 1761 ; for immediately upon a fiSh being caught? I afcertained its heat, and letting out part of its bleod, it immediately coagulated, although the blood difcharged was become warmer than that remaining in the veffels of the SiSh ; which, however, Still continued fluid. Indeed common experience and observation Shews us, that cold alone has no power to coagulate the blood. It of- ten happens that particular parts of an animal, Such as the fingers, Saee, noSe, ears, &c. are cooled nearly to the Sreezing point, and Srequently are in that ftate for a confi- derable time ; yet the blood retains its fluidity in thoSe parts, as I have experienced in my own fingers; and indeed in thoSe parts of an animal where the blood has been frozen, and again thawed, the blood appears as fluid as before, and circulates as ufual. Heat has the power of exciting adion in an animal; and we find that heat even incrcafes the ac- tion of coagulation ; for, if blood be heated to about 129°, it will coagulate five minutes fooner than when kept at it3 natural heat, and even fooner than the blood of the Same animal, taken at the Same time and cooled to 50° *\ Mr. IlewSon has laboured this point, endeavouring to Shew it is not cold that makes the blood coagulate ; and he has. laboured no leSs to fhew the real cauSe of Such a change. He took Srefh blood and froze it quickly ; on being thaw- ed, it was again fluid, but Soon aSterwards coagulated : this he conceived to be a Sufficient proof, that it was not cold which made the blood coagulatef. From the above obfervations, and experiments, it muit appear that cold, fimply, has no influence whatever upon the coagulation of the blood. And in moft of the cafes in which the blood is obferved to coagulate, the air is commonly in contad with it; this was next pre fumed to be the caufe oS its coagulation \ i but * TheSe experiments wer? mrde on the jugular veins of do^s, by taking a Section of the veins on eu^b Side filled witi blood, and immerliug them in water, either warmer, or cooler, or of the nitural heat, and obfcrving the comparative diff.p- trtce. + HewSon on the blood, page 21. % Ib'id, pajea:. L 2 20 General principles of the blood. the air has really no more effed than any other extraneous body, in contad with the blood, that is capable oS making an impreffion upon it; Sor the blood coagulates more readily in a vacuum than in the open air; nor will either of theSe SuppoSed cauSes aifift in explaining why it is not found coa- gulated after many kinds oS death, nor in the menftrual diScharge. Neither Mali they account Sor the very Speedy coagulation oS the blood which uSually takes place in all the veflels after death, or when it has been extravafated into cavities, or cellular membranes, where no air has ever been admitted. Reft is another caufe upon which the coagulation of the blood has been Said to depend : and although this opinion be not true in the Sull extent in which it has been taken, \ think that reft has greater influence in the change than any other circumftance whatever. But though reft Seems great- ly to diSpoSe the blood to coagulation, it is the operation of reft alone, without expoSure, which we are to confider; as otherwiSe we Shall be apt to conSound it with the two Sore- going cauSes, viz. cold, and the contad oS air. Since thereSore the blood may coagulate in the veffels, either oS a living, or a dead body, and Since it coagulates when ex'travaSated into different parts oS a living body, reft, like cold, or air, might be SuppoSed to be the Sole caufe oS the coagulation oS the blood : yet it is not reft, confidered Simply, hue reft under certain circumftances, which appears to poffeSs Such a power; for motion given to the blood, out of the veffels, will not of itfelf prevent its coagulation; nor will it even in the veffels themfelves, if all the purpofes of motion .are not anfwered by it. Mo- tion Seems to retard coagulation* ; yet we know Sor cer- tain that blood will in time coagulate, even in the veffels themSelves, and under certain circumftances Sooner, per- haps, than any where elSe; as Sor inftanee, when there is. a diSpofition to mortification. In this caSe we find the blood coagulated even in the larger veffels. I have leen a mortification come on the Soot, and leg, and when it had advanced only to a certain degree, the perSon died. On examining the parts above the mortified part, I Sound the crufal, and iliac arteries, filled com, pletely with Strong coagulated blood ; we may thence inter, * This is motion given to it in a veflel, without any empty Space, and having beads put into it, which are fliaken. General principles of the blood. 21 chat the tendency to mortification in the* veffels produced this diSpofition in the blood. If the coagulation Should be fuppofed to have arifen from the blood being Stopped in the large veflels, at the mortified part, let us reflect, that this cannot account Sor it; the Same thing ought then to hap- pen in an amputation, or in any caSe where the larger veS- Sels are tied up. In a priapiSm the blood does not coagulate, except it threatens mortification. The Separation oS the blood, either Srom itfelf, that is, when divided into fmall portions, or feparated from the living body, becomes one of the immediate caufes of the coagulation of the lymph ; thereSore, the contad" oS blood with blood, or with living veffels, in Some degree retards coagulation : this is the reaSon why blood which comes Srom the veflels Slowly, or falls from fome height, or runs Someway on the furface of a difn, coagulates fooner than when the contrary circumftances happen; and upon this principle it is, that blood, when Shaken in a phial, will coagulate the Sooner, -even if Shaken in a vacuum. A deep mafs of blood is alfo from the fame caufe, longer in coagu- lating than a Shallow one. From the above observations it muft appear evident, that neither cold, nor air, nor reft alone, have any influence on the coagulating power of the blood ; there mult, therefore, be fome other principle on which this prccefs depends , and, as it retains its fluid ftate while circulating, and even Sor a long time when at reft in the living veffels., and coa- gulates when the veffels or the body dies, it might naturally be SuppoSed that it was the liSe oS the body or veSlels which kept it fluid ; we know, however, that life in the body or veffels does not hinder the blood Srom coagulating under certain circumftances, but oSten rather excites congulation ; nor does death, in the body or veflels, in all cafes become a cauSe oS coagulation ; Sor we find that in many who die Suddenly, Srom a Strong impreffion oS the mind, the blood does not coagulate ; there is, thereSore, Something more then the mere Situation oS the blood, Surrounded with dead parts, that allows oS coagulation ; and that muft be a Something in the blood itfelf. From thefe obfervations it muft be evident, that the fluid ftate of the blood is conneded with the living veffsls, which is its natural fituation, and with motion ; and that where there is a full power of life, the veffels are capable of 22 General principles of the blood. keeping the blood*in a fluid ftate : I believe, however, wry little motion is required to keep up this fluidity when the other is preSent. A total Stagnation oS the blood, while the body is alive, as in a trance, or where the circulation has been Stopt Sor Several hours, as in the caSe oS perSons ap- parently drowned, does not make it coagulate ; yet where there are no adions going on, in a part, iS the blood Stagnates Sor a much Snorter time than in a trance, it will be found coagulated, as in mortifications; but then this cqagulation is to anfwer a good purpoSe, and ariies Srom neceflity*, which appears to ad as a Stimulus in diSpofing the blood to coagulate. As a proof that blood will not coagulate in living vef- fels, in a perfed and natural ftate, and ready to ad when powers were rcftored to it, I found that the blood of a fifh, which had the adions of life Stopped Sor three days, and was SuppoSed to be dead, did not coagulate in the veffels; but, upon being expoSed, or extravaSated, Soon coagu- lated. The blood oS a lamprey-eel, which had been dead to ap- pearance Some days, was Sound fluid in the veffels, becaufe the animal wr.s not really dead; there had, however, been no motion in the blood, as the heart had ceaSed ading; but upon its being expoSed, and extravaSated into water, it Soon coagulated f: yet under certain circumftances in life, it had been obferved, that the blood will in a Small degree coagulate : this is in the ftate oS torper. It is aS- (erted by Some author, whom I now do not recoiled, that * By action taking place from neceflity, effects are meant which arife in conSequenceoSSome unufual, or unnatural change, going on in the parts, and become a Stimulus to aftion. The Stimuli Sromthis caufe, may vary exceedingly among themSelves ; but as we axe unable to investigate them, I have included them under this general term, Stimulus of neceflity. f There fcre Some circumftances which hinder the coagulation of blood in living bodies although extravaSated, Two leeches had been applied, and had fucked till full. TheSe were preferv- ed for ten wpeks, and then had contained confiderable quantity of blood, wkkh appeared like that recently drawn from a vein, and coagulated when expoSed. I have known, in tapping a hydrocele, that a fmall veflel has been wounded, and the blood, as it extravaSated, got into the Sack, and when tapped fixty- nve days after, the blood has come out thickifh; but when ex- tracted it coagulated, and Separated into different parts, General principles of the blood* Oie blood of a bat coagulates when in that State ; and Mr. CorniSh, Surgeon, at TotneSs, Devonshire, to whom I ap-» plied Sor Seme bats in the torpid State, Sent me them, but in the carriage they always died ; however, he took oppor-^ tunitiesoS examining them, and he Sound that the blood was in a certain degree coagulated; but it Soon recovered its fluidity on motion and heat. From theSe remarks I Should conclude, that reft does not of itfelf in the leaft affift the coagulation oS the bleed ; but that this effed ariSes Srom the blood being Separated from the living veffels, and being deprived oS motion ; and that it happens Sooner, or later, according to other circum- Stances. It might be SuppoSed that theSe are rather nega- tive cauSes oS coagulation, than pofitive ones; but it is to be confidered, that in a living body, the ceffation oS a na- tural adion, the abSence of an uSual impreffion becomes a cauSe oS adion, of which innumerable instances may be given. I have now confidered the circumftances under which the blood coagulates, and Shewn that none of them alone, nor all of them combined, induce the blood to coagulate. My opinion is, that it eoagulates from an impreffion : that is, its fluidity under fuch circumftances, being improper, or no longer neceffary, it coagulates to anfwer now the necef-1 fary purpofe of folidity. This power Seems to be influ- enced in a way, in Some degree Similar to muScular adion, though probably not entirely oS that kind ; Sor I have rea- Son to believe, that blood has the power oS adion within itSelS, according to the Stimulus oS neceffity; which necef- lity ariSes out of its fituation. I Shall now confider the Simple ad oS coagulation, ab- Shaded Srom cauSes. Coagulation I conceive to be an operation cS life ; and I imagine it to proceed exadly upon the fame principle as the union by the firft intention ; it is particle uniting with particle, by the attradion of cohefion, which, in the blood, forms a folid ; and it is this coagulum, uniting with the furrcunding parts, which forms the union by the firft in- tention : Sor union by the firft intention, is no more than the living parts when Separated, whether naturally, or by art, Sorming a reciprocal attradion oS cohefion with the intermediate coagulum, which immediately admits oS mu« tual intercourSe, and as it were, one intercft. -4 General principles of the blood. To produce coagulation of the blood, however, fome- thing more is required than merely the reverfe of the caufeS above-mentioned, as having the power to keep it fluid ; for the blood becomes in many cafes inftantaneoufly incapable of coagulation, either in or out of the veffels, even when nothing has been added, or taken away, and muft he there- fore under the influence of fome other caufe. This, I be- lieve, muft be fought in fome property in'^erent in the blood itfelf: bcfides, Some natural operations deltroy this prin- ciple in the blood, when extravaSated. In many modes of destroying life the blood is deprived of its power of coagulation, as happens in fudden death produced by many kinds of fits; by angery eledncity, or lightening; or by a blow on the ftomach, etc. Li theSe caSes we find the blood, aSter death, not only in as fluid a ftate as in the living veffels, but it does not even coagulate when taken out of them. As in the bodies of Such per- Sons as no adion of life takes place, the mufcles do not contrad. There are partial influences, likewife, which deftroy the power of coagulation, as a blow on a part pro- ducing a confiderable extravaSation. This forms an ecchy- mofis, in which we fhall often find the blood not in the leaft coagulated. In healthy menftruation, the blood which is discharged does not coagulate; in the irregular or un- healthy it does. The healthy menSes, thereSore, Shew a pe- culiar adion of the constitution; and it is moft probably in this adion that its Salubrious purpoSes confilt; for if twice the ufual quantity is evacuated with the power of co- agulation, even from the fame veflels, the Same benefit is not produced ; much leSs when taken Srom another part by art. Many Subftances, when mixed with the blood, prevent coagulation; bile his this effed out of the body j but wc cannot SuppoSe that in a living body it can be taken into the blood in Such quantity as to produce this effed; Sor we find in a very Severe jaundice, that the blood is Still capa- ble of coagulating Strongly. That probably every inanimate fluid in nature, which is capable of being rendered folid, produces heat, during that change; and in the contrary change cold is commonly known ; it is on that principle Dr. Black has eftablifhed his very ingenuous theory of latent heat. Thus in the freezing of water, heat is produced. General principles of the blood. it To fee how far the coagulation of the blood was Similar in this reSpect to the Same change in other Subftances, I firft coagulated the white oS an egg, by applying to it rec- tified Spirits oS wine : the heat of'both was the Same beSore their union ; but I Sound upon unuhig them, that the white oS the egg was immediately coagulated, and that the heat of the mixture was increafed Sour, Sometimes five degrees, according as it coagulated, Slowly, or quickly. As the blood in the animals upon which we mcft commonly make our experiments is warm, it becomes a difficult matter to aScertain whether it produces heat upon coagulation. In holding the ball oS the thermometer in the Stream oS blood coming frem the arm, I found the heat raiSed to ninety-two degrees : I then took a cup of human blood, allowed it to coagulate, and put it up to the brim in water warmed to ninety-two degrees, till the whole mafs was heated to this point. I bled afterwards another perfon to the fame quantity, in a Similar cup, which was put into the fame water. Having two well regulated thermome- ters, one in each cup of blood, I obferved which cooled firft, for I did not exped fo much heat to be produced as to make it warmer ; but conceived, if any heat was form- ed, it would retard the cooling of the freSh blood ; but it rather cooled fafter, which I imputed to the coagulated blood parting with its heat Slower than the fluid blood. Thefe experiments I have repeated feveral times, with nearly the fame effed. I then conceived the experiment would be more conclusive if I could get blood in a fluid State, which was naturally of the heat of the atmofphere, for which purpofe I took the blood of turtles. A healthy turtle was kept in a room all night, the floor of which was ahout 640, and the atmofphere 6$°. In the morning the heat was nearly the Same. The thermometer was introduced into the anus, and the heat of that part was 640. The animal being fufpended by the hind legs, the head was cut off at once, and the blood caught in a bafon; the blood while flowing, was 650, and when col- leded, W2S 66°, but fell to 6$° while coagulating, which it did very Slowly : it remained at 65 °, and when coagula- ted, was Still 65°. Thefe experiments had been made Se- veral times, but not with that nice accuracy which was ob- tained by caufing all the heats to correspond exadly; yet as they were all known, and marked down, if any heat had M l6 General principles of the blood. been produced upon coagulation, its exad quantity would have been ascertained in each; and, indeed, in ionie, it Seemed to eso!, but in none it became warmer, trom theSe experiments I Should Say, that in the coagulation of the blood, no heat is Sormed. # Coagulated blood, is an inorganizcd animal fubftance. When the blood is thinly Spread beSore coagulation, or oozes out on SurSaces, in which ad it immediately coagu- lates, and coagulates in that Sorm, it may then be Said to Sorm an inorganized membrane, of which there are many; and organization is feemingly fo fimple in many (which we know to be conftituent parts of the body) that thefe coagula, more efpecially the thin ones, cannot eafily by their ap- pearances be distinguished from them. The coagulating lymph of the blood being common, probably to all animals, while the red particles are not, we muft fuppofe it from this aicne, to be the moft effential part; and as we find it capable of undergoing, in certain circumftance?, Spontaneous changes, which are neceffary to the growth, continuance, and preservation of the ani- mal ; while to the other parts we cannot affign any fuch uSes, we have ftill more reaSon to SuppoSe it the molt ef. fential part of the blood in every animal. Befides a difpofition for coagulation under certain cir- cumftances, as before defcribed, the blood has alfo a dispo- sition Sor the Separation of the red globules, and probably of all its parts; for I think I have reafon to believe that a difpofition for coagulation, and a difpofition for a Separa- tion of the red part, are not the fame thing, but arife from two difllrent principles. Indeed, a difpofition to coagula- tion would counteract: the effed, and hinder the feparation of the red particles from taking place. Thus we fee that reft, or flow motion of the blood in the veffels, gives a diSpofition towards a Separation of the red part, as well as when Ht is extravafated ; Since the blood in the veins of an animal acquires a difpofition to feparate its red parts, more than in the arteries, efpecially if it be retarded in the veins; the nearer, therefore, to the heart in the veins the greater will the difpofition for feparation be ; though it does not feem to retard coagulation. This is alv/ays obfervable in bleeding ; for if we tie up an arm, and do not bleed imme- diately, the firft blood that flows from the orifice, cr that which has Stagnated for feme time in the veins, will foonelt feparate into its three conftituent parts : this circumftance Getieral principles of the blood. 27 «xpofes more of the coagulating lymph, at the top, which is fuppofed by the ignorant to indicate more inflammation, while the next quantity taken Sufpcnds its red parts in the lymph, and gives the idea that the firft Small quantity had been of Such Service at the time of its flowing, as to have altered for the better the whole mafs of blood. Reft, there- fore, may be regarded as one of the immediate caufes of the feparation. III. OF THE SERUM. The ferum is the fecond part of which the whole mafs of blood appears to be compofed ;^ or is one of thofe Sub- stances into which the blood Spontaneously Separates itSelf. ,So far it appears as a Simple fluid, in which light I Shall firft .confider it; though we Shall find hereafter that it ij compof-. ed of two fubftances, which, in many of our experiments, feparate. Serum, I believe, is common to the blood of all animals; but there is more of it, I think, in thofe animals which have red blood: perhaps it may bear fome propor- tion to the qaantity of red particles in the blood, and may be of ufe to dilute it. The ferum is lighter than the other parts of the blood, and therefore fwims above them when feparated. It is com- monly feparated from the coagulating lymph when that fluid coagulates; and is, therefore, almoft always found when the blood is taken out of the blood veffels, and kept toge- ther in a confiderable mafs. When the lymph coagulates Strongly, we commonly find more ferum, becaufe k is then Squeezed out more forcibly than when the coagulation is formed loofely; it is not, however, neceffary for the lymph to coagulate, in order to Separate the Serum, Sor we find that it Separates in diSeaSe, as in the dropSy. It is Separa- ted alSo Srom the maSs oS blood in uterine-geStaticn> being die fluid in which the Scetus is immerSed or Swims, I have Seen it Separate Srom the remaining maSs before the coagulation ot the lymph. I obServed once in the blood oS a lady, that a Separation between the two fluids almoft immediately took place,' the Serous part Swimming on the top, while the lymph remained ftill fluid. From this appear, M 2 28 General principles of the blood. ance I had pronounced that there would be a great deal of ( buff, Suppofing that the transparent fluid at the top was co- agulating lymph; but I was mistaken, Sor when the lymph was coagulated, there was no buff, and the tranSparent fluid remaining at top, proved to be the Serum. In this there could be no deception, as there was no buSF, or Size ; for if there had been fize at the top of the coagu- lum, it might have been SuppoSed that this fluid, which ap- peared So Soon aSter bleeding, had been the coagulating lymph, and that the Serum had been Separated in the ad of coagulation as uSual. The Serum is commonly of a yel- lowifh colour, Sometimes more fo than at others ; and this, I fhould conceive arifes from the fubftanees diffolved in it*, by means of the water it contains ; for it probably fufpends every fait foluble in water, many of which are diffolved in it. If Serum be not coagulable. in itSelS, though it contains a large quantity oS coagulable matter, yet I conceive it to be in a more fluid State when circulating. As it is Separa- ted Srom a compound maSs, it appears in this reSped to be Somewhat Similar to the whey oS milk, though not ex- adly. This fluid undergoes no Spontaneous changes but what may ariSe Srom its Separation, Srom the coagulating lymph, except putriSadion. Though not coagulable in it- felf, yet one of its properties out of the body, is to coagu- late upon the application of certain fubftances. This is the principal change it undergoes, and during the procefs, , it more or lefs Separates into two parts; one oS which is not coagulable by Such means. The coagulable part, which I now mean to deScribe, feems to be in fome degree the fame with that in the white of an egg, fynovia, etc. and many other fecretions, but not exadly ; for thofe fecretions contain, as I conceive, a quan- tity of the coagulating lymph united to them, which makes them in part, coagulate after fecretion; and the further coagulation of thofe fecretions afterwards, by mixture with other fubftances, is owing to this part of the ferum. Though the ferum is coagulable under certain circumftances, and with certain mixtures, yet this power, or effed, may be prevented by other mixtures. Heat, to a certain degree, coagulates this part; and probably this is the only teft ne- ceffary to know whether a fluid Sound any where in the bo- * Tbe red globules are Sufpendedwithout being diffolved in the Serum, in which they are commonly examined. General principles of the blood* 29 dy, not coagulable in itSelS, is this part of the ferum ; but as many fubftances do alfo coagulate it, I Shall mention a few of them, although to me their effeds do not feem to throw any light on the fubjed. Heat coagulates the ferum at 1600, or 1650; it Stood at 1500, for fome time per- fedly fluid. There is a great deal of air contained in the ferum, which is let loofe by heat; but not from its coagu- lation, for when it is coagulated by other means, no air" is feparated. The ferum, which was a little whitiffi, coa- gulated in that degree of heat neceffary for Separating its air, which was extricated in very large quantities. This coagulum becomes firft like the fynovia, and then thicker. Many fubftances which do not coagulate this part of the ferum, do not, however, hinder its coagulation by heat; fuch as vinegar, acid of lemon, fait of wormwood, nitre, fea-falt. Serum coagulates with fpirits of wine, in about equal quantities, into a fort of curd and whey; which, upon heating, becomes fomething like a jelly, but the fpirit feems to evaporate. It coagulates with volatile fpirits, into a milky fluid, which becomes like a jelly upon heating; it requires a greater proportion oS the Spirit than the Serum; and the Spirit Seems chiefly to evaporate. When mixed with Salt oS hartlhorn, it does not coagu- late with heat, but makes a large efferveScence, till the whole is Sormed into Sroth. This again becomes a fluid, by the Sroth Subsiding, but at laft itSorms a SortoS coagulum, which is not tough. Being mixed with water, and let to Stand Sor twelve hours, it coagulates like pure Serum upon heating. IS this be mixed with Sal. cernu cervi, as above, it rather becomes more fluid, and continues So Sor a long time, with a Strong efferveScence; but it Sorms at length into a jelly, or pafte, though not a Solid one. Here I SuSped that the Salt is evaporated, and likewife x the water in the pafte, fo that it is not a true coagulation. When mixed with common water, it is coagulated by heat; but the water feparates with the other fubftance, and does not unite with the coagulum. Upon the coagulation of the ferum, by heat, I have obferved that it feparates a fluid, which is not coagulable by heat; and, I have reafon to believe, by none of the o- ther means, viz. fpirits of wine, etc. though this is not fo eafily afcertaiued ; for the other coagulating fubftances, as 30 General ^principles of the blood. fpirits of wine, etc. are applied in a fluid form, and there- fore, a fluid may remain after the coagulation of the ferum, which might be fuppofed to be the fluid feparated ; but from other experiments, it is proved that thofe fubftances coagulate the coagulating part, and unite with the other. J It is alfo obfervable in meat, either roafted, or boiled, or when cut, there flows from it a fluid, mere or lefs tinged with the red part, commonly called gravy. I conceived that this muft be different from the coagulating part of the ferum, believing that the heat had been Sufficient to coagu- late it; but I chofe to try it further, and therefore gave it fuch heat, as would have produced the effed if it had been coagulable by heat; but I found it did not coagulate. The fluid feparated from the coagulable part of the ferum, I conceived to be the fame with this. Thus then I faw there was in the ferum a matter coagulable by heat; and a fluid which was not fo. Purfuing the above obfervations on dreffed meat, I ob- ferved that the older the animal had been, the more of this fluid was contained in the meat. In lamb we have hardly any oS it: in young mutton oS a year old, but little; but in mutton oS three, four, five, or fix years old, it is in large quantity: in veal alfo we have but little; while wc have it in great quamity in beef; but perhaps we know left ingeneral^f the age of our beef, than of our mutton.* Poultry is- commonly killed young in this country, there- fore we have not the comparative trials; but in wild fowl, and what is commonly called game, we find the above obfer- vations hold good. I likewife obferve that animals who have jact had exercife, Such as houSe-lamb, veal, etc. have left of this fluid, than thofe of the fame clafs which have been allowed to go at large: nothing can be drier than the Eng- lish veal, though kept to a greater age than any where elfe ; while it is juicy in every other country, though killed much younger. In many of the trials refpeding the coagulation of the ferum, I obferved, that it had in Some caSes much more * It may be obferved here that this is very different from the jelly formed in baling, or rouSHng meat; that which forms -the jelly, is part of tue meat itfelf. diflclved down in this very .fluid, and the water in which it is boiled ; and we find that this effect is juSt the reverfe of the above, for in young meat ther* is the moft of this jelly* General principles of the blood. 3* coagulum than in others; and of courfe a lefs proportion of the fluid part that feparated, and vice versa: from the above obfervations too, I conceived that a deficiency of this fluid-part befpoke a greater quantity of coaguhling matter in the ferum ; and to afcertain this, I took the fe- rum of perfons of different ages. This fluid, like the fe- rum itfelf when united with the coagulating lymph, ap- pears only to be mixed with the ferum ; for it is Separated in the living body for many purpoSes oS the ceconomy; it is not therefore Serum in another Sorm ; but a diftintt fluid, which, before the coagulation, is mingled with the ferum, and feems to make a part of it. The following experiments sre, perhaps, not perfedly conclufive; Sor many were obliged to be made on blood taken Srom rh-fe who were not perfedly in health : pecu- liar diSpofiiior.s in the body r: ay make a material diff:rer.,2 General principles of the blood. by adding more water to the red globules they diffolve ; lemon juice diflblves the red globules : all this, however, throws but little light on this part oS the blood. When the globules are put into water they diffolve, which dcf.:roys their globular Sorm: it is thereSore the Serum, and probably the coagulating lymph alSo, when circulating, which confines them to this Sorm; but when the Serum is di- luted with water, they diffolve in it; and this appears to take place at once; as quick as water unites with water. I could not obServe that it was like the Solution oS a Solid body, as a Salt Sor inftanee; a drop oS blood requires about two drops oS water added to it to diffolve its globules : if urine alSo be diluted with water, the globules diffolve in it. However, aSter Standing Some days, the globules diffolve both in Serum and urine; but I think later in the laft. When the globules are not diffolved in arty fluid, the whole looks muddy, not transparent; but when diffolved in water the whole is a fine clear red. What are the pro- perties oS the Serum, and thoSe other Subftances that pre- serve the red part of the blood in a regular Sorm, I do not know. The red globules, when dried in the Serum, and moif- tened in the Same, do not again reSume their regular Sormj nor do they diffolve in it, as they do in water, but Sorm rather a Sort oS flakes. As the Serum and Solutions oS many kind of Salts do not diffolve the red globules, I conceived that it might be poffible for them to refume their globular figure (after having been diflblved in water) by adding Such a quantity oS Serum as to make the proportion oS water very little; but I could not produce this effect, although the men- ftruum was Such as not to diffolve Srefh globules. The red globules not diffolvingin the Serum, nor in the coagulating lymph, become Separable Srom thoSe parts, when circulating, and thereSore may be prevented Srom going where the coagulating lymph paffes in a natural State; which they certainly do not *; and which alSo is the reaSon why they are So perfedly retained in the coagulum when extra- vafated. The globules, befides being heavier than the Sj- rum, or the coagulating lymph, appear to have more Sub- stance, for they do not lofe So much upon drying, and when dried with Strum, they give v. kind cf roughnefs to the Sur- * This will be more Sully explained, when en the colour of parts from the blood. General principles of the blood. 43 face which Serum has not by itSelS. Theyappear not to be a natural part oS the blood; but as it were, compoSed out of it, or compoSed in it, and not with it; Sor they (eem to be formed later in life than either of the other two; thus we fee, while the chick is in the egg, the heart beating, and it then contains a tranfparent fluid before any red globules are formed, which we may SuppoSe to be the Serum, and the lymph. The globules do not appear to be Sormed in thoSe parts oS the blood already produced, but rather to riSe up in the Surrounding parts *. It would alfo Seem to be Sormed with more difficulty, than cither of the ether two parte. When an animal has loft a confiderable qucntity oS its blood, the other parts Seem to be Sooner made up than the red globules ; the animal looks long pale; but this is only conjedure, Sor we have no method of knowing the quan- tity of the other parts. From the above account it appears, that whatever may be their utility in the machine, the red globules certainly are not of fuch univerSal ufe as the coagulating lymph, Since they are not to be found in all animals, nor fo early in thofe that have them, nor are they pufhed into the extreme arte- ries, where we muft SuppoSe the coagulating lymph reaches; neither do they appear to be (o readily Sormed. Thicj being the caSe, we muft conclude them not to be the im- portant part of the blood, in contributing to growth, re- pair, etc. Their ufe would feem to be conneded with Strength; for the Stronger the animal the mere it has of the red globules ;*and the itrength acquired by exercife incrcafes their proportion; not only in the whole body, but, as we Shall find, occafions them to be carried into parts where in either a quiet or debilitated State of the animal they were not allowed to go; the uSe, therefore, oS a part, and the quantity oS red globules pafiing through it, are proba- bly pretty well proportioned to each other. This effed is So well known to Seeders of ycung animals, for the table of the epicure, that bleeding, «-o leffen the quantity, is im- mediately pradifed; as alio debarring the creature Srom • Thus, on Some oSthe firft appearances of the chick wc fir.d a zone Surrounding it, compoSed of dots, which contain red gl. * bules, but not in veflels, and which zone becomes vafcalarar. tcrwarda. Vide plate 1. O 9 General principles of the blood. 44 exerciSe, in order to prevent their increafing, and being carried So Sar Srom the heart, as they otherwWV would be. TheSe three Substances are of different Specific gravities : the Serum or fluid part is the lighteft; the folid part or lymph is the next in order; and the" red globules are the heavi- est. This is Seen in Such blood as Separates readily into its constituent parts. The Serum Swims upon the top, andthe red globules Sail to the bottom*, while the lymph would be SuSpended between the two, if the red part were not re- tained in the lymph, from its coagulation; but this con- stant effed is no abfolute proof of the difference in the Spe- cific gravities of the Scrum, and coagulating lymph; Sor w~ Still do not knew but that the red giobuhs, which are evidently the heavieft, make the coagulating lymph to Sink in the Serum. To afcertain this circumftance, I made the Sollowing experiment: I took Some blood, which Separa- ted eafily into its constituent parts; I then SuSpended in a portion of ferum a piece of coagulating lymph, which was free from red globules, and it funk to the bottom, but not very quicly; this proves that the lymph, when coagu- lated, is fomewhat heavier than the ferum. I then took as much of the bottom of the coagulum, con- taining the red globules, and put it into the ferum along with the lymph, to fee which of them funk the fafteft, and found that the piece with, the red globules funk much more quickly than the other; I Should think three times as fait. The ferum itfelf is much heavier than common water, for when the parts beforementioned were put into common wa- ter, in the fame manner as into the ferum, they both funk much fatter, and there was not that disproportion between the times of their falling, as in the Serum. But if the blood has a Strong difpofition to coagulate, and is not in large quantity, it will coagulate foon, and involve the red globules; yet there will then be feweft at top, and they will be more and more crowded towards the bottom; though there would appear in fuch blood to be no coagulating lymph at top free from the red globules, yet in meft of it a thin pellicle may be found, which can be pulled off. I have already obServed that the whole maSs oS blood, ta- ken together in a greater variety of claffes of animals, ap- pears of a red colour; and I Shall now further remark, that it is of a much deeper colour in fome claffes of animals than in others, which I believe ariSes Srom a greater num- ber of red w'~v'1ps beimr contained in a given quantity Haymarket, fell into an apopledic fit, in which She was infenfible, refpeding ideas- her breathing was very imperfed, attended with a rattling m her throat, and a Snort; the pulfe was very Steady, but rather flow. I opened the temporal artery, which bled'very Sreely ; but I obServed that when She breathed Sreely, the blood Srom the artery became red ; and when her breath- ing was difficult, or when She hardly breathed at all, the blood became dark, and this alternately Several times in the courSe of bleeding; yet all this made but little alteration in the pulfe. In many difeafes of the heart, as well as cf the lungs wc may often obferve the fame appearance. In many dif- eafes ot the heart, producing what is called angina pecto- ris, (the fymptoms of which arife from a vaft variety of caufes, palpitations being commonly one) we Shall fee that upon any exertion, the heart ad3 with great violence, and the breathing is very laborious, or rather imperfed, not corresponding with the violence of the motion of the blood; the face will become of a dark purple colour, the patients will be nearly expiring, and nothing but reft relieves them; •r this the following cafe is a Strong inftanee. A. B. when a boy, could never ufe the fame exercife that other boys did; he could not run up flairs, noraScend a hill without being out oS breath, and had almoft through his whole life, an irregular pulfe ; more efpecially when he ufed more exercife than he could well bear. Upon the leaft increafe of motion, he had a palpitation at the heart, wmch was often fo Strong, as to be heard by thofe that were near to him ; and his becoming foon fatigued, was by his acquaintance fuppofed to be owing to a want of Spirit or courage. r ^ With all this he grew to be a well formed and common Sized man, but St.Il he retained thofe defeds, which, in- deed, rather increafed as he extended his views, and with them extended his adions. About the age of thirty, he too, to violentexercife, fuch as hunting, and often in the caafc wouid ee Seized lo ill vrith palpitation*, and a'ra-fl * General principles of the blood. S3 total Suffocation, that he was obliged to Stop his horSe, and he held upon the Saddle. At Such times he became black in the Sace, and continued So as long as the fit lafted. It was often Several days beSore he perfedly recovered hi3 ufual health ; and frequently he could not lie down in his bed, but was obliged to fit up for breath: all thefe fymptoms gradually increaSed upon him, and at times, without any violence oS exerciSe or adion, he would feel as iS dying, and uSed So to expreSs himfelf: but as the caufe of there feelings did not appear to his friends, they rather treated him flightly. At laft mere anxiety of mind would bring on thefe feel- ings, palpitations, and Suffocations in Some degree. In the winter 1780, and 1781, he hunted very violently and alSo caught cold, which together brought on the above- mentioned complaints with greater violence than ever. He conSulted two gentlemen of the profeffion : the pal- pitation, the difficulty of breathing, the great oppreflion, with the blackneSs in the face (I fuppofe) they thought either ■aroSe Srom fpafms, or was nervous, for they ordered cor- dials, fuch as Spirit of lavender, wine, etc. I was Sent Sor, to give a name to' the diSeaSe. Upon enquiring into all the Symptoms, my opinion was, that there was Something very wrong about the conftrudion of the heart, viz. about the Source oS the circulation 'x that the blood did not flow at any time freely through the lungs, fo as to have the proper influence of the air, but much lefs fo when he was hurried; that a Stagna- tion of the blood in any one part about the heart would pro- duce in fome degree Suffocation ; and want oS due influ- ence oS the air upon the blood, being the Same thing, which was the cauSe of the darkneSs oS the Sace at thoSe times : that the means to be pradiSed were in Some degree contra- ry to what had been adviSed, namely, reft, gentle bleeding, care to eat moderately, keep the body open, and the mind eaSy; and as he had got the better of former attacks (al- though thofe were not So violent) I Saw no abfolute reafon ■why he Should not get the better, oS the preSent Eight ounces cf blood were taken Srom him that day, which re- lieved him. The Symptoms ftill continuing, though not So violently, I Saw him once more ; he loft about Sour or five ounces more blood, which alSo relieved him, but Still he did not get materially better : at Laft, as an addition to the above Symptom-;, he became yellev.-, his legs le_an t,o iv.e]J 54 General principles of the blood. with water, ar.e. all his other complaints gradually iucre:...\!, which made i:re SuSped that a depofit of water was begun in the cheft. He was now attended by a phyfidan ; was bliftcred en his lee;s, which threatened a mortification, and a cauftie was applied to the pit of his ftomach, (1 fuppofe for a pain there); nature was at Lft ween out, and he died. ■ I Solicited to open him, arid was allowed. On opening the* belly there was Sound in the abdomen a very Small quantity of bloody yellawifh ferum. Every viScus appeared to be Sound ; the gall-bladder was pretty Sull of bile, which was thick, but net ropy, as if the thinner parts had been Strained oft"; the duds were clear both to and from the gall-bladder. Upon opening the che(t the lungs did notcoh e.pfe, bein" a good deal cedematous, but othcrwiSe appearing Sound. There was alSo z little bloody Scrum in both xides of the cheft. TheSe I conceive were the ccnfequenccs of the Inft attack. The heart was very large, and very full of blood. Upon opening the right fide of the heart, I found no- thing uncommon, cither in the heart or the pulmonary ar- tery. Upon opening the left fide, I found the wives of the aorta thicker, and harder than ufual, having at the fame time the appearance of being very much Shrivelled. This diSeaSed ftrudure oS the valves account: for every one of what may be called his original fymptoms, and was fuch as to render them of very little ufe ; the blood, therefore, muft hr.ve fallen back into the cavity of the ventricle again at e- very fyftole of the artery. Whether this .hvivelled State of the valves of the aorta was a natural formation, or a difeafe, is not eafily afcer- tained; but if it was a diSeai'e, it mult have begun much earlier in lire than fuch difeafss commonly do, as the Symp- toms appeared when he was young*: From this construc- tion of valve, we muft See that it required the greateft quiet to allow the motions cf the blood Srom the left fide of the heart to go on Sufficiently, and that whatever interrupted this, produced a Stagnation, or an accumuk.tbn ofthe blood a'mof: in every part of the body; firft in the left ventri- cle, then the left auricle; pulmonary veins, pulmonary arteries 5 rigliT-rentricle, rhjht auricle, and a!! the vein- in . * [ have Seen it at a verv earlv period. General principles cf the blood. $$ the body ; however a Smaller quantity than uSual could get to the veins cS the body through the arteries, So that a kind of circulation went en. If we confidcr the efied arifing from this conftrudion of valves, Amply en mechanical principles, we cannot account for the darknefj of the arterial blood, which muft have paffed thiough the lungs, when there was no mechanical obftrudion to refpiration ; but Since it happens that when the heart either ceaSes to ad, or canncc get ridoS its blocd, (which muft have been the caSe in the preSent inftanee), refpiration ceaSes, or is perSormed fo imperfedly as*to have nearly the Same effed *; the perf ui is in reality in a State cf Suffocation. Suffocation is no more than imperfed ref- piration, which is the caufe oS imperfect blood paffmg to and Srom the leSt fide oS the heart; and it is thereSore im- material as to ccnSequences, whether a Stoppage to refpi- ration is the firft caufe, or is an effed, for in either way it is the caufe of impelled blood being introduced into the arterial fyStem." It may be difficult to account for the increafed fize of the heart, whether it was a mechanical effed, as the blood would be thrown back into it at, every Syftole of the aorta and diaftole cf the heart, or whether it -e.ro le from a par- ticular affedicn of that vifcus. The firft idea is the more natural; but it is not neceffary that the cauSe Should be of this kind ; for we fee every day enlarged hearts, where the fymptoms have been Somewhat Similar, and yet no vifible mechanical cauSe exifted ; and indeed it is a common effed where there is an impeded circulation. It is caSy to be conceived, firft, that the circulation could not, in the caSe of this patient, be carried on regularly and perfedly: Secondly, that a Stoppage to the blood's motion in either arteries or veins, but much more a retrograde motion in the blood in any part muft produce a Stagnation, which will be more cr lets extenfive, according to the quantity oS blocd paffmg that way : thirdly, that if it was only in a brand: of an artery, cr vein, the Stagnation would probably be only partial; but when i:: an artery, cr the veins of the whole body, as the aorta, or vena cr.va, it muft then be pretty univerSal; and as the retrogadc mo- * In fuch inspirations I conceive that fo little air is taken in as liartllv to reach the cells cf tie lungs, in as to be able to influence the blc-.d circulating on thofe cells. 5 5 General principles cf the bleed. tion in the blood began in the aorta, wc can eafily tractf its effeds. We alio find in imperfed conitrudions of the heart, &c. where there is a communication between the right and left fide kept up after birth, that the fame circumftances and appearances take place ; cafes of this kind frequently occur, of which the following is a Strong inftanee : I was feveral times confulted about the ftate oS a young gentleman's health, and though it could not be Said anato- mically, with precificn, what the real confirmation oS the heart was, yet it was imagined that the Symptoms aroSe Srorh Some imperfedion in that organ. From his infancy, every confiderable exertion produced a feeming tendency to Suffocation; and as Suffocation always ariSes Srom a want oS the due effed of air on the blood, while the cir- culation is- going on, the whole body muft change from the fcarlet tinge to the modena or purple; and in thoSe parts where the blood gives its colour moft, there will this effed be greateft, which is commonly in the face, and particular parts of the face, at the finger-ends, &c. While very young, nothing but crying brought on thofe fits, but when he was grown fo as to take bodily exercife, as run- ning, &c. then they became more frequent and more vio- lent ; and it is to be obferved, that the older he grew, the worfe he was likely to be; for with years approaching to maturity, his adions were likely to increafe: great care, however, was taken to SuppreSs Such adions as were Sound, from experience, to bring on the fits. No medical advice could be of the leaft Service, further than to inform him what experience had already taught, unlets to recommend occafionally, when his Sriends found that the fits of fuffo- cation were more eafily excited than ufual, that he Should lofe a little blood, So as to leffen the neceffary adion of breathing; putting, in this way, the quantity and motiott of the blood more upon a par, and at the Same time, not to indulge too much his appetite ; but all theSe precautions hardly kept him tolerably well. The heart, in proportion to the difficulty, aded with more violence, and one could rather have wifhed the contrary to have taken place. As he could hardly ufe any exercife of his own, motion was given him, fuch as riding Slowly on horfeback, in carriages, &:c. He lived to the age of between thirteen and fourteen, and though the diSorder did not deitroy him, yet it is moJt probable that he could not have lived long, as he was every General principles of the blood* 57 day arriving more and more at an age of adion, but not izi the fame proportion acquiring prudence. When he died he was opened by Dr. Poultney, who tranfmitted an account oS the appearance of the parts to the College of Phyficians of London, which is published in the third vo- lume of their Medical Tranfadions: Such parts as are im- mediately conneded with my iubjed, I Shall tranScribe. " Both lobes of the lungs were remarkably fmall, and fome parts of them flacid to fuch a degree, as to fuggeft an idea of their having been incapable of performing their Sundions *. The liquor pericardii was in due quantity, and the heart was firm in texture, and of the natural fizef. On examining the ventricles, and the beginning of the aorta, a canal, or paffage was Sound communicating with both ventricles, Situated in an oblique diredion near the bafis oS the heart. So large as to admit the end oS the' finger from the aorta with equal facility into either ventri- cle ; the feptum of the ventricle appearing to terminate with this canal. On examining the entrance of the pul- monary artery within the ventricle, it was judged that this entrance was much fmaller and more firm than common." It is difficult here to fay what would be the exad effed of" this communication on the motion of the two bloods; that is, whether the blood of the right fide was received into the left, or vice versa; if the oblique diredion of Lhis paifiige had been further defcribed, it might have ex-. plained this doubt, for if the paffage was dired, the blood would moft probably paSs Srom the leSt to the right, as the left ventricle acquires the greateft ftrength; the word ob- lique, however, and the expreffion, that the finger, from the aorta, paffed with equal facility into either ventricle, would make us fuppoSe that the obliquity led out oS the right ventricle into the aorta; but even with this obliqui- ty, I fhould not think it probable that the blood would paSs from the right to the left, becaufe the left ads with fo much more force: the defcription leaves us to account for the defed in refpiration another way. If the blood paffed from the right to the left, then it would have had the Same effed as the canalis arteriofus, and probably was * Although I have tranfcribed this, yet I do not lay muck'' flrcfs upon it. + This Shews there was no difeafe. * *■ General principles of the blood. the only one in the foetus. In this cafe too little blood would pafs through the lungs; but I do not conceive that. tins circumftance would affed refpiration, becaufe no Stag- nation would take place in the lungs; hut if the blood get from the left to the right, then too much blood would bo Sent to the lungs, as it would be found to take its courSe twice. On the other hand, iS the lungs he not capable of allowing a full diftention equal to the adions oS the heart, though naturally Sramed, the Same thing takes place. In natural deaths the pulSation oS the heart commonly Stops before breathing ceafes ; but in deaths arifing from a Stop- page of breath, fuch as hanging or drowning, the reverSe muft take place; and in Such we Shall always find dark blood in the teft fide, which plainly took place in the ex- periment above-mentioned. It may be fuppofed that in the lungs the bloOd cannot come in contad with the nir, but the circumftances above related, that the florid colour will extend fome depth into the blood, SI. sws that the effed of air can and does per- vade animal matter. Not attending to this fad at firft, I- covered the mouths of veflels filled with venal blood with gold-beater's Skin, touching the Surface'of the blood, and the blood constantly became of a florid red on the furface,. and even for fome depth. I put fome dark venal blood iirro a phial, till it was about half full,' and Shook the blood which mixed with the air in" thk motion, and became immediately of a florid red*. As the globules are the coarfeft part of the blood, and they appear to be fully affeded by the air in the lungs, we may fuppofe that the veffels of that vifcus do not run into extreme minutenefs, by which, apparently, no other pur- pofe would be anSwered. The blood of the menfes, when it comes down to the mouth of the vagina, is as dark as vend blood, and as it does not co-jgub.te, it has exadly the appearance oS the Hood in thoSe, where the blood continues fluid. Whether this ariSes from its being venal blood, or from its acquiring fhe.i colour after exrravafation, by its Slow motion, it i» not eafily determined; but txpon being expoSed it becomes ilorid : it is n^rurally of a dark colour, but rather muddy, • • Thefe cxperiir.euis I made in the Summer 175 c, when F was houfe fiigcon nr St. George's Hofpital, and iSr: Iliiijief ?#-idit them ever sStcr at his le-uures. General principles of the blood. 59 not having that transparency which pure blood has. Whe- ther this arifes from its mixing with the mucus of the va- gina, or from the ceffation of life in it, I will not pretend to fay. The red globules, however, are not diflblved, they retain their figure. Does air in the cellular membrane of an emphyfematous perfon produce, or continue the floridnefs of the blood or not ? * The furface of the blood becoming of a fcarlet red, whether expofed immediately to the air, or when only co- vered by membranes, through which we may fuppoSe its influence to paSs, is a circumftance which leads us to Sup- poSe, that it is the pure air which has this effed, and not limply an expoSed SurSace f. To aScertain this I made the following experiment: I took a phial, and fixed a ftop cock in its mouth, and then applying an air-pump to the cock, exhaufted the whole air : in this ftate keeping it Stopped, I immerSed its mouth in SreSh blocd flowing Srom a vein, and then turn- ing the cock allowed the blood to be preflcd up into the phial. When it was about half full I turned the cock back, and now Shook the phial with the bleed, but its colour did not alter 4s in the former experiments; and when I allowed the blood to Stand in this vacuum, its expofed SurSace was not in the leaft changed. The vaft number oS cells into which the lungs are divi- ded, the whole arterial and venal Syftem ramifying en the SurSace of thofe cells and of courSe the whole of the blood paffing through them in every circulation, together with the lofs of life upon the milling three or four breathings in the moft perfed animals, Shew the great nicety that is requir- ed in preferving the due properties of the blood for the pur- pofes of animal life : the time that we can live without air or breathing, is Shorter than that in which we die from a defed in any other natural operation ; breathing, there- fore, feems to render life to the blood, and the blood con- tinues it in every part of the body. This nicety is not nearly fo great in many of the more imperfed animals. The amphibia have not this divifion of lungs, nor does * Vide Cheftcr on Cafes. Cafe firft, the venal florid. £r. George's, a nun emphysematous ; blood very dark.^ + J may here obfeive, that, fixed air, as alfo Inflammable .<>*, have contrary effeds. 6* General principles of the blood. the whole of the blood pafs through the lungs in them, and they can live a confiderable time without breathing'. This, at prefent I only mention as a fad, not meaning to give my opinion of the mode of prcferving life, either in the blood or body, by the application of air to it; though, I will fay, that mere life in both is fupported by the air, and probably few of" the other properties conneded'with the blood depend fo much upon air as its life. But we may obfervej' that it was not neceffaTy Sor the blood to undergo this change, to render it fit Sor every purpoSe in the animal ©economy; for we find that venal blood anfwers Some purpoSes : thus the blood Srom the intestines, Spleen, &c. going to the liver, as we SuppoSe, Sor the Secretion of the bile, Shews that venal blood will do Sor Some Secreti- ons, though probably not absolutely neceffary. This appli- cation oS venal blood is a Saving of" blood, and it is not . neceffary Sor the Sormation of bile, that the venous blood Should proceed from the parts abovementioned ; for in birds, amphibia, &c. other veins, befides thofe, enter the liver. I have Shewn that Several Subftances mixed with dark coloured blocd, have the property oS rendering it of a florid red; and it muft have appeared, that by circulating through the body its dark colour is restored. As it is ca- pable of being rendered florid, by feveral fubftances, fo it may be rendered dark by feveral when florid : vital air has the power of rendering it florid ; but the other vapours, cr gaffes, which have the name of airs, fuch :.s fixed air, inflammable air, &c. render it dark. This change is pe- culiar to the living body; for if arterial blood is taken away, it retains its florid colour, although not in the leaft expofed to the air. As it is Sound dark in the veins, and as it perSorms Some offices in the courSe oS the circulation, which perhaps render it unfit Sor the purpoSes oS life, we may conceive, that the loSs oS colour, and this unfitneSs are effeds of the fame caufe : but, upon further observa- tions on this fluid it will be Sound, that it may be rendered unfit Sor the purpoSes oS life without lofing its colour, and may lofe its colour without being rendered unfit for fife- Slowneis of motion in the blood of the veins, is one circum- stance that caufes the alteration, but this alone will not produce the effed, for I have obServed above, that arteri 1 blood put into a phial and allowed to Stand quiet, dees not b-eome dark; but rift or flowneSs of-motion- in ivi -> General principles of the blood. Cyt parts, would appear, from many observations, to be a cauSeoSthis change in its colour: wc know that the blood begins to move more and more flowdy in the arteries: we know its motion in the veins is flow, in comparffon to what it is in the arteries; we Should, therefore, naturally Sup- poSe, (confidering this alone) that it wag the flowneSs of the motion that was the immediate caufe. Reft, or Slow- nefs of motion, in living, and probably healthy parts, cer- tainly allows the blood to change its colour: thus -be never fee extravafations of blood, but it is continually dark. I never Saw a perSon die of an apoplexy, from cxtravafation in the brain, but the extravaSated blood was dark; even in anueriSm it becomes dark in the anucriSmal Sac, alSo when the blood eScapes out oS the artery and coagulates in the cellular membrane, we find the Same appearance. TheSe observations refpeding apoplexy, Struck me much. J conceived at firft, that the extravaSations there muft confift oS venal blood; but, Srom reaSoning, I could hard- ly allow myfelf to think fo; for whatever might be the beginning of the diSeaSe, it was impoffible it could continue afterwards wholly venal; especially when the blood was Sound in a confiderable quantity; becauSe, in many cafes, great mifchief was done to both fyftems of veffels, and the arteries once ruptured would give the greateft quantity of blood; but to ascertain this with more certainty, I made the following experiment: I wounded the femoral artery of a puppy obliquely; the opening in the Skin was made at fome diftance Srom the ar- tery, by a couching needle ; the blood that came Srom the Small orifice in the Skin was florid. The cellular mem- brane Swelled up very much; about five minutes afterwards, I pundured the tumour, and the blood was fluid. In ten minutes I pundured it again; the blood was thinner, and more Serous, but Still florid. In fifteen minutes I pundu- red it again: at firft only Serum iffued; upon Squeezing a little blood came, but Still florid : the mats now Seemed to be principally coagulated, which prevented further trials. Some days after, when I cut into the Swelled part, I Sound the blood as dark as common venal blood ; So that here the change had taken place after coagulation. When I had plafter of Paris applied to my Sace to make a mould, in the taking it off, it produced a kind oSSudion on the fore part ofthe nofe, which I felt; and when the plailer was removed, on observing the part, it w-- red, fc2 General principles of the blood. as if the cells of the Skin were loaded with extravafaCed blood; this was then of a florid red, but it foon became of a dark purple, which Shewed that it was arterial blood, and that by Stagnating in the cells- of the body it became of the colour of venal blood. Blood may even be rendered dark in the larger arteries, by a Short Stagnation. I laid bare the carotcd artery of a dog, for about two inches in length , I then tied a thread round ifrat each end, leaving a Space oS two inches in length between each ligature, filled with blood; the external wound was ftiched loofly up: Several hours aSter, I opened the ftiches, and obServed in this "veflel that the blood was coagulated, and of a dark colour, the Same as in the vein. Thus I have alSo feen when a tourniquet has been applied round the thigh, and the artery divided, that when it was Slackened the firft blood came out of a dajrk colour, but wlnt followed was florid. This I have feen in amputations, when a tourniquet had been applied for a confiderable time; and, it is commonly obServed in performing the operation for the anuerifm. July, 1779, Mr. Bromfield had a patient in St. George's Hofpital, with an anuerifm in tho crural artery, about the middle of the thigh: the artery had been dilated about three incites in length. The operation was performed, in which the artery was tied up above the dilatation, three or more inches, for fecurky. When this was done, the tourniquet was Slackened, and a pretty confiderable bleeding was ob- Served, Seemingly at die lower orifice, leading, from the di- kted part, which, at firft, wis fuppofed, Srom its colour, to be the venous blood that had Stagnated in the veins, by means ofcthe tourniquet; but tiff; it could nor be; audit was found to flow from the lower orifice ofthe artery, which was immediately tied; we muft SuppoSe, that the motion of the blood, in making this retrograde courSe, was very Sow, Sor it had firft to paSs off into Small collateral branch- es, above where it was tied, then to analtomoSe with Simi- lar fmall ones, Srom the trunk below, and then to enter " that trunk; all of which muft very much retard its motion; and inuj.- 1, the manner of its oozing out of the veflels. Shewed Su-h a retardation. This motion of the blood, though in the arterial fyStem, was in fome refpeds finiilas jto the motion of the blood in bothfvftcma of veu:*h. General principles of the Mood. 6y This laft circumftance plainly indicates a communication of the arteries above the anuerifm with thofe below, bv means of the anaftomozing branches. 'I'he blood from the lower orifice flowed without any pulSation; which mutt have been owing to its coming into the large artery below by a valt number oS Smaller ones at different diftances, and oS courSe, at different times; but probably, the chieS caufe of this want of pulfation in the great artery was, that the power of the heart Was loft in the twro fyftems of fmaller arferies above, and "below; for the fecond fyStem, or thofe Srom below, became in a confide- " rable degree fimikir to veins; and the great artery in.the leg, below the anuerifm wras like a confiderable vein. A young man, Servant to Henry Drummond, Efq. hav-' Ing liad a knife run into his thigh, which,wounded the cru- ral artery, a confiderable tumour came on the part, con- futing chiefly of bkood extravafated, and lodged in the cel- 1'uk.T membrane. This in Some degree Stopped the flowing oS the blood from the cut artery, and on dilating the wound fo as to get to the artery, I obServed that the extravaSated blood in the cellular membrane was oS the venal colour. On expofmg the artery, which was firSt Secured Srom bleeding by a tourniquet above, and then Slightly Slacken- ing that instrument, the firft blood which flowed from above, was dark; and even was taken for venous blood by the operator; but he was foon convinced that it was arteri- al, by the ilorid colour of that which almoft immediately en- ■fucd. 1 obServed that the colour ofthe blood was as darkas that of any venous blood I ever Saw. From thefe experiments, and obfervation, we muft con- clude that the colour of the blood is altered, either by reft, or Slow motion, in living parte, and even in the arteries.; this circumftance takes place in the veflels as the motion of the blood decrenfes. Another observation occurs, viz. that the -whole of the limbs below the ligature, where the crural artery has been taken up, muft entirely be fupplied with fuch altered blood; and as this leg kept its life, its warmth, and the adion of the mufcles, it is evident that the colour of the blood is of little Service to any of thofe properties. It is probably from this -caufe, that granulations on the lower part cf the' lower extremity look dark when the perfon Stands eredj as well as in very indolent fbres, however Situated- 6a General principles of the blo«d.J Another obfervation Strongly in favour of the fuppMnV tion, that reft is a cauSe of the change of blood from the Scarlet colour to the dark, or modena, is taken from the common operation of bleeding; for we generally find the' blood of a dark colour at its firft coming out, but it becomes fighter and lighter towards the laft. Some reafons maybe given for this, firft, it has Stagnated in the veins, while the vein was filling, and the orifice making, which occupies Some time, and may render it darker than it otherwiSe might have been in the Same vein : Secondly, when there is a Sree orifice, the blood may paSs more readily into the veins Srom the ".:Ter:ci>, and therefore maybe Somewhat in the ftate of arterial blood,which mayoccafion the laft blood to berather lighter. What amounts almoft to a proof of this, is, that' although a ligature is tied fo as to Stop the paffage oS the blood to the heart, and thereSore it might be SuppoSed not to have So Sree a paffage Srom the arteries as in common, yet Srom the Sollowing observations, it appears that it cer- tainly has a much Sreer ; for if the orifice be large in a full Sized vein, the arm beyond the criiice will be much paler than the natural colour, and the blood will become more florid; but if on the contrary the vein be fmall and litde blood paffes, it will retain its dark colour; this', however,' would appear not always to'be the cafe. I bled a lady whofe blood, at firft was oS a dark colour; but She Sainted, and while She continued in the fit, the co- lour of the blood that came from die vein, was a fine fcarlet. The circulation was then very languid. We may obfervc that venal blood in the moft healthy, is commonly, if not always, the darkelt;. and when the bo- dy is the leaft out of order, it is then not fo much changed from the florid to the very dark purple. This I have often bbferved, and particularly recoiled a ftriking inftanee of it in a gentleman who had a flight fever ; his venal blood was quite florid, like arterial blood. This could not arife Srom zlic, increaSe of the blood's motion, or from being kept up' in the veina by il\c fever, for it was light*. * I believe the blood does not become dark by Handing in an inflamed part. I have Seen cafe* of apoplexy, where tiie per- fon died fome days after the attack. 1 have found ihe piaaia- ter inflamed in feveral places, even t"> the length of inflammato- ry transfufion ; forming dors, all of which were of a florid red co- lour, while- tiie other parts orthe Same, metiibvsne, the bloicl in General principles of the blood. *S The blOod will change its colour from the fcarlet to the modena in different fituations, according to the mode of circulation. In animals who have lungs, and a complete double circulation, the darkelt blood will be where it comes (if I may be allowed the expreflion) to get anew its bright colour; for inftanee, in the arteries of the lungs, and of courfe the brightest in the veins of the fame part, which will be continued more or lefs into the arteries of the o- ther circulation, where again it will begin to change, except in one Stage of life of fome animals who do not ufe their lungs, fuch as fcetufes; but in Such fcetufe* as convert animal-matter into nourishment, therefore, moft probably, muft have if influenced by the air, fuch as the chick in the egg, although not by means of the lungs of the chick, we find the blood in the veins of their temporary lungs of a florid colour while it is dark in the ar- teries ; therefore has become of a dark colour, in its paffage to and from the heart; but in the more perfed animals the blood, I believe, becomes darker and darker, as it proceeds from the heart, till it returns to the heart again; but this change is very little in the arterial fyftem, more especially in veflels near the heart, as the coronary arteries. The change oS colour is more rapid in the veins, but it is not equally made through the whole venous Syltem ; Sor it will be produced more quickly in the lower part6 oS the lower extremities, than in the veins near the heart: it begins, moft probably, where the motion firft has a tendency to become languid; and this uSually takes place in the very Small ar- teries ; Sor in bleeding in the Soot, or on the back of the hand, I have obferved, in general, that the blood is of a more florid red than in the bend of the arm. V. OF THE QUANTITY OF BLOOD, AND COURSE OF ITS CIRCULATION. It appears to me impoffible to aScertain the quantity of bloo d in the body; and the knowledge oS it would proba- bly give very little alfiftance towards better understanding the ceconomy of the animal. The quantity of blood is the larger veflels, and alfo the extravafated blood, were of the ufual dark colour. R 64 ('.<•.>:>. al principles of the bleed. probably as permanent a circumftance as :niy, and not de- p^n'din^ on ifnmedi;te.'adion : _wc have n^i one hour lefs ; the Support oS action, Such as the action of the brain, and General principles if the blood\ 6* mufcles, in which is produced uncommon wafte; and thirdly, fecretion; all of which will fluctuate except the fimple lupport; but more particularly the fupport of adion. I have already obferved that the anaftomofing of veffel? gives greater Space Sor blood. Probably a paralytic limb would give the neceffary quantity Sor Simple Support. There is nothing in the veins particular, So as to give an idea that they were intsnded to increaSe the quantity of blood ; they hold, however, more than the arteries, which certainly adds to the quantity : but the increaSe of fize lef- fens the velofity. They Sorm plexuSes, and what are called certain bodies, as the plexus retiSormis in the Semale ; the / carpora carvernoSa, and SpongioSa in the male. We See how little blood Supports a part in an aneuriSm ; and, pro- bably, flowneSs of motion is Suitable to little blocd. It muft have appeared in the account of the different co- lours, of the different parts of the body, arising from the proportion of red blood, that fome parts muft have much more blood than others, and we have now to mention, that fome parts have much larger veflels going to them, than others. This idea is confirmed, by the blood being tiie moving material of life, and taking a part in every adion of it: its quantity is to be found in proportion to thoSe ac- tions ; ami Since the body is a compound of parts, or ra- ther of adions, whoSe uSes are known to vary confidera- bly, we find blood direded to thoSe parts in proportion to their adions ; and this we judge of by the Size of the vef- fel, and rednefs of the part, in thefe animals which have red blood, and we may SuppoSe the Same in thofe which have not this part of the blood. The brain has confidera- ble veffels, etc. going to it, yet its Subftaace is white, which is in Some degree owing to its opacity. The tongue is vaScular. The thyroid gland is vaicular. The lungs al- low of the paffage of the whole blood in moft animals, and therefore have always a current of blood through them e. qual to the whole. The liver is extremely vaScular, which is known from its proportion of veflels, as well as its colour ; and as there is in this vifcus a peculiar circulation, the very great quan- tity of blood pafling through it, adds to the quantity in the whole body. The fpleen is extreme!;- vaScular, as are likewife the kiduies. The ltoaia:h, and inteltincs, have confide chic R 2 66 General principles of the blood. veflels going to them, and the muScles in general, more eSpecially thoSe oS labouring people; Sor labour increafes the quantity of blood in the whole, beyond fimple nourish- ment in the full grown, or beyond the mere growth in the young. In tracing the courfe of this nourishment in animals, which confifts ultimately in the blood ; from the moft Sim- ple to the moft complicated, there is a pretty regular Se- ries ; but this regularity is interrupted whenever there is a variety in the circumftances which are to be taken into the account; but the whole oS this forms too extenfive a Sub* jed Sor our prefent consideration. If I were to begin at the formation of the blood, I Should firft treat of digeftion in thofe animals which have Sto- machs ; but this is a diftind fubjed: we may, however, begin with its immediate confluences, as it produ«es the firft and moft effential change, viz. the converfion of the blood into a fluid qalled chyle. The chyle is the imme- diate effed or produd of digeftion, and is the feed, which, as it were, grows into blood, or may be faid to be the blood not yet made perfed. The chyle, to appearance, varies in different animals. In the quadruped, and in the crocodile, it is white ; but in moft other animals it is tranf* parent: where it is white its parts are more confpicuous than where it is tranSparent. In this reSped it is Similar to the red blood, and is Sound to confift of a coagulating matter, a ferum, and white globules, which render it of a white colour, and in fome degree refembles milk, Thefe glo* bules are fmaller than the red globules of the blood, and about the fize of thofe in the pancreatic juice ; they retain their figure in water, and therefore are not Similar to the red globules: they retain, alfo, their round form in the ferum. They are Specifically heavier than their own lymph, and ferum. One would naturally fuppofe from obferving the chyle to have globular particles in certain animals, that they form- ed the red globules in the blood; but when we confider that the chyle in fowls has no globules, and yet that they have red blood, we muft conclude that they do not anfwer this purpoSe. The firft motion oS the nourishment in moft animals il by the abSorption oS this fluid from the appendages of the Stomach ; and in many, this alone appears to be the whole, General principles of the blood. 67 as they have no Such organ or viScus, as a heart, to which it may be carried ; and in Such it may be SuppoSed to be in its mode oS diftindion Somewhat fimilar to the meSenteric veins and vena-portarum : the parts, thereSore, aflimilate, and diSpoSe oS it themSelves; but this ftrudure belongs only to the moft fimple, or the firft claSs of animals. In thoSe which are more perfed, where parts are Sormed for each particular purpofe, the chyle is brought to one organ, called the heart, having firft joined the venous blood, which now requires a fimilar procefs, and both are fent to the lungs, where, moft probably, the chyle receives its finishing procefs, and from thence it comes back to the heart again, to be fent to every part of the body*. In thofe animals that have hearts, we are to take into the account a number oS particulars : firft, the blood's mo- tion in conSequence of that organ : Secondly, the firft in- tention of that motion, viz. to be prepared in the lungs, which introduces breathing : thirdly, the variety in the kinds of lungs : fourthly, the different kinds of fubftance animals are obliged to breathe for the purpofe of matter, employed in the preparation of this fluid. In this investigation we Shall find there is not an exad or regular correspondence in all the parts So employed. This irregularity ariSes Srom animals breathing different Subftances; Such as Some breathing the common atmoSphere, in which is included the reSpirable air; others water, in which air is included, as fifti. Some breathe both air and water* while there are others which breathe air in their perSed ftate, but water in their firft periods, or imperfed State of life f. If we were to take a view of all thefe fyftems, each Should be confidered apart, with all its peculiarities or con- nedions; together with the different fyftems, as they gra- dually creep into one another, fome being perfedly dif- tind, while others partake more or lefs of both. The complete fyStem is always to be eonfidered as the moft perfed, although it may belong, in other reipeds, to a more imperfed order of animals. It has been fuppofed by phyfiologifts, that as the blood is found to confift oS different parts, or rather properties, that certain parts or properties were determined to certain * The circulation in fifti is an exception to this. \ In this account I do not include animals in embryo, and fome others, which do not breathe at all. 63 General principles of the blood. parts ofthe body, for particular purpoSes; but from the S\-. quent anaftomofis oS arteries, the great variety in their number, origin, and the different courSes which they take in different bodies, it is very evident, that there can be no particular blood Sent to any part oS the body where the whole blood can circulate. Many unnatural Situations of parts Shew this. For inftanee, the kidneys Sometimes have one artery only on one fide, and two, three, or Sour on the ether. On ohe fide they ariSe Srom the aorta as high as near the Superior mefenteric, on the other as low almoft as the divifion into the two iliacs : and in Some caSes a kidney has been Sormed in the pelvis, and the artery has ariS-m Srom the iliac; the Spermatic arteries too, Some- times, ariSe on one fide from the aorta, and on the other from the emulgents or the arteria capfuloe renalis. If there was a particular blood fent to every gland, we Should ex- ped to find urine Secreted in the tefticle, when its artery aroSe from the emulgent: but as the blood visibly confifts of different parts in thofe animals we are moft acquainted with, and whofe phyfiology is probably belt known to us, and as one part of the blood can be traced in the veflels, we can determine with Sufficient accuracy the proportions of blood fent, as well as the different kinds. Thus, the red part of the blood informs us, how far it is carried; and we find that our coloured injedions nearly correspond with this information. I may here firft remind the reader, that the red globules are the grofler part oS the blood, and therefore, whenever they are moft in quantity, we have the blood with all its parts in due proportion and unSepar- ated ; but the conitrudion in many parts of an animal is fuch, that the red blood is excluded, and this alfo excludes every coloured powder we can injed ; the vascularity, therefore, of fuch parts is not known, as has been men- tinned. Through them the coagulating lymph only can pafs, and probably the ferum, . for the fimple nourishment of the parts. Of this nature are tendons, cr tendinous parts, ligaments, claftic ligaments, cartilages, efpecially thofe of joints, the cornia, &c. Even the brain and nerves, have not the red blood puffed So far into their fubftance as ma- ny other parts have ; we fee, therefore, that the whole blood is not conveyed to all parts alike, and this we may fup- pofe to anfwer fome good purpole; yet, upon a more par- ticular veiw of this fubjed, we may find it dlSIicult to aS- Genera! p•:/:.-?/.'•.'«■ of tic bkod. €p Sign cauSes Sor this Seledion oS the blood; Sor in many unimals we find parts fimilar in conStrudion and ufe, Sue a as mufcles, which are furniflicd, Some with the win le blood, others with the coagulating lymph only, with all the gradations; it me animals having both red and white muScles; others having them wholly red, and others wholly white, as will be more fully explained. Even ve- nous blood can be rendered ufaful, when it is r.ot to an- lwcr the purpoSe of nourishment; Sor we find the blood cf the inteftine and Spleen going to the ii, cr, we mey prefeive for the Secretion cf the bile, as has been already obferved. The idea of particular kinds of blood being fent to parts having particular ufes, more efpecially where the part is employed Solely in diSpofing oS this fluid, Such as glands, is now, I believe, pretty well exploded; and, it is SuppoS- ed, therefore, that the whole mafs of blood is fuch as to be fitted for all the purpoSes of the machine. This idea gives to the parts themfelves, full power over the blood fo coair poSed, and makes us confider the ciaculation or motion of the blood Simply. > As the blood is compc-Scd of different parts, it might be fuppofed, that if any particular part had been expended in any procefs, the remainder, as returned by the veins, would Shew this by its difierci.t av.p rarar.ee or qualities. The only vifible difference that I could conceive to take place, was in the appearance, or the quantity of coagulating lymph.. To afcertain this, however, I made the following expe- riments: I opened the right fide oS the thorax in a living dog, and tied a ligature round the vena-cava inferior, above the dia- phragm. I then applied my hand upon the opening, which allowed him to breathe, that the circulation might go on and fill the larger veins. When the inferior vena-cava be- came turgid, I killed him. On the day following I examin- ed the blood in the different veins, and found a coagulum in the emulgent, mcfenteric, vena-cava inferior, Splenic, and in the vense-cavre hepaticnr, oS fizes proportional to the Sizes oS the veffels; nor was there any difference in any other way. Experiment the Second. Some blood was taken fro n the incScnteric vein of a living dog, and fimilar q^nliiei from the Splenic vein, the emulgent vein, and-he \cni- cava inferior, below the opening: of the en.u1^:::-,. 70 General principles of the blood. TheSe Sour quantities were taken in Sour Separate cups. They all Soon coagulated : iS there was any one later of coagulating than another, it was that from the mefenteric veins. On ftanding twenty-four hours the coagula were all of the fame firmnefs. VI. OF THE LIVING PRINCIPLE OF THE BLOOD. SO Sar I have confidered the blood, and in the com- mon way ; but all this will explain nothing in the animal ceconomy, unleSs we can refer it to Some principle which mayfhewthe nature oS its connedion with the living Solids in which it moves, and which it both Sorms and Supports. IS we Should find this principle to be fimilar to life in the folids, then we Shall fee the harmony that is fupported be- tween the two, and we Shall call it, the living principle of the blood. Without fome fuch principle, all we have been examining is like diffeding a dead body without having any reference to the living, or even knowing it had ever been alive. But, from the account I have given of the blood, it muft have appeared, that I have ftill in referve a property not hitherto explained ; for in treating of the co- agulation of the coagulating lymph, I have not been So Sull in my account as I might have been. As many phoe- nomena, reSpeding the coagulating or not coagulating of the blood, develope this principle, I have choSen in part to reServe it Sor this place; nor Shall I be So Sull upon the preSent occafion as I Should otherwiSe be, were I writing on this Subjed expreSsly. My intention being rather to explain many appearances in the animal ceconomy, and particularly the diSeaSes I am to treat oS, than to diScuSs this Single principle. I reServe the illuftration oS my doc- trine for Such parts of the treatife as Shall be employed on thefe fubjeds; the explanations and illustrations, there- fore, will be interfperfed through the work, by which means they will come more forcibly on the mind : from many circumftances attending this fluid, it would feem to be the moft fimple body we know of, endowed with the principle of life. That the blood has life, is an opinion I have ftarted for above thirty years, and have taught it, for General principles of the blood. 71 r.^ar twenty of that time in my ledures; it does not, therefore, come out at prefent as a new dodrine ; Luc has had time to meet with confiderable oppofiticn, and alfo acquire its advocates. To conceive th.t blood is endowed witli life while circulating, is perhaps carrying the imagi- nation as far as it well can go; but the difficulty ariSes merely from its being fluid, the mind not being accultom- ed to the idea of a living fluid*. It may therefore be ob- fcure at firft, and it will be the more neceffary that I Should be pretty Sull in my account of it; yet the illuftration of it in my account of inflammation, will, perhaps, do more to produce convidion than any other attempt, although Strong y Supported by fads. It is to me tomevihat aho- nifhin^, that this, idea did not early ftrike the medical en- quirers, confidering the StreSs which they have h.idci the appearances oS this fluid in cnitaSes ; Since h is probaoly more expu ilhe oS diSeaSe than any other part of the animal ©economy: and yet all this, according to thou, muft have ariStn from, what Shall I call it ? a dead animal fluid, on which a diSeaSe in the Solids muft have had Such an effed. This, I think, is giving too much to the Solids, and too little to the fiuius. When all the circumftances attending this fluid are Sully confidered, the idea, that it has life with- in itfelf, may not appear fo difficult to comprehend ; aod indeed, when once conceived, I do not fee how it is pof- fible wc Should think it to be otherwife ; when we confider that every part is formed Srom the blood, that we grow out of it, and if it has not life previous to this operation, it * It is juft as difficult for a man bor in the Weft Indies, to conceive water becoming a Solid I recollect a gentleman from Harbadoes, walking out with rne one frofty morning, when there was ice on t1 e gutters, and !, without having any thing elfe in my mind than juft common obfervation, Said, " it " has been a froft in the night." lie immediately caught at the word frolt, and afked me, *' tlow 1 knew that?" With- out: thinking particularly of the caufe of his queftion, I Said, " becaufe 1 fee the ice on the gutters." He immediately faid, " where?" and I anfwered, "there." Hav'ng been told that ice was a Solid, he put his ringers down upon it, but wit* fuch caution as befpoke a mind that did not know what it was to meet; and upon feeling the refiftance it gave, he gently pulled hh hand back, and looked at the ice, and then becaaie more bold, broke it, and examined it. S 72 General principles of the blood. muft then acquire it in the ad of forming ; for we all giri our affent to the existence of life in the parts when once formed. Our ideas oS life have been fo much connected with organic bodies, and principally thofe endowed with visible action, that it requires a new bend to the mind, to make it conceive that thefe circumftances are not infepar- able. It is witlhn theSe fifty years only, that the callus of bones has been allowed to be alive* ; butj I Shall endeavottr to Show, that organization and life, do not depend in the halt on each other; that organization may arife out of living parts and prcduce adion, but that life can never rife out of, or depend on organization. An organ is a peculiar conformation oS matter, (let that matter be what it may) to anfwer Some purpofe, the operation oS which is media- meal; but, mere organization can do nothing, even in mechanics, it muft Still have Something corresponding to a living principle ; namely, Some- power. I had long SuS- peded that the principle oS liSe was not wholly confined to animals, or animal Substances endowed with visible organ- ization and Spontaneous motion : I conceived that the Same principle exifted in animal Substances devoid oS apparent organization and motion, where there exifted Simply the power oS preservation. I was led to this notion about the years 55, or $6, when I was making drawings oS the growth of the chick, in the procefs of incubation. I then obferved, that whenever an egg was hatched, the yolk, (which is not diminished in the time of incubation) war, always perfedly Sweet to the very laft ; and that part oS the albumen, which is not ex- pended on the growth oS the animal, Some days beSore hatching, was alSo Sweet, although both were kept in a heat of 103° in the hen's egg for three weeks, and in the ducks for four. I obferved, however, that if an eez did not hatch, it became putrid in nearly the fame time with any other dead animal matter; an egg, therefore, mult have tne power of felf-prefefvation, or in other v—■? the fimple principle oS life. To determine how far eggs would Stand other tefts, to prove a living principle, I made tiie following experiments f : v'rh It"; ,IT-nt-e7ar rr ^ ^ fll0*ed CalIus to be endowed vith the j.nnciple of life, ^j muJi &\ bone f Plulos. Tranfact. vol. 4?,part t pare- 23, 0 ; as alfo CLf-r- General principles of the blood. 73 Having put a new laid egg into a cold about o, which froze it, I then allowed it to thaw; from this procefs I imagined that the preferving powers of the egg mh.;it be destroyed.* I next put this egg into the cold mixture, an . with it one newly laid; the difference in freezing was i:ven mi- nutes and a half; the frefh egg taking fo much longer time in freezing. A new laid egg was put into a cold atmofphere, fluctu- ating between 170 and 150 ; it took about half an hour to freeze ; but when thawed, and put into an atmofphere at 25°, viz. nine degrees warmer, it froze in half the time : this experiment was repeated feveral times with nearly the fame refult. To determine the comparative heat between a living and a dead egg, and alfo to determine whether a living egg b« fubjed to the Same laws with the more imperfed animals, I made the Sollowing experiments : A frefh egg, and one which had been Srozen and thawed, were put into the cold mixture 150 ; the thawed one Soon came down to 32° and began to Swell and congeal; the SreSh one Sunk firft to 290 and a halt, and in twenty-five minutes after the dead one, it rofe to 320, and began to Swell and Sreeze. The reSult of this experiment upon the frelh egg was Similar to what was obServed in the like experiments upon Srogs, eels, Snails, &c. where liSe allowed the heat to be diminished two or three degrees below the freezing point, and refitted all further dccreaSe; but in both the powers oS life were ex- pended by this exertion, and then the parts froze like any other dead animal matter. This is not a principle peculiar to liSe, but is common in many other caSes : it has been obServed that water could be So circumftanced as to be brought below the freezing point, without freezing; but juft as it began to freeze it rofe to 32°. In my experiments on the heat of vegetables, I obferved that the Sap of a tree would freeze at 32°, when taken out of the veffels of the tree ; but I found the trees often fo low as 150, and the fap not frozen. * However, this was at firft not fo certain, but the refult of the experiment proved it w.-.s fo. To be mora certain of kill- ing a part by freezing it, I believe it fliould be froze very flow- lv, Sor Simple freezing docs not kill. S 2 ' 74 General principles of the blood. From theSe experiments, it appears that a freih egg ha» the power of v.-tit'u0 I.-at, cold, and putrcfadion, in a d. .■ree equal to many of the more impcrfe<:t animals, which exlVoit exactly the'Same phceuornuia under the Same ex- pcv.mvnts; ant it is more than probable that this power arif;s from the Same principle ha both. Similar experi- ment have been made on the blocd: after a portion of blood had been frozen and th. n thawed, it Inns again been Srozm with a Similar quantity of nvin blood, drawn from th- fame perSon, and that which had undergone tliis pro- ceSs froze again much fatter than the freSh blood*. As all the experiments I had made upon the freezing of animals, with a view to he whether it was poSfible to re- store the actions of Ufe, when they were again thawed* were made upon whole animals ; and as I never Saw life return by thawing, I wifhed to aScertain how Sar parts were in this reSped, fimilar to the whole, efpecially Since it was alTsrted, and with Some authority, that parts of a man may be Srozen, and may aStcrwards recover ; Sor this purpoSe I made the Sollowing experiments upon an animal of the Same order with ourfelves. In January 1777, I mixed Salt and ice till the cold wa* about o; and on the fide oS the veflH containing them was a hole, through which I introduced the ear oS a rabbit. To carry off the heat as Saft as poSfible, the ear was held be- tween two flat pieces oS iron, that Sunk further into the mixtuic than the ear; the ear remained in the mixture ncariy an hour, in which time the part projeding into the vefiVi became Stiff, when taken out and cut into, did not bleed, and a part being cut off by a pair oS Sciflars, flew from between the blades like a hard chip. It Soon after thawed and began to bleed, and. became very flaccid, (o as to double upon itSelS, having loft its natural elasticity. When it Lad been cut cf the mixture nearly an hour, it became warm, and this warmth increaSed to a confiderable degree ; it alSo began to thicken in conlequencc of inflam- mation ; while the other ear continued oS its uSual temper- ature. On the day Sollowing, the Srozen ear was ltill warm, and it retained its heat and thickneSs Sor many clays after. About a week after this, the mixture in the veflel, being the Same as in the finmer experiment, I introduced both ears of the fame rabbit thrugh tke hole and froze * Vide Corrie on the Vitality cf the Blood rage 45. General principles of the blood. 75 them both ; the found one however froze firft, probably. Srom its being considerably colder at the beginning, and probably too from its powers not being So eafily excited as thoSe of the other : when withdrawn they both Soon thaw- ed and became warm, and the SreSh ear thickened as the other had done before. TheSe changes in the parts do not always So quickly take place, Sor on repeating theSe expe- riments on the ear of another rabbit, till it became as hard as a board, it was longer in thawing than in the former experiment; and much longer before it became warm ; in about two hours, however, it became a little warm, and the following day it was very warm and thickened. In the Spring, 1776, I obServed that the cocks I had in the country had their combs Smooth with an even edge, and not So broad as Sormerly, appearing as iS nearly one half oS them had been cut off. Having enquired into the cauSe of this, myfervant told me,that it had been common in that winter, during the hard Sroft. He obServed, that the combs had become in part dead, and, at laft, had dropt off; and, that the comb oS one cock had dropped off entirely ; this I did not See, as the cock by accident had burnt himSelf to death. I naturally imputed this effed to the combs having been frozen in the time of the Severe Sroft, and having, con- sequently, loft their life by this operation. I endeavour- ed to try the Solidity of this reaSoning by experiment. I attempted to Srecze the comb oS a very large young- cock, (being ef a confiderable breadth) but could only freeze the Serrated edges, (which proceffes were fully half an inch long); for the comb itfelf being very thick and warm refitted the cold. The frozen parts became white and hard ; and when I cut off a little bit it did not bleed, neither did the animal Show any figns of pain. I next in- troduced into the cold mixture one of the cock's wattles, which was very broad and thin ; it froze very readily, and, upon thawing both the frozen parts of the comb and wat- tle they became warm, but were of a purple colour, hav- ing lolt the tranfpareucy which remained in the other parrs oS the comb and in the other wattle : the wound in the comb now bled Sreely : both comb and wattle recovered perfedly in about a month : the natural colour returned firft next to the found parts, and increafed gradually till the whole had acquired a healthy appearance. Finding that freezing both the folids, and the blood, did not deftroy the life in either, nor the future adions depending en or- 7 6 General principles of the blood. ganlzation; and, that It alfo did not prevent the blood from recovering its fluidity, I conceived the liSe of every part of the body to be fimilar : what will affed, thereSore, the liSe oS any one part, will affed alSo that oS another, though probably not in an equal degree ; Sor in theSe ex- periments, the blood was under the Same circumftances with the Solids, and it retained its liSe ; that is to Say, when the Solids and blood were Srozen and aSterwards thawed, they were both capable oS carrying on their Sundions. The Sollowing experiments were made in the Same man- ner on living muScics, to See how Sar the ccntradions of living muScles aft^r having been frozen, correfpond with, the coagulation of the blood. A mufcle was removed from a frog's leg, with a portion of its tendon, was immediately placed between two pieces of lead, and expofed to a cold about ten degrees below>o, In five minutes it was taken out, when it was quite hard and white ; on being gradually thawed it became Shorter and thicker than while Srozen; but on being irritated did not contrad ; yet if at all elongated by force, it contraded again, and the tendinous expanfion covering the muSclc was thrown into wrinkles : when the Stimulus oS death took place, it became ftill Shorter. From a ftraight muScle in a bullock's neck, a portion, three inches in length, was taken out immediately aSter the animal had been knocked down, and was expoSed between two pieces of lead, to a cold below o, for fourteen mi- nutes ; at the end of this time it was found to be frozen ex- ceedingly hard, was become white, and was now only two inches long: it was thawed gradually, and in about Six hours after thawing, it contraded fo as only to meafure one inch in length, but irritation did not produce any fen- fible motion in the fibres. Here then were the juices of muScles Srozen So as to prevent all power oS contradion in their fibres, without destroying their liSe ; for when thaw- ed they Showed the Same life which they had before : this is exadly Similar to the Sreezing of bleed too Sait Sor its coagulation ; which, when thawed, does afterwards co- agulate, as it depends in each on the liSe oS the part not being destroyed. I took notice iff the hiftory oS the coagu- lation of the lymph, that heat of 120^ excited this adion in that fluid : to fee how far mufcular contradict was General principles of the blood. 77 Similar in this reSped, I made the Sollowing experi- ment *. As Soon as the Skin could be removed Srom a Sheep that was newly killed, a Square piece of muScle was cut off, which was aSterwards divided into three pieces, in the diredion oSthe fibres: each piece was put into a baSon of water; the wa- ter in each baton being of different temperatures, viz. oac 1250, about 27 degrees warmer than the animal; another •98°, the heat of the animal; and the third 550, about43 degrees colder than the animal. The mufcle in the water heated to 125°, contraded diredly, fo as to be half an inch Shorter than the other two, and was hard and Stiff. The mufcle in the water heated to 93?; after fix minutes began to contrad and grow Stiff: at the end of twenty minutes it was nearly, though not quite, as Short and hard as the above. The mufcle in the water heated 1055°; after 15 minutes, began to Shorten and grow hard: after 20 minutes it was nearly as Short and as hard as that in the water heated to 980. At the end oS 24 hours they were all found to be of the fame length and ftiffnefs. Here is alSo a Similarity in the excitements oS coagula- tion in the blood, and oS contradion in muScles, both appa- rently depending on the Same principle, namely, lifef. If it Should ftill be difficult to conceive how a body in a fluid ftate, whofe parts are in conftant motion upon one another, always Shifting their fituation with refped to themSelves and the body, and which may loSe a portion without affeding itSelS or the body, can poflibly be alive, let us See iS it is alSo difficult to conceive that a body may be So compounded as to make a perfed whole oS itSelS, having no parts diSfimilar, and having the Same properties in a Small quantity as in a great. Under thoSe circum- ftances, the removing a portion is not taking away a con- ftituent part, upon which the whole depends, or by which it is made a whole, but is only taking away a portion of the whole; the remaining portion being equal in quality to the whole, and in this refped is fimilar to the reducing a whole of any thing. This might be perfedly illuftrated without Straining the imagination, by confidering the opera- * Vide Philof. Tranf. vol 66, page 412. Paper on Drown- ing; alfo, Cbfcrvations on certain Parts of the Animal Eco- nomy. f The application of this principle' in difeafr, I Shall not at prefent take notice of. 78 General principles of the blood. thn of union by the firft intention. Union, by the firft inten- tion, is an immediate fympathetic harmony between di- vided parts, when brought fimply into contad, which I call, contiguous fympathy. In this cafe it is not neceffary that the very fame parts 'Should oppofie each other, efle "harmony, and confequently union, could never take places it is flmpjy neceffary that the two parts be alive, and they might be Shifted Srom one Sort oS a living creature to an- other for ever, without any injury to either, or without ex- citing irritation; and the whole would It ill be as perfe& as ever. Neither can the motion oS one living part upon another affed the body, becauSe all its parts are Similar and in harmony with each other. It is exadly the Same with the "blood, for neither its motion on itfelf, nor its mo- tion on the body, can either affed it, or the body, fincc all the parts are fimilar among them Selves. This is the cafe with all rhatter, where the property dees not depend upon ftrudure, or configuration, but upon the com- 'pound ; for water, is ftfll water, whether its parts are mov- ing on each other, or at lvft : and a Small portion has the fame property with the whole, and is in Sad, a Smaller whole. One of the great proofs that the blood poffclTcs life, depends oh the circumftances afleding its coagulation; and, at prefent, we are only to explain the principles upon which thefe are founded, which it will be in fome degree ncceflary to recapitulate ; but, perhaps, the ftrongeft con- vidion on the mind will arife from the application of this principle to difeafes, efpecially inflammation. While the olood is circulating, it is fubjed to certain laws to which it is hot fubjed when not circulating. It has the power of preferving its fluidity, which was taken notice of when treating of its coagulation ; or, in other words, the living principle in the body has the power of preferving it in this State. This is not produced by motion alone, for in the colder animals, when almoft in a State of death during the winter, when their blood is moving with extreme flowneSs, and would appsar to preServe Simply animal life through the whole body, and keep up that dependence which exifts between the blood, and the body already formed, the blood does not coagulate to accomplish thefe purpofes. If the blood'had not the living principle, it would be, in refpect of the body, as an extraneous fubftance. Blood is not on- ly alive itfelf, but is the Support of life in every part of the body; for mortification immediately follows, whenth- General principles of the blood. 79 circulation is cut off from any part, which is no more than death taking place in the part, from the want of the fuc- peflive changes oS SreSh blood. This Shows, that no part of the body is to be confidered as a complete living Sub- Stance, producing and continuing mere life, without the blood: fo that blood makes one part of the compound; without which life would neither begin nor be continued. This circumftance, on its firft appearance, would feem a little extraordinary, when we confider that a part, or the whole, are completely formed in themfelves, and have their nerves going to them, which are SuppoSed to give animal life ; yet that perfed living part, or whole, Shall die in a little time, by fimply preventing the blood from moving through the veffels : under this idea, it is not clear to me, whether the,blood dies fooner without the body, or the body without the blood. Life, then is preferved by the compound of the two, and an animal is not perfed without the blood : but this alone is not Sufficient, for the blood it- felf muft be kept alive ; becaufe, while it is fupporting life in the folids, it is either lofing its own, or is rendered inca- pable of fupporting that of the body. To accomplish 'all this it muft have motion, and thrt in a circle, as it is a con- tinuance of the fame blood which circulates, in which cir- cle it is in one vieu fuperfaturated, as it were, with living powers, and in another is deficient, having parted with them while it vifited the different parts oS the body. LiSe is in Some degree, in proportion to this motion, either Stronger, or weaker; So that the motion of the blood may be reckoned, in fome degree, a firft moving power; and not only is the blood alive in itfelf, but feems to carry life every where ; however, it is not fimply the motion, but it is that which ariSes out of, or in confequence of the motion. Here then would appear to be three parts, viz. body, blood, and' motion ; which latter preferves the living union be- tween the other too, or the life in both. Thefe three make up a complete body, out of which arifes a principle of felf-motion; a motion totally Spent upon the machine, or which may be Said to move in a circle, Sor the Support of the whole : Sor the body dies without the motion of the blood upon it; and the blood dies without the motion of the body upon it; perhaps, pretty nearly in equal times. So far, I have confidered the blood when compounded with the body and motion, in which we find it preferves its fluidity, and continues life in the body; but fluidity is So General principles of the blood. only neceffary for its motion to convey life, and the contt* nuance of life is, probably, owing to its being coagulated, and becoming a folid ; or at leaft, the Support of the body is owing to this caufe. For this, however, it requires reft, either by extravafation, or by being retained in the veffeli till the utility of circulating is loft ; or till it can anfwer fome good purpofe by its coagulation, as in mortification. Under any of thefe circumftances it becomes a folid body j for the moment it is at reft, it begins to form itfelf into a folid, and changes into this or that particular kind of tub- ftaftce, according to the Stimulus- oS the Surrounding parts which excites this coagulum intoadion, and makes it Sorm within itSelf> blood, veffels, nerves, etc. The coagulation is the firft Step towards its utility in the conftitution, and this arifes from its living principle ; S»r if that principle be destroyed it does not coagulate at all, that is naturally ; Sor I do not here Speak oS any chemical coa- gulation. I Shall now endeavour to prove that the.coagulation of the coagulating lymph bears Some analogy to the adions of muScles, which we know to depend upon liSe ; and which affords one oS the Strongest prooSs oS the existence of this principle: and though the adion oS coagulation itfelf be not fimilar to the adions of mufcles ; yet, if we can Show that they are governed by the fame laws, we may reafona- bly conclude, that the firft principle is the fame in both. When I was treating of the coagulation of the lymph, I took notice that cold did not caufe it, and Supported the o- pinion by feveral experiments ; at the fame time I mention- ed an experiment of Mr. Hewfon, to prove the fame thing, and which he conceived to be conclufive, but which does not appear to me in any way to affed his hypothefis. This* experiment I had often made, but with another view, viz. to illuftrate the living principle of the blood, which to me, it in fome meafure does, more efpecially when compared with fimilar experiments on living mufcles. As the coagulation of the blood is a natural procefs, and as all natural proceffesliave their time of adion, unlets in- , fluenced by fome exciting caufes, and Since cold is not a caufe of the blood's coagulation, even when removed out of the circulation, the blood may be frozen much more quickly than it can coagulate, by which change its coagu- lating power is fufpended. To prove this by experiment, T took a thin leaden veffel, with a flat bottom, of fome General principles of the blood. 81 «ridth, and put it into a cold mixture below o, and allow- -ed as much blood to run from a vein into it, as covered its bottom. The blood froze immediately, and when thawed, became fluid, and coagulated, I believe, as foon as it would have done had it never been frozen. As the coagulation of the blood appears to be that pro- cefs which may be compared with the adion of life in the folids, we Shall examine this property a little Surthcr, and See if this power of coagulation can be destroyed ; iS it can, we Shall next enquire, iS by the Same means liSe is destroyed in theTolids ; and iS the phaenomena are nearly the Same in both. The prevention of coagulation may be effeded by eledricity, and oSten is by lightening : it takes place in Some deaths, and is produced in Some oS the natural operations oS the body; all oS which I Shall now confider. Animals killed by lightening, and alSo by eledricity, have not their muScles contraded: this ariSes Srom death being inftantaneoufly produced in the muScles, which thereSore ■cannot be affeded by any ftimulus, nor consequently by the ftimulus of death. -In fuch cafes the blood does not coagulate. Animals who are run very hard, and killed in fuch a ftate, or what produces ftill a greater effed, are run to death, have neither their mufcles contraded, nor their blood coagulated ; and in both refpeds the effed is in pro- portion to the cauSe*. I had two deer run, till they dropped down and died ; in neither did I find the muScles contraded, nor the blood coagulated. In many kinds oS death, we find that the muScles nei- ther contrad, nor the blood coagulate. In Some caSes the muScles will contrad while the blood continues fluid, in Some the contrary happens; and in others the blood will ■only coagulate to the confiftenee of cream. Blows on the ftomach kill immediately, and the muScles do not contrad, nor does the blood coagulate. Such deaths as prevent the contradion oS the muScles, or the coagula- tion of the blood, are, I believe, always fudden. Death from fudden gufts of paflion, is of this kind; and in all thefe cafes the body foon putrifies after death. In many difeafes, if accurately attended to, we find this correspon- dence between muScles and blood ; Sor where there i3 * This is the reafon why hunted animals are commonly more ender than thofe that are Shot. T 2 • 82 General principles of the blood. Strong adion going on, the mufcles contrad Strongly after death, and the blood coagulates Strongly. ' It is unneceffary, I imagine, to relate particular inftances oS the effeds oS each of thofe caufes : I need only mentiorl that I have feen them all. In a natural evacuation of blood, viz. menftruation, it is neither fimilar to blood taken from a vein of the fame perfon, nor to that which is extravafa. ted by an accident in any other part of the body ; but is a fpecies of blood, changed, feparated, or thrown off from the common mafs, by an adion of the veffels of the uterus, fimilar to that of fecretion ; by which adion the blood lofea the principle of coagulation, and I fuppofe life. The natural dedudion from all thefe fads, and obser- vations, I think is perfedly eafy ; it is impoffible to mifsit. This living principle in the blood, which I have endea-i voured to Show to be Similar in its effeds to the living prin- ciple in the Solids, owes its existence to the Same matter which belongs to the other, and is the materia vitse dif- fufa, of which every part of an animal has its portion*: it is, as it were, diftufed through the whole folids and flu- ids, making a neceffary conftituent part of them,- and for- ming with them a perSed whole ; giving to both the power of prefervation, the fufceptibility of impreflion ; and, from their conftrudion, giving them conSequent reciprocal ac- tion. This is the matter which principally compoSes the brain; and where there is a brain, there muft neceffarily be parts to conned it with the reft oS the body, which are the nerves; and as the uSe oS the nerves is to continuej and thereSore convey the impreflion or adion oS the one to the other, theSe parts oS communication muft neceffarily be oS the Same matter; Sor any other matter could not con- tinue the Same adion. From this it may be understood, that nothing material is conveyed from the brain, by the nerves ; nor vice verSa, from the body to the brain : for if that was exadly the cafe, it would not be neceffary for the nerves to be of the * I consider that Something fimilar to the materials of the brain is diftufed throvigh the body, and even contained in the blood ; between this and the brain a communication is kept up by rhe nerves ; I have, therefore, adopted terms explanatory of this theory ; calling the brain, the materia vit* coa'cervata ; the nerves, the chords internuncije ; an J that diffalcd through the body, t'.^e mcteria v'.t .• difiiffa. General principles of the blood. 83 fame materials with the brain; but as we find the nerves of the fame materials, it is a prefumptive proof, that they Only continue the fame adion which they receive at either end. The blood has as much the materia vitse as the folids, which keeps up that harmony between them ; and as every part endued with this principle has a Sympathetic affedion upon fimple contad, So as to affed each other, (which I have called contiguous Sympathy) So the blood, and the bo- dy, are capable oS afleding, and being affeded, by each other; which accounts for that reciprocal influence which each has on the other. The blood being evidently compoS- ed of the fame materials with the body, being endued with the fame living powers, but from its unfettled ftate, having no communication with the brain, is one of the Strongeft proofs of the materia vitae making part of the compofition of the body, independent of the nerves; and is fimilar, in this refped, to thofe inferior order of animals that have no nerves, where every other principle of the animal is diffuf- ed through the whole. This opinion cannot be proved by experiment; but I think daily experience Shows us, that the living principle in the body ads exadly upon the Same principle with the brain. Every part oS the body is fuf- ceptible of impreflion ; and the materia vitx, of every part, is thrown into adion; which, if continued to the brain, produces fenfation ; but it may only be Such as to throw the part oS impreflion into Such adions as it is capable oS, according to the kind oS impreffion; So does the brain or mind. The body loSes impreffion by habit; So does the brain ; it continues adion Srom habit; So does the brain. The body, or parts of the body, have a recolledion oS Sor- mer impreflions, when impreffed anew ; fo has the brain ; but they have not fpontaneous memory as the brain has, becaufe the brain is a complete whole of itfelf, -and there- fore its adions are complete in themfelves. The materia vitse of the body being diffufed, makes part of the body in which it exifts and ads for this part, probably for this part alone. The whole, taken together, hardly makes a whole, fo as to conftitute what might be called an organ ; the ac- tion of which is always for fome other purpofe than itfelf: but this is not the cafe with the brain. The brain is a mafs of this matter, not diffufed through any thing, for the pur- pofe of that thing, but conftituting an organ in itfelf, the adions of which are for oth^r purpoSes, viz. receiving, by . 84 General principles of the blood. means of the nerves, the vaft variety of adions in the dif, fufed materia vita:, which arife from impreffion, and ha- bit, combining theSe and diftinguifhing from what part they come. The whole of thqfe adions form the mindj and, according to the refult, imprefs more or leSs of the materia vitx of the body in return, producing in Such parts conSequcnt adions. The brain then depends upon the bor dy Sor its impreffion, which is SenSation; and the confc- quent adion is that of the mind : and the body depends up- on the confequence of this intelligence, or effed of this mind, called the will, to imprefs it to adion ; but Such are not Spent upon itfelS, but are Sor other purpoSes, and are called voluntary. But mere compofition of matter does not give life; for the dead body has all the compofition it ever had: life is a property we do not understand : we can only fee the ne- ceffary leading Steps towards it. If nerves, either of themfelves, or from their connec- tion with the brain, gave vitality to our folids, how Should a folid continue life, after a nerve is destroyed ? or Still more, when paralytic ? for the part continues to be notir rilhed, although not to the full health of voluntary adion; and this nourishment is the blood; for deprive it of the blood, and it mortifies. The uterus, in the time of pregnancy, increafes in fub- ftance and Size, probably fifty times beyond what it natu- rally ij> and this increafe is made up of living animal mat- ter, which is capable of adion within itfelf. I think we may fuppoSe its adion more than double ; for the adion of every individual part of this viScus, as this period, is much increaSed, even beyond its increaSe of fize; and yet we find that the nerves of this part, are not in the fmalleft de- gree increafed. This Shews that the nerves, and brain, have nothuag to do with the adions of a part: while the veffels, whofe ufes are evident, increafe in proportion to the increafed fize: if the fame had taken place with the nerves, we Should have reaSoned Srom analogy. It is pro- bably impoflible to Say where the living principle firft begins in the blood : whether in the chyle itSeiS, or not till that fluid mixes with the other blood, and receives its influence from the lungs. I am, however, rather inclined to think, that the chyle is itfelS alive ; Sor we find it coagulates when extravafated ; it has the fame powers of feparation with the blood; and it acquires its power of a^fcioii in ths Genera! principles of the blood. *S lungs as the venal blood does. I conceive this to be fimi-' lar to the influence of the male and female on an eggr which requires air, and a due warmth, to produce the prin- ciple of adion in it; and is fomewhat fimilar to the venal blood coming to the lungs to receive new powers, which it communicates to the body. To endeavour to prove whether the chyle had the power of adion in it, Similar to the blood, I made the following experiment: I opened the abdomen of a dog, and pundured one of the largeft ladeals at the root of the mefentery, ^out of which flowed a good deal of chyle : I then allowed this part to come in contad with another part of the mefentery, to fee if they would unite, as extravafated blood does; but they did not; however, this experiment, though perform- ed twice, is not conclufive; for fimilar experiments with blood might not have Succeeded. From what has been Said with regard to the blood, that it becomes a Solid, when extravaSated in the body, we muft SuppoSe that Some material purpoSe is anSwered by it; for if the blood could only have been of ufe in a fluid ftate, its Solidity would not have been fo much an objed with nature. It appears to me to be evident that its fluidity is only intend- ed for its motion; and its motion is only to convey life, and living materials, to every part of the body. Thefe materials when carried, become folid ; fo that folidity is the ultimate end of the blood, as blood. The blood when it naturally increafes the body, or re- pairs a part, may be faid to be extravafated, although not commonly fo confidered; what is ufually understood to be extravafation, is when it ariSes Srom accident oS Some kind,, or diSeaSe in the veflel, and of courfe is obvious to the fight; but even this extravafation is of ufe by the blood co- agulating, although too often it is in too large a quantity. Accident does not calculate the, fize of the veflel ruptured* to be juft equal to the effed wanted by the rupture: but nature has made a wife provision Sor this overplus. As extravaSation ariSes from a rupture of the veffel, it is of fervice in the reunion of that veffel: if there are more folids ruptured than a veffel, as in a Sradure oS a bone, it becomes a bond oS union to thoSe parts; and this may be called, union by the firft intention: but the union is not that of" the two parts to each other, but the union oS the Woken parts to the intermediate extravaSated blood ; So that 83 General principles of the bloodl it is the blood and parts uniting, which constitutes the'unioft by the firft intention. This blood, So extravaSated, Sorms either veflels in itfelf, or veffels Shoot out from the original furface of contad in- to it, forming an elongation of themfelves, as we have rea- fon to fuppofe they do in granulations. I have reafon, how. ever, to bdieve that the coagulum has the power, under neceffary circumftances, to form veffels in, and of itfelf- for I have already obferved, „ that coagulation, although not organic, is ftill of a peculiar form, ftrudure, or arrange- ment, So as to take on neceffary adion, which I Should Sup- poSe is Somewhat Similar to muScular adion. I think I have been able to injed what I SuSpeded to.be the beginning of a vaScular Sormation in a coagulum, when it could not de- rive any veffels Srom the Surrounding parts. By injecting the crural artery of a Stump, above the knee, where there was a fmall piramidal coagulum, I have filled this coagulum with my injection, as if it had been cellular ; but there was no regular ftrudure of veffels. When I compare this ap- pearance, with that of many violent inflammations.on fur- faces where the red blood is extrLvafated, Sorming as it were Specks of extravafation like Stars; and which, when injeded, produce the fame appearance with what I have defcribed in the injedion of the coagulum.: when 1 com- pare thefe again with the progrefs oS vaScularity in the mem- branes oS the chick, one can perceive where a zone of Specks beyond the SurSace oS regular veflels cloSe to the chick, Similar to the above extravaSation, and which in a Sew hours become vaScular, I conceive that theSe parts have a power oS Sorming veffels within themSelves, all oS them ading upon the Same principle. But where this coagulum can Sorm an immediate union with the Surrounding parts, * it cither receives veffels at this SurSace, or Sorms veffels firft at this union, which communicate with thoSe oS the Sur- rounding Surface ; and they either Shoot deeper, and deeper,' or Sorm veffels deeper, and deeper, in the coagulum, till the whole meets in its centre: iS it is by the firft mode, viz. the Shooting oS veffels Srom the Surrounding Surfaces' into the coagulum, then it may be the "ruptured veffels in caSes oS accident, which Shoot into the coagulum, and where a coagulum, or extravaSation oS coagulable lymph is thrown in between two Surfaces only contiguous, there it may be the exhaling veflels of thofe Surfaces which now be- come the veffels of the part. In whatever way they meet General principles of the blood. 8 y irl the centre, they inftantly embrace, unite, or inefculate : now this is all perfedly, and eafily conceived, among living parts, but not otherwife. > : As the coagulum, whether wholly blood, or coagulating lymph alone, has the materia vitae in its compofition, which is the caufe of all the above adions, it foon opens a com- munication with the mind,, forming within itfelf, nerves. Nerves have not the power of forming themfelves into long- er chords., as we. conceive veflels to have; for we know, that m the union of a cut nerve,, where a piece has been taken oat, it is by means of the blood forming a union of coagulum; and, that the coaguluin gradually becomes more and more of the texture, and has, of courfe, more and more the ufe of a nerve,. Somewhat fimilar to the gra- dual change of blood into a bone, in fradures. It would appear then, that the blood is fubfervient to two purpoles in an animal: the one is the fupport of the matter of the body when formed ; the other is the fupport of the different adions of the body. VII. SOME UNCONNECTED EXPERIMENTS RES- PECTING THE BLOOD. The following experiments have rather been imagined $han fully executed, and the fubject is rather broached and touched upon than profecuted ; but as I have not time, at prefent, to go through with the experiment's, fo as to arrive at fome general refult, I thought it better to bring forward, what, in my opinion, Should be done, than to omit the fub- jed altogether*. I wilhed to fee if blood that coagulated with an inflam- matory cruft putrified later than that which coagulated with- out it; for I conceived that the ftrength of coagulation was fomething Similar to the ftrength oS contradion in a muS- * Many of thefe experiments w-?re repeated, by my defire, by Dr. Phyfic. now of r hiladelphia, when he adred as houfe- fur fions, and the fimple blood, all coagulated at the fame time, viz. in fix minutes; but that whfch had been mixed with the infufion of gentian was firmer than with the infu- fion of cohimba-root, but was not more firm than the coa- gulum of. the fimple blood.. The blood which had been mixed with the folution of opium did not coagulate for twelve minutes, and then the coagulum was very loofe. This experiment, with the opium, was repeated, and the refult was etfadly the fame. , Of extraneous matter in the blood. "Whatever is diffolved in the blood muft be only diffufed through it, not chemically combined with it, otherwife the nature of the blood itfelf would be altered, and the effect of medicine destroyed. The blood can receive and retain extraneous matter, capable of destroying the Solids, by Sti- mulating to adion So as to deftroy them. Extraneous matter in the blood is capable oS altering the chemical properties oS the Solids, in thoSe who work in lead, as is evident in the Sollowing caSe : Morgan, a houSe-painter, who had been paralytic in his hands and legs Sor a confiderable time, was thrown down, and had his thigh-bone broken juft below the little trochan- ter. The upper end oS the inSerior portion had paffed o- ver the outfide oS the other, and moved with the knee, So that the end of the lower bone was taken for the great .trochanter; but I difcovcred the fradure, by extending the General principles of the blood. 9§ leg, and got the portions of bone in their places, and bound up the limb with a wroller. It went on well for near a fortnight, only his hands Swelling at times, which gave way to fomentations ; in the third week he grew very ill, be- came low, had a kind of lethargy, a great deal of blood came out of his mouth, he funk ftill lower, and died about three weeks after the accident. On examining the body after death, the mufcle*, parti- cularly thofe of the arms, had loft their natural colour; but inftead of being ligamentous and femitranfparent, as happens in common paralyfis, they were" opaque, refem- bling exadly, is appearance, parts fteeped in a folution of Goulard's extrad. From this cafe it appears the lead had been evidently carried along with the blood, even into feh# mufcle* themfelve*. E 94 ] CHAPTER II. tF THE VASCULAR STSTEM* I. GENERAL OBSERVATIONS ON MUSCULA^ CONTRACTION AND ELASTICITY. IT is not my prefent intention to explain all the circum- ftances conneded with mufcular contradion and relax- ation, nor that other power of adion introduced into an animal body, called elasticity. I propofe only to ftate a Sew oS the Sads which throw Some light upon the vaScular fyS- tem, by Shewing that there is in veffels a power of muScular adion ; and that the co-operation oS elafticity is alSo necef- fary to their fundion; thefe may likewife affift in ex- plaining the manner in which the two powers are. combin- ed ; I may, however, occafionally be led to mention cauSes and effeds, which cannot be immediately confidered as ap- plicable to the veffels themSelves, though they will render many of the phenomena in the vafcular fyStem more eaSy to be understood. The common adion oS a muScle, Srom which its im- mediate uSe is derived, is its contradion; and the effect produced by it, is that oS bringing the origin and inSertion,' or the parts which it is fitted, to move nearer each other*; which is univerSally the caSe whether the muScle is Straight, hollow, or circular. It is likewiSe neceffary that a muScle Sliould relax, or be capable oS relaxation ; a condition which allows it to be ftretched, by permitting the parts aded upon to recede Srom each other. MuScles, in common, proba- bly, with every other part oS the body, have a power of * I do not here confider the circumflex tendons ; Sor, by the origin and infection, I mean the mufcular ends of the fibres. Of the vafcular fyflcmi 9S adapting themfelves to the neceffary "diftance between ori- gin and inSertion, in caSe an alteration has taken place in the natural diftance ; and I have reaSon to believe, that un- der certain circumftances, they have a power oS becoming longer, almoft immediately, than they are in the natural relaxed, or even the natural elongated ftate of their fibres-. This opinion will be beft illuftrated in inflammation. Mufcular contradion has been generally fuppofed to arife from fome impreflion, which is commonly called, a ftimu- lus ; I doubt, however, of an impreflion being alWays ne- ceffary ; and I believe that in many eafes the ceffation of an accuftomed impulfe may become the caufe of contrac- tion in a mufcle. The fphinder iridis of the eye contrads when there is t«o much light; but the radii contrad when there is little or no light. I can even conceive that a ceffation of adion requires its ftimulus to produce it, which may be called, the ftimulus of ceffation; for relaxation is not the Slate into which a mufcle will naturally fall upon the removal of a continued ftimulus ; a mufcle remaining contraded after abfolute death, when the Stimulus of re- laxation cannot be applied; fo that a mufcle can as little relax after death, as it can contrad. If a Stone is raifijd, and the raifing power removed, it falls; but it would not fall if not aded upon. When it has fallen it lies at reft, but fo it would have done, when raifed, if gravitation would have allowed it. The Stone is paflive and muft be aded upon. Whatever becomes a ftimulus to one Set of muScles, becomes a cauSe oS relaxation to thoSe which ad in a contrary diredion* ; and whatever becomes a ftimulus to one part oS a muScular canal, where a Succeflion oS ac- tions is to take place, becomes alSo a cauSe of relaxation in the part beyond it, as in an inteftine. Mufcular contradion^ in fome of the involuntary muf- cles, ' does not constantly arife from immediate Stimuli, as in the fphinders ; for the fphinder ani contrads whenever the ftimulus of relaxation is removed, which may be faid to produce the ftimulus for contradion. Mufcular adions have been divided into the voluntary, involuntary, and mixed, which is only dividing them ac- * This might be called a Sympathetic ftimulus, and is that which regulates the actions of the whole machine ; and which I have called, in another place the ftimulus of neceflity. 96 Of the vafcular fflem. cording to the different natural modes of Stimuli, or caufes: oS their adion : to theSe a Sourth might be added, where the adions are in conSequence of accidental Stimuli or im« preflions, to which both the voluntary and involuntary muf. cles are fubjed, viz. fuch as arife from affedions of the mind*, or are the immediate effeds of violence. The involuntary contradion Should be firft confidered, 33 the more neceffary operations of the machine are carried on by it; for the machine could even exift independent of any voluntary contradion ; but it could not go on if left wholly to the voluntary contradion oS the muScles, unlefs we were endued with innate ideas capable oS producing a will. This involuntary contradion is very extenfive in the Syftem, and is employed in carrying on a number oS ope- rations, oS which the circulation is one; and which may Said to be, in a great meaSure, the ceconomy of the animal within itfelf. The mixed kind of contradion is moft to our prefent purpofe, and is of two kinds, though it has been in gene- ral fuppofed to be of one kind only, and that belonging ■ folely to the muScles of refpiration, as being in them the . moft confpicuous. But in fad, we find another mode of involuntary adions in other mufcles of the body where it anfwers very uSeSul purpoSes. In theSe the involuntary contradion may be reckoned the natural ftate ; and it is a' kind oS permanent contradion, theSe muScles only relax- ing occafionally; by which means parts are SuStained or Supported ; the voluntary contradion oS Such muScles is alSo only occasional. All Sphinder muScles in Some degree partake oS this power, and thereSore Should be called, muf- cles with power oS occafional relaxation. For although many circular muScles may not have theSe mixed contrac- tion •;, as the orbicularis palpebrarum ; yet that muScle has a difpofition to contrad peculiar to itfelf. Its relaxation is to be reckoned of the adive kind, which may be called, the relaxation of watchfulnefs, and it is when tired oS this Species oS adion that it contrads; which, on the contrary, may be called, the contradion oS Sleep : or it may be con- fidered as an elongator muScle to the levator palpebral, with a diSpofition to remain relaxed while that muScle is contrac- ted ; but contrading when the elevator is tired. The na- * Mind and Will are oSten blended together; but Will hat nothing to do here. Of the vafcular fsflem* 97 ifetiral contradion of the orbicularis mufcle is involuntary ; {the relaxation, both natural and occafional is involuntary; .but it has likewife a voluntary contradion and relaxation, yvhich can be made to exceed the involuntary, refembling what is inherent in all the fphinders. Sphinder mufcles, as thofe of the anus and urethra, and probably the expulfatores, Seminis, and crura of the dia- phragm, have both a voluntary and involuntary contrac- tion. In the two Sphinders of the anus and urethra this is evident; and the involuntary contradion in theSe muS- cles I have called, Sphindoric. The Sphinder ani poffeffes it to a degree juft Sufficient to refift the preffure oS the air and Sceces, while the parts above are inadive, prevent- ing the eScape of thefe, till they give the ftimulus for ex- pulfion, and then an involuntary relaxation naturally takes place, fimilar to what happens in mufcular canals. The fphindoric contradion refembles, in its effeds, that produced by elaftic ligaments in other parts of the body, which adion may be called, contradile elasticity, as bring- ing back the parts to a certain neceffary ftate, and retain- ing them there. But elasticity would not here have anSwcr- ed all the purpoSes, Since, as it has no relaxing power, more Sorce would have been required to overcome its refiStence in the expulfion oS the Sceces than the gut above could have been able to exert. But the Sustaining power being muS- cular contradion, a relaxation or ceflation cf that contrac- tion during the time of expulfion, leaves nothing Sor the Sceces to do; but, by means of the adion above, fimply to dilate the relaxed parts. There is, likewiSe, in thelo muScles, a ftill Surther power oS contradion, which is pro- duced by the will, and for the purpoSe oS giving on parti- cular occafions greater Sorce than what is commonly neceS- iary. The voluntary adion oS theSe muScles is, thereSore, we find more powerful than the involuntary ; but upon the whole I think we have reaSon to SuppoSe, that the invo- luntary muScles are much Stronger than the voluntary. Can we believe that So thin a muScle as the colon of a horfe could Squeeze out its contents, confiftin^ of a column of dung about eight inches diameter, if thofe involuntary muScles had no more ftrength than the muScles oS an extremity ? When we See the bladder of urine throwing out its con- tents through a large tube, to a distance perhaps two yards beyond its extreme end, we muft fuppofe a much greater 58 Of the vafcular fjflem. force exerted than could belong to any Such quantity of vo: luntary muScle. For I believe that by graSping the bladder with both hands we could not make the water flow out to an equal diftance. It may be here obServed, that the power of involuntary contradion commonly remains longer than that of the voluntary, though I believe not in all inftances; which difference produces a greater variety in the former, than in the latter. Thus the mufcular action of the arte- ries is longer retained than that of the heart. Elasticity is a property of matter (whether animal or not) which renders it capable of restoring itfelf toits natural po- fition, after having been aded upon by fome mechanical power, but having no power of adion arifing out of itfelf; this is exadly the reverfe of mufcular contradion. MuS- cles, as has been already obServed, have the power of con- tradion and of ceffation, which laft is called, relaxation; but not the power of elongation, which would be an act of restoration, fuch as exifts in elasticity. A muScle, thereSore, has the power of action within itSelS, by which it produces its effects, but is obliged to other powers for its restoration, So as to be able to act again ; whereas elas- ticity is obliged to other powers to alter the pofition of the parts, fo as to require recovery or restoration ; but this it is capable of doing itfelf, and by this power it produces its effects, becoming a caufe of motion in other bodies. A body poffeffed of this property, when brought from the ftate of reft, is always endeavouring to arrive at this State, which it alfo endeavours to preferve ; and it is capable of fupporting itfelf in this ftate in proportion to the degree of elasticity which may belong to it. The action of elasticity is continual, and its immediate effects are produced whenever the refiftance is removed; by which it may be distinguished Srom other powers. Elaftic matter can neither be extended beyond its 'State of reft, or brought within it. Thus a fpring being bent, its concave fide is brought within this State, and the convex fide is car- ried beyond it: when under theSe circumftances it is leStto itSelS, both fides endeavour to reftore themSelves. The power of an elaftic body is permanent, always acting with a force proportioned to the power applied, and therefore reacts as the body is elongated, bent, or compreffed; but this is very different from the action of a mufcle, as this laft may act with its full force, cr only part, or not at all, Of the vafcular fyfem. 99 according to circumftances. Elafticity*, which has the power of refifting the adion of other parts, as well as of 'reftoring the fubftance endowed with it, when forcibly re- moved from a ftate of reft, is introduced into an animal body, in order to co-operate in many refpeds with the mufcles, and fo to ad as to reftore or fit them for a new adion, becoming in many cafes antagonists to the mufcles, which will be deScribed when we fpeak of the combination of the two. H. GENERAL OBSERVATIONS ON THE ELON- GATION OF RELAXED MUSCLES. Every thing in nature that has the power of adion has two kinds of motion exerted alternately, and a ftate of reft. Of the former the one may be called, the adive ; the o- ther, the ftate of recovery. In a mufcle the adive is the ftate of contradion ; the other, the ftate of relaxation : the ftate of reft is merely the ftate of inadion. The con- tradile ftate of a mufcle, as well as the relaxed, arifes from a power inherent in itfelf: but the recovery, or elongation, muft depend on fome other power. Simple relaxation of a contraded mufcle is not Sufficient to enable it to produce another requisite effed ; it is, there- fore, neceffary that there Should be an elongator equal to the quantity of contradion intended to be produced : and as no muScle has the power oS extending itfelf into what I Shall call, the ftate of recovery, an elongater of fome kind or other is required, to enable every mufcle to produce its effed, by a renewal of contradion. This, although in fome re- fpeds fimilar to the winding up of a clock, in others differs * It is to be obferved, that elaflicity in animals does not, like mufcular contraction, depend on life ; an elaftic body pofitffing that quality as perfectly after death as before. Elafticity ad- mits of two actions, a contraction, when the fubftance is ex- fended beyond the natural ftate, and an extenfion, when it !s convrefled within it; both theSe is poflefled by the elaftic parts which compote the vafcular fyftem ; whereas, mufcles have but one action, or, at leaft, but one which can produce an immedi- ate effect, and that is contraction. *00 Of the vafcular fyjlem. materially from it. For the mufcle being capable of relax: ing itfelf, there is no refiftence to overeome, except the vis inertiae and fridion of the matter to be removed ; whereas in the clock, the power that winds it up muft be greater than the fpring or weight, to be capable of overcoming rhe gravity of the weight, or the elafticity of the fpring, together with the vis inertiae. The elongation of mufcles is not the immediate cauSe of their relaxation, but the effed of a contrary and necef- fary motion of the eiongaters, by which they are recovered fo as to be enabled to renew their adion with effed. The eiongaters, or powers which enable mufcles to reco- ver themfelves, are not always mufcular; for when fimple elongation is required, is is effeded by other means, as e- lafticity, which is the caSe, in part, in the blood-veffels; and Sometimes by motion in matter foreign to the body, yet propelled either by muScles or elafticity, as is alSo the caSe, in blood-veffels. The eiongaters may be divided into three kinds, with their compounds. The firft kind is muScular, and theSe may either ad im- mediately, or they may ad on Some other Subftance, by which adion that Subftance becomes the immediate caufe of the elongation. ThoSe which ad immediately, and be- come eiongaters to other muScles by their contraction are in turn elongated by the contraction of thefe very muScles, to which they Served as eiongaters ; the two Sets thus be- coming reciprocally eiongaters to each other. This is the caSe with the greater part of the mufcles in the body, and in fome mufcles, as the occipito, Srontalis, two different portions are reciprocally eiongaters; yet theSe may ftrictly be confidered as two muScles ; Sor although there is no in- terruption, in the tendon they move the Same part in two onpoiite directions, like diftinet antagonilt muSdes. TheSe reciprocal eiongaters, by their mutual action on each other, bring out a middle ftate between the extremes of contraction and elongation, which is the ftate of eafe, or tone, in both. This appears not to be So much required Sor Cne eafe of the relaxed muScle, as Sor that of the pent moved ; either extreme of motion leaving the mufcle in an une.:Sy ftate. Wc find, therefore, that as Soon as any Set of muScles ccafe to act, the eiongaters which were ftretched during their action, are Stimulated either by this ceffation, cr by the uneaSy !t..te into which the parts moved have been put, they act to brkuj th.^to paris into a ftatj the furthjft rz~ Of the vafcular fyjlem. loi moved from the extremes which were uneafy, and by which the ftimulus arifing from both is equally balanced. This, however, can only happen in fuch parts of the bo- dy as are furnilhed with mufcular eiongaters; where thefe are wanting, the mufcles of the part having but one office, their ftate of eafe is that of fimple relaxation, as they can have no middle ftate from the action of antagonists, but Such are eommoniy muScular parts, or.fo constructed as not to be thrown into an UneaSy pofition by the action oS their muScles. I SuppoSe, however, that an elongated State in a muScle is an uneaSy State; a muScle, thereSore, that is Stretched, although in a relaxed State, is uneaSy and will contract a certain length, to what is probably the middle State. It is Still neceffary that Such parts as are fimply muScular, and having no antagonist muScles appropriated immediate- ly Sor Such purpoSes Should have their muScles elongated : this is Still perSormed by muScles, but in a Secondary way ; Sor inftanee, by a Succeffion oS actions in different parts, each perSorming the Same effect, the laSt action becoming an antagonist to the Succeeding. The Second mode oS elongation takes place in all the muScles which afffft in Sorming canals. In them the muf- cles, if once contracted, cannot be elongated, or the part dilated again ; but by the contraction of fome other part of the canal, propelling its contents into the relaxed part, and by that means ferving as an elongater. This, in fome in- stances, goes on in regular Succeffion, as we know the di- latation of the Sauces to be occafioned by the action oS the mouth and tongue ; that oS the ceSophagus, by the con- traction oS the Sauces; oS the Stomach, by that oS the ceSophagus ; the upper part of the inteftines by the ftomach, and fo on; the fucceffive contractions of the laft dilated parts pufhing on the contents, and in that manner becom- ing eiongaters of the mufcles next in fucceflion of action. Afirft propelling power, fuch as a heart, could in thefe in- stances have had but little effect, and would even have been unneceflary; Sor as there muSt be a Succeflion of contrac- tions and dilatations, its power would foon have been loft. This mode of propelling fubftances through canals, as Sta- ted above, would probably have been too flow for the circu- lation in many animals; but I believe is very much the cafe in others. roV Of the vafcular fyjlem. The elongation of the mufcles of the bladder, from the distention of urine, becomes the means by which they aire excited to recover themfelves fo as to renew their adion, and may be referred to the fame general-head. The third kind is by means of elaftic fubftances: which render the combined adions produced by mufcular contrac- tion and elafticity more complicated. Elafticity we find to be introduced both as an afliftant to the contradion of the mufcles, and as an antagonist or elongater ;' the natural po- fition being that which is produced by the elafticity.. Thus we See elafticity combined with muScular adion aflifting in the contradion oS muScles on one fide, and likewiSe per- forming the office of dongaters Or antagonists on the oppo- fite, by bringing parts, which have been moved by mufcles, back into their natural pofitiori. Such parts tod as have yielded to the action of fome other power, as gravitation, are brought back into what maybe called, a natural State, and are retained there by elafticity, till that power is again overcome by another, as in the necks of Some animals. We may hence See that the application oS thoSe powers is twoSold ; one, where the muScles and elaftic Substances aS- fift each other ; the Second, where they are antagonists, the elaftic being neither affifted by the mufcular parts, nor the mufcular by the elaftic : for many parts of the body are fo constructed, as to admit of but one kind of mufcular ac- tion, the other action arifing from elafticity alone -, it being? neceffary that Such parts Should have a determined or middle" ftate, though not intended as a State of eafe. Of this kind are the blood-veffels, trachea, bronchia, the ears of animals, ete. in'which therefore elafticity is intro-' duced to procure that determined ftate, and is chiefly em- ployed where the middle ftate is much limited. For it is to be obferved, that the middle ftate, when produced by mufcu- lar action, has not commonly a determined point of reft, but admits of confiderable latitude between the two ex- tremes ; except in the fphincters. Where it is produced by elafticity, it is always more determined, provided the elaf- ticity has fuflicient power to overcome the natural or acci- dental refiftance ; and where that is the caSe,' we muft Sup- poSe that a State in Some degree determined was neceflary to Such parts. But where the elaftic power is not Sufficient to overcome the natural, or accidental refiftance, then it is affifted by the mufcular, which forms one ofthe compounds Of the vafcular fyjlem. 103 cf the three modes of elongation ; inftances of which we have .in many joints. 'She relaxed ftate of a mufcle would appear in general to be the moft natural; but to this there are exceptions ; a de- gree of contradion appearing natural to fome mufcles. The face, for inftanee, is a part where the adion of the mufcles on one fide influences the pofition of the parts on the other fide ; a circumftance, perhaps, peculiar to the face; here, therefore, the mufcles bring and keep the fkin in one pofition, till altered by an increaSed adion in Some other muScle ; and when this increaSed adion ceaSes, the conftant and natural contradion oSthe whole (fimilar to that oS the Sphinder) immediately takes place *. Sphinder muScles are the moit remarkable inftances of this, being always above three parts contraded f. • The conftant and regular degree of contradion in thofe fphinder mufcles, Serves the purpofes of elafticity, and may have Superior advantages ; . as we know that they have a power oS relaxing when their eiongaters ad, which no elaftic Subftance can have. Hence, we See, that where a continued adion only is wanted, there is elafticity : whee an alternate action and relaxation, there is the action of rriufcles ; where only an occafional relaxing power is re- quired, there are muScles under under certain restrictions ; and where a conftant power oS contraction is neceffary, but which is occafionally to be overcome by muScles, there are introduced both elafticity and muScular powers co-operat- ing with each other in their actions. Where conftant action is not neceffary, muScles alone are employed, as in the greater number of moving parts in moft animals ; and where any pofition is required to be eonStant, and the motion only occafional, Srom being Seldom wanted, their elaSticity alone is employed Sor the purpoSe * As a proof that this is mufcular contraction, and not elaf- ticity. we find that the face in a dead body does not keep its natural form, nor refume it when loft. \ The parts Supplied with fphincters, do not contract after being dilated in the dead body, which they certainly would do if the contraction in the living body had arifen from elafti. eity. Y !04 Ofthe vafcular fy/te/n. of conStant pofition, and muScles Sor the occafional' ac- tion*. When a pofition is to be pretty conftant yet elaftic Sub.' Stances are not employed, we have muScles endowed with the power oS conStant contraction to a certain degree, but capable oS either relaxation, or a greater contraction, as in the Sphincters. We find, thereSore, that in many parts oS an animal body fitted Sor motion, a tolerably conStant pofition is neceffary at the Same time that an occafional Self-moving power is a|! So wanted, to Serve as a Sort oS auxiliary to the performance oS the neceffary action. For fuch occafional actions, muf. clcs, affifted by elaftic Substances, are employed ; the elaftic power eafing the muScles in the fixed pofition, and the muScular giving the increaSed occafional action ; and in o. ther parts ofthe boc;, where a more conftant adion was wanted, and could not be completely obtained by elaStici- ty, there are to. be found mufcles endowed with the pro- perry of both permanent and occafional contradion. The elaftic power is very remarkable in fuch parts of an animal body as require a conftant effort to fupport them elasticity-being introduced to ad againft the power of m- vitation, as in the necks of animals whofe heads are held horizontally, or beyond the centre oS gravity. This is ef- fected by an elaftic ligament, and-is Strikingly illuftrated in the camel, whofe- neck: is long. Between the vertebra oi the neck and backs oS fowls, are placed elaftic ligaments- for the fame purpofe ; the wings of birds and hats are alfo Surnnhed with them, by which means they are retained clofe to the body when not ufed in flying. On the abdo- men of moft quadrupeds are likewhe to be Sound elaftic ligaments, eSpecially on that oS the elephant, which is a conftant Support to the parts in their horizontal pofition, and even the cellular membrane of the elephant has a de- gree of elasticity much above what is generally met with in cellular membranes. Hence there is lefs expence of mufcu- * fome bibalves (as the oyfter) hive a ftrone mufcle naffin* betwee, the fiiells for clofing them occafionallyf bu forop^ delate1"!-: ,nUfde- "? "^ UfC °f' aS this« perfoledPby foue z d fe^ T^ I0'"' °f thC tW° ^ which » Shen t'Z M r * the conrra^" of the mufcle; and when the mufcle ceafes to contrad, the elasticity ofthe Yin* ment expands ic, f0 that the Shell is opened } S Of the vafcular fyfletn. 105 ferc conntradion in fuch parts. The thraehea and it; branches are inftances of thefe two powers ; being com- pofed of cartilages, mufcles, and membranes, the propor- tion of mufcular fubftance, however, is fmall, the muf- cles which ad principally upon this part .being thofe of re- fpiration ; but the tendency of the adion of the proper mufcles of the trachea is to comprefs and alter the fize of the trachea.; this is counteraded by -the elafticity of the cartilages, and membranes, exerting a conftant and regu- lar endeavour to keep it of one certain fize. The external ears of many animals furnilh us with ano- ther inftanee oS the joint application oS theSe two powers; Sor being chiefly compoSed.oS elaftic cartilage, they retain a general uniformity of Shape, although that is capable of being altered occafionally by the adion of the mufcles. It is however to be obferved, that in alt cafes where thefe two powers are joined, the muScular, as it can always ad in oppofition to the elaftic, muft be the ftrongeft and ca- pable of being carried further than the other ; it therefore jmuft always be .proportionably Stronger than it otherwife need to have been. Parts in which thefe two powers are employed, arc ca- pable of being in either three ftates,-the natural, the Stretch- ed, and the contraded ; but in Some parts the natural State may coincide either with the Stretched., or contraded, and consequently Such parts are only capable of being in two States. The natural ftate is produced by the elaftic power fimply, the contraded is the effed of the mufcular power alone, and the ftretched is produced either by fome foreign force or body protruded, which may he effcded by a muf- cular power. Y 2 J,o.6 Of the vafcular fydem. - III. OF THE STRUCTURE OF ARTERIES. The arteries in an animal, as Sar as we can examine them, are endowed with the property oS elaftrcity, the ufe oS which we perceive in the action oS thoSe parts -, and this power is at all times demonstrable, while the muScular has been by Some overlooked, by others denied, and has only been afferted by others as appearing neceffary by reafoning from analogy. The quantity of elafticity in any artery, on which an experiment can be made, is eafily ascertained, as it only requires the application ot an oppofing Sorce, to prove both its power and extent. But it will appear Srom experiment, that the power varies according to the diftance.Srom the heart, being greateft at the heart; while probably the ex- tent may be the Same in every artery. To endeavour to aScertain the elafticity of arteries, I made comparative experiments on the aorta and pulmonary artery. Having cut off a portion of about an inch in length from the afcending aorta, at half an inch above the valves, and having flit it up, it meaSured,tranSverSely,two inches and three quarters, but when ftretched to its full length, three inches and three quarters, having gained rather more than one third, and having required a force equal to the weight o{ one pound ten ounces to produce this effe6t. A fimilar fee- tion was made of the pulmonary artery in the fame fubject, which meafured two inches one half, tranfverSely; and when Subjeded to trial in the Same manner, was ftretched to three inches and an halt, being rather more in propor- tion than the aorta ; So' that the pulmonary artery appears to have rather more elafticity than the aorta. It is not im- poffible that this difference might ariSe Srom the aorta hav- ing loft Some of us elafticity by uSe ; Sor although I chofe Sor my experiment the arteries oS a young man, where I conceived them to be perfedly found, Vet if there could have been' any diminution -of :the elafticity from ufe, it would be moft confiderable in the aorta. Thefe experiments were made on different arteries with nearly the fame refult, and feemed to prove that there was almoft the fame extent of elafticity, though not the fame powers. • An artery being compofed of an elaftic and inelaftic Sub- Stance, its elafticity is not altogether fimilar to that of a Of the vafcular fyf em. £0« .body which is wholly elaftic. There is an effed produced from ftretching it that is expreffive oS the nature of both thefe fubftances, till it gives way or breaks ; Sor an artery has a check to its yielding to So great a degree, and is Stopt at once, when ftretched to a certain point % which check is occafioned probably by the muScular, together with tne internal inelaftic coat. To prove the muscularity oS an artery, it is only necef- Sary to compare its adion with that of elaftic Subftanccs. Adion in an elaftic body can only be produced by a me- chanical power; but muScles ading upon another princi- ple, can ad quickly or Slowly, much or little, according to the ftimulus applied; though all muScles do not ad alike in this reSped. If an artery is cut through or laid bare, it wrlll be Sound that it contrads by degrees till the whole cavity is cloSed; but if it be allowed to remain in this contracted ftate till af- ter the death oS the animal, and be then dilated beyond the State oS reft of elaftic fubftances, it will only contrad to the degree oS that ftate ; this it will do immediately, but the contradion will not be equal to that oS which it was capable while alive. The pofterior tibial artery oS a dog being laid bare, and its Size attended to, it was obServed to be So much contrad- ed in a Short time as almoft to prevent the blood Srom paffmg through it, and when divided, the blood only oozed out from the orifice. ! On laying bare the .carotid and crural arteries, and ob- serving what took place in them while the animal was al- lowed to bleed to death, theSe arteries very evidently be- came Smaller and Smaller. When the various uSes of arteries is confidered, fuch as their forming different parts of the body out of the blood, their performing the different fecretions, their allowing at one time the blood to paSs readily into the Smaller branches, as in blufhmg, and at another preventing it altogether, as in palencfs Srom Sear ; and if to theSe we add the power of producing a diSeaSed increaSe oS any or every part oS the body, we cannot but conclude that they are poffeffed of muf- cular powcrr,. The influence of the heart in the body, like that cf the Sun in the planetary fyftem, we know extends to cverv part; * This jives a determined f:zc to an artery. £°8 Of the vafcular fyfem. all the parts of the vafcular fyftem being fupplied according to the neceflity it has, though every part is not equally en- dowed with power, or diSpofition to make uSe oS that power. The arteries, upon the whole, maybe Said to poffeSs con- siderable living powers, and to retain them Sor a long time. This is evident when we obServe what muft happen in transplanting a living part of one body with an intention that it Should unite with another body and become a part of it : the part transplanted muft retain life till it can unite fo as to receive its nourishment from that into which it'has been inferted. It is however to be fuppofed, that in fueli Situations, life can be retained longer than in others, al- though it is well known that it is preferved in the vaScular fyftem, even when there is no colateral alfiftance. I found in the uterus of a cow, which had been feparated from the animal above twenty-four hours, that after its having been injeded and allowed to Stand another day, the larger vef- fels were become much more turgid than when I firft in- jeded them, and that the fmaller arteries had contraded So as to Sorce the.injedion back into the larger. This con- tradion was So obvious that it could not but be obServed at the time, which was Sorty-eight hours after the Separation Srom the body oS the animal. This Shews too the muScular power of the fmaller arte- ries to be fuperior to that of the larger, and that it is pro- bably continued longer after the feparation from the body ; a property which the involuntary mufcles poffefs to a de- gree greater than the voluntary, in the former of which claffes the mufcular ftrudure of the arteries is to be confi- dered. To aScertain how long the living power exifted in an ar- tery after feparation from the body, or, perhaps, to Speak more properly, aSter that communication with the body was cut off*, by which we have reaSon to SuppoSe life to be con- tinued in a part, I made the following experiments, for .which I chofe the umbilical arteries, becauSe I could con- fine the blood in them, and keep them .diftended Sor any length oS time. In a woman delivered on the ThurSday af- ternoon, the naval String- was Separated Srom the Scetus; it was firft tied in two places and cut between, So that thf blood contained in the chord and placenta was confined in them. Of the vafcular fyf cm. I0 — —------------- —-----r\ loweft part, 3 Illiac artery --- 2-----------------2*f — £ Axillery-------1-------------------if - - > Aa 120 Of the vafcular fyflem. Crural . . . |°-.....iA- • v Humeral . . -At- • • • • • A • • \ l Radial . . . A......A equal to the [whole. Experiments on the power oS arteries to contrad lon- gitudinaily. To prove that arteries do not produce the Same power cf mufcular contradion in a longitudinal, which they do in a tranSvcrSe diredion, the following experiments were made : Experiment I. A longitudinal Sedion oSthe aorta aScen- dens, meafuring two inches, when ftretched and allowed again to contrad, meaSured the Same length. Experiment II. A longitudinal Sedion ofthe aorta de- Sccndens at the lower part of the thorax, oS a given length, after having been Stretched, contraded exadly the Same length. Experiment III. Two inches oS the Same carotid artery uhd in the Sixth experiment, when ftretched longitudinal- ly, recovered itSelS, So as not to be longer than before the experiment. Experiment IV. A portion of that humeral artery uSed in the d hth oSthe Sormer experiments was not altered in it. original length, wln»n it recovered itfelf after being ftretch- ed.0 TheSe experiments appear to be decifive, and prove that the mufcular power ads chiefly in a tranfverfe diredion; «ct it is to be obferved that the eh-.tic power of arteries is greater in a longitudinal than in a tranfverfe diredion. This appears to be intended to counterad the lengthening efted ofthe heart, as well as that arifing from the adion ofthe mufcular coat'; for the tranfverfe contradion of that coat lengthens the artery/ therefore Stretches the elaStic, v> hich again contrads upon the diaStole of the artery. From the account we have given of thofe fubftances which ccmpoSe an artery, we may perceive it has two pow- ers, the one elaftic and the othtr muScular. "We See alfo that the larger arteries are principally endowed with the e- laftic power, and the Smaller with the muScular, that the elaftic is always gradually diminishing in the Smaller, and tie mufcular increafing, til!, at k.ft, probably, the adion ul an artery is alnioit wholly muScular ; yet I think it is not Cf the vafcular fyflem. 121 to be SuppoSed but that Some degree oS elafticity is continu- ed to the extremity of an artery ; for the middle ftate can- not be procured without it; and I conceive the middle ftate to Be effential to every part of an artery. Let us now apply thoSe two powers of adion ; or, to Speak more pro- perly of re-adion, with their different proportions in the different parts of the arterial fyftem. From thefe we muft fuppofe the elaftic to be beft fitted for Sustaining a force applied to it, fuch as the motion of the blood given by the heart, and propelling it along the veflel : the mufcular power, moft probably, is required to affift In continuing that motion, the force of the heart being partly Spent; bin- certainly was intended to diSpoSe of the blocd when arri- ved at its place of destination ; Sor elafticity can neither alfilt in the one nor the other ; it is Still, however, of ufe through the whole to preferve the middle State. Elasticity it better adapted to Sultain a Sorce than muScular power ; for an elaftic body recovers itfelf again, whenever the ftretch- ing cauSe fufpends its adion ; while muScles endeavour tj adapt themSelves to circumftances as they ariSe. This is verified by different forts of engines whole pipes are made of different metals. A pipe made of lead will, for inftanee in time dilate and become ufelefs* ; whereas a pipe of ho 1 will read on the fluid, if the force of the fluid be in propor- tion to the elaftic power ofthe iron ; but the lead having little or no elasticity whenever it is Stretched, it will remain So, and every new force will Stretch it more zrA i,;.;rc Y/e are therefore to SuppoSe treet the Sorce cf the heart is not capable of Stretching the artery So much as to deSLroy its elafticity; cr in other words, the force ofthe heart is not able to dilate the artery beyond the contrading power. As the motion of the blood is mechanical, elafticicy is beft adapted to take off the immediate force of the heart ; and, as we go from the heart, this property become lefs necefla- ry ; becaufe in this courfe, the influence of the heart is gradually leffened, by which means a more equal ;,;oilou of the blood is immediately produced, and even in the rirlt artery a continued ftream is at all times obtained ; ahhough it is considerably increafed by each coritradicu of the heart. Without this power the motion of the blood in the aorta * This accounts for the fize of anenrifiiis wliofe coats uvjfl have loft their elasticity before they could be i.ilaUu. A a 2 122 Of the vafcular fyflem would have Been fimilar to what it is in its paffage out of the heart, and would have been" nearly the Same in every part of the arterial fyStem. For though the motion of the blood out of the heart be by interrupted jerks, yet the whole arterial tube being more or lefs elaStic, the motion of the blood becomes gradually more uniform from this caufe. Elafticity in arteries acts like a pair of double bellows ; although their motion be alternate, the ftream of air is continued ; and it it were to pais through a long elaftic pipe, reSembling an artery, the current oS air would be.ftill more uniform. The advan- tage arifing Srom elafticity in the arterial Syftem, will be more complete in the young Subjed than in the old ; Sor in the latter, the elafticity of the arteries being very consi- derably diminished, more efpecially in the larger trunks, where the force of the heart ought to be broken, the blood will be thrown into the fecond and third order of veffels with increafed velocity. In the young, the current h flower, from the re-adion of the elaftic power during the relaxed ftate of the heart, whereas at the heart, the mo- tion is equal to the contraction of the heart; and as the heart is probably twice the time relaxing that it is in contracting, from this caufe alone we may fuppofe the whole is two thirds lefs in the fmaller veflels. As elaf- tic bodies, I have already obferved, have a middle ftate, or State of reft, to which they return after having been dilated or contracted by any other power, and as they muft always be aded upon before they can re-act, the ufe of elafticity in the arterial fyftem will be very evi- dent, it is by this means that the veffels are adapted to tiie cifterent motions of the body, flexion and extention ; fo that one fide of an artery contracts while the other is elon- gated ; end the canal is always open for the reception of blcad in the curved, ftretched, or relaxed State. The mufcular power of an'artery renders a Smaller Sorce cf the heart Sufficient Sor the purpoSes oS circulation ; for tiie hea:t need only act with Such Sorce as to carry the blood through the larger arteries, and then the muScular power pi" the arteries takes it up, and, as it were, removes the load of blood while the heart is dilating. In confirmation of this remark, it is obServablc in animals whoSe arteries , are vc^y mufcular, that the heart is pr.nortionably weaker, So that the muScular portion oS the vefltis becomes a Second part t j tli2 heart, acting where the power of the heart begin* Ofthe vafcular fyftem. 123 to Sail, and increafing in Strength as that decreaSes in pow- er. Befides this, it dilpoSes of Such part of the blood as is neceffary for th« animal ceconomy, principally in growth, repair, and fecretions. At the extreme ends of the arteihs, therefore, we muft SuppoSe that their actions are varied Srom that of fimply conveying blood, except thoSe arteries which are continued into veins. IV. OF THE VASA ARTERIARUM- The arteries are Surnifhed with both arteries and veins, although it cannot be Said that they are to appearance very vafcular. Tiieir arteries come Srom neighbouring veflels, and not Srom the artery itSelS which they Supply. This we See in difledion ; and I Sound by Silling an ar- tery, Such as the carotid, with fine injedion, that Still the arteries ofthe artery were not injected. On laying the coats of arteries bare in the living body we can diScern their veffels more evidently Some little time after the expoSure, Sor then they become veffels conveying red blood, as in a beginning inflammation, growing turgid, when the arteries may be eafily diScerncd Srom the veins by the difference oS colour oS the blood in each : theSe observations will alfo generally apply to the corresponding veins. Perhaps arteries aiferd the moft Striking inftanee oS ani- mal Subftance furnifhed with two powers existing in the Same part, one to refiSl mechanical impulSe, the other to produce adion. The firft oS thefe powers is greateft where there is the moft impulSe to refill; thereSore we find it particularly in the arteries, neareSt to the heart, the better to Support the Sorce oS that organ ; but in thofe parts where gravitation is gradually increafing, the diminution oS power in the artery is not in proportion to the diminution oS the. Sorce of the heart. In the veins, the allotment oS Strength is commonly the reverSe ; Sor as they have nothingmechanical to i\.fiSt, but the effed oS gravitation, their principal Strength is at the extremities. 124 - Oj the vafcular fyflem. We are to SuppoSe that die power oS the h ■::■-■ rt, and the mechanical Strength of the arteries, bear a juft proportion to each other ; and therefore by ascertaining the l.fft we may give a tolerable good gueSs with refped to the ether. In this view, to determine the Strength ofthe ventricles, So far as I was able, I made comparative trials of the Strength of the aorta and pulmonary arteries in a healthy young man. I Separated a circular Sedion of each, and on being flit, they meafured three inches and three-eights, their breadths being alSo equal. On trial I Sound the aorta being Stretched to near five inches, broke with a weight of eight pounds. The pulmonary artery ftretched to near five inches and a half, and dicn broke with four pounds, twelve ounces. This experiment I have repeated, but with very different refults , for in one experiment, although the aorta took one pound ten ounces to ftretch it, while the pulmonary artery took only fix ounces ; yet to break this pulmonary artery required eleven pounds, three ounces, while the aorta broke with ten pounds, four ounces ; but this difference \ impute to the aorta having loft its elafticity, which is very apt to happen in that veffel. There is nearly the Same proportion of elafticity in both arteries ; but the ftrength of the aorta in the firft experi- ment appeared to be nearly double that of the pulmonary artery ; while in the fecond it was lefs : yet we muft fup- pofe the refult oS the firft experiment nearer the truth; for we feldom find the pulmonary artery difeafed, while the aorta is feldom otherwife. The mechanical ftrength of arteries is much greater in the trunk than in the branches ; which is evident from accidents and from injedions in dead bodies. For when we inject arteries with too much force, the firft extravafation takes place i'i in the Smaller veffels. This can only be proved by Subtile injedions, which do not become Solid by cold ; Such injedions keeping up an equal preffure through- out the arterial Syftem ; and the Smaller arteries being Sound to give way firft, viz. thoSe of the mufcles, pia-mater, and the cellular membrane ; which contradids Flaller's theory of the relative Strength of the cocts ofthe veffels. I am however inclined to fuppofe that they are even wraker in proportion to their fize, viz. in proportion to the diminished force of the heart, or motion of the blood ; but ho.v far this is die cafe I will not venture to determine Of the vafcular fyflem. 125 is mechanical ftrength is not fo much wanted in the fmall- er arteries, as mufcular ; for the mechanical ftrength of mufcles appear to be leSs than the power of their own con- tradion ; experiments, therefore, made in the dead body upon parts whofe ufes arife from an adion within them- felves when adive arc not conclusive. The flexor policis longus, being one of the moft detached mufcles in the body n. feeding ftrudure and ute, has been Seleded Sor experi- ments on this Subjcd, and is Scund to raiSe by its adion a greater weight than it can Suftain aSter death. This how- ever is liable to Sallacy, as the two experiments are made on different muScles, one certainly healthy, the other moft probably weakened by the diSeaSe preceeding death. The coats of arteries are not equally Strong on all fides cf the fame artery ; at the bending of a joint they are Strongest on the convex fide through the whole length of the curve ; this is molt evident in the permanent curves, fuch as in the great curvature oS the aorta. Arteries are likewiSe ftrongeft at the Sharp angles made by a trunk and its branch, and at an angle Sormed by a trunk divided into two. Tivi'e parts have the bleed as it were daShing againft them. TheSe likewiSe are the parts which firft loSe their elafticity and Sooncit offffy, being generally more ftretched than the other parts oS an artery, and making a kind oS bag. TheSe circumftances are chiefly obfervable in the curva- ture of the aorta, that oSthe internal carotids, and the di- vifion of the aorta into the two iliacs. V. OF THE HEART. The heart is ail organ which is the great agent in the motion of the blood, but is not effential io animals of every clafs, nor Sor the motion oS the blood in every part where it is perfed ; it is lets So than the nerves, and many even poffeSs the organs oS generation, that have no heart. Its adions in health are regular and charaderiftic oS that ftate; and in dilcaSe its adions are in Some degree charaderiftic «f the diSeaSe; but although there is that cennedion be- 126 Of the vafculir fyllem. tween the body and the heart, yet there Seems not to be Such a connedion between the heart and the body ; Sor the heart may be in Some degree difcrdered in its action, yet the body but little affected ; it is thereSore only to be con- fidered as a local agent very little affecting the conftitution Sympathetically, except by means oSthe faikire in its duty. The heart in the more perfect animals is double, anfwen- ble to the two circulations, the one through tho lunj-s, the other over the body; but many that have only Single hearts have what is analagous to a double circulation ; and this is perSormed in very different ways in different animals, fo that one oSthe circulations in theSe is perSormed without a heart. A large claSs of animals, well known 'and pretty perfect in their construction, namely, all the claSs oS fifh, have no heart Sor the motion oS the blood in the great circulation, or that over the whole body, having only a heart Sor the lungs or branchea, while the Snail has only a heart Sor the great circulation, and none Sor the lungs ; as alSo in the liver oS the moft perfect animals, the motion oS the blood, in the vana portarum, and vena cava hypatica, is carried on without a heart. The absorbing Syftem in every animal has no immediate propelling power ; thereSore this propell- ing power is not univerSally neceffary. The heart varies in its Structure in different orders oSanimalsj principally with reSpect to the number oS cavities and their communica- tions with each other, yet in all nearly the Same purpoSe is anSwered. I Shall here obServe, that in the bird and quad* ruped there is a double circulation, which requires a dou- ble heart, namely, a heart for each circulation, each heart confifting of an auricle and ventricle, called the right and the left; and from their forming but one body among them, they are all included in one heart; the right fide, or heart, may be called the pulmonary, and the left may be called the corporeal. In many claffes of animals there is to be found only one of thofe hearts ; and according to the claSs, it is either the pulmonary or corporeal. In the filh, as was obferved, the heart is the pulmonary ; and in the Snail, the heart is t! e corporeal; So that the corporeal motion oS the blood in the fifti, is carried on with out a heart; and in the Snail the pulmonary motion is carried on without a heart ; and in the winged inSects which have but one heart, as alSo but one circulation, there is this heart, anSwering both pur- Of the vafcular fyftem. 127 pofcs ; and in all thefe varieties, breathing is the principal ob'ect. The heart in moft animals is compofed principally-of a Strong muScle thrown, into the Sorm of a cavity or cavities ; but it is not wholly muScular, being in part tendinous or ligamentous, which laft parts have neither adion nor re- action within themSelves, but are only aded upon; they are therefore made inelaftic and rigid to Support the Sorce of the ading parts in this adion, without varying in them- felves. The heart is in all animals which have red blood, the reddeft mufcle in the body. Thus in the bird whoSe muS- cles are moftly white, the heart is red; we find it the Same in the white fiSh. As it differs in the different orders oS animals reSpeding the number oS cavities, it may admit oS diSpute what are to be reckoned truly hearts, and what only appendages; Sor Some oS its cavities may only be confidered as reServoirs peculiar to Some hearts. The moft fimple Sorm of heart is compofed of one ca- vity only, and the moft complicated has no more than two; it would feem indeed to increafe progreflively in the num- ber of cavities from one to four, which includes the mix- ed ; yet two of thefe belonging to the heart with four ca- vities, ought not to be called parts of the heart although they belong to it. The fingle cavity of the heart in the moft fimple clafs, or the two in the moft complicated, are called ventricles. The other cavities belonging to it are called auricles, many of thofe which have one ventricle only have no auricle, fuch as infeds ; but there are others which have both a ventricle and auricle, fuch as fifh, the fnail, many Shell fifh ; fome of the laft clafs have indeed two auricles with only one ventricle ; which fhows that the number of auricles is not fixed under the fame mode of circulation ; thofe animals which have two diftind ventri- cles, conftituting four cavities, are what are called quad- rupedes, or mammalia, and birds. If the auricles are con- fidered as parts of the heart, we might clafs animals which have hearts according to the number of their cavities, viz. monocoilia, dicoilia, tricoilia, tetracoilia ; the tricoilia is a mixture of the dicoilia and tetracoilia. This is the cafe ia diftind claffes of animals ; but it takes place in other clafles at different Steves of life ; for the foetus of the clafs poffef- B b I 23 Ofthe vafcular fftcm. fing fcur cavities may be claffed with the mixed, having but cne auricle, by the communication between the two and alio one vcnt.'.^kj, by means of the union between the two arteries which produce an union of blood aldiQUgh not fo the fame way. Thofe pafidges however are Shut up almoft immediately after birth, or at leaft the canalis artcrioSus*, which immediately prevents the foramen ovale Srom pro- ducing its former effeds; therefore it is not fo 'neceffary it Should be Shut up in the adult. I have Seen it, to common appearance, as much open as in a foetus. The heart may be confidered as a truly mechanical engine; for although mufcles are the powers in an animal, yet thefe powers arc themhlves often converted into a machine, of which the heart is a Strong inftanee ; for from the difpofi- tion of its muScular fibres, tendons, ligaments and valve?, it is adapted to mechanical purpoSes ; which nuke it u complete organ or machine in itfelf. It is moft probable that by means of this vifcus a quicker Supply oS blood is Surnifhed than otherwise could be effected. In birds and quadrupedes the heart by its adion firft throws out the blocd, both that which is fit for the pur- poSes oS life, and that which requires to be prepaired; the laft having loft thoSe Salutary powers in die growth, repairs, Secretion, etc. in the machine. It may be Said to give the firft impulSe to tire blood, pro- ducing a greater velocity where the blood is fimply convey- ed to the parts for whofe ufe it is deitined. This velocity is alternately greater and lets, and Srom the conftrudicn of the arteries alone is gradually diminished, becoming more uniform where flowneSs and eveneSs in motion is neceffary. This velocity of the blood in thoSe parts where it is to be confidered as paffinjy only, allows a much largcrquantity to flow through the part to which it is deStined than cthcrwifc could be transmitted. The heart is placed in the vaScular Syftem, to be ready to receive the blood Srom the body, and to propel it back on the body again, although not in the centre cS the v.hcle; but it is reaSonable to SuppoSe that its fituation is Such as to be beft Suited to the various parts oS the body ; Some parts * There have been infUnccs of the car.;!:: r.rtcricfas bcir.j open in the a.hit. Of the vcfular fyftem. 129 requiring a brink, others a more languid circulation. Some alSo require a greater Supply oS blood than others. We may SuppoSe that the parts near the heart will re- ceive more blood than thoSe at a greater diPcance, becauSe the refiftance will be lets if the veffels arc oS equal fize in proportion to the fize oS the part. The fituation oS the heart in the body varies in different animals. One would imagine when the animal was divided into it; feveral por tons appropriated for the different purpoSes, that the fitua- tion oS the heart would be nearly the Same in all; but we find this not to be the cafe; its fituation depends upon the organs of refpiration, more than any other part. It is placed in what is called the cheft in the quadruped, bird, amphibia, in fifh, and in the aquatic and terrcftrial iut cd ; but not in what may be called the cheft in the flying infed. The cheft in the above named animals Seems belt Suited to contain the lungs and branchia, and therefore the heart is placed there ; but as the lungs of the flying infed are placed through the whole body, the heart is more diffuSed, extend- ing dirough the whole length of the animal. The fitua- tion, therefore, ofthe heart is chiefly conneded vv.h that oS the lungs; and when it is united with the body at large, it is becauSe the lungs are alSo So diSpofied. We muft SuppoSe that theSe two have a relation to each other. A heart is compoSed of an auricle and ventricle ; and it h the ventricle which Sends the blood through its courSe in the circulation ; and Srom what has been Said, it muft co- pea;- that the ventricle is the true heart, the other parts hav- ing only Secondary uSes ; and as the ventricle is the part which propels the blood to the different parts of the body, its mufcular power muft be adequate to that purpoSe, and thereSore it Iras a very Strong muScular coat. Much more pains than were neceffary have been taken to dined and deScribe the courSe and arrangement oS the muScular fibres cf the heart, as iS the knowledge oS the courSe of its fibres could in the leaft account Sor its adion. But as the heart can, in its contraded ftate, almoft throw out its whole contents, to produce this effed, its fibres muft pafs ob- liquely. Its red colour ariSes probably Srom its being at the Soun- tain head of the circulation : Sor thoSe animals that hive but little red blood have it only in thofe parts n?ar cue heart; 13 b 2 130 Of the vafcular fyftem. and the heart being neareft to its own powers, receives the blood before the veffels can fo ad as to difpofe of the red blood, or allow of a kind of feparation by diftance; its conftant adion too renders it more red, as happens in other mufcles. The ventricles in the quadruped, bird, and amphibia, are called right and left, and this accords very well with the fituation in fuch animals ; but where there is only one ventricle, and that in fome ading the part of right, as in fifh, and in others ading the part of the left, as in the fnail, we ought to have fome term expreffive of their im- mediate ufe, and fuch as would apply to all animals that have fuch a vifcus. The auricles of the heart are to be confidered only as re- fervoirs for the blood to be ready to fupply the ventricles; for an auricle is not to be found in all the animals which have a ventricle ; nor does the number of auricles always correfpond to thatrof the ventricles. Where the veins en- tering into the heart are fmall, in comparifon to the quan- tity of blood which is wanted in the ventricles, there we have an auricle ; but where the veins near to the heart are large, there is no auricle ; as in the lobfter, and generally in inSeds. In the Snail, where the veins in common are large, yet as they are Small where they enter the heart, there is an auricle ; and as its office is Somewhat fimilar to a large vein, it has Some oS its properties, viz. being in Some de- gree both elaftic and muScular. The name Sinus venoSus is a very proper one ; and as a proof that it is only fuch in the circulation, there are no valves placed between it and the veins. As the heart is an engine formed to keep up the motion of the blood, and as it is neceffary that this motion Should be determined in a particular diredion, it is adapted, as are alSo the other parts oS the vaScular Syftem, to this pur- poSe. The heart is Sormed into a cavity through which the blood muft paSs, receiving at once a confiderable quantity of this fluid, upon which it immediately ads with equal force, although not progreffively, as an inteftine ; and that this motion of the blood may be regulated, and a retro- grade motion prevented, we find the valves conftruded. Of the vafcular fyflem. *3* A valve, I believe, is in general understood to be a part in every machine, calculated to allow whatever is to pafs to move in one diredion only ; and the valves in the vafcular fyftem are intended for this purpofe. They are of two kinds, having two modes of attachment, which is fuited to the adion of the part to which they are attached, and making a very effential difference in their formation. They are thin inelaltic membranes, having no adion within themSelves, with one edge fixed, the other looSe in Some, but not entirely So in others ; they are either attach- ed in a circular Sorm, or in an oblique one. The circular attachment belongs to thoSe oS the ventricles, and the ob- lique to thoSe oS the arteries and veins. The circular arc the moft complex, requiring an additional. apparatus to make them anSwer die intended purpoSe ; it is neceffary that their looSe floating edges Should be restrained Srom in- verting themSelves into the auricle upon the contradion of the ventricles : this is done by tendons, which arc fixed at one extremity along the edge oS the valves, and at the other to Some part upon the infide of the ventricle. The tendons which are longeft are inSerted into columns of mufcle, the intention oS which is very evident; Sor if they had gone the whole length in form of a tendon, they would have been too long when the heart contraded, and the valves in Such a caSe would have allowed oS being putti- ed into the auricles, So far as to admit of the blood efcap- ing back again into the cavity; but the carnise columnar keep the valves within the ventricle, in the contraded State oS the ventricles; and the dilatation oS the ventricles counterads lhem and places the valve in their proper fituation in that State. If the valves in this cavity had been placed obliquely a- long the inner fides of the ventricle, as in the beginning of the arteries, and in the veins, the attachment then would not have been permanent; for it would have varied accord- ing to the relaxed or contraded ftate of the heart; it would have been Snort in the contraded ftate, and longer in the relaxed; therefore to have a fixed bafe, it was neceffary for them to be attached all round the mouth of the ventri- cles. I have reafon to believe, that the valves in the right Side of the heart do not fo perSedly do their duty as thoSe of the left, therefore we may fuppofe it was not fo neceffary* T32 Of the vafcular fyftem. The veffels of the heart are called coronary arteries and veins. In quadrupeds and birds, there are two coronary arteries, which ariSe Srom the aorta juft at its beginning, behind two oS the valves oS the artery; Srom this cir- cumftance a theory reSpeding the adion oS the heart was raffed; but in the amphibia they ariSe at Some diftance, and not always Srom the Same artery in the Same Species, oSten from the Subclavian, and often from the anterior furface of the afccnding aorta, which is refleded back. In the fifh they arife from the artery as they are coming from the gills. The veins paSs into the right auricle. Ih all animals, which have an auricle and ventricle, So far as I know, there is a bag (unattached) in which they are placed, called a pericardium*, but the inSed tribe, whether serial, aquatic, or terrcftial have none, their heart being attached to the Surrounding parts by the cellular membrane, or Some other mode of* attachment. In thofe animals which have this bag, it is not a Smooth termination oS the cellular membrane, as the peritonaeum may be Sup- poSed to be ; but a diftind bag, as in man, and in all quad- rupeds. The uSe oS this bag is probably that the heart may move with more caSe and Sacility; the two parts, to wit, the contained and containing, ading as a kind oS joint with a eapSular ligament, and like Such joints it contains a fluid, but not a Synovia, as the two Surfaces aie not hard like car- tilage ; befides, the heart is kept very much in its place, which we muft SuppoSe is oS uSe. I have conceived it alSo to be poSfible, as it is a pretty Strong membrane, that it might in Some degree preServe the heart Srom too great dis- tention ; Sor I have obServed by injedions, that a little Sorce will diftend it beyond its natural Size, iS a part oS the pe- ricardium be taken off; but in the heart mentioned by Dr. Baillie there was no particular increaSe oS bulk. This bag has, like moft others, a Huid which moiftens the two Surfaces. In other cavity oS the body the fluid is no more in quantity than what is fimply SuSficient to moiften * There have bceninltanc.es where the pericardiim ha* been wsnting in the human Subject: a cafe of this kind is pnblifned by Dr. Baillie, in a periodical work, entitled, " Trarifaciiors " of a Society infiitated for promoting medical and chirur^hal " Knowledge." Of the vafcular fyftem. '33 the parts. In this bag, however, it is more, Srom whence it has acquired the name of liquor pericardii. There may be about a tea fpoon-full in the whole. This fluid appears to be Serum, and is commenly a little tinged with blood which ariSes Srom the transudation oS the red blood aSter dcath. That this cavity has more water in it than moft other cavities of the body, may ariSe Srom their being a greater action of thofe parts on one another than takes place in o- thers ; it may alSo fill up the interftices Sormed between two round bodies, So that when the pulmonary artery and aorta are filled, they may more eafily affume a round figure. The fize oS rt heart we Should naturally SuppoSe is pro- portioned to the fize of the animal, and the natural quan- tity of blood ; which laft is, we might conceive, ever in proportion to the fize oS the animal ; but I believe theSe modes oS calculation will not be found to be juft.; Sor cer- tainly Some animals have much more blood in proportion to their Size than others ; and I believe the heart is not in fize proportioned to the Size oS the animal, but bears a cou-.pound proportion or ratio to the quantity oS blood, to be moved, and the frequency of the Stroke it has to make ; for when it is decreaSed in the one refpect it muft be increaSed ■ in the other ; and as a proof of this we find when an ani- mal lofes a confiderable quantity oS blood, the heart increaSes in its SrequencyoS Strokes, as alSo in its violence. That it principally bears proportion to the quantity of blood is evident; Sor the right ventricle is equal in fize to the leSt, if not larger, which Sends its blood to the lungs only, which are infinitely Small when compared to the body ; and the hearts of thofe animals which have but one ventricle, as filh Sor inftanee, which is fimilar in uSe to our rirht, are per- haps made as large in proportion to die fice cf the body as both ventricles in the quadruped. The ftrength of a heart is commonly, if not always, in proportion to the Size ofthe parts to which the blood is carried with the velocity with which the blood is propelled, which becomes a collateral proof that It is an univerfal a- gent in the circulation. In the complete heart this is not equal in every part of the fame heart; the right ventricle beina; much weaker than the let, but ftill in the above pro- portion;. The iiropovtion b?:./een th; two will be, beft t34 Of the vafcular fyftem. known by ascertaining the difference in the ftrength of the two arteries, and this again will differ according to the whole parts the blood is Sent to by the heart. In the fifh, for inftanee, it is only neceffary it Should bear the proportion in ftrength to the whole fifti, that our right ven- tricle bears to our lungs, which is not in the leaft equal to that of the left ventricle ; or in other words, its ftrength Sliould commenfurate with the fize of the lungs; how- ever, it is moft probable that the right ventricle in the qua- druped is Stronger than in this proportion, becaufe it is obliged to move a larger quantity of blood than is contained in any other part ofthe body ofthe fame fize, and with great- er velocity ; in the double heart, therefore, fuch as the hu- man, the two cavities are not of equal ftrength, each be- ing nearly in proportion to the Size of the parts, or rather to the diftance the blood is to go ; the right ventricle only throwing it into the lungs, the left into the body. As a proof of this dodrine, we find that in the fcctal ftate oS this claSs oS animals, the two ventricles and the two large ar- teries, are equal in ftrength. Indeed, Srom reaSoning, wc Should exped this, and even that the right ventricle Should rather be the Strongest; Sor at this peried it Sends the blood to the lower extremities ; but Since both the arteries unite into one canal we muft SuppoSe it to be neceffary that the velocities of the blood in both Should be equal ; upon exa- mination we find the two ventricles to be nearly equal in thicknefsin this young ftate ofthe animal. The mixt kind of heart, as that of the turtle, etc. is un- der the fame predicament. The two ventricles are to be confidered as joint agents in the circulation; and as the pulmonary artery and aorta are equally Strong, it becomes a proof that the ftrength of the heart muft be equal every where. If we were to cftimate the ftrength of the ventricles in thofe poffeffed of four cavities, by the ftrength ofthe aorta and pulmonary arteries, either by their abfolute Strength or elafticity, we might come pretty near the truth. Dr. Hales made an experiment on a horfe, to aScertain the ftrength of the arteries, which gives us the power ofthe left ventricle ; but ail this explains nothing, for its power is equal to the ufe wanted. The power of contraction of the ventricle muft be within the Strength of the artery ; but it i3 hardly poSfible to aScer- tain what is the ftrength of an artery, nor, if wc could, Of the vafcular fyflem. t^d would it aScertain the ftrength of the ventricle, for the force of the he rt is in part immediately loft by the blood being allowed to pafs on, although not fo freely as if the artery was open at the other end ; in proportion, there- fore, to the retardment, the artery is affeded. We can afcertain the elaftic power of a given fedion of an artery, and alfo its abfolute ftrength, but we are not unacquainted with the Size oS a Sedion that will give the ftrength of the artery to which it belonged when the whole was in a per- fed ftate or form. Experiment I. A Sedion of a found aorta, clofe to the valves, three quarters of an inch long, was ftretched tranf- verSely to its greateft extent, which ftate was afcertained by meaSuring it with a pair of compaffes, and the artery was allowed to contrad. The weight required to Stretch it again to the fame degree was one pound ten ounces. To break the artery required ten pounds and a quarter. Experiment II. A fedion of the pulmonary artery, Simi- lar to the former in length and fituation, required fix ounces two drachms to Stretch it to its full extent. To break it re- quired eleven pounds three quarters. The ufe of this vifcus is in general very well known \ however, its ufe has been frequently fuppofed to be more univerSal than it really is. It gives to the blood its motion in rnoft animals, and in all it Sends the blood to the organs of refpiration : in the flying infed it fends the blood both to thofe organs and to the body at large ; but in fifh to thofe organs only, the body at large in them having no heart. In the amphibia there is an attempt towards a heart both for the lungs and body, but not two diftind hearts. In the bird and quadruped there is a diftind heart for each. We may fay, therefore, that there is one heart Sor reSpiration, and another Sor the life, nourishment, etc. of the animal; thefe constitute the two ventricles. As the extent of thefe two circulations is different, the two hearts, or in other words, the two ventricles, are Suit- ed in their Strength to the different extents oSeach circula- tion, as was obServed above in treating of the_ ftrength of the heart. How far the heart is alone capable of carrying on the cir- culation is not to be afcertained ; for although the circula- tion is carried on in paralytic cafes, yet this does not ex- C c x26 Ofthe vfu'arftem. elude the involuntary nervous influence of the part; thit, however, varies very much in different claffes of animals > for I have already obferved concerning the ftrudure of the arteries, thct their mufcularity ^lifted in the circulation and that in proportion as the veflels in general were endow' cd with this power the heart was weaker. I believe that the quadruped has the Strongest heart of any clafs oSani- mals ; and I believe that their veffels have the leaft muf- cuiar power, more eSpecially near the heart. The Immediate uSe of the heart in an animal, would Seem to be generally Subject to as little variety as that oS any o tner vifcus ; but perhaps the heart is Subjed to more varie- ty tlwn any other part in its construction. I have obServed that :: is either Single, double, or mixed, that it is tin e wiinout an auricle, Single with one auricle, Single with two auric es, double with a union oS the two, makin* tne mixed, and double with two auricles. With refpect to its life, it is in the moft Simple kind oS Single heart, o propel die hood through the body, immediately from the venn--, wmch blood is to receive its purification in tiis paffage, when the lungs are diSpoSed throughout the bo- oy, as in the flying iufiecl. In another Single heart it is in- tended to mix both the purified and the adulterated blood, and of courSe to throw it out to the bodv and lungs equally in this mixed ftate, as in the lobfter. In the fingle heart, w:t,. an auricle, its ufe is, in one clafs, to throw the blood throughout the body, after being purified, as in the Snail; ana m another fingle kind, with an auricle, it is to receive the blood Srom the body, and Send it to the lungs enly, as in al! fifh. Li the Angle heart with two auricles! it is form- eo to receive the blood both purified and unpuiified, and cn.'poie of.it to bodi body and lungs in that ftate, as was ooterved m the lobfter : the fame thing happens, in Some degree, m the turtle, Snake, fetus, etc. In the double heart with two auricles it ads like an union cSthe heart of the inzlf v;itfh z-\ of the h^> one heart receiving the blood puri^d Srom the lungs, and Sending it over the body, as i11 ^ ii:ajV ,nd the Cther receivi"g 'he blood Srom the body, and .ending it into the lungs to be purified, as in the ioo x rom the above account we muft See that the imme- oiate uSe ar.f,ng from the heart in one clafs of animals will net agree with ,ts immediate ufe in another; but ftill in a! it is the engine employed to throw the blood to thofe p;.rts mto which tne arteries condud it. Of the vafcular fyftem. 11 y It is impoffible to fay what the quantity of blood is that is thrown out of the heart at each contraction. The fize of a relaxed heart, in the dead body of any animal, gives us the fize of the cavity, or what it h capable of holding ; but mufcles Seldom or ever are obliged to relax themSelves to their Sull extent in common adions, although they often are when extenfive effeds are to be produced. The heart, like every part conftrudcd Sor action, has its times of ac- tion beyond, and alSo within its natural limit oS action ; but it is its natural action which Snould be afcertained. If we compare the adions of the heart with thofe of the body, we may SuppoSe that the common quantity oS motion in the heart is about half what it can perforin, that is, it relaxes three-fourths and contracts one-half ; therefore a ventricle which contains Sour ounces, will, in common, on- ly dilatcSo as to contain three, and will only contrad So as to throw out two. The queftion is, when the heart ads with more frequen- cy, as from exercife, does it, or does it not alfo dilate and contract more Sully, and alSo act with greater velocity in its contraction ? I believe that all theSe circumftances take place; for in exercife, the pulfe not only becomes more frequent, but fuller, as if more was thrown out of the heart; and the heart is found to make a greater emotion in the cheft, ftriking with its apex againft the infide of the cheft with greater force •", which can only arife Srom a greater quantity being thrown out, and with greater velocity. The breathing corresponds with the quantity of blood and the velocity; Sor if a larger quantity paiies through the * The reafon why die apex of the heart Strikes againfl the cheft in its a.Iions, was, 1 believe, firft accounted Sor by ti e late Dr. William Hunter, in his lectures, as far back as the year i 746. The fyltolc and diaStole of the heart, Simply, could not produce fach an effrct ; nor could it have been produced, if it had thrown the blood into a Straight tube, in the direc- tion ofthe axis in the left ventricle, as is the caS; with die ven- tricles of fifh, and Some other chfles of animals ; but by its throwing the blood into a curved tube, viz, the aorta, that ar- tery at its curve endeavours to throw itfelf into a Straight line to increafe its capacity ; but the aorti being the fixed point againit the back, and the heart in fome degree loofe or pen- dulous, the influence of its own action is thrown 11 on itil-lf, and it is tilted forwards ?.?f-.rA the infide ofthe cheft. C C 2 138 Of the vafcular fyflem lungs in a given time, the breathing muft be in the fame proportion increaSed; iS with a greater velocity, the Same thing muft neceffarily take place ; and if a greater quantity Js dvrown out, and with a greater velocity, then the arte- ries muft relax in proportion, Since the different parts muft correfpond with each other; we muft fuppofir, therefore, that in health, whenever there is any exertion greater than common, (which always increafes the pulSe) the heart di- lates more, contrads more, and does both with greater velocity; this I conceive ariSes Srom a neceffity, which be- gins firft in the veins ; Sor when the body is in adion, die , blood in the veins is obliged to move with greater velocity than when at reft : how Sar there may be other reaSons for this, I will not pretend to determine. Another queftion naturally ariSes; as we find that the times of repetition of the pulfe or adions of the heart in- creafe in many difeaSes, Does the Same thing happen, that is above SuppoSed to ariSe, Srom exerciSe in health ? viz. Does the heart dilate more, contrad more, and alSo con- trad with more velocity ; I believe this caSe does not in the leaft correSpond with our Sormer pofition. The pulSe in Such circumftances, although Srequent, is Small and hard, Showing the arteries to be too much contraded by their muScular power, and thereSore unfit to receive a large quan- tity oS blood Srom the heart in any given time. The breath- ing does not correSpond with the Srequency of the pulfa- tions, as in the Sormer inftanee; yet it is poflible that near- i ly the Same quantity oS blood may paSs as when in health, the velocity in the contraded State oS heart and veffels mak- ■ ing up Sor the quantity in the enlarged. That it moves falter in fuch ftate of veflels, is, I think probable; Sor in bleeding, the blood in the veins during Such a ftate of vef- Sels, is commonly more florid. Observations upon the heart's motion, while under the influence oS artificial breathing. I. I obServed that the auricles contraded but very little, So that they did not nearly empty themSelves. II. That the ventricles were not turgid at the time of their diaftole ; Sor I could feel them foSt, and could eafily compreSs them. III. That the ventricles became hard at the time oS their Syftole. Cf the vafcular fyftem. 139 IV. That the heart, when. it ccaSed to ad, became nearly twice as large as when ading, and that it recovered its Small Size again whenever it began to ad. Observations on the above appearances. From the firft observation it would appear, that the au- ricles are only reServoirs, capable oS holding a much larger quantity than is neceffary Sor filling the ventricles at any one time, in order that the ventricles may always have blood ready to fill them. From observation the fourth, it would appear, that any idea we Sorm ofthe Size oSa heart Srom thoSe in dead bodies, muft be Sar Srom the truth; Sor the blood coming Srom every part oS the body to the heart, in Some meaSure dii- tends it while it is in a relaxed ftate, So that when the heart begins to contrad (as muScles do Some time after death) it is kept dilated by the contained blood. However, it may be obServed that the increaSed fize of the heart would be lefs in the prefent caSe, than natural; Sor the very quick motion oS this viScus, under this irritation, hindered a Sull diaftole ; but when I leSt off blowing, and the heart ceaSed ading, it became large ; and on reSuming my artificial breathing, it again became Small; which I did three times in the courSe of this experiment. But I think I have ob- Served in general that the heart is not So much affeded bv the ftimulus of death as die other mufcles oS the body. We Seldom See a dead body that is not Stiff; but we very often find the heart large and flabby, not in the leaft con- traded : and I am not certain but this may be the cafe alfo with Some of the other vital parts, as the ftomach and in- tcftines. It is to be Set down as a principle, that the adion oS e- very muScle is alternate contradion and relaxation ; and it cannot be other wife ; but as there is a neceflity Sor a more conftant and regular motion in the heart, than probably in any of the other mufcles, more difputes have arifen about the cauSe of its regular alternate motion. Some have ac- counted for it from the pofition of the mouths of the coro- nary arteries refpeding the valves of the aorta, Suppnfine, cn.v.eoufly, that the heart has its biood in the time of its relaxation*; but the circulation, whether exift in? or not, * Tiiis will be readily under;:.vid when I come toc-offnn the mod. of a tun in the valves of the arteries. 140 Of the vafcular fyflem. has not Such immediate effed upon a muScle ; nor would it account Sor the adion oS the auricle in the fame animal, nor would it account for the action of the heart in a fifh ; but Srom what we Shall obferve on the valves of the aorta, we Shall find that this opinion immediately Sails to the ground. An eaSy experiment may put this beyond a doubt; Sor, if the heart of a dog be laid open and the coronary artery wound- ed, it will be found to jet out its blood as the aorta dif- tends. Others have accounted for the alternate motion of the heart, from the courSe of its nerves paffmg between the two great arteries, So as to be compreffed when the ar- teries are dilated; but this could only produce relaxation. We know too that Such immediate compreffion on a nerve has no Such immediate effed upon a muScle ; and it would moft probably make it contract; Sor when the nerves of the heart are cut, it does not ftop its motion, but rather makes it contrad for the inftant. The heart's motion does not ariSe from an immediate impulSe Srom the brain, as it does in the voluntary muScles, and as it is only in the quad- ruped and bird that the nerves can be influenced in their paffage to it; it does not account Sor this alternate motion in other claffes of animals.. The flowing of the blood into the heart has been affigned as a caufe of its contradion; but even that will not account Sor it; although it will for m3ny of its phenomena, yet not for all; for a local ftimulus merely is too mechanical to produce all the variety attend- ing the adion of this vifcus ; it would not be attended with that regularity which it has in health, nor that irregularity which we find in difeaSe ; neither could it ever flop, unkfs when abSolute death took place ; nor reSume its adion if it ever did Stop. We find that thoSe parts which have occafion Sor the immediate Stimulus to produce adion, have that adion very irregulvr; as lor inftanee, the bladder of urine and inteftines. The bladder is taking up its adion as Sim- ply Sor itfelf, and not Secondarily, however beneficial that might be for the whole in a Secondary degree; but the heart's adions ariSe Srom its being So much part oS the whole, as the whole immediately to depend upon it; there- fore we muft look out Sor another cauSe of this regular al- ternate adion cf the heart, than that arifing Srom median- ilm or mechanical impreffion; Something more immediate- ly conneded with the general laws of the animal ceconomy, The alternate contradion and relaxation of the heart confthutss 2 part of the circulation ; and the whole takes Ofthe vhfular fyftem. 141 place in fconSequence of a neceffity, the conftitution de- manding it; and becoming the ftimulus, it is rather there- fore the want of repletion which makes a negative impref- fion on the conftitution, which becomes the ftimulus, than the immediate impreffion of fomething applied to the heart. This we fee to be the cafe, wherever a conftant fupply, or Some kind of aid, is wanted in confequence oS Some ac- tion ; we have as regularly the ftimulus Sor reSpiration, the moment one is finifhed an immediate demand taking place ; and if prevented, as this adion is under the influence of the will, the ftimulus of want is increafed. We have the ftimulus of the want of food, which takes place regularly in health, and fo it is with the circulation. The heart, we find, cannot reft one Stroke, but the conftitution feels it; even the mind and the heart is thereby Stimulated to adion. The conftant want in the conftitution of this adion in the heart, is as much as the conftant adion of the Spring oS a clock is to its pendulum, all hanging or depending on each other. The neareft dependence of the heart is upon the lungs, and probably they ha\ c the fame upon the heart; the two together become in their immediate uSe interwoven with the whole ; Sor a Stoppage of refpiration produces a Stop- page of circulation, and a restoration of refpiration pro- duces a restoration''of the circulation or heart's motion. Thus, in my experiments on artificial breathing, the heart foon ceafed ading whenever I leSt off ading with my bel- lows ; and upon renewing my artificial breathing, it, in a very Short time, renewed its adion, firft by flow degrees ; but became quicker and quicker till it came to its Sull ac- tion. I believe this experiment cannot be reverSed; we cannot make an artificial circulation, So as to know, that if we Stopped the heart's motion, we Should So readily Stop reSpi- ration ; and on producing the heart's motion, reSpiration would again take place ; but if we could do this, I doubt very much its being attended with equal fucceSs, becauSe I believe that in all deaths, reSpiration ftops firft ; however it muft be SuppoSed, that iS the heart Stopped Sor any length oS time, refpiration would alSo Stop ; and iS I were to take the Sollowing caSe as prooS, it would appear that reSpiration would not go on without the heart's motion. A gentleman was attacked with a pain in the fituation oS the pylorus. The pains were Such as indicated its Seat 142 Of the vafcular fyacm. to be in the nerves of the ftomach and its connedions. It ■ was fuch as he could hardly bear. The other attending Symptom was a total Stoppage in the ad'ions of the heart; and of courfe the Sace was pale and ghaftly. Not the leaft ' Signs of motion in the heart could be felt. In this ftate he was about three quarters of an hour. He was attended by Drs. Hunter, Sir George Baker, Sir William Fordyce and Dr. Huck Saunders. As he was perfedly fenfible at the time, and could perform every voluntary adion, he ob- ferved, that he was not breathing, which aftoniftied him; and at firft conceiving he muft die if he did not breathe, he performed the ad of breathing voluntarily. This Shews that breathing depends on the adions of the heart; and it alfo Shews, that under certain circumftances the actions of both may be fufpended, and yet death not be the confe- quence. As he Spoke while in this fit, without attending to his breathing, it Shews that the breathing which produces } Sound, is voluntary ; and if we had only the power of in- voluntary breathing, then probably we could net fpeak; for it is probable we could not regulate the adion of the glot- tis and tongue, which are voluntary, to fo regular an adion of the lungs ; for in Speaking, it is the one ading So as to correSpond with the other, both becoming voluntary. A gentleman who had a Singular afthmatic affection, his breathing gradually ftopt, and again gradually recovered, but became violent, and this constantly and alternately held two or three minutes; and when the breadiing ceaSed yet he Spoke, although but faintly. In thofe animals which have two ventricles, it has been aflerted by feme, that their adions arc alternate; but ob- fervation and experiment fliews us, that the two auricles contrad together, and that the two ventricles alSo con- trad together. This c«n be obferved Simply by looking on the heart in its adions ; and if we in that State make a pundure into the pulmonary artery and the aorta, we Shall find the jet in both at the Same inStant, corresponding with the contradions cS the ventricles. Indeed the circulation in the Scetus is a prooS of it; for in the child there would otherwife be two pulfations in Stead of one. This alternate motion of the hoavt is quicker in fome clafles of animals, than others ; in Some being extremely quick, in others very flow. In all the more inferior or- ders cf animals, I believe it is the floweft; and this may Of the" vafcular fyflem. M3 probably be in fome degree in proportion to their imper- Fedion. It is alfo flower, probably, in each clafs in pro- portion to the fize; and we know it is Slower in each Species, in fome degree in proportion to the fize ; though not exadly fo. The impulfe is alfo found to be quicker in the young than in the old of each fpecies, in greater pro- portion than what we find arifing from fize only. Thus the motion of the heart of a catterpillar is extremely flow, and alfo of a fnail. The motion of the heart in fifh is not frequent; and we know it is extremely Slow in the amphibia. But in thoSe poffeffed of two ventricles, as in birds and quadruped, the motion of this vifcus is much quicker. In them too it differs very much in proportion to their fize, although not nearly in the fame proportion. Thus a horfe's pulfe is about thirty-fix in a minute ; while a man's is about Seventy. In the Same Species it is nearly of equal quick- nefs ; for in a man of three feet high, the pulfe was eigh- ty, while a man above eight feet high, had a pulfe about fe- venty. VI. GENERAL OBSERVATIONS ON BLOOD- VESSELS. By the veffels in an animal, are commonly understood thofe canals which carry the juices ofthe body, called the blood oS the animal, to and Srom the heart, Sor the im- mediate purpoSes oS the animal ceconomy ; and in thoSe animals where no heart is to be Sound, yet veffels are Sound, though their uSes arc not So demonstrable ; and in Some of a Still more interior order, where no veffels can be demonstrated, yet, Srom analogy, canals may be SuppoSed to exift ; and thoSe Should ftill be called veffels*. The vaScular Syftem in an animal, is, in Some degree, to be confidered as the efficient part ofthe whole animal * Cf this, I am not certain. I have an idea, that fome animals abforb their nourishment, even without action, Somewhat fimi- lar to a fponge ; but difpofe of it immediately by converting it into its own increafe. D d 144 Of the vafcular fyflem. refpeding itfelf; every other part of the body being mor* cr lefs SubServient to it, and depending upon it, Sor. exist- ence and Support; and thereSore the greateft attention Should be paid to every circumftance that can poffibly ex- plain the various uSes of the veflels ; Sor there is no opera- tion reSpeding the internal ceconomy oSthe animal, but ij perSormed by them ; inSomuch, that Sor the convenience oS the veflels in performing thofe peculiar adions, they Seem to constitute various combinations, which are called crgansf. And although many parts have actions, in- dependent of the veffels, yet thefe are not for the pur- poSes of growth, fupport, etc. So that the veflels are conftruded for the immediate uSe oSthe machine, and may be called labourers in the machine. This naturally im- plies Something that i$ not a veflel, or veffels ; a Something that constitutes the different parts of the body, and is only more or lets vaScular. They are probably the very firft ac- tive parts in the Syftem ; Sor we find them in adion be- Sore they have Sormed themSelves into a heart; and in Such a State oS parts we find them the only part that has any Strength ; the other parts only preparing for adion : this is fo remarkable that we can diffed the veffels of a chicken in the egg without injedion, the other parts eafily giving way. TheSe parts are formed of living animal matter, fo compofed as to conftitute the different ftrudures fitted for theh different ufes in the machine ; yet fome parts are fo vafcular as to appear almoft to. confi ft wholly of veffels; z% if veflels were formed into fuch ftrudures; but this, wx cannot conceive, for then they muft lofe the adion of vef- ills. In thoSe animals where the vafcular Syftem is connected with a heart, which may be called the termination, as well .as origin of the veffels, we find that viScus to make So ma- + I erhapsit may be diiffsdt to give a definition of an organ that will meet every ones ideas ; or will dhtinguiih thofe bo dies, accurately, from what may he faid, not to be an organ. A mal'Je maybe called an organ ; but I would only confider it aniongrhe materials of which an organ is compofed. I have the fame idea of elaftic Sublrances, ccilular membrane, bone, cartil- ;.");(,', etc I would, 3t p-efeut, dc-n.-c an organ to be a part of a particu- lar conltnictioo. compofed of a variety of S.ibltances, which are ccnY.iined together to ani'w er Some particular purpofe, which is »he r.i'ilt of the actions ottlie whole. Of the vafcular fyflem. I a 5 terial a part of this Syftem, as to require particular atten- tion. In many oS theSe animals, we find two Syftems of vef- Sels, the arteries, and veins ; and moft probably they exift in all of them ; there is alfo a third, which confifts ot the abSorbents. The heart is the Source oS the arteries, and the termination of the veins and abSorbents. The two firft depending on each other, form the circulation; and the third, is effential to both, bringing the materials which are to circulate*. The arteries are to be confidered as the ading part cf the vafcular fyftem, Since they perform a variety of adions, the ufes of which are very important in the animal cecon- omy. They may be called univerSal, or constitutional, for their adions are immediately produdive of health, cr difeafe, in the conftitution ; and iS they could be diSeaSed as a Syftem, that diSeaSe would, of courSe, be univerial ; as their adions are expreffive of health, or diSeaSe, they be- come alio one means of discovering either. There is no internil operation in the machine refpeding growth, natural repair, and Secretion, that is not perform- ed by them : no new part is Sormed, nor additional altera- tion made in the ftrudure of natural parts, nor repair for the lofs of natural fubftance, either by diSeaSe or accident, but is made by the arteries, although of all operations we know nothing, but from the effed produced. Thefe oper- ations are performed by the termination of the arteries, which may be fuppofed to be of three kinds : one may be called arterial, conveying debelitated blood into the veins, and through their whole length, mav be called arteries : another kind confifts cf the feparaters from the blood, per- forming the different fecretions : and the third contains the Sormers and Supporters ofthe body : the two latter kinds I Should not call arteries, they are the workers, or labour- ers. Tiie abforbing Syftem alfo takes a very adive part in the auimal ceconomy, whether natural or difeaSed, and Serins in many adions to be the antagonist ofthe arteries; while the veins are much more paifive, being principally employ- ed in returning the blood to the heart. * This fy.lem is toi exten'.ive to be defcrib?d, hi the pre- ffnc work, although it wll be necefftrv t>deferibe on.; ufe n.>: hitherto atcrlbcu-jd to ir, as it explains one part of my f. !te..i of difeafe. j 46 Oj the vafcular fyflem. It is probable, that every part of the body \& equally vafcular, although they may not all have equal quantities of blood paffmg through them, which muft arife from the fmallnefs of the veffels, and not from their being Sewer in number. When we Say that a part is very vaScular, we can only mean that it is vifibly lo, by having a large vef. Sel, or veffels, going to it, and ramiSying in it; Srom which circumftance it contains a certain proportion of red blood, rendering the veffels vifible ; which may alfo eafily be made conSpicuous by injedions. Where the veffels are fmaller this is not the caSe. When we Say, thereSore, that a part is not vaScular, we mean it is not vifibly So; but ftill we muft fuppofe Such parts to be equally vaScular, fo Sar as refpects their ceconomy within themSelves ; but in Such parts I conceive the blood to be more languid in its motion. Many parts appear to be much more vaScular than they really are, from their veffels dividing, andanaflomhing, and taking a winding courSe before they terminate*; for it is by the number of terminations cf an artery ii a given Space, that a part is made vafcular, or not vafcular : mufcles ap- pear to be more vafcular than they really are. When partt have another ufe, in which blocd furnifhes the materials to be diSpofed of, as in Secretion, and reSpiration, where veffels fitted for Such purpoSes are Superadded, then parts become propcrtionably more vaScular. When blood doea not Seem to be the matter to be diSpoSed oS, yet if there are other operations continually carried on in a part, befides its Simple Support, as in a muScle, which has both the power oS contradion, and confiderable SenSation, etc. then the veffels are larger, and of courfe appear in great numbers: this is evident in the living body, for if a mufcle is hardly allowed fo ad, its veffels become Small, and it becomes pale ; but iS thrown into a more violent adion, Sor a con- tinuance it becomes red ; we cannot here SuppoSe an in- creaSe oS veffels, but only an increaSe oS Size. Thus we have parts vaScular in proportion to the quantity of adion they are capable of, or under the neceflity of performing: and this particularly in parts whoSe uSes may be called dou- ble, as the organs of fecretion in general, brain, and muS- cles ; even in inflammation, and in proportion as thefc * By fimply cutting into the fp? rmar'c arterv rf a bull it ap- pears to be extremely vafaikr, though, according to o r dta et \ afcului iry, it is as ii:tle fo as any part. Ofthe vafcular fyflem. 147 parts are employed in their peculiar adions, they become to appearance more vaScular. Some animals have natural- ly red muScles, without its being the effed oS confiderable adion : this is very remarkable in the hare ; but the red- neSs in the muScles cS this animal may be intended to adapt its muScles naturally Sor violent exertions at all times. Muf- cles are oS different colours, reSpeding red and white, in the Same animal; but that I believe is alSo in proportion to the quantity of adion the parts are put to. This effed the epicure is well acquainted with; he knows that the wing of a partridge is whiter than the leg : and that the leg of a woodcock is whiter than the wing. The yeal of this country is a remarkable inftanee of this; for the calf is hardly allowed to Stir, and the mufcies are white; but when the calf is allowed to follow its mother, the muS- cles are oS a reddifh colour: it may be, however, remark- ed, that white meat is commonly the leaft juicy ; and we find it remarkably So in thoSe animals which are Sed Sor this purpofe, becauSe, they require nothing but their Sim- ple Support, and having little cr no adion within them- Selves, they have but little wafte. Such change oS appear- ance we find carried to a confiderable extent in the uterus, at the time of the menScs; but much more particularly at the time cf uterine-geftation, where the veflels increaSe both in fize and length, in proportion to the adions re- quired. But parts whofe uSe in the machine may be Said to be paffive, as tendon, cellular membrane, ligaments, in-; vefting membrane, bone, and cartilage, which laft is pro- bably the moft paffive, have all Small ve ffels, and oS courSe but Sew that are vifible. As bene, however, is compoSed of two parts, viz. animal Subftance, and earth, it is pro- bable there may be more adion required to Sorm the latter, than either tendon or cartilage, and thereSore there will be more veffels. As a further proof that this is a general principle, we find that all growing parts are much more vafcular than thoSe that are come to their Sull growth; becauSe growth is an operation beyond the fimple Support cS the part : this is the reafon why young animals are more vaScular than thoSe that are Sull grown. This is not peculiar to the na- tural operation oS growth, but applies aifb to diSeaSe, and reftoration. Parts become vaScutar in inflammation ; the callus, granulations, and new formed cutis, are much more vafcular in the growing ftate, or when juft formed 148 Of the vafcular fyftem. than afterwards; for we fee them crowded with blood-veS, tels when growing, but when full grown, they begin to lofe their vifible veflels, and become not even So vaScular as in the other neighbouring original parts, only retaining a Sufficient number of veflels to carry on the fimple ceconomy oSthe part; which would now Seem to be leSs than in an ori- ginal part. This is known by injedions, when parts are in die growing ftate, or are juft grown, and Sor Some time after. We may obferve, when the fmali-pox is cured, that the remains of the puftules are red, and continue So for fome time; which is owing to thoSe parts being vifibly more vaScular than common : and thoSe who have had die fmall-pox Severely, are, in general, aSterwards mere pale than others, when thoSe parts have arrived at their perma- nent ftate. IS we cut into a part that has had a wound, or fore, upon it, which has been healed for a confiderable time, we Shall find that the cicatrix, and the new formed parts, are not nearly So vaScular as the original, which correspond* with what has been advanced ; for we know that thoSe parts are not equal in power to original parts. In Short, when- ever nature has confiderabic operations going on, and thofe are rapid, then we find the vaScular Syftem in a proportion- able degree enlarged. The number of veffels in a part, and alfo the circulation cf the blood through them, appears to keep pace with its fenfibility; for firft we find that moft probably all parts endowed with veflels are fenfible ; and all fenfible parts are, to appearance, very vafcular. Where any increafed adion is going on, requiring Increafed fenfibility, there is alio an, increafed circulation through thoSe veffels, as in the parts of generation, during the lime of coition, more cSpecially in the female ; and this increafe of veffels, circulation, and fenfibility in a part, takes place in difeafe, as is well iliuf- trated in inflammation, where the whole feems to be in- cre.ffed in the Same propoction, efpecially the two laft, viz. circulation and feniioihty. Thefe observations cerei only be made in animals which have red blood ; and beft in thofe which hive the moil red flood ; but it is not noifihle to aScertain, with accurac, tltf •v--o port Ion that one blood-veffel bears to another, So as to know the exact quantity of blood each p—t may poffff-;; which would h-etcer aScertain ■ he adion of the ea-t; for d:ey may he Said not to be n:-.ffu-abie whh env decree cf Of the vafcular fyflem. 145 accuracy; and therefore fuch inveftigation muft be taken in the grofs. Veflels have a power cf increaSe within themSelves, both in diameter and in length ; which is according to the necef- fity, whether natural, or diSeaSed. The neceflity appears to ariSe Srom an increaSe of the part to which the artery is going, the formation oS a new part, or an irritation. The firft may be reckoned the natural increaSe oS the body: the Second, the occafional increaSe of parts, as oS the uterus, in uterine-gefiation, where the vefltis are increafed in width, in proportion to the whole Solid contents1, including the young : befides this, they ace considerably increaSed in length before they reach the uterus, which obliges the Sper- matic artery, in particular, to be thrown Into a Serpentine form : this is more remarkable in Some animals than in the human Species. Inftances oS new Sormed parts, where the veffels are in-- creaSed, are to be Sound in the Stag, cr all thoSe of the deer kind which eaft their horns; fuch animals having the arteries confiderably increafed zt the time the young horn is growing, fo that the carotid arteries, which before had only to Supply the head, and the external carotid, which beSore had only to Supply the fides cS the head, now become larger, and are continued into the horn, which is extremely vaScular. ASter the Separation of the Scetus, or the Sull growth of the horn, the veffels naturally leffen, to adapt themfelves to die diminished fize of the parts. It is curious to obferve how veffels become enlarged upon any irritation ; not only the arteries, but the veins; and not only the fmaller branches, but the larger trunks. This was evident in the Sollowing caSe : I applied a cauftic to the ball oS the great toe of a patient every other day, for more than a month, and after each application the furrounding parts put on a blufli ; and all the veins on the top of the Soot, as well as up the leg, immediately began to Swell, and became large and Sull. This was So remarkable, that the patient watched for this effed, on the days on which the cauftic was applied, from its happening only on thofe days. In difeaSes where there is an increaSed fize oS the part, as in tumors, etc. the increaSe oS veffels is no leSs conSpicuous; and they have the power of dilatation, and increafe of Strength, in proportion to the fize of the veflels ; which 15° Ofthe vafcular fyftem. are now endowed with new difpofitious, and adion, dif- ferent from thofe they had before. The arteries often perform difeafed operations in the boi dy, which become fymptoms both of local and constitu- tional adions, as in inflammation, fever, etc. for they are not only adive in local difeafe, but their adion often be- comes a Symptom of a constitutional difeafe, whether ori- ginal, ot ariSing from a local caufe: but thefe fymptoms become moftly fenfible to us in thofe arteries whofe adions we can Seel; becauSe they have a peculiar adion in their1 diaftole, as well as in their SyStole, which is fenfible to the touch; Srom which SenSation, we, in many caSes, judge of the ftate of the body at the time; as alfo the ftate of the caufe, when it is local, and out of fight. The heart, the Source of the circulation, is alfo affeded from the fame caufe; fo that its motion, and the motions of the arteries* commonly, if not always, correfpond. VII. VALVES OF ARTERIES. The arteries arifing Srom the heart, I believe in all ani- fcnals, have valves, which are So many flood-gates, to hin- der a return oS the blood into the cavities: and as there tre two main arteries in the human body, So there are two Sets oS valves, viz. one belonging to each artery. TheSe are Situated at the beginning of the artery, and from their Shape, are called femilunar. Veins have fimilar valves, al- moft through their whole courfe. The valves are inelaftic, being fimilar to the inner coat of an artery ; but the differ- ence in the properties of the valves, and the arteries themfelves, which are elaftic, will be, Surther confidered in in treating oS the uSe, and mode of adion of the valves. Each of thefe fets is made up of three valves *; but in veins, there are commonly only two. This difference in the valves of the arteries, and veins, is perhaps to bring the artery into a more rounded figure, than could have taken place by t .vo valves only : each of thefe valves is of a femilunar * I have found in the human Subject, only two valves to the aorta ; b-it this is very rare. Of the vafcular fyftem. \$\ form, having one convex edge, and the other nearly Straight. Thefe valves are attached to the infides of the artery, at its very beginning, by their femicircular edge, which is ob- lique ; the points, as it were, running a little way into the artery. Thefe terminations in each valve come clofe to one another; but the loofe edges, which constitute the diame- ter, are not cut Straight off, but rounded. There is, be- sides, a fmall body on each, attached to, or near, the edge, between the two points, called corpora-feSamoidea. TheSe bodies are not placed exadly on the edge, but rather on that fide next to the artery, leaving the edge oS the valve looSe : this Situation is beft adapted to their intended uSe; the rea- Son oS the looSe edge being a little rounded, and oS the bodies called corpora-SeSamoidea being placed there, ariSes Srom there being three valves to eadi artery. Each of thefe valves, with its artery, forms a pouch, whofe mouth, or cavity, opens toward the artery; and the convexity of eivchcf the valves, when the artery is dilated, makes near- ly the third of a circle, which is turned inwards, towards the centre of the artery, as well as towards the heart. It is from this oblique diredion in the attachment that the valves perform their office, fimply from the adion of the heart upon the blood ; and the blood upon the artery. This is entirely mechanical; depending on mechanical princi- ples alone, as much as the adion of a joint. I have above obferved, that the area dcfcribed by the valves is the Same with the artery, when that veffel is in its Syftole, their outer SurSace lining the inner Surface of the artery; but the artery being elaftic, its diameter becomes larger when the blood flows into it; and the valves being inelaftic, their looSe margins, or edges, are brought more into Straight lines acroSs the area of the mouth of the arte- ry, and nearer to each other, fo as to make an equilateral triangle. Thus they are fitted to catch the returning blood ; and the artery re-ading with confiderable force on the blood, preff-s on the valves, fo as to puffi them inwards : thefe having no preffure on the fide next the heart become convex on this fide, Shutting up entirely the mouth of the artery. Kcre then is an effed arifing naturally out of a variety of caufes, viz. the oblique diredion of the valves ; their want of elafticity ; die elafticity of the artery; and the dilatation of the artery ; fo that the return of the blood does not open the mouths of the valves, and in that way, E e 152 Of the vafcular fyflem. Shut up the mouths ofthe artery. To demonstrate this, let us. SuppoSe the extreme length of each of thefe valves to be an. inch ; then the circumference, of the artery, when in its fyftole, will be three inches: in that caSe the valves lie clofe to the fides ofthe artery, and deScribe a circle of three-inches circumference, (as in figure I.); but if you dilate this artery, as far as the valves" will allow, which will be rather more than one fifdi, the valves will run nearly in- to Straight lines., and make an equilateral triangle, (as in figure II.) whoSe fides are a little curved inwards. As the artery is filled Srom the contraction ofthe heart, it is dif- tended: and as it is diftended, the valves do more and more their duty, till at. length, by the full distention of the arte- ry, they are made to bulge inwards, and the loofe edges, with the corpora-feSarooidea, are pufhed Surther towards one another ; by all of which pofitions the area ofthe ar- tery is entirely Shut up. Figure I. Shews the artery in its Syftole,- with the three valves, nearly cloSe to its Sides. The two black dots are de- signed to rcpreSent the mouths of the coronary arteries, now covered by the valves. a a a. ... .The circular fedion of the aorta. b b.....The mouths of the coronary arteries almoft co- vered by the valves. c c c.. • • .The hollow pouch of the valves. d......The area within the valves. Figure II. Shows the artery in its diaftole, where the three valves, run nearly into Straight lines, making an equilateral triangle of the area of the aorta, d d d. But as their edger are rounded, and the bodies of the valves make a curve in' wards, they by thefe means fill up in part this triangular fpace, as is feen at f; and the corpora-fefamoidea, fill up the other part at e. In this way the whole area of the ar- tery is filled up. a a a......The circular fedion ofthe aorta, in its State of diaftole ; being now larger about one fifth. b b. ... ... .The mouths of the coronary, how quite ex- pofed. e c c e c c. . .The hollow pouch ofthe valves, now enlarged. fi.lSX. Fy.l Fn, Of the vafcular fyflem. lS3 d d d.......The circular edges which fill up more of the area of the artery dian if they were Straight. e e e.......The corpora-fefamoidea. The foregoing account is proved by injections againft the valves ; but it is ftill more clearly proved that the diaf- tole of the arteries makes the valves do their duty, when it is injeded with the current of blood : for in proportion as the artery is diftended, the valves recede from the fides of the artery : and if the artery is fully diftended, the commu- nication is entirely cut off between the two pieces of injec- tion, viz. that which is widlin the heart, and that which is within the artery. It may be objeded here, that it will re- quire a certain quantity ot blood to make thefe valves do their office : and when there is not that quantity, it muft be done by regurgitation. To this it may be snSwered, that nature always keeps a due proportion ; and all the parts de- pend On one another : So that the quantity ©S blood, that is juft Sufficient to keep the animal alive, is Sufficient to diS- tend the artery So as to Shut the valves*. The valves oS the pulmonary artery do not do their duty So completely as thoSe oS the aorta ; Sor in them we do not find the corpora-SeSa- moidea ; and iS we injed a pulmonary artery, towards the right ventricle, it does not So completely hinder the injec- tion pafling info that cavity : nor are the two portions of injedion completely Separated when the artery is injected from the ventricle as in the left fide. So far as refpeds in- jections, the fame observations are applicable to the valvulae tricuSpides ; thereSore I believe the valves oS the right fide oS the heart, are not So perSed as thoSe oS the leSt: Srom hence we may SuppoSe that the univerSal circulation requires, to be more perSed than that through the lungs. We muft See Srom this account oS the adion of the valves, that the * As people advance in life, efpecialjy men, we find the a« orta lofing its elafticity : and as it is acted upon with great force by the impetus of the blood, it lofes that elafticity in the ftate of its diaftole ; which throws the valves continually acrofs the area »f the veflels; and as the valves in thofe cafes com- monly become thicker, are often very irregular, and bony, we find that they neither recede from the fides of the aorra, during the contraction ofthe heart, nor towards it during the fyltole ofthe artery : So that more blood is allowed to regurgi- tate into the ventricle, than in a regular circulation. 154 Of the vafcular fyflem. mouths of the coronary crtsries are opened by the adion of the heart; for as the arteries dilate, they become more and more expoSed. VIII. OF THE DIVISION, OF BRANCHING, OF ARTERIES. As all the arteries in animals poffeffed of a heart arife from, or begin at that heart, by one, or two trunks only, they are obliged to divide into, or fend off branches, or fmaller trunks, which again divide into ftill fmaller, till at laft the whole body is fupplied by the ultimate divifions. This is called the branchinji, or ramification of arteries; and is fomewhat fimilar to the branching of a tree. This branching of an artery dees not depend on the artery itfelf, or on the powers propelling the blood, as in in a tree, but is governed by the formation ofthe body; that is, according as a greater, or lefs quantity of blood, or a greater, or lefs velocity is neceflary to different parts. Various modes of branching are made ufe of to anfwer the above purpoSes. In general the moft Savourable mode Sor the Sree paffage oS the blood is adopted, viz. branching with acute angles; more cSpecially thoSe which are to carry the blood Seme confiderable way ; and ftill more So in thoSe which are at a great distance Srom the propelling impulSe oS the heart; which I Shall now more particularly confider. As the Sorce oS the blood in the artery is Stronger, the nearer it is to the heart, the difference in the velocity of the blood, near, and at a diftance from the heart, if there was. nothing to retard it, would be too great for the difference in parts ; the near and the diftant parts being in many in- ftances of the fame kind. To keep up a velocity Sufficient Sor the parts, and no more, nature has varied the angle of the origin oS arteries, at different dift.inces, Srom the Source oS the circulation. Thus we find that none the heart the arteries ariSe by obtufe angles , Some of them being rcfled- cd and the angles become kefs and leSs, till at ten :h they Of the vafcular fyftem. 155. are very Sharp. The meft remarable inltance oS this is in the intercoftal and lumbar arteries ; becauSe Since they are a Set of branches in the body, whofe length and uSes are fo much the fame, if there be any difference in the angles, at the origin of the arteries, at equal diftances from the heart, it muft be made with regard to their length, Srom the ori- gin to the part Supplied. We find a difference even in the arteries which ariSe Srom the iutercoftals ; Sor they are much more obtuSe at the beginning of the intercoftals, than at their termination. The reaSon why this is not So evident, in all the acteries of the body, is, that there are fo few arteries on the fame fide of the body, which take the fame courfe, go to the fame diftance, and have the fame office: for fome parts require a greater velocity than others, which will make a difference in the origin of the two ar- teries, fuppofing they Should go the fame length, and take the fame courfe. We fee the fame thing in the Secondary arteries, Such as the Subclavian; Sor it Sends off its branches near its origin, at much more obftuSe angles than it does farther on. Haller, in his Phyfiology, Says, That the ar- teries ariSe at an angle oS Sorty-five degrees; which is the greateft angle in projedion : but he did not confider, that in projedion there are two powers, viz. gravitation, and the Sorce applied ; while the blood in the arteries has only one. It may be aflked, Whether the, blood in an artery of a given fize, arifing Srom a large one, is Sent in with the Same Sorce as if the artery had arifen from a much fmaller trunk ; or from an artery of the fame fize with itfelS, whoSe blood paffed with the Same velocity as in the large one ? We find Small arteries coming off at once from large ones, inftead of being a third, fourth, or fifth, Srom the large one. Arteries Send oft" their branches at a longer, or Short- er diftance, according to circumftances ; or, in other words, they divide, and Subdivide, mere quickly in Some places than in others. I believe this quick divifion is more pe- culiar to glands, than moft other parts, though it does not take place in all, as in the tefticle. They divide alSo quick- ly in the the Subftance oS the brain. In the kidney, this is alfo remarkable ; they wculd Seem in that gland to be hur- rying to their termination. The Same happens as Soon as, the arteries enter the Subftance oS the brain. Other parts appear to have the arteries elongated beSore they enter the part, as the Spermatic artery ; more efpecially in Some ani- mals, as the bull, boar, etc. and in the female, in the 156 Of the vafcular fyflem. time of uterine-geftation, where we Sliould exped the quickeft circulation, we find the arteries elongated very considerably, which throws them into a Serpentine courSe j ail oS which muft retard the blood's motion in the pan. We alSo find arteries playing in the parts, ramifying and anaftomofing, which diminishes the velocity oS the blood ; fuch as thoSe oS muScles, membranes, etc. We may Sup- poSe from the foregoing inftances, that in fome, a quick Supply of blood was neceffary in fuch parts : in the one for the drain ; in an other, for the fupport of the living powers : while in others, a more regular, flow, and even motion, anfwered the purpoSe better. Arteries, in common, paSs in as dired lines from their origin to their destination, as poSfible; but this is not uni • vcrfally the cafe, for in many parts they run in a terpen- tine manner; fo much fo in fome as to form a body of themfelves. Thus the fpermatic artery in the male of ma- ny animals, more efpecially the bull, is fo convoluted, as te form 3 body. In the female alfo, the fpermatic artery increafes its Serpentine courSe in the ftate oS uterine-gefta- tion. The internal carotid artery in man, and many other animals, as the horfe, where it paffes through the Skull, runs in a Serpentine diredion ; and in the lion, bull, etc. it forms a plexus. This would appear to anfwer too pur- pofes ; one to leffen the impulfe of the blood, as in the ve- tcbral, and internal carotid, the fpermatic artery, etc. the other to allow of the Stretching oS the parts, upon which the artery paffes, as the mouth, or lips, the uterus, and other parts oS the body, which admit oS being ftretched, or relaxed, as the bladder, ftomach, enteftincs, etc. indepen- dent of their elafticity. We find not only the different fyftems of veffels com- municating with each other, as the arteries with the veins, the veins with the heart, to be continued into the artery a- gain, and the abforbents with the veins, to communicate, in the end, with the whole, but alfo the branches of each fyftem, communicating with one another, which is called anaftomofis. Anaftomofing of veffels, is the opening of one veffel into another ; fo that if one of them be prevented from carrying its contents, the office can be performed by the other. Tiie moft common mode of anaftomofing is, when two Of the vafcular fyflent* 157 veffels run into one, or are continued into each other; or one veffel opens into another, from which others arife ; but diere is a peculiar communication between the two caro- tids, as well as between them and the vetebral, where a ca- nal of communication paffes diredly between them ; and this mode oS communication takes place between the two deScending aortas oS Some oS the amphibia. This anaftomofing is much more frequent in the- fmall- er than the larger arteries. We feldom find trunks anafto- mofe with one another. One reafon for this is, the great difproportion in number between the larger and fmaller arteries; but the anaftomofis is much more frequent in the fmaller in proportion to their number. The ufe of this is to give freedom to the circulation, as the chance of a Stop being put to it is greateft in the fmalleft arteries ; the cir- culation in them not being So Strong ; and paffing through parts liable to be preffed upon : this is readily feen in the transparent parts oS the living body, v/hen viewed through amicroficope. In Some part oS the body we find anafto- mofis in pretty large trunks ; but theSe are in parts effential to life, very liable to be compreffed ; or both. The meScnteric artery anaftomoSes by large trunks ; the mySentery being a part effential to liSe, and very liable to comprefllon, Srom indurated fceces compreffing the ar- tery. In this caSe, if they only anaftomofed by the fmall branches, on the inteftines, the circulation might not be kept up Sufficiently to preferve the gut. We obfcrve the fame thing in the brain; for there the arteries anaftomofe by large trunks, beSore they are distributed to the brain. The uSe oSthis is, that all parts oSthe brain might have art equal quantity oS blood at all times, even where'accident- had put a Stop to the circulation in any one veffel; for the fmall anaftomofis on the pia-mater, would not be fuflicient to keep up a due circulation ; every where in the brain as I believe the arteries do not anaftomofe in the fubftance of the brain itfelf. There are large anaftomofes in the hand, and foot, for the fame reafon, as in the inteftines. All the ufes arifing Srom the anaftomofing of the veffels are, perhaps, not yet perfedly understood : general rea- Sonscan,T think, be afligned Sor them ; but theSe will not apply to all caSes ; there is Something, therefore, more than we are yet acquainted with. The abforbents, and the veins, upon the whole, anaftomofe more frequently than the arteries \> yet that circumftance is reverted re- 158 Of the vafcular fyflem. fpeding the veins in Some places ; and in the inftances die uSes of theSe fyftems of veffels are alfo in fome mea* fure reverted. Where all the three Syftems of veflels have nearly the fame mode of adion, we find that their manner of anaftomofing is Somewhat fimilar ; and probably the dif- ferences might be eafily accounted for. Wherever they appear to be fimply carriers, then their mode of anaftomofing is Somewhat fimilar : however, the abSorbents anaftomoSe more Srequently than the veins ; and the veins more than the arteries ; and, probably, the ab- forbents anaftomoSe every where. This is not So much the caSe with the veins; and not in the leaft So in Some parts with the arteries* Let us See if we can atfign reaSons Sor all this variety in the different Syftems oS veffels. The abSorbents, from the office oS abSorbing, are to be confider- ed only as carriers ; and as they have no propelling Sorce applied to their contents, and their coats are not Strong, it is very probable, that a Sree communication between veS- fel, and veffel, Should take place; upon the Samegeneral prin- ciple, the veins alSo anaftomoSe ; although perhaps not fo frequently ; and this difference may be, becaufe they have in Some degree, a propelling power applied to their con- tents ; namely, the action oS the heart. The arteries hav- ing a very Strong propelling power applied to their con- tents, it was in then not neceffary as a general principle ; but where they are placed in fimilar circumftances, we find them fimilar in this reSped. Although the anaStomoSing oS veffels is upon a general principle very proper, yet in many caSes it would appear in the following p rts to be xer-j improper. The arteries do pet anaftomoSe in the kidnic s. This cannot "ariSe fimply from there being no occafion for it, on account of there being no lateral, mechanical obitrudion; Since Srom the fame mode of reafoning, the veins Should not anaftomoSe; which- they do, very Srtely : this want oS anaftomofis in the arteries, therefore, r.nfwers fome purpofe in the cecono- my of the part. In the liver, the branches of the vena- pcrta do not anaStomofe although the arteries do in their Smaller branches; we may, thereSore, SuppoSe Some par- ticular purpofe anSwered, befides free communication ; and I believe the arteries do not anaftomofe in the fubftance of the brain ; which makes the brain appear lefs vafcular than it really is. We may obferve, perhaps, as a general prin- Of the vafcular fyflem. \ $tf eiple, that arteries near to their destination, where they are to perforin their particular fundions, do not anafto- mofe. Thus the artery of the kidnies, the vena-porta* • th: arteries in the fubftance of the brain, do not anafto- mofe } nor do the arteries on the villous coat of the in- teftines. IS it be questioned, whether anaftomofes are a means of retarding, or accelerating die circulation, I Should anSwer, that they appear to me, to retard the blood's mo- tion ; although we find veffels anaftomofing as Sreely with one another, at the greateft diftance Srom the heart, as near to it; but at the Same time we may obServe, that where we Should SuppoSe it was neceffary Sor the circulation to be brifk, we find no anaftomoSes in the arteries, as in the lungs, . the kidnies ; and I bdieve hardly in the liver, except on the peritoneal coat, whoSe arteries are continuations of the hy- patic artery. I believe that the anaftomifing of veffels increafes their volume on the whole, and therefore allows a greater quan- tity of blood to be in them, than if they did not: that kind of net work too, which they make, increafes the mag- nitude oS the vaScular Syftem; for to anfwer this purpofej they take lateral • and circular courfes; which give them greater length, than iS they had Simply paffed between ori- gin, and destination, in Straight lines. The better to aScertain the velocity of the blood in the 2Tteries, at the different diftances from the heart, it will be neceffary to' know whether an artery be a cylinder, or a cone; and when it divides into any number of branches, whether the whole of thefe, taken together, be lefs, equal, or greater, than the veffel, or veffels, from which they 2- rofe ; and, therefore, whether they hold lefs, the fame, or more blood. It may be chferved, that arteries keep a pret- ty exad proportion with each other; the branches, with the trunk, etc. through the whole fyitem ; and therefore, whatever maybe their Shape, they preServe it pretty regu- lar, viz. iS they are cylindrical, they are So regularly; if conical, the Same. I Sliould Sufpcct, however, that the anaftomofing of the arteries, in fome degree, interferes with this regularity; but it is probable that the ultimate * This veflld Should be conHdend as an aiterv. Ff loo. Of the vafcular fyflem. branches may come back again, and correSpond with the original trunk. To aScertain this, it is neceflary to make choice of arteries, which for Some length either Send off no branches, or at leaft Such as are very Small, when com- pared with the trunk: Sor it is impoffible to meaSure with anv degree of accuracy the fize of branches, and then cal- culate their different capacity, in comparifon with that of the trunk, from whence they are derived : and I think it is reafonable to fuppofe, that whether an artery divides or not, the fize muft be the Same in both; Sor it is nccefTary that the ultimate effed ihculd be the fame. The arteries which are beft adapted for this experiment, are thofe of the placenta, and of the tefticles ; particularly in the bull. The carotid arteries in fome animals are to^ Jerably well formed for experiments of this kind; for though thefe do not give us the exad pioportions which the one end bears to another, yet they plainly demonstrate which end is the largelt. Tne arteries oS the placenta evidently increaSe in Size, the nearer they approach to the placenta ; and this is So very confiderable as to require no experiment, unleSs it be intended to aScertain the difference corredly. In the Sper- matic artery oS the bull, it is equally evident; but as thefe arteries are much longer than the diftance between their origin, and the parts which they are to Supply, it may be SuppoSed that this increaSe is peculiar to them, in order to aniwer Some particular purpoSe : but the carotid arteries in Some animals afford Sufficient proof that the arteries in com-" men become larger as they paSs on and ramify ; for the ca- rotids may be reckoned ramifying arteries, as they fend off branches. The carotid artery of the camel, among quadrupeds, and of the Swan, among birds, are very proper arteries for Such, experiments. To be as accurate as pofhble, I injeded the arteries of two camels, and the arteries of a Swan ; and that one end might not be more diftended than the other, the artery was well warmed, and placed in a perfedly horizontal pofition: the pipe was fixed into the lower end*, and the injcdion made fo warm, as to keep fluid fome time after having been in- jeded: in this pofition it was allowed to ccol. I made * The fixing tl e pipe into the lo.ver end was rather in fevoer of incrcaa::? the fize of iLh ei.d. Ofthe vafcular fyftem. 161 fedions Srom each end ; and, that they might be perfedl Y equal, I took a hard piece of wood, an inch thick, and bored a hole through it to the Size oS the artery, fo as to contain a Sedion exadly of that length, having a moveable button fixed at one end, which could be turned upon the hole, or off, at discretion. The artery being introduced through the hole, a projeding part was cut through, by a thin knife, in order that the artery might be divided at right angles to itSelf. After doing this, the artery was with- drawn, and the button was then turned upon the hole, fo as to Stop that end ; and the cut end of the artery introdu- ced to the bottom, or button : this piece, fo enclofed, was Separated in the Same manner. Having taken a piece oS the carotid artery from each end., which were of courfe exadly of equal lengths, I weighed them, and found that the Section of the upper end was one grain and a half heavier than that of the lower. The carotid artery of another camel, meaSuring three feet and a halS in length, was Sound to Send erf Sorty-four Small branches, about the fize oS the human interccital ar- teries ; with one as large as the ulnar. Of this artery, a tranSverSe Sedion, of one inch in length, being taken from each end, and weighed ; that from the lower end was found to weigh two Scruples, frcteen grains and a half: while that from the upper end, weighed only two Scruples, four- teen grains and a half. In Similar Sedions of the oppofite carotid, which fent off forty-feven branches, the difference in weight, between the uppsr and lower Sedion, was five gram0. Similar Sections Srom carotid arteries of a Swan being weighed, the lower fedions were found to be three grains and a half heavier than the upper ; the lower fedion weigh- ing thirteen grains and a half. Had the lateral branches been preferved an inch Ion ;, being the length of the fedions of the trunk, I believe each hiighi have weighed above a grain ; and in that cafe, the forty-four would have been nearly equal in weight to the trunk : Should this be true, the arteries increafe very confidcrabiy, not only in their ramifications, but in their trunks. I imagine if the carotid artery, in the camel, did not Send off any branch in its courfe. it would increaSe in fize, nearly in the Same propevi ion with the umbilical arte- ry, or the tpev.natlc, in the bull. i6z Of the vafcular fyftem. It is to be obServed, that as arteries divide they increafe in Size, much Safter than iS they did not: Sor inftanee, if a Sedion of an artery, two inches long, is equally divided into two, the fedion that is the further from the heart Shall be heavier than the other, perhaps, by one grain; but if the moft diftant fedion had divided into two branches, the two, taken together, would have: been a grain and a half heavier; if three branches, two grains heavier, etc. The increafe of fize in the arteries asithqp ramify, is an effed of the numerous ramifications. From what has been already faid, it muft appear that ar- teries form a cone, whofe apex is at the heart: and if this be the cafe, in the adult, we fhall find that it muft be more fo in the young fubjed ; and will every day become lefs, as the child increaSes in growth. The capillary arteries in the foetus are probably as nume- rous as in an adult, perhaps more So ; for we know that there is the fame number oS principal arteries in each. As far as we can trace them, they Seem to fend off the fame number of fmaller branches ; and in many parts we find a great many more fmall veffels in the foetus than in the adult. In the eye, the membrane of the ear, etc. in all grow- ing parts, Such as callus, granulations, etc. we find a great many more veffels, than in Similar grown parts ; or in the fame parts, when completely formed; not in proportion to the fize of the part, but more in number.. Thefe are Strong proofs that many arteries are obliterated in the adn;t. How much more vafcular, therefore, muft a child be, than an adult, in proportion to its fize, when in a much Smaller compaSs a greater number oS arteries are accumulated ! From this it would appears that the only great change in the vaScular SyP:em, is elongation oS the veffels. As we find very little difference between the blood of a fcetus, and of an adult, it is natural to infer, that the Smalleft veffels are nearly oS the Same fize in both ; for the termination of toe arteries, or what may be called the operative part of the arterial Syftem, being intended to perSorm the Same Sundions in the Soetus, as in the adult, it is reaSonable to SuppoSe, that the increaSe is in the length of the whole vaS- calar Syftem ; and that the increafe in the fize oS the trunks is in an uniform gradation, from the capillaries, towards the heart; but never becoming equal to the capillaries. Of the vafcular fyftem. 163 If the preceding account be true, or nearly fo, we fee that there muft be a great proportional difference between the fize of the two extremes of the arteries, in the young fubjed, and the adult. We may venture to Say, that the aorta in the child in not one-fourth of the fize of that vef- Sel in the adult; and that the capillaries are rather larger than thoSe in the adult, which would of itSelS make tiie whole capillaries in the foetus more dian four times the fize of the aorta in th * feme ; and as theSe arteries are very Short, the cone, oS courSe, inereaSes very fait. In the Soetus in utero, we arc to confider that the aorta, at the beginning from the ventricle, h larger than in the a- dult, in proportion to the quantity oS blood that paffes through the foramen ovale : and beyond the entrance of the canalis arteriofus the aorta is increafed in proportion to the Size of the canalis arterioSus ; and it is at this part its fize is to be eftimated : this probably makes the aorta, be- yond the entrance oS the canalis anterioSus, twice as large as in the adult, in proportion to their Size ; but the draw- back upon this, Srom the body, is the placenta; Sor the placenta is to be confidered as part oS the body, diSpofing of the blood that afterwards circulates through the lungs: however, when it is Separated, it may take away with it nearly its own proportion of blood ; although I rather Suf- ped it does not. But I do not SuppoSe it is equal to the quantity paffmg through the Soramen ovale, and canalis arterioSus ; and iS So, then the body has the overplus.' The aorta of a Scetus is, therefore, not only larger than tin.: of an adult, but larger than in that proportion wdiich the fize of the foetus bears to the fize of the placenta : or it may b* put in this view, that befides the difference in the fize ofthe aorta, in a young fubjed (as before obferved) and in an adult, the fize of the aorta, in the foetus, is ftill larger, viz. more than in that proportion which the circu. !aticn in the lungs of the adult, bears to the circulation in the lungs of the foetus; which is probably much more than that of the placenta. Experiment on the arteries of a child. I injeded the d^fcending aorta of the foetus, juft above die diaphragm, in the fimie manner as I did the ccradds in the camel, and fwa*n, by which means I injeded the mV- ficnteric artery, the fubject of experiment. i 64 Oj the vafcular fyftem. This artery has a trunk, which at firft docs not put o:T branches, and then fends off feveral; which may be called fo manv trunks. Thefe again do not immediately give off branches, and are thereSore meaSurable with the trunk, Srom which they ariSe. I firft made a'Sedion of the trunk of the mefenteric ar- tery, near its root, before it fends off any confiderable branches, one-third of an inch in length ; and then ano- ther Sedion of the Same artery, having the Same length, cloSe to the origin oS the firft branch : all the branches arif- ing Srom it being preferved of the Same length with the trunk itSelf. When they were weighed in oppofition to each other, the trunk without the branches was found to weigh thirteen grains and a half; while that with the branches weighed eighteen grains ; four grains more than the trunk. A fedion of the aorta, near half an inch long, being made juft above the origin of the inferior mefenteric artery, was weighed againft a fedion of the fame length, including the inferior mesenteric, likewiSe of the Same length ; the laft Sedion weighing one grain more than the other. The higheft amounting to fix grains, the lowcft to Seven. A Sedion of the lower end of the aorta, including a portion of the two iliacs, was weighed againft a Sedion of the two iliacs, which was equal in length, and theSe were Sound to weigh rather heavier. By the above is confirmed what I formerly afferted ; that an artery, not giving off branches, does not increaSe So Salt as another which dors, if we include all the br.mchc.0. From all that has been find, it appears that there muft be a much grecter quantity of blood in a foetus, than in an adult, in proportion to their difference oS Size ; and that the heart mult be larger and Stronger, in proportion, to move tills blood; which will probably Still circulate in tne Smaller veflels with leSs velocity. The whole oS thefe differences, between the foetus and" the adult, mult be intended for the purpoSes of growth; and indeed we may difcern the ncceSfity ot it: for if a child w:J.s not more vafcular in proportion to its fize, then the a- dnit, its growth, we might conceive, would only be in pro- portion to the number of its veffels; which would be twelve tonos 1: is than tccy .ire ; for a new corn child is only onc- twe'fth in fize to that cf an aclfft. A child would, there- fore, grow falter and faftcr ever: year; for inltancc, in Of the vafcular fyftem. i6S proportion to its fize, as the veffels would become nume- rous in that proportion. But this is not really the cafe, for children grow lefs and lefs, every year, in proportion to the fize ; only adding its firft year's growth to itfelS every Succeeding year ; though, perhaps, not quite So much, as the veflels rather decreafe in number* That this is the caSe may be proved by taking the eye Sor an example, which grows more the firft year after concep- tion, than it does any year after ; fo that the disproportion between the veffels of this part, in thofe two States, is par- ticularly great. The growth of an animal is, therefore, in proportion to the number of its capillary veflels: as the body grows, the veffels elongate to keep pace with that growth : the ca- pillary veffels at laft come to a ftand; and the arterial fyf- tem is daily lofing ground. The heart grows in proportion to the increafed length of arteries, that it may be able to throw the blood through the whole, but not in proportion to the fize of the whole body; becaufe the veffels do not increaSe in number, or Size, in proportion » the Size of the body. But as the heart increafes only in proportion to the fize oS the whole vaScular SyStem ; while the body increaSes Safter, and more, the heart cannot be in proportion to the fize oS the whole body; hence its adions muft in time loSe the power of e- longating the body, and become merely Sufficient to nourifh what is already Sormed. Perhaps it does not even conti- nue to do So much ; Sor it is not impoffible, that the body may begin to decline Srom the moment it ceaSes to grow; the'heart liaving pufhed the growth of the body, even be-' yond its own powers: to preferve it in that ftate. 166 Of the vafcular ftftem. IX. OF THE ACTION OF THE ARTERIES AND THE VELOCITY OF THE BLOOD's MOTION. Arteries during their diaftole, which ariSes Srcm an increaSed quantity of blood being thrown into them, uu creafe much more in length than width, being thrown in- to a turpentine courfe ; thereSore, inftead of the term diaf- tole, it Should rather be called, the elongated ftate. It is however, the increaSed diameter that becomes Senfible to the touch. This, probably, ariSes from the mufcular coat Oppofing the dilatation of the arteries, while it cannot the lengthening. The dilatation of the attery producing the Stroke, is either felt by the finger, or raay be Seen when Su- perficial ; but were we to judge ot 'the real increaSe of the artery by this, we Should deceive ourfelves ; Sor when co- vered by the integuments, the apparent effed is much great- er than it really is in the artery itfelf; for in laying Such an artery bare, tiie nearer we come to it, the lefs vifible is its pulSation ; and when laid bare, its motion is hardly to be either felt, or Seen. The more an artery is covered, especially with Solid bo- dies, the more is the pulSation to be felt, or Seen : thus tu- mors over large arteries have a confiderable motion given to them; and have often been SuppoSed to be aneuriSms. The knowledge of this fad arifing mere from experi- ment than common obfervation in the living body, may be a fufficient reafon for keeping to the old expreSfion, dilata- tion. This circumftance, which has been but little taken no- tice oS, produces an effed, which has alSo been unobServed. If the arteries had been dilated by the force of the blood's motion, as has been fuppofed, its motion Sliould be much lefs retarded than it is ; for even fuppofing that the in- creaSed area of the artery is the fame when elongated, as if dilated, and therefore holds unequal quantity to a dilated one, it muft appear evident, that the blocd v.hi not arrive fo quickly at tiie oppofite end. The continual repetition of the caufe cf this turpentine courfe coliccs the arterxs in many places to retain thi, Of the vafcular fyflem. 167 State, efp icially in parts that do not yield readily, as the Skull, upon which the temporal artery is placed ; and this reten- tion of the terpentine courfe, is ftill more obvioas in thofe arteries which have loft a good deal of their elafticity. However, this increafe of the artery is fo manifeft, as to be feit, or Seen : and produces what is called the pulSe ; which muft gradually diminish in proportion as the arteriesr divide into Smaller branches ; a Small artery having a pro- portional pulSe, and the arterial Syftem increafing as it goes along; both of which cauSes dimmifh the velocity of the blood, render the diaftole lets, and its motions more uni- form. From the deScription I have given of the heart, with its action, and the parts of whicli an artery is compofed, it muft appear that an artery is at all times Sull of blood, which is moving on with more or leSs velocity ; bscauSe it receives it Srom the heart, at interrupted periods; and when a given quantity is thrown in at one end, this will make a confiderable difference between this part and the other ; which part will oS courSe be more upon the Stretch; Sor although the artery dilates, yet as it is Srom the impulSe of die blood, the blood muft move much Safter on in the diaftole of the artery, than its Syftole. This part oS the artery will contrad, and throw the blood into the remain- ing part; but not with the Same Sorce it was received ; but Stiil the artery beyond will receive it Safter, than it will give it. By thefe means, all the parts oS the artery are brought to a more equal ftate ; Sor this additional quantity oc blood, that was at firft in the one part only, is in fome degree equally diffufed through the whole arterial fyftem ; by which means too, it is becoming proportionably flower in its motion: but all thefe circumftances will vary ac- cording as the arterial fyftem confifts of cylinders, or cones, and if of cones, then according to the extremity, which is the bafe ; ill of which may be conjedurcd, but cannot be exactly eftimated. Yet that the force of the heart might not be loft, the elafticity of the great artery, over the fmaller, is happily applied ; becaufe it propels the blood more forcibly on, between the Strokes of die heart: for although we are to fuppofe that the heart, which was capa- ble of difhnding a part, So as to make it read, and Send the blood through any given length, was alSo capable offending 168 Of the vafcular fyflem. it through that length at once ; yet we muft See, that by an elaftic power being applied at one end, while this is gradu- ally loft towards the other, the elaftic part acts with a Superior Sorce over the other, in the proportion as the other has lets elafticity. This other being alSo leSs upon the Stretch, is" overcome by that which is more So ; which is al- ways the end next to the heart: Sor the muScular part re- taxes, requiring hardly any Sorce to diStend it; and indeed, as the muScular power has contraded the artery, within its middle, or Stationary State ; and this more and more, as we get into Smaller veffels, the mufcular coat is at firft Stretched by the recovery of the elaftic power; fo that the blood paffes into the fmaller branches with much leSs re- sistance than it would have done if the veffels had been elaftic in proportion to their fize. TheSe proportions, however, in the blood's motion, arifing Srom the elaftic jpower ofthe arteries, will not be the Same in the Scetus, and adult; and will be ftill more different in the aged Subject: for in this laft the elaftic power oS the artety is diminishing, as well as the muScular, the coats becoming more rigid: befides which, the veffels vary Srom-a conical Shape, (whofe apex is at the heart, and bafis at their extremities) towards a Cylinder ; and this change is alSo increaSed by the lofs of many of the fmaller veffels ; fo that as we grow up, the bafe of the cone is gradually diminished from two cauSes. The elaftic power will allow of a quantity of blood in the animal, beyottd the natural ftate of the artery ; and the rnufcular power will allow oSa Smaller, without the animal being affeded, although the muScular alone would have anSwered both theSe purpoSes. Arteries then are the con- ductors, and diSpoSers oS the blood ; as conduders, they arc in every animal above filh, both paffive, and active; paffive, in admitting oSthe propelling power oS the heart; and active, in continuing that power to the extreme part. Befides theSe reaSons Sor a difference in the velocities of the blood, at different diftances Srom the heart, I conceive there is a material difference between the velocities ofthe blood, in thoSe veffels which carry red blood, and thofe which carry only the coagulable lymph, and the Serum; for where the red blood goes, there is a quicker return, than where theie is only the coagulable lymph, and ferum. For this, there are two reaSons, viz. that where the red blood paffes, it is commonly nearer to the heart, while the other parts go to a greater diftance : but, befides this, the vef- Of the vafcular fyflem. id, fels which carry the red blood, are larger, and I believe ramiSy more quickly; the velocity therefore oS the blood, is greater in them. Where the lymph and .Serum paSs on- ly, the velocity oS the blood is languid, and ,if appears merely to carry nourishment, fuch as in tendons, ligament, etc. So Sar we are to confider the above as a general principle arifing out of the conftrudion oS a blood-veffel; but they are Secondary, or collateral circumftances, ading iq as to accelerate, or retard, the blood's motion. Since the Solids and fluids have a mutual dependence on each other, and Since the Solids anSwer various purpoSes, for which, quantity, velocity, etc. are peculiarly neceflary, we find that this intercourfc between the two is with great exadneSs kept up. I have already obServed that the an- gles, by which branches oS an artery ariSe, either retard or allow of a Sre:r motion in the blood; but Nature ap- pears to have taken Still more care in retarding the blood's motion, where velocity might do mitchieS. She.Seems al- So to have taken more care about the blood's motion in Some parts than in others : as Sor example, in the brain ; a part which probably cannot bear the Same irregularity in quanti- ty, or velocity, of the blood, as many other parts oS the body. I Sliould SuppoSe, that by Sending Sour arteries to the brain, inftead oS one, or which would have been more re- gular, two, the Sorce of, the motion oS the blood is broken, as well as by the winding. courSe oS the internal carotid ar- teries. The verterbrae, likewiSe, are intended, we may SuppoSe, to prevent a too great velocity oS the blood; both becauSe the artery is longer than it need be, and the blood is hindered Srom moving in a Straight line : but befides the Serpentine courSe oS the arteries of the head, they pafs through a bone ; but principally the carotids, where the bony canal is clofely applied to the coats of the ar ery ; fo that there can be no pulSation here, but a greater velocity of the blood in thofe parts, and probably lefs in the brain. This I Should fuppofe retards alfo the motion oS the blood in the brain ; becauSe the blood paffmg through a Smaller place than common, muft meet with a greater refiftance, and thereSore a Small quantity muft paSs through this part iii a given time, So that the pulSation of the arteries in the brain Sliould be leSs than any where elSe : Sor we may Sup- poSe, that the motion is considerably loft by the blood com- G £ 2 I'7« Of the vafcular fyflem. ing into an elaftic canal oS the Same diameter, with that through which it paffed, beSore it came into the bony canal. IS then this motion is loft, and the quantity of blood is really leflened in a given time, its motion muft be more re- gular, and the pulSation leSs. In Some animals, die carotid artery is Sound to divide and Subdivide, Sorming a plexus, and the branches unite again before it goes to the brain.' This is called, rete mi- rabile ; and in animals, which have it, will certainly break the force of the blood's motion : but fince it is not univer- fal, fome peculiar purpofe muft be anfwercd by it. It is not in the horSe, and aSs, Sor inftanee ; but it is in the lion. Where the veffels anaftomofe, there is alSo a confiderable retardation to the blood s motion ; and they are Sound to a- naftomote a good deal on the pia-matter, beSore they enter the brain ; but I believe not within its Subftance. «e X. OF VEINS. The veffels* carrying the blood Srom any part of the bo- dy towards the heart, are called the veins: they are more paffive than the arteries ; and feem to be from their begin- ning, to their termination in the heart, little more than condudors of the blood to the heart, that it may receive its Salutary influence Srom the lungs. However, this is not univerSally the caSe, Sor the vena portarum would Seem to affume the office of an artery in the liver, and therefore becomes an adive part; and we have many veins formed into plexufes, fo as to anfwer Some purpoSe, not at all Sub- fervient to the circulation ; but ftill in this reSped, they are not to bereckoned adive. They differ Srom the arteries in many oS their properties, although in Some they are very Similar. They do not compoSe So uniform, or regular a Syftem of veflels, as the arteries, either in their Sorm, or ule, being * A vein is commonly a canal, efpecially that wMc'i carries red blood ; but in many animals it is entirety cellular yet I ufe the word as a genera! term, when applied to the blood. Of the vafcular fyflem. 171 fubjed to confiderable variety in their ufes, which are, however, paffive, not adive; and often anSwering, Srom their conitruction, collateral purpoSes. The coats of the veins, upon the whole, are not So thick as thofe of the arteries ; but differ materially in different Situations of the body. Thus they become thinner, and thinner, in proportion to their fize, the nearer to the heart: however, this ia not equally fo through the whole venal fyS- tem, but principally in the depending veins, as thoSe of the extremities, more efpecially the lower in the human, and ftill more fo, the nearer to the extreme parts. In fuch parts it is often difficult to diftingulih the vein from the ar- tery : yet this is not to be remarked in the veins of afeend- ing parts, or thefe coming from the head, or fuch as are horizontal, efpecially in the human fubjed ; and in ani- mals who have a large portion of their body horizontal, there is a little difference in the coats of fuch veins at dif- ferent diftances from the heart. I fufped the mufcular powers are much greater in what may be called aScending veins, than either deScending, or horizontal: and I believe, in general, it is very confiderable; Sor iS we look at the back oS our hand, and compare their Size in a warm day, or beSore a fire ; and in a cold day, they hardly appear to be the Same veins. They are not So Strong in their coats as the arteries, and their ftrength is in an invcrSe proportion to their fize in the extremities; and the reaSon is very ob- vious. They are more denSe in their coats than the arte- ries, yet in the dead body they Seem to admit oS the tran- sudation oS the blood ; Sor when there is the leaft degree of putrefaction, we can trace the veins with the eye, on the fkin, as if very large, the cellular membrane and the Skin being tinged Sor Some way on each fide of the vein. In the liver, we find injedions efcaping the vena cava hepatica, and getting into its iubitance in a peculiar manner. They have nearly the fame elafticity with the arteries. They are fimilar to the arteries in their ftrudure, being compofed of an elaftic, and mufcular fubftance; the elaf- tic in fome degree preferving a middle ftate, although not fo perfedly as in the arteries. The mufcular power adapts the veins to the various circumftances which require the area to be within the mkide ftate, and affifts the blood in its motion towards the heart. 17a Of the vafcular fyflem. The coats of the veins themSelves are vafcu'ar; although not very much So. The arteries arife from the neareft fmall ramifying arteries ; and the corresponding veins do not terminate in the cavity of the vicn to which .they be- long;, but pais off from the body of the vein, and join Some others from different parts; and at laft terminate in the common trunk, Some way higher. On laying open the jugular vein oS a dog, and clofing »ip the wound for fome hours, and then opening it, I ob- served the veffels of this part very diftindly. They were becoming inflamed, therefore turgid ; and I could eafily distinguish between the arteries and veins, by the colour of .the blood in them. Veins have interruptions in their cavities, called valves. They are thin inelaftic membranes, oS an exad Semilunar form; their unattached edge being cut off Straight, not curved, as in thole of the arteries ; and this is, becaufe there are only two oS diem, whofe circumference adheres to the fides of the vein. They are not placed in a tranfverfe diredion, fo as to cut the axis of the vein perpendicular- ly ; but obliquely, ps the valves at the beginning of the ar- teries, making a pouch, whofe mouth is turned towards the heart. They ,are attached in pahs, the two making two pouches, whoSe edges come in contad. In the larger veins of many animals, as the jugular veins of a horfe, .etc. there are often three valves, as at the beginning of the aortas but not So completely Sormed : theSe valves as it were, cut the veins into two at this part. TheSe two valves are not always of equal fize. At this part there are always two Swellings in this Sorm ; but I believe more in ,the adult, than in die young fubjed. They are not formed from a doubling of the internal coat, as has been imagined; for the internal coat is elaftic ; but the valves are rather ef a tendinous nature; from this circumftance, together with their Shape, and their mode of attachment to the fides of the vein, they alv/ays do their office whenever the vein is full, in the fame manner as the valves cf the arteries. The valves of the veins are chiefly in the extremities, ju- gular veins, and the veins on the exterior parts of the head; but never in the veins of the brain, heart, lungs, inteftines, liver, fpleen, nor kidnies. Ofthe vafcular ffttm. 173 Where a fmaller vein opens into a larger, there rt often a valvular ftrudure at the acute angles; but this is not conftant. The veins, taken altogether, are much larger than the arteries; but in the extremities, the veins that attend an artery, are fottietimes lefs. Neverthelefs, there are com- monly two oS them; but befides theSe, there are Superfi- cial ones, which are much larger than thoSe deeply Seated. The beft way, however, of judging, is by comparing them with the correfponding arteries, where there are no fuper- numery veins, as in the inteftines, kidnies, lungs, brain, etc. we find that they are larger than the arteries ; and this too, where a confiderable wafte has taken place of the 2rte- rial blood in the different fecretions. From this circumftance the blood's motion in them is flower; and they allow a greater quantity to be in the body at all times. There is a greater number of trunks of veins in the body, than oS arteries, at leaft vifible veins ; Sor wherever there is an artery, in common there is a vein ; and in many places too, one on each fide, which Sometimes make a kind of plexus round it; befides, there are many veins where there are no corresponding arteries, as on the SurSace of the bo- dy ; for in the extremities many of the larger veins pafij Superficially; but thoSe become fewer and Sewer towards the trunk oS the body. They are numerous alSo in the neck oS the human Subjed ; but in Some oS the vificera, as the inteftines, the veins and arteries correSpond in number very exadly. Dr. Hales, however, in his Staticks Says, that he has Seen a number oS arteries throw their blood in- to one vein, which, iS true, Shews that there are more Small arteries than veins. Although veins generally attend the arteries, there are Some exceptions, even in corresponding veins, as in the piamater; but they cannot all attend the arteries, there be- ing more Superficial veins on the extremities, and neck; but the large trunks do. The Supernumerary veins are not fo regular as thofe that attend the arteries, being hardly a- like in two people. The veins may be faid, upon the v/hole, to accompany the arteries ; and it is moft reafonable that this Should bi 174 Of the vafcular fyflem. the cafe, Since both perform the fame office of conduding the blood, the fame courfe muft anfwer equally in both: this, however, is not univerfally the cafe, Some veins being intended for particular purpofes, as the vena portarum; fome forming bodies, as the penis, plexus reteformis, and others varying their courSe Sor convenience, as in the brain ; the veins oS this viScus taking in general a very difftrent courSe Srom the arteries, but this is principally in the larger veins oS the brain ; Sor the Smaller, which are in the Sub- ftance, accompany the arteries. The intention of this Seems to be, that the largeft veins, called the finuSes, Sliould be So formed as not to be compreffible ; probably that there Should be as little chance as poSfible of any Stoppage to the circulation of the blood in this part. But in Some parts of animals they vary their courfe from the arteries, where we do not fo well fee the intention, becauSe it is not the caSe in others. Thus the veins in the kidnies of the cat kind and hysena have the veins, in part, paffing along the SurSace in the external membrane, like the finuSes in the brain. Veini Seldom or ever take a Serpentine courSe, becauSe a retard- ment in the blood's motion in them anSwers no particular purpoSe in the ceconomy of the parts ; and the more readily the blood gets to the heart the better. However, the plex- uSes, although not intended to retard the motion oS the blood, anSwer other purpoSes not immediately conneded with the circulation. Veins, upen the whole, anaftomoSe more Srequently than the arteries, eSpccially by their larger trunks, and more particularly in the extremities ; Sor we oSten See a canal of communication going between two trunks, and one trunk Shall divide into two, and then unite again. Where the veins and the arteries correSpond, their anaftomofes are nearly the Same". I believe they do not anaftomoSe in the lungs or liver ; however, the veins corresponding to the ar- teries, do not always Sollow this rule; Sor the veins in the Spleen and kidnies anaftomoSe in very large trunks, while the arteries do not at all. This oS the larger veins anafto- mofing more Srequentiy, is becauSe a vein is more eafily compreffed, and the blood has a ready paflage into another; beliefs, the valves render it more neceflary, for when the blood has got paft a valve, it cannot take a retrograde courfe, but may take a lateral: and indeed it is principally in thofe veins winch have valves that wc find thoSe large anaftomof- Of tht vafcular fyflem. 17 r ing branches; by this means the blood gets freely to the heart. As the area of all the veins is larger than that of the arteries, the blood will move more Slowly through them 5 and this is evident from every obfervation that can be made. It may be obferved in the large Superficial veins in the ex- tremities oS the living body, and the difference oS velocity in the blood Slowing from a vein and artery in an operation is very great. The blood, however, moves with a good deal of velocity in a vein: for if we Stop the circulation in the beginning of any of the Superficial veins of an extre- mity, and empty the vein above, immediately upon remov* ing the finger the blood will move along the vein falter than the eye can follow it; yet its motion is fo Slow as to allow the blood to lofe its fcarlet colour, and acquire the modena red ; and this more fo as it paffes on to the heart. The blood moves more Slowly in the veins than in the arteries, that it may come into the right auricle more Slow- ly ; for if the two venae cavae were of the fame fize with the aorta, the blood would have the fame velocity in them which the auricle, as it is now conftruded, could not have borne : but it may be probable, that the blood is affifted in its paffage into the auricle by a kind of vacuum being pro- duced by the decreafe of the Size of the ventricles in their contradion. , From the number of anaftomofing branches, efpecially by larger trunks, from the blood beiiig liable to temporary obftrudions in many places, and alSo moving with little force, its courfe becomes often very irregular, and unde- termined ; much more fo than in the arteries. The firft caufe of the blood's motion in the vein of a quadruped, is the force of the heart; for I think we muft fuppoSe that the heart can, and does carry on Simple circu- lation ; becauSe in paralytic limbs, where voluntary muScu- lar adion is totally loft, and where, I conceive, the invo- luntary is very weak, the circulation is continued, although,' I believe, with much lets velocity than in perSed and Sound' parts : befides, we have obServed, that the arteries continue the motion oS the blood in them where the heart either Sail/ to do it, or where an increaSed motion may be want- ed. The arteries, thereSore, will affift the, heart in pro- It h 176 Cf the v.fcuhr fydcm. pt'lling the blood through the veins ; however, it is affifted by collateral cauSes. The Second cauSe, is their muScular contradion ; which molt probably is in the diredion of the blood's motion, affifted by lateral preffure oS all kinds; becaufe the valyes will favour this courfe wherever they are. However, as the vr.lves are not univerfal, the motion of the blood in fome veins muft be carried on without them, and therefore they are not absolutely neceffary. Since we See the veins afluming the office of arteries in the liver of quadrupeds, birds, amphibia, and fifh, and much- more So in many oS the inferior orders of animals, the mo- tion of whofe blood is firft derived from the heart, we mufl fuppofe that veins have confiderable power in carrying on the circulation ; but the refiftance being continually removed at their termination into the heart, will dired and aflift the blood's motion in that diredion, more eSpecially when influenced by the adion of the veffels themfelves, or any lateral preffure. In thoSe veins which are accompanied by the arteries," the pulSation of the artery affifts in propelling the blood towards the heart; more efpecially where there are two or more attending an artery. When treating of the motion of the blood, in the arte- ries, I obferved that its motion was not in an Uniform ftream, but interruped, which arofe from the heart's ac- tion ; but as it receded from that vifcns,- that its motion gradually became more uniform, till at laft-it was nearly a continued ftream. However, it is not certain, but an al- ternate accelerated motion is continued into the veins, im- mediately from die heart, although it may not be an eafy undertaking to aScertain this: for fimply cbfervihg an ac- celerated motion in the blood of the veins, more efpecially the fmell ones, does not prove that this was an alternate increafe immediately from the arteries. Every artery has a pulSation in itSelf, immediately from the heart; but a fecondary vein, or one that is a third or fourth in order of fize cannot, becauSe it has more than one caufe ading upon it: for fuch vein is receiving the impulfe of the heart at verv different times, owing to the larger trunk receiving blood by a number of Smaller veins that come from a variety of parts : fo that if the trunk was to * receive it by Starts Srom the Smaller veins, it would only be a tremor, cr ccnSuSed motion. This'is a reaScn why this caufe could produce none in the Secondary veins. The Sad is, however, that there is a pulSation in the veins; Of the v ifular fyflem. I 77 Sor when we bleed a patient in the hand, or foot, weevs dently See a Strong jet, much more in Some than in others ; and much more here than in the bend of the arm. The query is, Docs this arife from the immediate ftroke of the heart ; or is it by the lateral preffure, occafioned by the Swell of the arteries ? To aScertain this the better, it is ne- ceffary to obServe Several things : we may remark that the pulSation in the veins is more in Some parts than in others : thus I Sliould SuppoSe it was more in the veins of the kid- ney, Spleen, lungs and brain, eSpecially the laft, than in many other parts : but this Srom the lateral Swell oS the ar- teries cannot, Srom the above observations, affed all parts alike ; Sor the veins on the back oS the hand being Superfi- cial, and not Surrounded with vaScnlar parts, could not be affeded by arteries : but ftill it may arife from the late- ral fwell of the fmaller arteries; and this acceleration, given to the blood's motion in the fmaller veins, is carried' to thofe on the back of the hand. But I think I have feen the difference in the projedion fo great, that it hardly could arife from that caufe alone: and, indeed, iSthis was the only cauSe, we Should have it in Some degree in every vein; for every vein is So far Surrounded as to be in Some meaSure affeded Srom the Swell of the arteries of the part : but we certainly do not perceive it in fo great a degree in the bend of the arm. The larger veins, near to the heart, have a pulfation which arifes from the contradion of the heart preventing the entrance of the blood at that time, and producing a Stagnation. This I faw very evidently in a dog whofe cheft I opened, and produced artificial breath- ing : but I could not fay whether this aroSe from the con- tradion of the auricles, ventricles, or both : but the vena cava fuperior has a contradion in itfelS, in both dog and cat, and, probably, in the human Subjed. Even breathing produces a Stagnation near the thorax ; Sor during inspi- ration the veins readily empty themSelves ; but in expira- tion there is a degree of Stagnation. Coughing, Sneezing, or Straining, in any way where the thoracic and abdomi- nal muScles are concerned, produces this effed. I think it is probable, that where there is an univerSal ac- tion oS the vaScular Syftem, the adions oS the arteries and veins is alternate. That when the arteries contrad, as in ma- ny Severs, the veins rather dilate, more eSpecially the larger. f I It 2 ( 17* ) PART II. CHAPTER I. UNION Br THE FIRST INTENTION. I Mat obferve, that all alterations in the natural difpo- fitions of a body are the refult either of injury or dif- eafe ; and, that all deviations from its natural adions arife from a new difpofition being formed. Injury is commonly fimple ; difeafe more complicated. The difpofitions arifing from thefe are of three kinds; the firft, is the diSpofition oS reftoration in conSequence of fome immediate mifchief, and is the moft fimple. The fecond is the difpofition arifing from neceflity ; as for inftanee, that which produces the adion of thickening parts, of ulceration, etc. This is a little more complicated than the former, as it may arife both from accident and difeaSe, and thereSore be- comes a compound oS the two. The third is the diSpofition in conSequence oS diSeaSe; which is more complicated than either, as diSeaSes are infi- nite. Yet many local diSeaSes although complex in their natures, are So fimple in their extent, as to allow the re- moval oS the diSeaSed part, becoming when that is done; fimilar to many accidents. As diSeaSe is a wrong adion oS the living parts, the res- toration to health muft firft confift in ftopping the diSeaSed i8o Union by the f>ft intention. diSpofitions and adions, and then in a retrograde motion towards health. In treating Systematically oS Such complaints as arc the objed oS Surgery, we Should always begin with the molt Simple, and advance gradually to the more complicated, by which means we Shall be more clearly understood. There are many complaints requiring the attention of a Surgeon, which cannot be called diSeaSe, becauSe having been produced by Something Soreign to the body, as in acci- dents, they are to be confidered as a violence committed upon it, altering in Some degree the ftrudure of parts, and confequently interrupting the natural operations al- ready deScribed. ..... The partsfo hurt not being able to purSue their original or natural mode of adion, are obliged to deviate from it; and this deviation will vary according to the nature of the violence, the nature of the part, and the ftate of the con- stitution at the time. An alteration in ftrudure requires a new mode of adion for its reftoration ; as the ad of reftoration cannot be the fame with what was natural to the parts before any alte- ration had taken place. > . CO The alteration of ftrudure by violence, requires only the moft fimple change in the natural adion of the part to reftore it; and of courSe die. moft fimple method oS treat- ment by a.rt, iS it be Such as to require any affiftance at all; Sor there are many accidents where none is neceffary. It will be proper to obServe here, that there is a circum- stance attending accidental injury which does not belong to diSeaSe, viz. that the injury done, has in all CaSes a ten- dency to produce both tire diSpofition and the means of cure. The operations of reftoration ariSe naturally out of the accident itSelS; for when there is only a mechanical altera- tion in the ftrudure, the Stimulus of imperfedion taking place, immediately calls forth the adion of reftoration; but this is contrary to what happens in diSeaSe ; Sor diSeaSe is a. diSpofition producing a wrong adion, and it muft con- tinue this wrong adion till the difpofition is ftopped, or wears itfelS out; when this Salutary effect, however, has once taken place, the ftate oS the body becomes Similar to that in a Simple accident, viz. a conficioaSneSs oS imper- fedion is excited, which produces the adion of reftora- tion. Union by the firft intention. 181 In injuries arifing from accident, we have hitherto fuppo- fed that the parts have no tendency to any difeafed adion, independent of the accident; for if they have, it is proba- ble that fuch a tendency may be Stronger than the difpofi- tion for reftoration, and in that cafe they will fall into the peculiar difeafed adion, as was explained when treating of fuSceptibility. Let us take the Scrophula and cancer as ex- amples, and we Shall find, that iS a part be hurt, which has a Strong tendency to Scrophula, it will, moft probably run into the Scrophulus mode of adion, in preference to that of reftoration ; and therefore, we have many joints, when injured, affirming the fcrophulous adion, called white 1 welling; or if a woman, beyond thirty years of age, re- ceives a blow on the breaft, it is more likely to acquire the cancerous mode of adion, than that of reftoration; which Should be well distinguished Srom what is immediately con- Sequent, viz.'the inflammation; Sor on this depends a knowledge oS diSeaSes. Although accident may be Said to produce an effed on a part (whatever that effed may be) which has a tendency to its own cure, yet there are oSten not only immediate confequences arifing from that effed, as inflammation ; and again, the confequences of this inflammation, as fup- puration; but the bafis of difeafes are alfo frequently laid by it, not by producing them immediately or naturally, but by exciting fome fufceptibility of the conftitution, or of a part, into a difpofition for a difeafe, which may be latent for a confiderable time, and then come into adion. Thus fcrophula, cancer, etc. often arife from accident, even where the parts in conSequence of the injury have gone through the immediate and the Secondary Stages oS a cure. ThoSe effeds oS accident which ariSe Srom the nature of the parts hurt, may be divided into Such as take place in Sound parts, and Such as effed parts already diSeaSed. The firft is what I Shall at prcSent treat oS, the Second, being conneded with diSeaSe, is not to our preSent purpoSe. The injuries done to Sound parts, I Shall divide into two Sorts, according to the effeds oS the accident. The firft kind confifts of thoSe in which the injured parts do not communicate externally, as concuffions oS the whole body, or oS particular parts, Strains, bruiSes, and Simple Sradures, either oS bone or oS tendon, which Sorm a large Jivifion. The Second confifts of thefe which have su. ex- 18i Union by the frftl intention. ternal communication, comprehending wounds of all kindg, and compound fradures. BruiSes which have destroyed the life of the part, may be confidered as a third divifion, partaking, at the begin- ning, of the nature of the firft, but finally terminating like the fecond. I. OF INJURIES, IN WHICH THERE IS NO EXTERNAL COMMUNICATION. The injuries oS the firft divifion in which the parts do not communicate externally, feldom inflame; while thofe oS the fecond commonly both inflame and Suppurate. The Same operations, however, very oSten take place in both, though the order in which they happen is reverSed; the firft becoming like the Second, by inflaming and Suppura- ting ; and the Second being in many caSes, when properly treated, brought back to a reSemblance oS the firft, and united by the firft intention ; by which inflammation and Suppuration are prevented. But when the liSe of a part has been destroyed by the accident, it muft neceffarily Sup- purate ; and thereSore theSe injuries will be rendered Simi- lar, in this reSped, to thoSe of parts which communicate immediately, and have not been united by the firft intention. That injury which in its nature is the moft fimple, and yet calls forth the adions of the part to recover from it, is a degree of concuffion*, where the only effed produced is a debility of the adions or fundions oS the whole or part, fimilar to that occafioned by a bruiSe, in which the continu- ity of the fubftance is not interrupted ; in fuch a ftate the parts have little to do, but to expand, and reinstate them Selves in their natural pofition, adions, and feelings ; and this is what happens in concuffion of the brain. The rupture of a fmall blood-veflll is, perhaps, the next in order of fimplicity; where the continuity of the part is broken, extravafation takes place, and the blood is diffufed into the common cellular membrane, into the interftices * Fere I mean concuSfion as a general term, not confining it tp the brain. Union by the ft/ft intention. 183 of Some part, or into a circumScribed cavity. But Should die veflel be either very large, or eflenrial to life, Such as arc femoral, bracheal, or coronary arteries; or fhould the rupture take place in a vital part, as the brain, or in inter- ftices or cavities belonging 10 a vital part, as in the cavi- ties of the brain, or pericardium, in ail fuch cafes the in- jury may kill Srom the extravafation aionc, however incon- fiderable may be the original mifcnLr. The operation of reftoration in this cafe, when the vital parts are not concerned or difturbed, confifts firft in the coagulation of the extravafated blood between the ruptured parts, laying, as it were, the foundation of union, next in clofing the ruptured veflel, or iD promoting its inofcula- tion, and Sometime after in bringing about an abSorption cf the Superfluous extravaSated blood. If the veffel cloSe, that effed is produced by the muScular contradion of its coats; but in what way it inofculatcs, whether by the two Ori- fices when oppofed having a mutual attradion, and inftead oS contrading the two portions oS the ruptured veffel elon- gating, So as to approach each other reciprocally and unite*; or whether a new piece oS veffel is Sormed in the interme- diate coagulable lymph, is not eafily determined. InoSculation, however, can only take place where the extent oS the parts divided is not great, and the oppofitc SurSaces remain near each other ; but even then it is moft probable that we-muft in part aficribe to another mode of union the communication oS veffels which takes place be- * fnofculaticn is a term commonly ufed by writers, but whe- ther it was derived from theory or obfervation is not material. The very few inftances where it ian be obferved, together with the want of accuracy in thofe who firft introduced the term, would incline me to think that it arofe Srom theory, or opinio!! only. 1 never could get an opportunity of coit-rving it in all my experiments, and observations on inflammation, except in the coats of the eye In many inflammations of that orgin, we find an artery or arteries parting from the tunica conjunctiva to the cornea and ramifyb g on that part. Thefe have been often cut acrofs to prevent the influx of blood ; rhe two ends are feen to fliriuk, but in a little time they are agsin perceived to unite, and the circulation to be carried en as before. In this there can be no deception; and to perform, therefore, fuch an operation effectually, a part of the veflels flu ail d be re- moved. I i i$4 Union by the firft intention* tween the two divided furfaces ; for where inofculatioii does not, or cannot take place, the union of the ruptured. veffels is produced by the coagulation of the extravafated blood of this part, which becomes vafcular. That the blood becomes vafcular, is clearly Shewn in the cafe of the blood extravafated on thetefticle. The Superfluous extravaSated blood is taken up by the abSorbents, by which means the whole is reinstated as much as it is in the power of the parts to do it. I may obferve here, that the power of recovery in the arteries is greater nearly in proportion to the fmallneSs of their fize, which is combined with feveral caufes, viz. their diftance Sroni the heart, their elafticity, their divifion into Smaller branches, and their accumulated diameters becoming larger, which allows them to recover. Secondly, there is an increaSed power within the Smaller artery itfelf abftraded from the above circumftances. This includes a great variety of cafes, and the moft Sim* pie difference which can happen between diem will be owing to the magnitude oS the ruptured parts, or to a dif- ference in the parts themSelves; or to the magnitude of the injury ; or to a difference in the effeds. It will compre* hend fimple fradures of all kinds, broken tendons, as is of- ten the cafe with the tendo-achilles; even many injuries of the brain producing extravafated blood, which is pro- bably the only way in which the brain can be torn wheq there is no fradure. Some of thefe will often require art to reinfbte them in the natural pofition, out of which they may have been put by the accident, or by fome peculiar circumftance attend- ing the nature ofthe part, as we fee in a fradure of the patella, or broken tendon, where the upper part being too far pulled up by the mufcles, it muft be reinstated by the hand of the furgeon, to bring the parts into a fituation more favourable to their recovery. But extravafations, even from the moft fimple accidents, are often fo Situated as to obftrud the adions of life; as for inftanee, in that affedion of the brain, which is called apoplexy. The fame thing happens in extravafations into the pericardium, or into any of the other vital parts, where little can be done, although much is wanted. In many o- ther parts, where the adions oS life cannot be affeded, yet the extravafations are often too confiderable to allow die parts to go through their proper modes of restoration. Union by the firft intention. i%$ The quantity of extravafated blood being often fo large as to diftend the parts, and form a kind of tumor, called ec- chymofis, of which I Shall now treat. The extravaSated blood in Such caSes being the only vifi- ble complaint, to remove it is the cure, which may be ef- fected by abSorption ; or, iS neceffary, by an operation. An ecchymofis we may confider aS oS two kinds, one in which the blood coagulates when extravaSated, the other where it remains fluid ; but this diftindion makes little dif- ference in the difeaSe itSelf, and oS courSe little in the mode of treatment; it Should be obferved, however, that the firft kind, for the moft part, terminates well; while the fecond Sometimes inflames and Suppurates. When theSe injuries get well by the abSorption of the blood, the cure is gradual, and often takes a confiderable time; but if the tumors become lefs and do not inflame, they fhould be allowed to go on to perSorm their own cure; and even where inflammation takes place, that fhould be permitted to advance to Suppuration, and the tumors to threaten burfting before they are opened by art, or what I believe would be Still better pradice, thdy fhould be left to open of themfelves. In fome inftances, a blow the caufe of the ecchymofis, may have injured the Superficial parts or Skin fo much as to produce inflammation ; and under Such circumftances I fhould recommend the caSe to be treated as an inflamma- tion arifing Srom any other caufe, without paying atten- tion to the blood underneath. It often happens that the blow has deadened the Skin over this blood, which deaden- ed part, as is uSual in Such caSes, muft, in a certain time, afterwards Separate Srom the living. Where this has taken place, and the extravaSated blood has coagulated, it has often been found to remain in the ca- vity, as a mere extraneous body, without ading, and with- out even allowing the ftimulus of an expofed furface, or of an imperfed cavity to take place. The edges of the Skin all round-'Shewing the difpofition to contrad over this blood, as if it wa!s a living part to be preferved, nothing has fcem- cd to be wanting to finish the cure but the blood being alive with due powers oS adion. In thefe cafes the common pradice has been to Scoop out the blood and diftend the internal Surface with waTm I i 2 186 Unix* by the'firft intention. dreftings to Stimulate it to inflammation, etc. and a Sore being the conSequence of this m :tho.l it goeo. on as fores commonly do. But in other caSes where the opening Lull ing to the coagulated blood has been very Small, I have fcen diat without any other means being uSed the blood has been gradually Squeezed out of the orifice by the contrac- tion of the Surrounding parts, till the whole cavity became So much contraded as to contain no more than what Seemed to Serve as a bond oS union to the parts ; and thus the cure has been completed without Surthsr trouble. The follow- ing cafe was treated in this way. CASE. Mrs. B—t fell backwards and pitched upon a pail which was behind her, and the left labium pudendi Struck againft its handle with the whole weight of her body. Within five minutes after the accident, the bruited part Swelled to as great degree as the fkin would allow; from which Sudden appearance of. the Swelling, and Seeling of fluduation, I concluded that blood had been extravaSated by tie rupture of fome fmall artery. I bled her, and de- fired a poultice to be applied to the part, in order to keep tiie Skin as eafy as poflible under fuch distention. Believing the tumor to arife from extravafated blood, I did not chufe to open it, that the bleeding might be Sooner ftopped by the preffure of the extravaSated blood againft die fides of the cavity. Some hours after the accident the fkin burft, and a good deal of blood came away. On examin- ing the wound I found the opening of confiderable fize, leading into a cavity as large as the egg of a goofe, and fill- ed with coagulated blood, which I did not remove for the reafons given above, that it might affift in ftopping the veS- Sels which were ftill bleeding. The poultice was continu- ed, the bleeding gradually became lets ; and every time I examined the part, I found the cavity diminished, but ftill filled with coagulated blood, which continued to be pufkd out of the wound, and after Some time a flcugh came off Srom the bruiSed fkin, which enlarged the fize of die wound. About a Sortnight after the accident the parts were all So much collapSed, as to have Sorced out the blood entirely, and there Seemed only a Superficial Sore, not above an inch long aud half an inch wide. What may it be SuppoSed would have been the conSequence, if I had enlarged the t Union by tie firft intention. 187 opening, fcooped out the blood and dreffed the part with lint, or any other application I might think proper ? The effed of fuch treatment would certainly have been a large fore, nearly of the Same fize with the cavity; and the fides of the cavity would have inflamed and Suppurat- ed. Is there not reaSon to believe that the coagulated blood, by remaining in the wound, prevented inflammation aver the whole Surface, and allowed the parts to contrad to their natural pofition, So as to leave no other Sore than that where the Skin had burft and Sloughed ? This pradice Should be generally followed in fuch cafes of ecchymofis. The fecond fpecies oS ecchymofis is that in which the blood has not coagulated but remains fluid. This cafe, al- though it alfo Srequently occurs, does not always terminate So wed as the former, nor allow of fuch a Salutary termi- nation, where an opening has been made, either by the accident, or by art; Sor then Suppuration will be produced all over the cavity ; more caution is, thereSore, neceffary to prevent an opening. It has oSten the appearance oS an incyfted tumor ; but being an immediate conSequence of fome accident upon the part, its nature becomes readily un- derstood, though fometimes from its fituation it has the fymptoms of an aneurifm attending it; neither does the caufe of it contradid this idea. If formed over a large artery the tumor will be attended with a pulfaticn; but when Srom this caufe it cannot be made to Subfide by preffure, yet it is not, therefore, to he fuppoSed harmleSs, as in Sad it requires to be treated with great caution. If the pulSation Should arife Srom the real influx oS blood, this will Soon be Shewn by the increaSe of the tumor, and will lead to the proper treatment, viz. opening it and Stop- ping the bleeding veffel. This Seldom happens from con- tufion, the kind oS accident deftroying in Some degree the free exit of the blood out of the artery; and if the tumor Sliould not increaSe aSter a certain period, even iS there be a pretty evident pulSation, we may then be certain that'it aflumes this Symptom Srom Some neighbouring artery cr arteries. The ecchymofls which is produced on the head of a child during birth, has Sometimes a pulSation, arifing from that of the brain, as the futures are ftill open ; and every tumor of the Scalp, whether Srom.a blow or any o- ther cauSe, may be mistaken Sor ancuriSm, if it appears 18S Union by the firft intention. beSore the forrtmelle be clofed, and Should it be opened without proper examination, may diSconcert the ignorant Surgeon. That the blood does not coagulate in this Species of ec- chymofis, muft ariSe from Some peculiar mode of adion in the veflels, occafioned by the effeds of the injury : for I apjSHfehend that in fuch cafes, the blood dies in the ad of extravafation, in the Same manner as the blood of the metj- ftrtral difcharge whenever it is effufed. The ecchymofis which we have mentioned, as happen- ing very commonly to children in the birth, particularly under the Scalp, requires nothing to be done ; as by waiting with patience, the whole will in general be abforbed. Although this is commonly the event in new born infants, yet ecchymofis does not terminate alike favourably in other cafes, the tumor often remaining for a confiderable time without undergoing any change, and aSter months, Some- times disappearing, but at other times inflaming and Suppu- rating. When an extravafation of bioOd takes place between tire fcaip and head, in confequence of a blow, which is very common, and continues fluid, we find a kind of ridge all round the bag, and by preffing all round the edge of the bag, the finger links, fo as to give diftindiy, (we conceive) the feel of a depreffed bone ; but this feeling of a depref- fion following the edge ef the ecchymofis all round, is a proof that it cannot be depreffion of the bone ; becaufe no depreffion could be fo regular, nor would any depreffion be of the fame extent with the ecchymofis. The edge of the Scalp Surrounding the ecchymofis Seems to be raffed, and I believe it is ; if fo, then Something fimilar to the ad- hefiVe inflammation muft have taken phtce to Set bounds to the extent of the ba'g, and to hinder the blood from getting into the cellular membrane. It might perhaps be the beft pradice to make a Small o- pfcning into fuch tumors with a lancet, and by letting out the blood get the fides of the cavity to heal by the firft in- tention. When the parts inflame and firpputate, the cafe is to be treated as an abfceSs. This Sometimes disappears by reSolution : but this being feldom permitted, the ecchymofis is reduced either to the State oS a Srelh Wound, which is allowed to Suppurate, or an abSceSs ; Sor Surgeons are induced to open early, by See- ing-an inflammation, andfeeringa fluduation, two Strong Union by the firft intention. IS9 motives when every circumftance is not well attended to ; but in fuch cafes I Should wait till I obServed evident Signs oS Suppuration, viz. the thinning of the Skin over the mat- ter, and pointing of the contents, which are the only true marks of the formation of the matter, as well as of its coming near the Skin. IS the blow Should have deadened a part of the Skin, then a Separation of the Slough will take place, and expofes this cavity fo as to produce Suppuration. And this is to be confidered as a Step ftill Sarther removed Srom the moft Sim- ple Species oS injury, than where the blood coagulates. I am not able, under Such circumftances, decidedly to fay which is the beft pradice, whether to leave the Slough to Separate, or to make a Small opening and allow the blood to efcape ilowly Srom the cavity. In both kinds of ecchymofis, when inflammation has ta- ken place in the Skin from the violence, if it has not advan- ced to fuppuration, the objed of the furgeon Sliould be to bring about the reSolution oS the tumor; when he finds there is no Surther increaSe oS the tumor, fie may conclude that reSolution is beginning to take place; which being cleariy ascertained, he is then to affift in exciting the abr Sorbents to do their duty, in order to take up the extravaSat- ed blood. I believe the beft exciting power is preilure, which if urged beyond the point oS eafe, Sets the abSorb- ents of the parts to work, for the purpofe oS removing the fubftance which jfreffes, or the part that is preffed: but moft commonly the body preSfing, iS it be Subjed to the laws (or powers) oS abSorption ; and in this caSe the extra- neous Subftance prefling on the inner Surface of the cavity, is the extravafated blood which we wifii to have removed. The following cafes explain this. A lady fell and Struck her Shin againft a Stone, a confi- derable ecchymofis came on almolt immediately, and the fkin over it inflamed to a confiderable degree. The blood had net coagulated, there was therefore a perceptible fluc- tuation underneath, and her phyfician recommended an o- pening to be made. I was Sent for, and on examining the part, was rather of opinion, from the Surface being a regu- lar curve, and no part pointing, that matter had not form- ed ; I therefore recommended patience; the Subfidmg of the inflammation, and the application of fuch preffure as (he could bear without uneafinefs, cauSed the whole tumor to be abSorbed. 100 Union by the firft intention. A man was brought into St. Ceorge'3 HoSpital whofe thigh had been run over by the wheel of a cart; a very large enchymofis was formed on its infide, and a confider- able inflammation of the Skin had taken place. The blood had net coagulated, therefore a fluduation could eafily be felt; but as there was no appearance of pointing, Similar to that of matter coming to the fkin, I was in hopes that Suppuration was not coming on ; and although the inflam- mation was confiderable, I SuppoSed that it might ariSe ra- ther Srom the violence of the accident than from the extrava- fation : I waited therefore the event; faw the inflammation gradually go off, and as that fubfided I obServed the tumor decay, although it was very flow in its decreafe : I then direded a flight comprefs fo be applied, after which the tumor evidently diminifhed much falter than beSore, till the whole was abSorbed. The union by the firft intention uSually takes place So Soon aSter the injury, that it may be Said to be almoft im- mediate ; Sor when the blood has coagulated in Such a fitu- ation as to adhere to both SurSaces, and So as to keep them together, it may be Said that the union is begun. It is not, however, immediately Secure Srom mechanical violence, and the blood itSelf by lofing its power of retaining life, may likewife be rendered unfit to preferve the communica- tion with the adhefing furface, (by which it is conneded with the body at large) and thus the union be of courfe pre- vented. If there be no fuch impediment, then the union of the parts may be very quick ; but it will be in fome de- gree according to the quantity of extravafated blood inter- pofed; for if that be large, the whole blood will not be- come vafcular, but the furSace only which is in contad with Surrounding parts, and the reft will be abSorbed as in the enchymofis. Where* the quantity is Small, as in a Slight wound without laceration, and where all the divided Sur- Saces can be brought into almoft abSoIute contad,their union will be firm in twenty-Sour hours, as happens in a hair-lip, or wounds oS the Scalp. Although under Such circumftances the blood Seems to change into a Solid Sorm very quickly, yet when the Situa- tion oS the wound particularly Subjeds the parts to mecha- nical violence, w. fhould not truft to this union being com- pleted in So Short a time. In the hair-lip, Sor inftanee, perhaps forty-eight hours may be required to.make it perfedly Secure, and except Union by the firft intention. IQI when the Stitches by producing ulceration might make Scars, there can be no harm in allowing Such parts even a longer time for thtir union.. But in wounds of the Scalp, this caution is not neceffary; and indeed in fuch cafes it is Scarcely required So snake ftitches at all. In cafes oS accidental- injury, whether they be in them- felves flight or cuniid-erable, in whatever fituation ox par*: they may have happened, iS the Saluury procefies, above deScribed, go on readily, no other effed of injury, or irri- tation, or pain, in conSequence of nature's operations is felt. No univcrSai Sympathy or fever takes place, except what ariSes Srom the mere injury done, but all is quiet as if nothing had happerfcd. This is Sometimes the cafe even in a fimple fradure of the bones oS the leg, in futures cf the Skull, etc. However, the magnitude cf the accident often produces effeds which are alarming, and more par- ticularly when they happen to parts effential to life. TheSe effects are oSten the cauSe oS much danger, the conftitution becoming affeded according to the nature and importance of the parts injured. Thus concuffion and extravaSation affeding the brain, muft likewifc affed the conftitution, from its natural adion and influence on the body being diminished, increaSed, or otherwise disturbed. Trie Same thing happens Srom an injury done to any other vital part of the body, and the effeds will be according to the uSe oS Such parts, or the influence which they have on the SyS- tem. However, thefe immediate and falutary operations do not always take place fimply, for they are often altered by other circumftances; as the accident fofnetimes becomes the caufe of irritation, and produces another operation of the parts, called inflammation, which kj often oS Singular Service, by increafing the power of union in the broken parts. This inflammation will generally be in proportion to the degree of injury done, the nature of the parts injured, and the ftate of the conftitution at the time, which in other words, is in proportion to what is requifite for the firft powers of union. But it Sometimes happens, that inflam- mation goes further than is required, and produces a vari- ety of adions fucceeding each other in regular progreffion. This may occafionally be o'bferved in certain Simple frac- tures, in which the extravaSated blood ading as an extra* K k 102 Union by the firft intention. fl cous body, becomes the caufe of the fuppurativc inflam- mation ; and the fimple is in this way brought to a State rcfembllng the compound Sradure. The inflammation, however, does not extend over all the lacerated parts, as when diey are expofed at the time oS the injury, many of theSe having united by the firft intention. We may here obferve, that accident of the moft fimple kind may produce effeds which do not allow the common operations of nature to take place, as when a large blood- veffel is broken, or when a fradured rib penetrates into the lungs, or a compreflion of the brain ariSes Srom a Sradure oS the Skull. But none oS theSe accidents admit of the modes of cure above-mentioned, as they each require par- ticular treatment, and therefore are not to our prefent pur- pofe. II. OF INJURIES WHERE THE WOUND COM- MUNICATES EXTERNALLY. The fecond divifion of injury arifing from accident, is where the ruptured parts communicate externally, produc- ing effeds different from the former*. Thefe may be di- vided into two kinds, viz. wounds made by a Sharp cutting instrument, and contufions producing death in the parts injured. Wounds are Subjed to as great a variety as any thing in Surgery. A wound is a breach made in the continuity of the folids of a part, beginning moft commonly on the external fur- face, and proceeding inwards ; although fometimes its diredions is from the infide outwards, as in compound fradures. A gun-lhot wound may be Said to partake of both circumftances, as it paffes through a part: wounds oSten admit of the fame mode of cure with accidents which do not communicate externally, but then it requires the art of the furgeon to place them in the fame fituation, or un- der the fame circumftances. A wound is either fimple or compound; the fimple is what I have now to explain, and is of fuch a nature as to admit of union by the firft intention. Of this defcription Union by the firft intention. l93 we may likewife confider wounds which are the confe- quence oS certain Surgical operations. The Sorm oS the instrument by which wounds have been inflided will alSo make a difference in their nature ; Sor if it be Sharp it will make a clean cut wound ; if obtuSe in its Shape, a bruiSed one, and may alSo deaden a part, and the parts may likewiSe be torn aSter having been cut; all of which varieties will render a different treatment neceffary towards effeding a cure. In the moft fimple cafes of wounds, a number of blood- veffels bciig divided, there is an effufion of blood, which efcaping by the wound, the internal parts are left expofed, efpecially the cellular membrane ; and thefe if not brought into contad with cofrefponding living parts immediately, or by means of the coagulated blood, will inflame and fup- purate. Accidents of this kind differ from thofe of the firft divifion by communicating externally, a circumftance which makes them oSten require very different modes of treatment. In caSes where parts have been Sorccd out of their natural fituation, they Should be~redued, that when cured they may anSwer their natural purpoSes, as in Srac- ture, dislocation, &c. Wounds admit of three modes of treatment, arifing from their fize, fituation, and the nature of the parts wounded. One mode is artificial, two are natural, in which laft the conftitution is allowed to perform the cure in its own way, which ^'ill be explained when we fpeak oS Scabbing. TheSe being different Srom the Sormer, and Srom each c- ther, it might be thought that I Should have confidered them firft as being natural proceffes ; but tho firft can be put in- to the Same ftate with the two others, and thereSore ought to precede them. For this purpoSe att muft be employed by the Surgeon to bring the Separated SurSaces in contad ; that by retaining them there till union Shall have taken place, the injury may be removed Srom the ftate of an expoSed wound. This treatment oS Srefh wounds with a view to cure them by the firft intention, is equally proper after many opera- tions, as in accidental injuries. Inftances of this often oc- cur after diffeding out tumors, Scalping when no fradure is ' found, and when trepanning has not been performed ; and it has been put in pradice even where the trepan has been K k 2 194 Union by the firft intention. -. ppltod. It has been employed alfo after amputations ; in Short, wherever a clean cut wound is made in found p-irts, and when the Surfaces can be brought into contact, or where there is fuflicient Skin to cover the part, this pradice may, and Sliould be followed. In no cafe, however, of a breach of continuity, can we entirely prevent the parts from retaining the appearance of a wound, for the breach in the Skin will more or lefs remain, and the blood will coagulate, become dry, and Sorm a Scab. But this operation of nature reduces the injury to the ftate of a mere Superficial wound, and the blood which is con- tinued from the Scab to the more deeply Seated parts, re- taining its living principle, juft as the natural parts do at the bottom of a Superficial wound, the' Skin is formed under this Scab in the one caSe as in the other; yet iS the Scab fhould either irritate, or a part underneath loSe its uniting powers, then inflammation, and even Sometimes Suppura- tion, may be produced. It is often, however, only inflam- mation that is produced ; the Scab here preventing the fur- ther progreSs of mifchief in the fame manner as the Scab- bing of the pus on a fore prevents the procefs of Suppura- tion, which becomes one oS the uSes of pus. In many of the cafes in which we mean to produce union by the firft intention, it is not neceffary to be very nice ill Springing out the blood, with a view to make the two fur- faces of the flefh come entirely into contad, the blood it- felf anfwering a fimilar purpofe. In feveral cafes, having brought the two portions of loofe fkin together, I have feen the two cut edges unite almoft immediately, and though the cavity underneath wras diftended with blood yet it did well, the tumor gradually decreafing as the bbod was ab- forbed ; this is to be confidered in the fame light as an ec- chymofis. When the portion of Skin is not fufneient to cover the whole wound, and the cut edges cannot be brought toge- ther, ftill the Skin Should be made to cover as much as it can, in order to diminifh the Size of the parts that muft o- therwiSe Suppurate and Sorm a Sore ; as in conSequence of this mode of treatment, the living extravaSated blood is confined in the wound, and coagulating there, unites the two SurSaces together. The mouths ofthe veffels are foon Shut,peither by inoScu- lation, or their own power oS contradion, and by the blood becoming vaScular, as in the former Stated caSe of union Union by the firft intention. 195 by the firft intention ; and if there Should be any fuperflu- ous extravafated biood, we know that it will be afterwards abforbed. The blood being alive, this uniting medium becomes im- mediately a part oS ourSelves, and the parts not being of- fended by it, no irritation is produced. The red particles are abforbed, and nothing but the coagulating lymph is re- tained, which being the true living bond of union, after- wards becomes vafcular, nervous, etc. This mode of treatment by art, though an imitation of the former, can feldom be SuppoSed equally complete; perhaps we ought not to exped it to be So in any caSe, as there are circumftances often attending the artificial mode of treating wounds, which do not occur in the natural. The ligature ufed Sor tying a blood-veffel leaves an extra- neous body in the wound *; a part deprived oS liSe by the inftrument, etc. will become an extraneous Subftance, and the Surfaces cannot always be brought into contad, So as to allow a perfed union to take place. In Such caSes, union is prevented by the blood lofing in part its living principle, eSpecially in thoSe parts next to the external Surface ; arid perhaps the art employed by the Surgeon himSelS may affift in changing the original ftate oS the wound, as the patting 1 oS needles and ligatures muft always produce Suppuration through the whole paffage. TheSe Subftances So cii cumftanced, moft probably be- come the cauSe oS irritation, and consequently of inflam- tion. But if the pofition of the parts be Such as in any fort to allow of union, although not readily, the inflammation will go no further than the firft Stage, and will even give affiftance to the firft mode of union. The poffibility of effeding a cure by this method is pro- bably limited to fome certain diftance of time after the wound has been received, though that fpace may admit of fome latitude; perhaps the fooner it is done the better; but while the blood continues to be extravafated it certainly may be attempted upon our firft principles of union. * If Such a wound has a depending angle, and the veffels fliou'rt even be tied nearer the upper angle than the lower, yet I would advife to bring the lool'e end of the thread out of the wound at the lower, lor by that means the matter will flow much more eafily. IQC» Union by the firft intention. Where the former bond of union is loft in a part, to pro- duce a new one a Secondary operation takes place, namely, inflammation ; and if this is likewife loft, then a third mode of union will ariSe, which is by means of granula- tion. If the divided parts are allowed to remain till the mouths of the divided veffels be entirely Shut, inflammation will inevitably follow, and will Surnifh the Same materials Sor union which are contained in extravaSated blood, by throw- ing out the coagulated lymph ; So that union may ftill take place, though Some time later after the divifion oS the parts. This inflammation I have called the adhefive ; and the in- flammation that precedes Suppuration, I have called the Suppurative inflammation. If the parts, however, conti- nue teo long afunder, Suppuration muft follow, and pus is unSriendly to union. We may here obServe, that Suppu- ration takes place on expoSed Surfaces, with a much lefs degree oS inflammation and in much leSs time than on thoSe which are not expoSed, and Srom their not being oppoSed by living Surfaces, which tend to bring on the adhefive ftate, they continue it much longer. Whether this coagulating lymph iffues Srom the half clo- fed mouths oS the veffels which were cut, or Srom the Sur- face of the opened cells, is not eafily determined ; but moft probably it is from the latter, as it comes on about the time that the fwelling of the furrounding parts begins to appear. There is reafon to fuppofe it to be the fame kind of dis- charge with that which caufes the fwelling, and which is continued through the whole courfe of this Stage of inflam- mation ; for on examining the dretfings of fuch wounds as are allowed to fuppurate, feveral days after the wounds have been made, the lint is generally adhering to the fur- face by means of the coagulating lymph ; the fuppuration not having yet fufficiently taken place to looSen it. When theSe operations are completed in due order, the fimple operations of the animal are entirely confined to the part, neither the mind nor the conftitution Seeming in Such caSes to be at all affeded, except that there is a Seeling of tenderneSs in the part. But whatever theSe SenSations may be, they ariSe entiielyfrom the injury done, and not from the operation of union, unlets when the fuppurative in- flammation comes on. The inflammation often runs fo high, even where the parts have been brought into contad, as to deftroy, by its Union by the firft intention. t^ Violence, that union which the extravaSated juices were in- tended to produce, the conSequence of\vhich is Suppura- tion at laft. Is it by this exceSs of inflammation that the extravafated juices loie their living principle, and become as it were extraneous bodies ? or is it not poffible, that in thel"e caSes the inflammation may be the effed rather than the cauSe of the lofs of the living principle, by the blood firft lofing its living principle, and inflammation arifing from it as a conSequence ? The time requisite to complete this union will be nearly the Same as that oS the firft intention ; and probably Sooner iS there be no particular tendency to Suppuration ; but if there be, union may be SuSpended Some time longer, Sor here the uniting medium will be thrown out in larger quan- tity, and where the union is moft eafily effeded, there is lefs of this medium ; when two furSaces unite by inflam- mation, they are commonly in contad, or elfe moft pro- bably union Srom this cauSe would not So readily take place. We Shall find in the description of the adhefive inflamma- tion, that the union oS two fides oS a circumScribed cavity is very Soon effeded, and foon becomes Strong. There is another mode of union, which, although upon the fame principle, yet differs with regard to the parts which are to be united. I have hitherto explained union as taking place only in the divifion of correfponding parts of the fame living bo- dy, but it is equally poffible to unite different parts of the fame, or of different bodies, by bringing them into contad under certain circumftances. There is feldom occcafion for fuch pradice; but accident, or rather want of atten- tion, has in fome cafes been the cauSe oS union taking place between different parts oS the body. The ehin has been united to the breaft, the tongue to the lips or cheek, etc. and when this happens it has commonly been through the medium oS granulations. The attempt to unite parts of two different bodies, has only been recommended by Talia- cotius. The moft extraordinary of all the circumftances reSpeding union, is by removing a part oS one body and afterwards uniting it to fome part of another, where on one fide there can be no affiftance given to the union, as the divided or feparated part h hardly able to do mere than prefervc its own living principle, and accept of die union. IQ3 Union by the firft intention. . The poffibility of diis fpecies cf union Shews how Strong the uniting power muft be; by it the Spurs oS the young cock can be made to grow on his comb, or on that of ano- ther cock; and its tcfticles, after having been removed, may be made to unite to the infide of any cavity of an a- nimal. Teeth, after having been drawn and inferted into the Sockets oS another perfon, unite to the ne\M Socket, which is called transplanting. Ingrafting and inoculating of treei Succeed upon the Same principle*. * That the living principles in two bodies which have a perfect affinity to one anodier, fhould not only be a preferva. tive, but a caufe of union is evident; but even in bodies which appear foreign to one another, the ftimulus of an extraneous body is not produced where union is not intended, and cannot take place, although we Should at firft fuppofe that the extra- neous ftimuhis would be given, and Suppuration Succeed. This is verified by the eggs of many infects, which are laid under the fkin of different animals, producing only the adhe- five inflammation in the Surrounding parts ; by which the Skin is thickened and a nidus is Sormed for the eggs. The Guinea worm, called vena medenefis, is alfo a Striking inftanee of this ; for while the animal is endowed with the liv- ing principle, it gives but little trouble, yet if killed, gives the ftimulus of an extraneous body, which produces Suppuration through its whole length. Other inftances of" the fame fort are : The antrum bovis, which lays its eggs in the backs of cattle. The asftrum tarenui, which lays its eggs in tt.e back of the rein deer. # The antrum nafale, which lays its eggs in the notes of rein deer. The antrum hceinorrhoidale, which lays its eggs in the rectum of horfes. The aftrum ovis, which lays its eggs in the nofe and frontal finuSes of ruminati g animal?, particularly Sheep. The little infect in Mexico, called migna. which lays its eggs under the Skin; and laflly the cheggars, which get in the feet of animals. Union by the firft intention. 199 III. PRACTICAL OBSERVATIONS RESPECTING UNION BY THE FIRS F INTENTION. It is with a view to this principle of union, that it has been recommended to bring the fides (or lips) of wounds together; but as the natural elafticity of the parts makes them recede, it has been found neceflary to employ art for that purpofe. This neceffity at firft Suggested the pradice oS Sewing wounds, and aSterwards gave riSe to various in- ventions in order to aiffwer this end, fuch as bandages, fticking-plafters, and ligatures. Among theSe, the hand- age commonly called the uniting bandage, is preferable to all the reft, where it can be employed ; but its application is very confined, from being only adapted to parts where a roller can be ufed. A piece of fticking-plafter, which has been called the dry Suture, is more general in its ap- plication than the uniting bandage, and is thereSore pre- Serable to it on many occafions. I can hardly SuppoSe a wound, in any fituation, where it may not be applied, excepting penetrating wounds, where we with the inner portion of the wound to be clofed equally with the outer, as in the caSes of hair-lip. But e- ven in Such wounds, if the parts are thick, and the wound not large, the fides will Seldom recede So Sar as to make any other means neceffary. The thy Suture has an advan- tage over ftitches, by bringing a larger furface of the wound together, by not inflaming the parts to which it is applied, and by neither producing in them fuppuration or ulceration, which ftitches always do. When parts, therefore, can be brough together, and efpecially where fome force is re- quired for that purpofe, from the Skin 11 >-. being in large quantity, the fticking-plafter is certainly die beit applica- tion. This happens frequently to be the caSe aSter removal oS tumors, in amputation, or where the fides oS the wound are only to be brought together at one end, as in die hair- lip ; and I think the difference between Mr. Sharp's croSs Stitch, aSter amputation, as recommended in his Critical Enquiries, and Mr. Aiiion's pradice, Shews Strongly the Superiority oS the fticking platter (or dry future). In thofe parts ofthe body where the fkin recedes more than in others, this treatment becomes moSt neceffarv; and as the Scalp L 1 fccd Univi by the firft intention. probably recedes as little as any, it is therefore feldom neccf- Sary to apply any thing in wounds oS that part; the prac- tice will certainly anfVer beft in Superficial wounds, be* caufe the bottom is in theSe more within its influence. The Sticking-plafters fhould be laid on in Stripes, and thete Sliould be at Small diftances Srom each other, viz. a- bout a quarter oS an inch at moft, iS the part requires cloSe confinement; but when it does not, they may be at greater diftances. This precaution becomes more neceffary if the bleeding is not quite Stopped, there Should be paS- fages left for the exit of blood, as its accumulation might prevent the union, although this does not always happen. If any extraneous body, fuch as a ligature, fhould have been left in the wound, fuppuration will take place, and the matter Should be allowed to vent at Some oS thoSe openings, or Spaces, between the flips oS platter. I have known a very confiderable abSceSs Sormed in conSequence oS this pre- caution being negleded, by which the whole oS the recent- ly united parts has been Separated. The interrupted Suture, which has generally been recom- mended in large wounds, is ftill in uSe, but Seldom proves equal to the intention. This we may reckon to be the on- ly one that deServes the name oS Suture ; it was formerly uSed, but is now in a great mcaSure laid afide in practice, not Srom the impropriety oS uniting parts by this proceSs, but Srom the ineffedual mode oS attempting it. In what manner better methods could be contrived, 1 have not been able to Suggeft. It is to be understood that the above me- thods oS bringing wounded parts together, in order to unite, are only to be put in pradice in Such caSes as will admit of it; Sor iS there was a method known, which in all caSes would bring the wounded SurSaces into contad, it would in many inftances be improper, as Some wounds are attend- ed with coutufion, by which the parts have been more or leSs deadened; in Such caffs, as was Sormerly obServed, union cannot take place according to our firft principle, and therefore it is improper to attempt it. In many wounds which are not attended with contufion, when we either know, or fufped, that extraneous bodies have been introduced into the wound, union by the firft intention Should not be attempted, but they Should be al- lowed to Suppurate, in order that the extraneous matter may be expelled. Wounds which are attended with lace- ration, although free from contufion, cannot always be Union by the firft intention. SOI united by the firft intention, becauSe it muft frequently be impoffible to bring the external parts, or Skin, fo much in contad, as to prevent that inflammation wdiich is natural- ly produced by expofurc. But even in cafes cf fimple lace- ration, where the external influence is but flight, or can be prevented, (as we obferved in treating of the compound fimple fradure) we find that union by the firft intention of- ten takes place ; the blood which fills up the interftices of the lacerated parts having prevented the ftimulus of imper- fedion in them, and preventing fuppuration, may after- wards be abforbed. Many operations may be fo performed as to admit of parts uniting by the firft intention ; but the pradice fhould be adopted with great circumSpe£tion ; the mode of ope- rating with that view, Should, in all caSes, be a Secondary, and not a firSt, consideration, which it has unluckily been too oSten among Surgeons. In caSes oS cancer, it is a moft dangerous attempt at refinement in Surgery. In the union of wounded parts by the firft intention, it is hardly or never poffible to bring them fo clofe together at the expoSed edges, as to unite them perfedly by thefe means; Such edges are thereSore obliged to take another method of healing. If kept moift, they will inflame as deep between the cut furfaces as the blood Sails in the union, and there Suppurate and granulate ; but iS the blood is allowed to dry an^ Sorm a Scab between, and along the cut edges, then inflammation and Suppuration of thofe edges will be prevented, and this will complete tb,e union, as will he deScribed by and by. As thofe effeds of accidental injury, which can be cured by the firft intention, call up none of the power of the conftitution to atfift in the reparation, it is not the leaft af- feded or disturbed by them ; the part* are united by the extravaSated blood alone, which was thrown out by the in- jury, either Srom the divided veffels, or in conSequence of inflammation, without a Single adion taking place, even in the part itSelS, except the clofmg, or inofculation oS the veffels, Sor the flowing oS the blood is to be confidered as entirely mechanical. Even in caSes where a Small degree of inflammation comes on, it is merely a local adion, and So inconfiderable, that the conftitution is not affeded by it; becauSe it is an operation to which the powers belonging to the parts themSelves are Sully equal. The inflammation LI 2 202 Union Ay the firft intention. may produce a Small degree of pain, but the operation of union gives no SenSation of any kind whatever. The firft and great requisite for the restoration of injured parts, is reft, asitallows that adion, which is neceffary for repairing injured parts, to go on without interruption, and as injuries oSten excite more adion than is required, reft becomes ftill more neceflary. But reft maybe thought to confift merely in abstaining from bodily exercife ; this will in general be proper, as moft parts of the body will be af- feded either immediately, as being engaged in the adion itfelS, or intermediately by Some connection with the injur- ed parts. Thus, if the injury be in the limbs, and not fuch as to prevent walking together, Still perfons Sliould not be allowed to walk ; and we find Srom the want oS this cau- tion, complaints in thoSe parts are commonly longer in re- covering than in others ; Sor by keeping the limbs at reft, the whole progreffive motion is ftopped, a thing more dif- agreeable to the mind than any prevention oS motion in the body. If an arm be injured, it is not fo, the want of its ufe is not fo diftreSfing to the patient, becaufe he can enjoy locomotion, and may have no objedion to keeping his hands quiet. Reft is oSten admitted Srom neceflity, as in the fradure of a leg, but feldom where motion is only an inconvenience. But it muft appear, that the rup- ture of a veffel requires union as well as the Sradure of a bone, although the veffel having more powers oS reftoration within itSelS than the bone, and having leSs occafional dis- turbance Srom other powers, eSpecially oS Sradures of the loweft extremities, yet the reft Should be propor- tioned to the miSchief which would follow from the want of it; and this will vary according to the fituation of parts. The fame principle of reft Should apply to every in- jury, although this is not often allowed to be the caSe. Thus where an injury produces inability to move a part, eSpecially iSin a joint, it is Srom Sear oS the loSs oS motion, not only allowed to be moved by its own muScles, which would be the moft proper mode, iS motion at all was necef- Sary, but is moved by the Surgeon, or by his diredion, who, not Satisfied with mechanical violence, has recourSe to ftimulants, as warm applications, in order to route up the internal adion oS the parts, and at the very time when every thing Sliould be kept quiet till reftoration ofthe injury has taken place. In many parts of the body this practice r r'ui l\ llt j'. f itiiititicn. 203 is not So injurous as in others, in which it may be attend- ed wtth very Serious conSequences. Thus when a man has Suffered a conculfion oS the brain, and perhaps a blood- veffel has given way, the mind is deranged, becoming ei- ther deSedive or too acute, and iS theSe Symptoms Sliould continue but a little while, the medical alliftant applies blifters to remove the effed, either Sorgetting, or not rightly judging die cauSe. This is even carried further, we hardly fee a man taken with all the figns of an apoplexy, where a paralyfis in Some part takes place, or hemiplegia , but that he is immediately attacked with cordials, ftimu- lants, eledricity, etc. Upon a Suppofition that it is ner- vous, debility, etc. the poor body is alio tortured, becauSe It cannot ad, die brain not being in a condition to inilu- encethe voluntary muScles ; we might with exadly the Same propriety Stimulate the fingers when their muScles were torn to pieces. I muft own I never Saw one oS them which had not an extrayaSation of blood-in the brain when opened, excepting one, who died of a gouty affedion in the brain, with Symptoms Similar to apoplexyf. Such a caSe, moft probably, would require a very different mode of treatment, therefore when it happens to be a gouty man, blif- ters, to the head, feet, etc. would probably be the beft pradice ; but furely this would not be the proper prac- tice in a rupture of a veffel j> we.ought to bleed at once ve- ry largely, eSpecially from die temporal artery, till the pa- tient begins to Shew figns oS recovery, and to continue it till he might begin to become Saintifh. We Should give Saline purges Sreely, to diminish impetus and promote ab- Sorption ; then great quietneSs Should be enjoined, and as little exercife of the body as poSfible, and eSpecially to avoid coughing and Sneezing. Plain Sood Should be direded, and but little of it; nor will fuch cafes eyer allow of being * It may be obferved here, that the only difference be- t vecn an apoplexy and hemiplegia is in degree, for they both arife from extravafations of l>lood. f For many years I have been particularly attentive fo thofe who have been attacked with a paralitic ftroke, forming a hemi plegia. 1 have watched them *hile alive, that I might have an opportunity to open them when dead; and in all 1 found an injury don? to the brain, in conSequence ofthe extravafation of blood. 1 have examined them at all Stages, wl^en it was recent, Some of weeks ftanding, others of months, and a Sew years, in which I Saw riieprogrefs of reparation. 204 Union by thifirfi intention. routed to adion, when as much recovered in their texture as nature can accomplish, to the Same degree that other parts will admit of or even require. TheSe observations lead us to confider the means of re- lief, for, befides reft, it often happens that the parts can be relieved from the fecondary confequences of the injury, fuch as inflamarions, etc. But this leads to constitutional and local treatment, and will be included in the hiftory of inflammation. I have already mentioned that when the falutary effeds above defcribed take place, the conftitution is not in the leaft effeded, yet it is proper in all cafes where much mif- ehief might arife from a failure, to pay a little attention to the conftitution. The patient Should eat plain food, drink weak liquors, and have the body kept open ; this treatment with reft Suitable to the cafe, will in many tinftances pre- vent evils that might otherwiSe occur and prove trouble- fome. IV. OF SCABING. The operations which I have deScribed prevent inflama- tion, eSpecially that Sort of it which produces fuppuration; but even where the parts are not brought together, fo as to admit of union by the firft intention, nature is always en- deavouring to produce the Same effed. The blood which is thrown out in conSequence ofthe accident, and which would have united furfaces brought into contad, is in part allowed to eScape, but by its coagulation on the Sur- face a portion is there retained, which drying and forming a Scab*, becomes an obftacle to Suppuration. The inflama- tion may be greater than where union can be effeded, but not nearly So great as when Suppuration takes place. * A Scab may be defined firft, dried blood on a wound, dried pus on a fore, a flongh from whatever cauSe allowed to dry, mucus, Srom an inflamedSurface, as in the nofe. Union ty tloe firft intrttti&n. 205 The blood lying on the freSh Surface, although not now alive, and therefore not fitted for union with the living parts underneath, yet precludes the neceffityof any further cifcharge as a covering to the expoSed SurSace, which is one of the ufes oS pus. This might be confidered as the firft mode of healing a wound or fore, for it appears to be the natural one, requir- ing no art ; and in the State of parts beforementioned, the complete union is in fome degree indebted to this mode of healing, by uniting the edges that were not or could not be brought into clofe contrad, by means of a Scab; proper at- tention to this has, I believe, been too much negleded. Many wounds ought to be allowed to Scab, in which this procefs is now prevented ; and this ariSes, I believe, from the conceit of furgeons, who think themSelves pofleffed of powers Superior to nature, and therefore have introduced the pradice of making fores of all wounds : a Scab how- ever muft always be on a SurSace, it is only a Superficial wound, or on Superficial parts oS deeper wounds, that Scabs can Sorm. How far this pradice may be extended, I do not know, but there are cafes in which it fhould be difcouraged, as where deep feated extraneous bodies have been introduced, as in gun-Shot wounds, or where deeper Seated parts have been filled ; but it will anSwer extremely well, where the Superficies only is deprived of life. Superficial hurts are very common, on parts oppofite and near to fome bone, as en the head, Shin-bone, fingers, etc. but more eSpecially on the Shin. In all Such cafes its better to let them Scab, if they feem inclined, or will admit of it ; and if that Sliould not fucceed, they can but fujM purate at laft, and no harm is done. In many deep feated wounds, where all the parts have remained in contad, thofe underneath will unite much bet- ter if the furface be allowed to fcab. Some compound fradures (more efpecially where the external wound is -ve- ry fmall) Should be allowed to heal in the fame way ; for by permitting the blood to fcab upon the wound, either by itfelf, or when foaked into lint, the parts underneath will unite, the blood under the fcab will become vafcular, and the union will be complete, even w here the parts are not in contad. 106 , Union by the firft intention. How Sar this pradice may be extended is not yet afcer- tained. A Small wound doing well under this treatment is a common caSe, and Some examples oS large wounds are men- tioned, though theSe do not So generally Succeed ; but I do not know that there is any danger in the attempt. In ma- ny caSes, therefore, which Seem doubtSul, where the ex- ternal contufion is not very great, or not continued of the fame fize as in the deeper feated parts, it may be tried. In fome of thofe cafes which have been allowed to Scab, the parts injured have appeared ready to go into inflamma- tion ; a red circle has been Seen all round, produced by the irritation oS the Scab. Suppuration takes place underneath the Scab, and the pus makes its eScape Srom under its edges: but even in Such caSes, I Should be cautious oS treating it as a Suppurating Sore : I Should allow it to go on, and ocafion- ally preSs the Scab in order to Squeeze out the pus ; for it very oSten happens that the red circle Surrounding the Scab becomes oSa duiky brown, which is the beft Sign of reSo- lution, the Suppuration diminishes, and the whole does well. But iS inflammation Should proceed Sarther and Seem to be increaSed by the mode oS treatment, it muft not be urged Surther ; the Scab Should be poulticed in order to Sof- ten it, that it may come off eafily, and it fhould afterwards be treated according to the nature ofthe fore. Tins pradice fucceeds wonderSully well in caSes where we find applications of all kinds difagree with the fkin. A perSon Shall get a blow on the Shin, which Shall probably deaden a part, a poultice is then oSten applied, that poul- tice brings out pimples on the Surrounding fkin, theSe pim- ples increaSe and become Sores oS Some breadth, the poul- tice is increaSed in breadth to cover them, new pimples a- riSe, and So on, that I have feen a whole leg Sull of thoSe Sores. In Such, I always allow the wound to Scab, and to ac- complish this, the beft way is to take off the drelfings in the morning, and put on trowSers, without Stockings, and by the evening the parts are Scabbed ; or we may powder them with lapis calam : or chalk finely powdered, and de- fire the patient to go bed, Sor the firft night, with the trowSers on; where the Sore has been only one, I have made a circular pad, and bound that on till the Scab was formed. Union by the firft intention. 207 The mode of affifting the cure of wounds by permitting a fcab to Sorm is likewiSe applicable, in Some caSes, to that Species oS accident where the parts have not only been lacerated, but deprived oS life. If the deadened furface is not allowed to dry or Scab, it muft Separate from the living parts, by which means thefe will be expofed, and Suppura- tion brought on ; but if the whole can be made to dry, the parts underneath the Slough will cicatrize, and the dried fiough will at laSt drop off. I have feen this take place aS- ter the application of a cauftic, and many othei floughs. Where this can be effeded, it is the beft pradice, as it will preclude inflammation and Suppuration, which, in molt cafes Should be avoided if poffible. I have treated many cafes in this way, and the living parts underneath' have formed a Skin as the Slough Separat- ed. This will more readily take place where the cutis is not deprived oS life through its whole Subftance ; Sor it has a much Stronger diSpofition and powers to reftore itSelf than the cellular membrane has to form a new cutis ; in- deed the Skin formed upon entire new fleSh is very different Srom the original cutis ; therefore as the Skin is the part moft liable to theSe accidents, we have the beft chance of Succeeding in this way when the cuds alone is injured. This practice is the very beft for burns or Scalds, after the inflammation has either been considerably prevented, or Subdued, by proper applications or by time, Sor which there probably are moreremidies than Sor an inflammation arifing Srom any other cauSe, as if" there was Something Specific in Such cauSes. Whatever will abate an inflamma- tion arifing Srom accident, will have the Same effed upon a Scald or a burn ; and Srom the diversities oS applications, we have opportunities oS knowing the beft. Oil was long an application, but which has no virtue; Spirits has alSo been Jong applied, and with very good effed. The com- mon application, which is a Soap made with lime water and oil, Seemed to anSwer■ better ; and now vinegar is Strongly recommended, and I think with jultice, as Sar as 1 have Seen. Cold leffens all inflamations, and is a very good .applica- tion where it can be applied, but it cannot be applied So univerSally as many others : however, cold has this disadvan- tage, that the pain, although removed while under the ap- plication, occurs with double Sorce when it is removed, M m 208 Union by the firft intention. much more than Srom any oS the applications, and the reaSon is evident, Sor as the warmth returns, the pain is increaSed by the warmth, even in Sound parts; on the contrary, it is recommended, that when a part is burnt to hoJd it to the fire as hot and as long as it can be held, which undoubtedly leffens the Succeeding inflammation, and Soon gives eaSe. This I have oSten Seen, and probably it can only be accounted Sor on the principle oS producing the ad oS contradion in the veflels. I have taken a bucket oS cold Spring water with me, when I have made an attempt on a waSp's neft, and put my hand into it, aSter having been Stung, and. while my hand was in the water I felt no pain, but when I took it out, the pain was greater than when I put it in. This is not the cafe with other applications, for their fpecific vir- tues are not counteraded by any natural circumftance at- tending the body, and then they can be applied with a con- tinuance to any part where the Skin is thin. The blifters commonly break, and fo much the better, as the applica- tion can come in contad with the inflamed furface, but on the hand, foot, fingers, and toes, efpecially in work- ing people, and thofe who walk much, the blisters feldom break of themfelves ; they Should be pricked with a needle to take off the tenfion. When the inflammation has gone through its Stages, then the parts Should be allowed to dry. This in many parts is very awkward, as when a large SurSace oS the body is Scald- ed, for expofure is neceffary, and in fome parts it is almoft impoffible, as behind the ears, armpits, etc. To keep the cloths Srom fticking to the parts, it is neceffary to powder it with Some inpffenfive powder, Such as lapis calaminaris, very fine powdered chalk ; this does not hinder evapora- don, the principle oS Scabbing ; and iS the diScharge Should be So much at firft as to moiften the firft powdering, then Strew more over the whole, till it Sorms a hard crult. This is hardly neceflary on the Sace, but it will rather dry Sooner by being at firft powdered. In Such caSes nature will go on infinitely Sarthcr than if the parts had been dif- tuibcd by our applications. Union by the firft intention. 2©0 V. ACCIDENTS ATTENDED WITH DEATH IN A SUPERFICIAL PART. In the SoTegoing account of injuries done to the body, and of the modes of reftoration, we have been fo far from confidering inflammation as one of them, that hitherto it has been inculcated to guard againft it with the utmoft care. It Sometimes, however, takes place, and is one oS the modes oS reftoration when the methods abovementioned Sail, as well as a mode of reftoring parts under diSeaSe, we Shall thereSore proceed to explain its principle ; but as there are accidents already mentioned, which often advance to Suppuration, I Shall now treat oS them. Among the divifions oS accidents, one is where death is produced in the injured parts, and where inflammation and Suppuration muft take place, in conSequence of the dead parts which Separate not being within the power of the former treatment to producs a cure; but it Should be re- membered, that die inflammation, which is the forerun- ner oS Suppuration in Such caSes, is not nearly So great as even the inflammation arifing Srom a wound that Suppu- rates. In many accidents, Such as bruiSes, the Skin pre- serves its living powers, while the cellular membrane un- derneath has become dead ; this will afterwards produce an abfeefs, and muft be treated as abfeeffes commonly are, re- membering that, in the prefent cafe, the abfeefs, after be- ing opened, will be later in acquiring the healing difpofi- tion than abfeeffes are commonly; the dea^ cellular mem- brane muft feparate, which will come away like wet dirty lint. It fometimes happens, that in one part, the Skin; in another, the cellular membrane only Shall become dead; and in Such cafes, I have oSten obServed that the bruiSed Skin floughs much Sooner than the cellular membrane ; an abScefs, therefore, is frequently forming under the found fkin while the other parts are healing, a circumftance which often difappoints both the patient and furgeon. When the wound, or the dead part, is confiderable, it is probable the treatment will, in general, be very proper, becaufe the degree of mifchid calling up the atteudon of 21 o Union by the ft:ft intention. the Surgeon, and producing acquieScence in the patient, he ^ will be induced to Submit to whatever may be thought ne- « ceffary. The beft application, at firft, will probably be a ' poultice, which Should be either Simple or medicated, ac- i cording to the nature oS the Succeeding inflammation, and continued either till the inflammation has Subfided, and Suppuration come on Sufficient to keep the parts moift, or till the Slough has entirely feparated, when the Sore may be dreffed according to its particular diSpofition. But Such accidents as have a Superficial part killed, when the Slough would readily Separate, and the part Suppurate kindly, are often treated improperly at firft, by the patients them- Selves applying Friar's balSam, or Some Such medicines; but theSe not being within the power of Scabbing, inflam- mation comes on and alarms the patient, a poultice uthen commonly applied, which removes the firft drefling, and the Slough appears, which gives a diSagreeable appearance to the wound, and it is SuppoSed to be a Soul Sore. From Such an idea various methods are employed, and the appli- cation oS red precipitate, etc. but with no good eSTed: and the patient becomes fretted Srom a Sore, apparently So trifling, being So difficult to heal; but it is impoffible that Such a Sore can heal, while there is a Slough to Separate. It is, thereSore, the Surgeon's bufineSs to inform himSelf oS the nature of the complaint, to explain it to his patient, who will then become better Satisfied, and leSs uneaSy about his own Situation. When this piece of Slough comes away, the fore will put on an appearance according to the nature of the conftitution, or of the part, and is to be treated accordingly. [ 211 ] CHAPTER II. FUNDAMENTAL PRINCIPLES OF INFLAM- MATION. AN animal in perfed health is to be confidered as a perfed machine, no part of it appearing naturally Weaker than another, yet this is not ftridly true ; but Still if no relative adion, with regard to external matter, was to take place, the machine would, in itfelS, be tolerably perSed Sor its own adions. As the animal, however, is employed upon common matter, and thereSore liable to ac- cidents, which interrupt the natural operations, it becomes absolutely neceffary Sor its continuance, that it Should pof- SeSs, within itSelS, the power of repair; we find it accord- ingly endowed with powers of repair upon many fuch oc- cafions ; but where parts give way from their own natural adions, this mifchief cannot be repaired '; becaufe, if they are not able to fultain their own adions, they cannot re- cover when diSeaSed or injured. It is Sound that Some ftrudures oS parts more readily give way than others, and consequently are much longer in repair, either when diSeaSed or injured by accident. We alSo find that different Situations, oS Similar parts, give them advantages or dis- advantages, with regard to their powers of restoration. This is principally known Srom injuries being done to them, or in conSequence of thoSe injuries-Srom the attack of a difeafe. It is alfo Shewn in the common adions of the body, or parts, of which, in health, we have comparative trials. We never can know what a thing is incapable of doing till it gives way, which giving way is either a difeaSe, or productive of it: nor can we know the powers of reftora- tion in the part till tried. As a proof that parts cannot always be proportioned to the adion or powers appihd, which have no adion within themfelves, but arc only aded upon by external force, we 512 Tundmr.enial principles cf 'ufiain'.nc.lior.. adduce the inftances of a broken patella, or broken tend* achillis, or a thickening oS the valves oS the heart. In the firft, however, there is commonly another power Super- added befides fimply the adions oS the parts viz. the body falling and being ftopped at once. In the valves of the aorta, however, and the valvula mitralis, we have the beft examples, Sor they become thickened from the actions of the parts themfelves ; while no fuch effed takes place in the valves of the pulmonary artery, even an anueritm proves the Same. Where there is a difference in ftrudure, there are com- parative powers to refift the ccnSequences oS adions, at- tended with Injury, Such as their admitting more or leSs readily of thickening, ulceration, or mortifications and their comparative powers of reftoration. When we com- pare the powers of reftoration in muScle, nerve, cellular membrane, ligament, tendon, bone, etc. with each other, dieyare Sound to be very different. MuScles, Skin, and probably nerves, poffeSs the greateft powers oS that kind; and the cellular membrane, ligament, tendon, bone, etc. the leaft, and are, in this reSped, pretty equal among them- Selves. How Sar elaftic ligaments have powers oS refift- ance and repair, I do not know, but I Should SuppoSe they had them in a very considerable degree, Srom the veffels not giving way So readily as in many of the others. Their comparative powers become pretty^evident in molt cf dieir difeafes, but chiefly, I think, in mortification. As mortification is the moft fimple effed of debility, it gives the comparative powers of parts in the moft fimple manner. We find that mufcles, fkin, and often blood- vehels, Stand their ground, while.they are deprived of their conneding membranes which has either Sloughed off, or ulcerated ; tendons likewiSe flough off as far as theSe muS- cles, and Stop there. I have alSo obServed, that difference in the fituation of fimilar ftrudures in the body makes a material difference both in the powers oS refiftance to injuries, and of repa- ration when injuries have taken place. This difference feems to arife in proportion to the diftance of the parts from the heart, or fource ofthe circulation. Thus we fee mufcles, Skin, etc. becoming more readily diSeafed in the legs than any where elSe, and more flow in their progreSs towards a cure ; but this is not wholly to be laid to the charge oS Situ- ation cr diftance Srom the Source cf the circulation, fome Fundamental principles of inflammation. 213 jwrtion of it is to be attributed'to pofition, the legs being depending parts, and thoSe parts which are moit diftinct happen alto to be the moft dependent*. We find an hori- zontal pofition affnt in the repair oS Such parts, but even then they are not equal in their powers to parts Situated a- bout th- cheft ; the difference therefore is prinGipaliy to be attributed to fituation, or diftance from the heart. Th« fame diSeaSe that Shewed the comparative powers between the mufcle and tendon, Shews alio that th£y are equally af- feded by pofition ; thus we fee ulceration and mortification taking place in the lower extremity, as fuch, more readily and with leSs powers oS repair, than happens in parts near the cheft. This is ftill more the caSe if the perSon be tall. This is- Seen by changing a limb Srom a horizontal pofition, in which it was ealy to a dependent one, wherein it feels pain ; becauSe the new pofition increaSes the length oS the column oS blood in the veins. I am inclined to believe that the retardation oS the cure is more owing to a Stagnation of the blood in the veins, Srom the length oS the column, than from a deficiency oS the motion oS the blood in the arteries. As the readineSs of a part to fail into diSeaSe, and its back- wardness to admit of cure, ar.fes from pofition, it is in Some degree compenfiited by reft and a change of the pe- tition. TheSe differences in the ftrudure, Situation, and pofi- tion oS parts in the body, make, I believe, but little diffe- rence in the progreSs oS Specific diSeaSes ; the venereal dif- eafe, however, certainly does not make fuch progrefs in bone, tendon, etc, as in die fkin, nor does the cure ad- vance fo rapidly in thofe parts ; but both thefe effeds may be attributed to another caufe, which is, that bone3 and ten- dons are more deeply feated. 1 believe, however, that po- sition makes no difference in the uneaSe itfelf, although it may have fome influence upon the power of cure, and per- haps in all Specific diSeaSes, in the progreSs towards a cure ; for a venereal Sore is always approaching nearer and nearer to the nature of a common l'o,c, and therefore is more and more readily influenced by what influences a common fore. - * We find in mofl vnt'iors the wt ole Liu to this, v£ ...L < fiiJl more fully diitulV in the .-ifbry jf e> ,i::ijju. 214 Fundamental principles of inflammation. But in diSeaSes, Sor which there is at preSent no cure, as [ the cancer, I believe it makes no difference where it is Si- tuated, or in what it is placed, except in the caSe oS Such parts as have a tendency to Such diSeaSes, which no one of the parts abovernentioned has more than another. I have So Sar confidered, m the general way, die com- parative powers of different ftrudures, of diiferent fixa- tions, and of different pofidons in fome parts of the body when affeded by difeafe. Difeafe is the only circumftance which expofes theSe principles to our view, but to See how Sar the Same principle was carried in natural operations, of which the molt remarkable is the growth oS parts, I made Several experiments on Sowls. The firft was the common experiment of tranfplanting the fpur of a young chicken from its leg to its comb, in which experiment I always found that the fpur on the comb, when it took root, grew much falter and became much larger than that left on the leg. This I attributed to the greater power of adion in the comb than in the leg, although they are pretty nearly at equal diftances from the fource of the circulation ; but probably pofition alfo favoured it, as there was no Stagna- tion in the veins of the head. In the power of producing fuch effeds in difeafe, as well ,as in the growth of parts, 1 was then defirous to know the comparative degrees between the male and the female. I wished alSo to aScertain if the parts peculiar to the male could grow on the Semale, and if the parts of a female, on the contrary, would grow on a male. Although I had formerly tranfplanted the tefticles of a cock into the abdomen of a hen, and they had Sometimes taken root there, but not frequently, and then had never come to perSedion, yet the experiment could not, Srom this cauSe, anSwer Sully the intended purpoSe; there is I believe, a natural reaSon to believe it could not, and the experiment was therefore disregarded*. I took the Spur from the leg oS a young cock, and placed it in the Situation oS the Spur in the leg oS a hen chicken, it took root, the chicken grew to a hen, but at firft no Spur grew, while the Spur that was leSt on the other leg oS the cock, grew as uSual. This experiment I have repeated Several times, in the Same Summer with the Same effeds, which led me to con- * Vide book on Teeth. Fundamental principles of inflammation. ' 2-15 ceive that the Spur oS a cock would not grow upon a hen, and that they were, therefore, to be confidered as diftind animals, having very diftind powers. In order to aScertain this, I took the Spurs of hen chickens and placed them on the legs of young cocks. I found that thofe which took root, grew nearly as fall, and to as large a fize as the natu- ral Spur on the other leg, which appeared to be a contra- didion to my other experiments. Upon another examina- tion oSmy hens, however, I Sound that the Spurs had grown considerably, although they had taken Several years to do it; Sor I Sound that the Same quantity of growth in the fpur of the cock, while on the cock during one year, was as much as that of the cock's fpur on the hen in the courfe of three or four \ ears, or as three or four to one; whereas the growth of the hen's fpur on the cock was to that of the proper Spur oS the cock as two to one. TheSe experiments Shew that there is an inequality oS powers in different parrs ofthe fame animal, and that the legs have much lefs than the comb ; they alfo Shew that there is a material difference in the powers of the male and the female. The Spurs of a cock were found to poflefs powers beyond thofe of a hen, while at the fame time, the one animal as a whole, has more powers than the other ; yet when I apply thefe principles to the powers of cure in local difeaSes of the two fexes in the human race, I can hardly Say that I have obferved any difference. It is to be obferved, however, that women commonly live a much more temperate life than men, which certainly muft have confiderable influence both with re- gard to refitting and curing diSeaSes. In all complicated animals, among which man is the moft complex, the parts are compoSed oS different itruc- tures, and we find that in Such animals the powers of ac- tion of thofe different ftrudures within themSelves are very different; when they are therefore excited to any common adion, the varieties produced Should be well known and particularly attended to. Befides, every fimilar ftrudure in different animals does not always ad in the Same man- ner. Thus we cannot make a horSe vomit; nor can we give many Specific diSeaSes, which attack the human Sub- jed, to any other animal, more particularly the morbid poifons. The mode, therefore, 01 adion in one animal does not implicitly dired to the mode of adion in another ; nor does the fame ftrudure in the fame animal always ad N n . 2\6 Fundamental principles ef inflammation. in the fame way at all times : it ads at various times in a way fimilar to the fame ftrudure in various animals; and befides, the Same ftrudure varies its action in different Situ- ations in the Same animal. Befides, the exterior adions of lite make a very material difference in the internal adions of animals, or in the excitement of diSeaSe, either univer- Sally or locally ; Sor there are parts which cannot bear one mode oS liSe, while there are other parts which cannot bear another. Parts and mode oS life being in oppofiticn with each other. A great many of theSe varieties depends upon the difference in the natural ftrength and weaknefs of the parts ; but as thofe vary very confiderably in different ha- bits, fo the varieties are increafed ; and likewife, as many occurrences in liSe produce the principle of ftrength or weaknefs, we have thofe varieties ftill more increafed, as well as diSeaSe. TheSe observations, r.s heads, I Shall treat more Sully, but not as my principle Subjed, attending to them only So far as they are conneded with inflammation, and may il- lustrate the varieties in that adion. I. OF THE DIFFERENT CAUSES WHICH IN- CREASE AND DIMINISH THE SUSCEPTIBI- LITY FOR INFLAMMATION EITHER IN THE WHOLE BODY OR IN PARTS. Susceptibility for inflammation may be Said to have two cauSes, the one originaJ, the other acquired. The ori- ginal conftitutes a part of the animal ceconomy, and it is probably inexplicable. OS the acquired it is probable that climate, and modes oS liSe, may tend confiderably either to diminish or increaSe the SuSceptibility Sor inflammation. The in fluence, however, of climate may not be fo great as it commonly appears to be, for it is generally accompa- nied by modes of life that are not Suited to others; and if we confider how much lefs pernicious many climates are now than they were Sormerly, arifing from the mode of liv- ing being different, we may be led to allow lefs influence Fundamental principles of inflammation. 217 to climate; and on the other hand, if we confider how difeafe becomes multiplied and varied in the fame climate, we Shall fee that climate alone is not attended with fo much variety as may have been fuppofed. It is obferved by fome of the ableft phyficains of this day, that the fever called inflammatory, is now not So common in this country as it was Sormerly repreSented to have been ; that it is now Seldom that in Severs they are o- bliged to have recourSe to the lancet, at leaft to that exceSs which is deScribed by authors in Sormer times. They are now more obliged to have recourSe to cordials than evacua- tions, and indeed the diSeaSe called the putrid fever, and putrid fore throat, are but of late date. I remember when the laft was called, FothergiU's fore throat, becaufe he firft pub- lished upon it, and altered the mode of pradice. I remem- ber when praditioners uniformly bled in putrid fevers ; but figns of debility and want of fuccefs made them alter their pradice. Whether the Same difference takes place in inflammation I do not know, but I SuSped that it does in Some degree, for I am inclined to believe that fever and inflammation are very nearly allied, that is, that either will be according to the conftitution, which is not the cafe with Specific dileafes, excepting in their common modes of adion, which confift either in fever or inflammation ; but I believe we have much lefs occafion for evacuations in inflammation than there were formerly, the lancet, therefore, in inflamma- tion, and alio purgatives, are much more laid afide. How Sar climate varies the conftitution So as to alter the nature of difeafes, I do not at prefent know; but it would appear Srom Dr. Blane's account, that inflammation is hardly a diSeaSe in the Weft Indies. How Sar an alteration in the mode of life is the caufe of this difference, I will not pretend to fay, but certainly the way of life is very much altered. We certainly live now more fully tlxin they did formerly. We may be faid to live above par.- At the full Stretch of living, therefore, when diSeaSe attacks us, our powers cannot be excited Surther, and we fink, So as to require being Supported and kept up to that mode oS life to which we have been accuftomed. A kind of conftant State and variety of mind may often alter constitutions So much as to alter the mode of diSeaSed adion, which is much more common in Some countries N n 2 218 Fundamental pri/u iples of inflammation. t, an others. We may be pretty certain that this State of mind often produces inflammation oS the gout. Probably there ri but little power in art to concert the SuSccptibility oS inflammation ; however, if the lufccntibi- lity of the body be fimilar to that of the mind it ouj.t to be in fome degree correded by art. The mind is correded by reafon, together with habit, but the body can only have the laft employed upon it; it might be made lefs SuScepti- ble by the immediate cauSes coming Slowly upon it, or by avoiding thoSe cauSes and even ading in diametrical oppo- sition to them; this will at leaft anSwer in the acquired SuS- » ceptib^lities. The acquired fufceptibility for inflammation, or indeed for any other difeafe as it is acquired by art or ha- bit, may be leffened Simply by a ceffation oS thoSe habits; and if the habit is of any particular kind, which is always' ascertainable, then the habit oS the contrary is to be uSed, which muft alSo be ascertainable. ' fc' Strength and weakneSs are the oppofites oS each other, and thereSore muft have very different effeds in diSeaSe. * They have very different powers in refifting diSeaSe in their mode oS adion, and alSo their readineSs to terminate that adion. Strength, probably, under every circumftance, produces good effeds, or at leaft it is always more in the power of management, by art, than weakneSs; I can conceive, however, that too much ftrength might ad with too much power, becoming unmanageable under diSeaSe that excites adion. In inflammation, v/hen the conftitution is Strong, then it will be commonly the moft manageable, Sor ftrength leS- Sens irritability: but in every kind oS conftitution, inflam- mation will be the moft manageable where the power and the adion are pretty well proportioned ; but as every part oS the body has not equal ftrength, theSe proportions can- not be the Same in every part oS the Same conftitution. According to this idea oS Strength, the Sollowing parts, viz. muScles, cellular membrane, and Skin, and more So in proportion as they are nearer to the Source oS the circula- tion, will be moft manageable in inflammation and its con- Sequences, becauSe they are Stronger in their powers oS ac- tion than the other parts oS the body. The other parts, as bone, tendon, ligament, etc. Sail into an inflammation which is leSs in the power of art to Ii 111» ental principles of inflammation. 2IQ. manage, becaufe, though the conftitution is good, yet they have lefs powers within themfelves, and therefore are at- tended with the feeling of their own weaknefs ; and I be- lieve they affed the conftitution more readily than the Sor- mer, becauSe the conftitution is more affeded by local diS- eaSe, when the parts have leSs power within themSelves of doing well; and the effeds, if bad'On the conftitution, re- fled a backwardnefs on the little powers they have. Strength and weaknefs of the conftitution, or of parts, are Synony- mous terms with a greater or leSs quantity oS animal life, or living principle joined with powers oS adion. The inflammation, iS in vital parts, will be ftill lets ma- nageable, Sor although the parts themSelves may have very Strong powers, yet the conftitution, and the natural ope- rations of univerfal health, become fo much affeded, that no falutary effed can So readily take place, and thereSore the diSeafe becomes leSs manageable. If the vital part is the ftomach, or Such as the ftomach readily Sympathises with, inflammation, in Such parts, will be ftdl lets manageable, Sor no operation can go on well, cither in the ftomach or in other parts, where the viScus is affeded, as the powers of reftoration become weaker than ever. In weak conftitutions, although the inflammation be in parts which admit of the moft falutary operations, in the time of the difeaSe, and in Situations the m,oft SavOurable to reftoration aSter diSeaSe, yet the operations oS inflamma- tion are proportionably more backward, as to their Salutary effeds, in Such conftitutions, and more or lets according to the nature of the parts affeded, which I Shall now con- fider more Sully. II. EFFECTS OF STRENGTH OR WEAKNESS OF CONSTITUTION, AND OF PARTS, WHILE UNDER INFLAMMATION. Whatevfr. is to be the conSequence of injuries, efpe- cially inflammation, is produced much more readily in a ftrong constitution than in a weak one. A wound, for in- fta-nce, made upon a perfon of an healthy conftitution, and 226 Fundamental principles ef infi.nrwation. found parts, \frill unite almoft at once ; it admits readily of an union by the firft intention. A greater Strength of con- stitution and of parts, admits of refolution, while in the adhefive Slate of inflammation, very readily, and thereSore tends much to prevent the Suppurative inflammation Srom taking place, Sor it gives a better diSpofition to heal by the adhefive ; So that the union of parts by the firft intention, the inflammation and refolution, as well as the readineSs to change from the one t© the other, according as tiie prece- ding, is prevented, depends equally upon the ftrength and health of conftitution and parts inflamed. We may alfo obferve, that a greater Strength and SoUndneSs of the con- stitution, or parts in flamed ■, when the inflammation has got beyond the Stage of refolution, and has affirmed the difpo- fition for Suppuration, haftens on inflammation and Suppu- ration, and alfo brings it foon to a termination, while, at the fame time, the matter is brought more quickly to the (kin by ulceration, Whatever, therefore, is the Step which nature is to take, wh'never an injury is done, or a neceffity for inflamma- tion has taken place, it is performed with readinefs and Sa- cilityih Strong constitutions and parts. WeakneSs of conftitution and weaknefs of parts, are fuppofed to be the immediate caufe of moft tedious or chro- nic difeafes. It appears to be often ufed as a general term, as have alSo nervous, bilious* to denote any thing Sor which we cannot well account, and to which, I am certain, there has been affixed no precife rneaning. Every adion that is not acute, eSpecially a mild continuation of Some oS the fymptoms of a former violent difeafe, is called weaknefs. Thus a gleet is called a weaknefs, diarrhoea is called a weaknefs, fiour albus is called a weaknefs ; none of which I conceive fimply to arife from weaknefs ; for I believe that weaknefs feldom or ever becomes an immediate caufe of diSeaSe, or adion oS any kind; but it oSten becomes the prediSpofing cauSe of diSeaSe, many diSeaSes not taking place, except where weakneSs is an attendant, as agues, Scrophula, nervous, etc. none of which are fimple weak- neSs ; and it may continue many diSeaSes when they have already taken place. This is, I think, very evident in ma- ny diSeaSes which would terminate well if there w:-> Strength in the conftitution to perform the right adions. However, where there i6 a itrong Suiceptibihty- for any one Fundamental principles of inftantmafim* 22.1 diSeaSe, in which weakneSs might alSo become a predifpof- ing caufe, I can believe that, in Such caSes, weaknefs, eS- pecially if fuddenly brought on, may become an imniecbate caufe of that difeafe; as, for inftanee, a man may, from a wound, or any other caufe, have a Strong tendency to a locked jaw ; if you bleed that man freely, it is a thoufand to one but that a locked jew comes on : weaknefs produces a conSciouSneSs of its own want of powers, or incapacity, which produces increafed action, that even proceeds the length of unnatural adions, called nervous. Thefe ef- feds are no lefs vifible in acute difeafes in fuch conftitu-- tions, which include accidents, or violence, of all kinds; fer they run into too violent adion, wdiich is not of a fa-r lutary kind, and therefore may be called unnatural difeafed sedion. When a wound is rmde in a perfon of a weak habit, there is a great backwardnefs in the two cut furfaces to unite by the firft intention, therefore inflammation takes place if there be ftrength of constitution to produce it, which is not always the cafe ; fo that in fuch habits inflam- mation is more likely to be a confequence; but this does not arife from a greater readineSs to inflammation in the habit, but Srom a want oS power and difpofition to heal, which renders inflammation neceffary ; however, in this caSe the want oS powers or diSpofition to unite may partly depend upon a different principle from that of weak parts or folids; it is probable that the blood of people of weak habits is weak in its living principle, which it therefore very foon loSes upon extravaSation, So a,s to become unfit Sor a bond oS union, hy which it degenerates into an ex- traneous body, and therefore the Suppurative inflammation muft take place if there be Strength to produce it. In weak habits and difeafed parts, inflammation is flow in any of its falutary effeds, and is hardly capable of either producing the adhefive or Suppurative inflammation; if they Should take place, it is but impel fediy, and the Sur- rounding inflamed parts oS the Suppurating SurSaces are hardly capable of refolution, but continue Inflamed ; we even find in many conftitutions, where the animal powers are very much weakened, that inftead of their readily run- ning into inflammation, it is hardly poSfible to promote it, even Srom a breach oS continuity in the Solids, which, in moft other cafes, is fureft oS being followed by inflamma- tion : Such constitution;, are in general thefe which «re 222 Fundamental principles of inflammation. dropfical: I have Seen Several caSes, where the power has been So weak, that the wound, aSter tapping, has not uni- ted by the firft intention, nor has even acquired the adhe- five ftate oS inflammation, and has admitted water to paSs through it Srom the abdomen Sor Several weeks without the peritoneal inflammation being excited. In the Same drop- fical habits, I have Seen Scarifications in the legs or feet not inflame, So that the cells were not united, but continue to diScharge the water Sor many weeks. In Such caSes of extreme weakneSs, this total want oS inflammation wculd appear to be a Salutary effed ; Sor in many dropfical caSes, where the parts have powers to inflame, but not Sufficient to go through the different ftages oS the inflammation, and at laft reSolve, as in healthy conftitutions, the inflamma- tion generally produces a total lots oS animal powers, and the parts mortifies, which oSten produces death in the whole, So that in Such caSes the parts only ad to deftroy them- Selves*. As a Surther prooS that debility is oSten the cauSe of increafed inflammation, in confequence of any violence, and often the caufe of mortification, is plainly Shewn in Mr. Dick's account of dropfies among the troops in the Eaft Indies, Edin. Med. Com. In the firft year of the attack in any man, he durft not venture to fcariSy the legs, but when they were attacked with the Same diSeaSe the year Sollowing, which was oSten the caSe, whenever he at- tempted to ScariSy the legs, a violent inflammation and mor- tification were the conSequence. He was in this Second attack obliged to have recourSe to Strengthened; and we may obServe that, in the caSe oS tapping, iS the conftitu- tion is irritable, the cavity oS the abdomen commonly Stel. the effed, and inflammation of the peritoneum, and death is the confequence. As the effed which this inflammation has upon the con- stitution is by Sympathy, it muft be in proportion to the readineSs with which the conftitution aflumes that adion. This SuSceptibility is Stronger in Some constitutions than in others ; and every constitution is more SuSceptible oS Sym- pathy with Some parts oSthe body than with,others. The kind oS conftitution which is leaft affeded by this inflammation, is that which is in general moft healthy, where Sympathy hardly takes place ; this happens to be the caSe with Such constitutions as can moft readily perSorm * Vide paper on the Recovery of drowned People. Fundamental principles of inflammation. 223 all the different operations with eafie ; and when the parts inflamed are able to manage their own bufinefs, they there- by affed the conftitution lefs ; for we Shall find, that a conftitutidn may be affeded by a local difeafe, merely be- caufe it is beyond the power of the part. to cure itfelf. But it is to be obferved, that constitutions in full viocr, or which have not been in the fmalleft degree accuftom d to local diSeaSe, take the alarm much more readily than thoSe which are hot in Such Sull health, or which have been ac- cuftomed with local diSeaSe. Thus, if a man in perfed health gets a very bad compound fracture in the leg, or has his leg taken off, either for this fracture or in confequence of any other accident, he ftands a mucli worfe chance of re- covery than one who has been accuftomed to a local dif- eafe: even the man with the compound fradure will do much better, if his leg is not taken off, till the firft Symp- toms are over ; or at leaft we may be certain that the Symp- toms arifing from the amputation will not be nearly fo great as thofe that arife at firft from the fradure, or would have arifen from the immediate amputation. This would appear to be a contradidion to the above pofition ; but upon an accurate inveftigation I think it may be accounted for ; for firit, I do not look upon full health, as the beft condition to refift diSeaSe ; diSeaSe is a State otbody which requires a me- dium ; health brooks diSeaSe ill, and Sull health is oSten a- bove par; perSons in full health are too often at the Sull Stretch oS adion, "and cannot bear an increaSe, eSpecially when diSeaSed ; and as I beSore obServed, it is a new im- p'-elfron on the conftitudon, and till it be in fome degree ac- cuftomed to local difeafe, it is lefs able to besr fuch as is vio- lent ; befides, the removal of a difeafed part which the con- stitution has been accuftomed to, and which is rather fret- ting the conftitution, is adding leSs violence' than the remo- val oS a Sound part in perSed harmony with the conftitu- tion ; the difference, hpwever, is not wholly owing to that cauSe, Sor the circumftance oS a constitution being accuf- tomed to a mode oS life, etc. which it is to continue, makes a confiderable difference. O o * 224 Fundamental principles of inflammation. III. OF PARTS OF THE BODY MOST SUSCEP- TIBLE OF THE THREE DIFFERENT IN- FLAMMATIONS TO BE TREATED OF. All parts of the body are SuSceptible of inflammation, although not all equally So ; r.or will ail p; rts ofthe body ad- mit readily oS the three different kinds oS inflammation I mean, to treat of; Some parts admitting readily oS one only, others oS two, and others oS all the three; which difference appears to be according to the Situation of the inflamed parts in the body, and alio the nature of the parts inflamed. The cellular membrane the firft. The cellular membrane free fro;- the adipoSe, appears to be more SuSceptible of the adhefive inflammation, than the adipoSe membrane, and much more readily paffes into the Suppurative. Whether this ariSes Srom Surfaces inflaming more readily than other parts, I will not pretend to Say. Thus we See that the cel- lular membrane conneding parts together as muScles, and the cellular membrane conneding the adipoSe to muScles, eafily inflames and runs readily into Suppuration, and, as it were, Separates the muScles Srom their lateral conexion, and even feparates the adipoSe Srom the muScles, while the Skin and adipoSe membrane Shall only be highly inflamed, and the matter So Sormed muft produce ulceration through all this adipoSe membrane, to get to the fkin, and then through the fkin, in wdiich laft mentioned parts it is much more tedious ; ulceration, therefore, does not So readily take place in thoSe parts as it does in the common con- neding membrane. MuScles, ner/cs, and blood-veffels, are parts which nature wishes to retain, and the adipofe membrane contains a fubftance which is properly no part ofthe animal, viz. oil ; it may therefore be more difficult for this part to be abforbed than what are properly the parts of the animal itfelf. As a deficiency in the power to heal becomes a ftimu- lus, or an incitement to inflammation, we find that fimilar parts, in proportion as they are removed from the Source. oS the cirulation, Such as the lower extremities, are more ready to inflame than others not So circumstanced ; and Fundamental principles of inflammation. 225 what adds to this backwardnefs is their being depending parts, which adds to the incitement. The deeper feated parts of the body, and more efpecial- ly the vital, very readily admit of the adhefive inflamma- tion, which is proved by difedions ; for we hardly ever open a human fubjed where there arc not in the circum- Scribed cavities confiderable adhefions: and moft probably many in the common cellular membrane, if they were e- qually vifible. hue deeper Seated parts, however, do not m common So readily paSs into the Suppurative inflammation ; and Luis readineSs to accept of the adhefi, e, moft probably becomes a caufe why the fuppurative inflammation does not io readily take place. . , ■ But if the inflammation comes on at once, witn great violence, it would appear to path almoft at once over tire adhefive, immediately to the Suppurative action ; or per- haps where it may appear to have done this, there may be an erySepelatous diSpofition ; Sor although it is not the cul- pofition oS the erySepelatous inflammation to tuppurate, yet it has a greater backwardnefs to produce adhefions. lffs effed we oSten find take place in the abdomen, in the thorax, etc. and I have already mentioned that I Suipect the erySepelatous inflammation does, in Some degree, re- verSe the' common rules of the common mflammatton by being more ready to Suppurate in deep Seated parts than in the Superficial, and extend much farther towards the cen- tre of the body. . . . . . ,. ■ ISuSped too, that the coverings oS the brain, viz. pa and dura-mater have Something of this ^Spofition f hey appear to Suppurate very readily, or with veryTttk^mfkm- mation; for from a flight blow on the head, we hnddirfc membranes much oStener Suppurate than w^^d^n°^as Similar blow on the Shin-bone ; for inftanc a blow o, th bone will only produce fuppuration on the external mr face ve y Seldom in its internal cavity ; but a blow on the head' ffiSl not even produce the adhere inflammation • 1 r 1 n^il make thofe membranes iuppurate. m In'lSatl "he'et nutated, is always more violent on that to of the point of inflammation next to the exter- nal fmface. Q q 2 226 • Fundamental principles of inftarvnalnn. This effed we often find take place in the abdomen, in the thorax, etc. and I have already mentioned that I in \ ttt inflammation, wherover fituated, if there be a continuity of parts between it and the external furface, will be greater on that fide next to the external furface of the part, than towards the centre of the part. This alfo equally takes place in inflammations, although clofe to the different outlets of the body, and is probably moft eafily demonstrated in them. Thus, for inftanee, if an inflammation comes on in the Socket oS a tooth at its root, inflammation will not take place on the infide of the jaw, but towards the outfide ; and if it is beyond the union of the lips with the gum, it will attack the fkin over the inflamed part, while all the internal parts, fuch as the gums on both fides, but principally on. the infide. The ton ute iS in the lower jaw, Shall be perfedly Sound. If an inflammation attacks the cellular membrane on the outfide of the gut near the anus, although the gut is in contad with the inflamed part, yet the inflammation ex- tends to the Skin of the buttock, while the gut remains pretty free from inflammation. If an inflammation attacks the peritonaeum covering an inteftine, and if adhefions between it and the peritonaeum lining the abdomen are a confequence, the inflammation immediately paffes through the abdominal mufcles towards the Skin, while the proper coats oS the inteftines Shall in moft caSes remain Sound ; however, this is not always the caSe, although much more commonly So than the reverSe : we See the Same thing in the obstruction oS the natural paf- Sage oSthe tears called fistula lacrymalis, Sor there the Sack and Skin ulcerate on the inner angle oS the eye, while the the infide oS the noSe deSends itSelS by becoming thicker; fo much fo in many cafes as to Stop the cavity of the note, and unite with the Septum, which has been the cauSe of the failure of the operation for the fistula lacrymalis. We even find, that if an abfeefs forms in a frontal Sinus from an obftrudion in its dud, that the matter makes its way through the Srontal bone externally, inftead oS getting into the noSe. The Same observations are applicable to abSceffes in the antrum, which are common caSes ; and indeed, if we ob- ferve accurately, we Shall find that nature rather defends fuch parts as are either deeper feated, or on the infide of outlets, as will be explained hereafter. Fundamental principles of inflammation. 227 The Specific qualities in difeafes alfo tend more rapidly to the Skin than to the deeper feated parts, except the can- cer ; although even in this difeafe the progreSs towards :ho Superficies is more quick thanks progreSs toward the center. The venereal has Something oS the Same diSpofition with the cancer, although not So much. In Short, this is a law in nature, and it probably is upon the Same principle by which vegetables always approach the SurSace oS the earth. That this is a general principle in vegetation requires no il- lultration,but what isthe immediate cauSe is not fo eafily de- termined. I conceive it might be the light, not warmth, Sor the ground is oSten warmer than the air, or SurSace, in- to which vegetables are often growing. To aScertain this, as far as I could, by experiment, I took a tub, about eighteen inches deep, and about two wide, and filled it with fine mould, in which I planted fome hearts and peas ; their eyes were placed in various diredions, and over the fuj face was Spread a cloSe mafhed net. The mouth of this tub was turned down, was raifed about three feet from the ground, and was fufpended between two pofts. Round the tub, and over its bottom, which was uppermoft, were placed wet Straw, mats, etc. to take off any influence the Sun or air might have upon its contents, and a Small hole was bored in its bottom, to which was fixed a Small long tube that came through the ttraw. This was intended Sor pouring Some water, if I found the earth get dry, into the tub. Under the mouth of the tub I placed looking glaffes in fuch a way that the light was thrown upon the mouth of the tub, or furface of the earth. The weather was fine ; fo that through the whole day there was the re- fledion oS the light Srom the looking glaffes upon the Sur- Sace oS the mould, which was much more powerSul than day-light without the dired rays ofthe fun. This I con- tinued till I conceived that the beans and peas had grown fome length, but not finding their tops coming down through the SurSace oS the mould, I examined the contents ofthe tub, and found that they had all grown upwards to- wards the bottom of the tub, and that in thofe whofe eyes had been placed downwards the young Shoot had turned round fo as to rife up. As one experiment leads to ano- ther, I wiltieu to fee how a been would grow if kept in con- stant rotatory mo'.ion. For this purpofe I put Some earth in a baikctj having the 111 ipe of a cylinder, and about a foot diameter, with die two ends of wood for greater ftrength, - "* Fundamental principles of inflammation. through the centre of which I fixed an ads or Spindle ; in the earth I planted a bean, about half way between the Sur- face and axis,with its eye to the fu-face. The balket was laid acrofs the mouth of a large tub, with the ends of the Soindle refting on the edges oS the tub, which were fitted to o oe another So as to allow oS eaSy motion. Round the oa.kct was rolled Some Small cord, to the end oS which w^s luS- pended a box, water tight ; into this Was put lead, So as almoft to make it fink in water, and which was Sufficient to turn the baflcet round in the open air. This lar*e tub was filled with water, and the box placed upon it, and the Spindle withc the bafket placed acroSs the mouth oS the tub; a very Small hole was boared at the lower end of the tub, wheh allowed the water to eScape, but very Slow- ly ; as the water Sunk in the tub the box dcScended, and as the box deScended the baiket was turned round. This tub took about twelve hours in emptying, and during that time the Spindle with the baSket, only turned about one and an half. The tub was repeatedly failed, and when I con- ceived the bean might have grown fome inches, if it had grown at all, I examined it, and found it had grown as much as if it had been planted in the common ground, but it had no particular diredion but that of paffrng in a Straight line Srom the bean, which was at firft towards the circum- Serence, the diredion in which it was planted ; but in its courSe it had met with a Small Stone, which had turned it into the diredion oS the axis, and it had gone on in a Straight line in. diat diredion. Here, as there was no fix- ed inducement to grow in any one diredion, the bean grew in a Straight line, in that diredion given it by chance. This circumftance of the deeper feated parts not fo rea- dily taking on the fuppurative inflammation as thofe which are Superficial, is Shewn in cafes where extraneous bodies irritate any parts ; for we find that extraneous bodies are in general capable of producing inflammation, but if thefe extraneous bodies are deeply Seated, they may remain Sor years without doing more than producing the adhefive in- flammation, by which means they are incloSed in a cyft, and only give Some uneafineSs; or iS they are Such as can be made to change their Situation by the adions oS the body upon them, as pins and needles, or Srom gravity, as is the caSe Sometimes with bullets, then the parts through Fundamental principles of ^inflammation. 22£ which they pafs Seem not to be much altered or disturbed* : but if the Same body was nearer to the Skin it would pro- duce Suppuration. This is proved by the caSes that have occurred oS people Swallowing pins, needles, ckc. they h.ivc been found to travel almoft over the whole body, without producing any efivcl, except in Some Situation* exciting Some SenSation ; but when thdy lave come near to the Skin, the very.Same fubSh.nce ha* generally produced Suppuration. This principle fliews itSelf very remarkably in the catile which feed in ble-eh fields ; there is not one of thefe killed without having their Stomachs, etc Stuck full of pins, and no teeming inconvenience takes place, Sor they appear to be healthy, and fatten as readily as other cattle. However, it is to be remarked that thefe pins are not found in the fourth or digesting ftomach, there- fore do not give that disturbance to the constitution that might be expeded. It is probable that thefe caSes of pins, etc. owe their want oS power in producing Suppuration, not entirely to Situation, but in Some degree to the nature oS the Subftance, metals perhaps not having the power of irritation beyond the adhefive, Sor when the adhefive nas taken place, the part appears to be Satisfied. This appears alfo to be the cafe with the introdudion o. glafs, even in Superficial parts ; a piece of glafs Shall enter the fkin juft deep enough to bury itfelf, inflammation Shall come on, the wound in the Skin, if brought together. Shall heal by the firft intention, and the inflammation Shall not exceed the adhefive, but rather degenerate into the diS- pofition for forming a Sack, by which means a Sack is form- ed round the glafs, and no disturbance is given to the no- tability of the parts. This was the cafe with Mr. Knight, apothecary, who had a piece of glafs three-fourths of an inch long run into the palm of his hand, and remained there for ten weeks, without any further inconvenience than retarding the motion of the hand, and Sometimes giving a pricking pain, when the Sack was made to preSs upon the points of the glafs ; this inSenfibility, however, antes frora * This circumflance of fuch bodies moving in various direc- tions and not towards the furface. is a proof of the truth of mv priociple, f»r their motion arifes from a mechanical caufe, and is ruled by it; which ever wpy it is directed they muft move whether by gravitation, as is the cafe with bullets or by the mechanical preflure of the part upon the two en is of t..s pin, which will dcteuifue the motion tovvarJ* the point;. 230 Fundamental principles of inflammation* - a Sack being Sormed with Such properties, but it cannot be alTigned as a.cauSe in the caSe of bodies moving-as pins. Whether this fad, of external parts affirming the Suppu- rative inflammation more readily than the internal, ariSes Srom unknown properties in the parts themSelves, or Srom circumftances which attend Situation, Such as heat, cold, etc. is not eafily determined ; but whatever be the cauSe, the effeds are good, as many Situations oS inflammation, viz. the internal, would prove dangerous, if the parts were always, or often to Suppurate ; of two evils, nature chooSes the leaft; while on the other hand, when near the ex- ternal SurSace, it becomes the leaft evil to produce Suppu- ration, in order to get rid oS the extraneous matter. Ac- cidents may be aSfigned as one cauSe of this frequency up- on the external SurSaces, but the cafes of pins abovemen- tioned, (which is accident) Show, that even when it ariSe6 from accident, the parts near the external furface much more readily fuppurate ; and in all caSes arifing Srom the conftitution, or Spontaneous, the external inflammations exceed the internal, in number, violence, and extent. IV. OF THE TWO PARTS THAT IIAVE THE OR- DERS OF INFLAMMATION RESPECTING PRI- ORITY INVERTED. I formerly divided the SurSaces capable of taking on inflammation into two ; the firft of thefe was the cellular membrane in general, together with the whole circum- Scribed cavities; die Second was all the outlets in the bo- dy, commonly called mucous membranes; Sor inftanee, all the duds of glands, and the alimentary canal. The firft order of parts, I have already obferved, ge- nerally (if not always) take the adhefive firft in the true inflammation, and then all the three inflammations in Suc- ceffion ; Sor the adhefive is immediately admitted in the cellular membrane and circumScribed cavities, to exclude, if poffible, fuppuration, where Suppuration, and of courSe ulceration, would prove hurtSul. Fundamental principles of inflammation. 231 In the following parts the order of inflammation, with regard to its being adhefive or fuppurative, appears to be inverted ; as the ulcerative is a confequence either of the adhefive or of the fuppurative inflammation, it is ruled equally by both. In internal canals *, where adhefions in moft cafes would prove hurtful, the parts run immediately into the fuppurative inflammation, die adhefive inflamma- tion in common being excluded ; fuch parts are the inter- nal furfaces of the eyelids, nofe, mouth, trachea, air-cells of the lungs, oefophagus, ftomach, inteftines, pelvis of the kidneys, ureters, bladder, urethra, uterus, vagina, and indeed all the duds and outlets of the organs of Secretion, which all theSe parts mentioned may be in Some degree rec- koned, and which are commonly called mucous mem- branes. In Such parts, if the inflammation is but flight, the Suppurative in common takes place, which is almoft immediate, as it is not retarded by the adhefive Stage, which accounts Sor the quickneSs oS Suppuration of thefe parts in many cafes. I have known a violent difchargc of pus come on the furface of the urethra only a few hours after con- tamination. Thefe fads are Shewn us every day in va- rious inflammations of thoSe parts, and particularly in the gonorrhoea, cold in the nofe, lungs, inteftines, etc. The matter Srom Such is generally not called true matter, or purulent, but is oSten So, if not always, having all the cha- raders of pus ; however this will be according to circum- ftances. Since thofe furfaces are, in general, Secreting furfaces, fuppuration would appear to be only a change in the fecretion ; and I think I have vifibly Seen, or could vi- fibly trace, the one change gradually leading into the other : the different parts, thereSore, of which the pus is compof- ed, will not always be in the fame proportion, fo that the matter will feem to vary from true matter, towards that of the common fecretion of the part, and vice verfa. But this does not alter the pofition, Sor it is common to matter Srom a Sore ; and even common to our ordinary Secretions. If this inflammation, which produced fuppuration on thofe Surfaces, becomes more violent, or has Something of the erySepelatous diSpofition, we find that it moves Srom th« * I make a distinction between an Interred cavity and a ca. nai; the*/;: re very different in their con It nut: m their ufes, and alfo t'h'.h mode of acVion :n difeafe are vcrv d.dhrer.t. F P lyi Fundamental principles of inflammation. fuppurative to the adhefive, and throws out the coagulating lymph. I have fcen this in the inteftines, oSten ton the in- fide of inteftines that had been Strangulated in a hernia. I have been able, alSo, to produce it on rhe infide oS the va- sdna oS an afs, by injeding a Strong Solution oS corrofive Sublimate. But if of the eryfepelous kind, thefe furfaces will take on the adhefive adion immediately or at firft. This is evidently the cafe in what is called the ulcerous fore throat; I have Seen it in the trachea, I have feen it thrown up from the lungs in branches, I have feen it in the pelves of the kidneys, ureters, bladder and urethra. This is contrary to the mode of adion of the eryfepe- latous inflammation in the cellular membrane and circum- Scribed cavities, for there it hardly produces adhefions, and when it Suppurates the Suppuration takes place firft. The common inflammation and the erySepelatous would Seem to change adions fimilar to the adhefive and the Suppura- tive, according as they are changed to places of different difpofitions, never ading in the fame way under the fame apparent circumftances, and, therefore, Something Speci- fically different. As the adhefive inflammation is common- ly excluded from fuch furfaces in the true inflammation, fo of courfe is the ulcerative in fuch cafes; for it is in ge- neral only as a confequence of the adhefive and fuppurative having previoufly taken place, with the confinement of pus, that ulceration becomes neceffary; for the ufcerative in fuch cafes is a confequence of a Stimulus arifing Srom preffure Srom within. In inflammation we Seldom pay attention to more than the continued and the univerSal Sympathy; how Sar the contiguous takes place without adhefions, Surther than SenSation, I am not certain. I believe it never produces inflammation without them ; for we may obServe, that a tefticle Shall be confiderably inflamed, and the fcrotum not in the leaft affeded. The fcrotum Shall even inflame and Slough off, without the tefticle being affeded till death or expofuretakespk.ee in the tunica vaginalis; then \i be- comes an expoSed or imperfed furface, fimilar to the open- ing, or application of a cauftic in the hydrocele ; but I know that contiguous fympathy produces a nervous tender- nefs or fcnlibility, cxpreffed by the word fore. Thus I have feen complaints in the vifcera oS the abdo- men prcdv.ee a vaft tenderneSs in the Skin oS the r.bdcmen ; and alSo complaints cS the lungs, produce a tenderneSs in Fundamental principles of inflammation. 233 the fkin of the cheft oppofite to the complaint. The re- mote Sympathy Sometimes takes place when particular puns are inflamed. The continued is that Sympathy which increaSes the in- flammatory Space, by which means the inflammation Spreads beyond the irritating point. This becomes more a Subjeel: of furgery than any of the Sympathies, becaufe it increafes the local complaint, and it takes its peculiarities from the conftitution at large, as well as from the nature of the pans inflamed ; as much can be learned from it in an inflamma- tion as from any other Symptom. The univerSal fympathy, or constitutional, is where the whole conftitution feels the local difeafed adion. V. THE NATURAL CAUSE OF THE ADHESIVE INFLAMMATION BEING LIMITED. As the body is made up of diffimilar parts, whofe con- ftrudiou and Sundions are peculiar to themSelves, yet all tending to the benefit oS the whole, we find them alio keeping themSelves diftind in many oS their diSeaSes as long as they can ; and iS it is a diSeaSe Somewhat peculiar to the part it will be kept in proportion longer confined. Thus a cancer in the breaft will Spread falter in the glandular part of the breaft than in the Surrounding parts which may even be in contad with it. A difcs.Se taking place in any part oS a lymphatic gland, will communicate its difeafe to the whole of that gland much fooner than to the furround- ing cellular membrane. Even a diSeaSe common to all parts alike, iS it takes place in any diffimilar part will keep diftind at firft. Thus an inflammation in a lymphatic gland is not taken up by the Surrounding cellular membrane, till the inflam- mation has made Some confiderable advancement, and then it begins to inflame. Thus a lymphatic gland Shall inflame and the furrounding parts Shall not, till other proeeffes be- fides inflammation are going on, viz. Suppuration ; this, however, will be more or lefs, according to the ccnftitu* P p 2 Z*\ F:n:dame;ital frinc'p'es of inflammation. tion, Sor if it has a Strong SuScepdbiiity for the erySepela- tous, thediflimil ir parts will more readily Sympathize with the Scat of the diSeaSe. Thus the investing membranes have not thii Sympathetic connexion with the parts which they either cover or line, nor have the parts either covering the investing membrane, or lined by it, any Sympathizing afiedion with it in the adhefive Stages of inflammation. Thus the peritoneum is both a lining and a covering, and fo is the pleura. If the peritoneum which lines the cavity of the abdomen in- flames, its inflammation does not affed the parietes of the abdomen ; or if the peritoneum covering any of the vifcera is inflamed, it does not affect the vifcera. Thus the peri- toneum Shall be univerSally inflamed, as in the puerporal Sever, yet the parietes oS the abdomen and the proper coats oS the inteftines Shall not be affeded; on the other hand, iS the parietes oS the abdomen, or the proper coats of the inteftines are inflamed, the peritoneum Shall not be af- feded. The fame principle will lead to diftindions between an inflammation of the lungs and that of the pleura; but I fufped that the reticular or conneding fubftance, which joins the air-cells of the lungs, has a greater fympathetic affedion with the air-cells, or reciprocally with each other, than the beforementioned parts ; and this may arife from the thinnefs oS the air-cells. And it is alSo upon the Same principle that inflammation oS the pia-mater is Seldom con- tinued into the Subftance oS the brain, although the pia-ma- ter may be in Some degree confidered as a continuation of the fame veffels. '"' Contiguity of parts does not communicate inflammation. Thus when an inteftine is inflamed the inflammation is not communicated to the peritoneum, lining the abdomen, al- though in contad ; but I have already obferved it produces fomewhat of a forenefs, even to the external touch; but if continuity by adhefions takes place, then inflammation will be continued from the one into the other. The fecond caufe of the limitation of inflammation is fimple contad. I have already obferved, that expofure of internal furfaces becomes an immediate caufe of inflamma- tion ; and when it extends further than the furface of ex- pofure, it is then by continued Sympathy only, and that a whole cavity, iS wholly expoSed, will wholly acquire the inflammation; but we may now obServe, that although a Fundamental principles of inflammation. 235 eavity is opened and So far rendered imperfed, yet fimple contad of its fides renders it perfed again, and fets bounds to the immediate caufe. To explain this further, we may obferve that there is no fuch thing in an animal as empty fpace, exclufive of out- lets or refervoirs, which cannot be reckoned internal or circumScribed cavities, Sor they are perSed by not being Such. Every part oS the body is either conneded by a continuation of one part into that of another, or by fimple contad. This takes place equally, either in the common cellular membrane, or in the circumScribed cavities; for, if a wound is made either into the cellular membrane, or into a cir- cumScribed cavity, we find that the SurSaces oS both, be- yond the cut edges, are naturally and generally in contad with one another, Sor without this, union by the firft in- tention would not take place, either in circumScribed cavi- ties, or in the common cellular membrane. To explain this pofitiofj, let me SuppoSe a caSe. If we make a wound into the cavity of the belly, and in a found ftate of thofe parts, we Shall find that every viScus is in contad with Some other vifcus, and that the whole in- fide oS the peritoneum is in contact: with the vificera in ge- neral ; So that no Space is unfilled while this contad of parts remains. If this wound is not allowed to heal by the firft intention, ftill we Shall find that no inflammation will take place, or extend Surther than the attachment oS thoSe parts to the cut edges ; except what is owing to continued Sympathy. If this was not the cafe, every part oS the Same cavity muft inflame, becauSe every part would be e- qually imperfed; Sor iS this contad was removed, upon the receiving oS the wound, or at any time afterwards, the whole cavity muft inflame, becauSe every part is equally under the Same predicament with regard to expoSure. The Same thing would take place in the common cellular mem- brane, if thofe cells were not (in a natural State) in contad. Inflammation, in cafe of wounds, would as readily extend over the furface of each cell, as air does through the cavi- ty of each cell when blown into. Now this fimple and na- tural contad of natural parts, keeps off the inflammation beyond the cut edges of expofure ; and inflammation only takes place at this part, to preServe this contad, as alSo to Serve as a bails for the future operations. This, I appre- hend is upon the principle of contiguous fympathy, two 23*5 Fundamental principles of inflammation. furfaces being fimply in contad, mutually agreeing not to inflame; or perhaps, more properly expreffed, by being in contad there is a mutnal harmony which prevents their being excited to inflammation. This circumftance is a rea- fon why we Should- not attempt to bring circumScribed ca- vities to univerSal Suppuratiem, by fimply opening them, and allowing d em to coliapSe ; Sor we may be pretty cer- tain, that union only will take place at the expoSed edges of contada which excludes the general cavity, and which is the reafon why the operation for the radical cure in the hydrocele often fails. \f^ on the other hand, this natural contad of parts did not preferve the whole beyond the cut edges, then we muft allow, that the cavity is under the fame predicament with the cut edges ; and if the cutetiges inflame, fo mud the whole. In cafes of fpontaneous inflammations of chcumfcribed cavities, we find where this contad is completer!, that the inflammation and its confequences are the leaft; for in- stance, in the abdomen, in the caSes oS the peritoneal in- flammations, the inflammation is the greateft where the furfaces are not fo well oppofed to one another, viz. in the angle between any oS the two viScera. This Sad oS fimple contad being Sufficient to exclude the irritation Sor inflammation, was well illuftrated in a wo- man who had the CeSarian operation performed upon her, where a wound oS eight inches long was made into the ca- vity oS the abdomen to extrad the child. ASter the child was extraded, the wound could not be brought exadly together ; thereSore So Sar gave riSe to a peritoneal inflam- mation ; but the belly cOllapfing, and falling on its con- tents, they all came in contad as before, and the .woman living twenty-fix hours, gave time for the inflammatory irritation to take place. After death it was found, that the inteftines were united to the peritoneum, all round the wound for about half an inch in breadth, and the fur- face of the inteftines which lay unattached and expofed at the bottom of the wound were inflamed, while every o- thcr vifcus as well as the peritoneum, beyond the adhefions, were free from inflammation. Ulceration does not Seem to obey this law So much, and the reaSon is, that ulceration is a Second operation, and is preceded by inflammation, So that pus is brought equally through every part, iS equally SuSceptible oS ulceration, which all parts are net, although not depending upon their Fundamental principles of inflammation. 237 being Similar or diffimilar. Thus a muScle or artery will not ulcerate So readily as cellular membrane ; but iS pus was Sormed on the infide of an artery, or in die centre of a mufcle, they would ulcerate very readily, and the ulcera- tion would not Stop, or remain Stationary, when it cme to the cellular membrane, but would go on ; if pus too be formed in a lymphatic gland, ulceration would go on in the parts between hand the external Surface, as faft as it did in the gland, if not fatter, becaufe, inflammation would have gone before, and as it were aifiniilated the parts, and all from this caufe, viz. being equally difpofed to ulcerate. The caufe of the Spreading of inflammation is Sympathetic; but, the caufe of ulceration is immediate. VI. OF INFLAMMATION—ITS STAGES. I have given the moft fimple idea I can form of an inju- ry done to a part, with the natural, immediate, and con- sequent means oS reftoration. I have alSo treated of cites wjiere they become a little more complicated, requiring the aid oS art as a Substitute for the firvffiicity of the firft. The action of the parts is not neceffary in either of thefe, except that of the biood forming its veffels and other Solid parts, and becoming oS the nature oS the parts in which it is extr.waSated. But I tcok notice that the violence dona was often So great, or that reftoration did not take place So readily, as in all caSes to exclude irritation ; we had, therefogt, an adion in fuch cafes taking place in the parts called'inflammation. That this adion affifted in the re- storation by producing an extravafation of the coagulating t lymph, which became the fecond bond of union. I have alfo Stated what may be called the natural tendency to in- flammation, to Serve as a kind of leading principle. We Shall find that inflammation may arife from very different caufes, and often without any apparent caufe, and that its operations are far mare extenfive than fimply the ad of producing union in parts divih d by violence; for it more commonly produces union in whole parts or in natu- ral Separations, Sue* as the common cellular membrane, large circumScribed cavhics, joints, etc. becaufe Such Sur- 233 Fundamental principles of inflammation. faces are not naturally difpoSed to unite, but only in con- Sequence of Some uncommon action being produced; and although theSe adhefions are unnatural, yet that tendency of the parts to admit oS this union becomes a Species of cure. It is in conSequence of the parts taking on, in Some degree, the Same mode of adion which divided parts do when brought in contad, that in Such caSes Suppuration is pre- cluded. As inflammation oSten ariSes Srom diSeaSe, its Sa- lutary purpoSes are in many inftances not So evident, al- though they may finally take effed ; as it likewiSe takes place in diSeaSe, cr becomes the ultimate in diSeaSe where it did not begin it, as in the Scrofula, cancer, etc, and fome indolent tumors ; on thefe accounts too its falutary purpofes are fometimes not obvious. However, upon the whole, as inflammation is an adion produced for the re- ftoration of the moft fimple injury in found parts, which goes beyond the power of union by the firft intention, we muft look upon it in fuch inftances, as one of the moft fim- ple operations in nature, whatever it may be when arifing from difeafe, or in difeafed parts. Inflammation is to be confidered only as a diiturbed ftate of parts, which requires a new but falutary mode of adion to reftore them to that ftate wherein a natural mode of adion alone is neceffary : from fuch a view of the fubjed, therefore, inflammation in itfelf is not to be confidered as a difeafe, but as a falutary operation, confequent either to fome violence or fome dif- eafe. But this fame operation can and does vary; it is of- ten carried much further even in found parts, than to ac- complish union, producing a very different effed, and form- ing a very different fpecies of chfeharge from the former ; instead of uniting and confining the parts, rather Separat- ing and expofmg them, which procefs is called fuppwration, and varies with circumftances. However, even this in found parts leads to cure, although in another or Secondary way ; and in diSeaSe, where it can alter the diSeaSed mode of adion, it likewiSe leads to a cure ; but where it cannot ac- complish that Salutary purpoSe, as in the cancer, ScroSula, venereal difeafe, etc. it docs mifchief. This operation of the body, termed inflammation, re- quires our greateft attention, for it is one of the moft com- mon and moft extenfive in its effeds of any in the animal body ; it is both very extenfive in its cauSes, and it becomes itfelf the caufe of rn.tn" local effeds, '. th falutary anddif- caf.d. Fundamental principles of inflammation. 13 9 It has its different Stages in which it produces more im- mediately its different effects, which are local ; fuch as ad- hefions, fuppuration, and ulceration, and often death in the part inflamed, together with Secondary complaints which arc univerSal, as fever, nervous affections; and when in parts that cannot heal, or in constitutions which are too weak, the hectic fever, next difiblution, or univerfal death. However, by its forming thofe adhefions, it often precludes the neceflity of fuppuration ; and alfo entirely prevents many local difeaSes where probably Suppuration would be the conSequence, iS Such adhefions had not taken place, with all the train oS confequenees of fuppuration, fuch as abfeeffes, fiftula:, difeafed bones, etc. which are prevent- ed by it. It is alfo one of the modes of action in many Specific diSeaSes, and in morbid affections proceeding Srom poifons. Inflammation is not only occafionally the cauSe oS diS- eaSes, but it is oSten a mode of cure, fince it frequently produces a refolution of indurated parts, by changing the difeafed adion into a falutary one, if capable of refolu- tion. By thefe extenfive powers inflammation becomes die firft principle in furgery. In one point of view it may be confidered as a difeafe in itfelS where it takes place with- out any vifible cauSe ; and it may be looked upon as an in- cre.ife of the mifchief, when it is a confequence of fome injury ; but in either cafe it is a fign of powers, and of ne- ceffary powers ; for if a part under the influence oS Such irritation as fhould naturally excite inflammation, had either no powers or difpofition to exert them, the confequences would be much worfe, for mortification would probably take place. I intend at prefent to confider the molt com- mon cauSes and effeds of" inflammation, together with the end propofed by nature, in producing it, and the uSe to which it can be applied in Surgery. It becomes thereSore neceflary, firft to begin with de- scribing its moft Simple Sorms, together with its general effeds, and then to particularize as I proceed. Inflammation has feveral vfrell marked local peculiarities by which it is diftinguifhed. I Shall, call by the name of inflammation whatever pro- duces the following local effeds, viz. pain, fwelling, and <^<1 240 Fundamental principles of irftamma;:on. rednefs, in a given time, and theSe dependent on or theef- Seds oSone immediate cauSe. Inflammation pppears capable of arifing Srcm three cauSes which maybe called remote. Firft, from fome accidental force applied to a part, mak- ing a wound or bru'fie which cannot recover itfelf, unkis by inflammation. Such violence at leaft is naturally ca- pable of exciting it. Secondly, from fome irritation which does not deftroy the texture of parts, but fimply the natural adions, as ma- ny irritations, fuch as preffure, Sridion, heat, cold, blif- tcrs, pungent applications, a.id often fevers of every kind. Thirdly, From a particular difpofition in parts them- felves, as boils arifing fpontaneoufly without the constitu- tion having been preconcerned, fo little fo, as to have giv- en the idea that Such inflammations were healthy. Each of diefe will be of a kind peculiar to the conftitution ; but from whatever caufe inflammation arifes, it appears to be nearly the Same in all, Sor in all it is an effed intended to bring about a reinstatement oS the parts nearly to their na- tural Sundions. Inflammation may firft be divided into two kinds as firft principles, viz. the healthy and the unhealthy. The healthy probably confifts only of one kind, not being divifible but into its different Stages, and is that which will always attend an healthy conftitution or part, is rather to be confidered as a reftorative adion than a diSeaSed one, and would rather appear to be an effed ot a ftimulus than 211 irritation. The unhealthy admits of vaft variety, (dif- eafes being almoft numberlefs) and is that which always at- tends an unhealthy conftitution or part, and will be accord- ing to the kind of health in that conftitution or part, but principally according to the conftitution ; however, many parts naturally have a tendency to run into inflammations of particular kinds. Moft of thefe arifing from the nature of the conftitution, are, I conceive, in melt cafes, if not in all, Called- ahhourh eironeoufly, the eryfepelatus inflam- mation ; v....iLh whl be further taken notice of. The Simple ad of inflammation cannot be called Speci- fic, Sor it is an uniform or fimple adion in itSelS ; but it may have peculiarities or Specific adions Superadded. Inflammation is cither fingle or compound ; it may be called Single when it has only one mode of adion in the part inflamed, as in its firft ftcgec; compound, when at- Fundamental principles of inflammation. 241 tended with another mode of adion, or when it produces other effeds. Inflammation is capable of producing three different ef- feds, viz. adhefion of the parts inflamed, fuppuration in the parts, and ulceration of thofe parts ; which I have called the adhefive, the Suppurative, and the ulcerative in- flammation ; the laft or ulcerative, is properly Speaking, only a Secondary effed of inflammation, not being perform- ed by the Same veffels ; however it is poffible it may keep up inflammation, as it always keeps up a fpecies of violence, viz. a rieftruction of the parts. The two firft do not take place in the fame veffels, at the fame tine, but Succeed one another, although all the three effeds may exift at the Same time in the different parts of the fame inflammation. . . I have placed the adhefive firft in order, although it is not always fo, for with the refped to the priority oi thofe three adions of inflammation, it depends principally up- on the nature of the parts, together with the degrees ot violence of the inflammation. To explain this more fully, we fhall firft divide tne bo- dy, reSpedmc inflammation, into two parts, viz. the cel- lular membrane, or the body in general, togetner with the circumScribed cavities as belonging to tne firtt ; and then all the outlets of the body, as the fecond. We, Shall treat of each according to the nature of the parts, and ofthe in- flammation joined, and obferve their effeds, which will Show that the common effeds of one, as to priority, may be changed into thofe of the others and become fecond or third, according to the nature of the parts, the uniamma- ation, and its degree of violence. . We may obServe that intlamation, but more eSpecially the fupperative, inthe firft order of parts, more readilyta.tes ri -co n arer to the Surface of the body than in parts more deVy f^ted, and as a proof of this obfervation, it has been formerly obferved that tumors, and even extraneous bodies, will rnckc their way Srom Some deeper-Seated part to the fkin, but no inflammation Shall take place to. tney arrive near the Skin; but this circumstance wnl be mure fully defcribed when I treat on fippuration. _ if does not fe-m neccffiry that both furfaces which sue to be united Should be in 1 ft.ue of indamation icr the poP of effedingan union; it appears only neceflary t.eat on. mould be in fuch a State, winch is to tarnuu the ma- 242 Fundamental principles of inflammation. terials, viz. to throw out the coagulating lymph, and the oppofite uninflamed Surface Should be in a Slate of inflam- mation, te admit of union; for I juft obServed, that extra- vaSated blood produces an union without inflammation ; and we often find adhefions of parts which can hardly be called inflamed. Thus atrufs applied to a rupture will produce adhefions as has been obferved, although it may fit very eafily. In deScribing inflammation it will be Sound that the principal theory of inflammation will be introduced in the adhefive Stages; for in the firft Stated parts it appears only preparatory to the fuppurative either in preventing or pro- moting it. When inflammation takes place in the firft order o£ parts, it is commonly the adhefive, but it will be according to circumftances whether the Suppurative or the ulcerative follows firft. That either the one or the other Should Sol- low, Seems to riSe in many caSes Srom an increaSe of the in- flammation ; but it Sometimes happens that the Suppura- tive takes place almoft immediately, and probably Srom two cauSes ; the firft is, the intenfity of the inflammation, its exceeding the adhefive almoft immediately ; the Second, an. inflammation oS a different kind, where the adhefive make* no part oS the inflammation, and fuppuration takes place in the firft inftanee. I SuSped that the erySepelatous in- flammation has very little oS the adhefive in its nature, and therefore probably thefe inflammations are in fome degree of this nature, and go into fuppuration without adhefions. In Some caSes ulcerations muft take place prior to Suppura- tion, as when an inflammation happens on a Surface, viz. the Skin, as for inftanee, in a chancre, and with fuch vio~ lenee as is neceffary for fuppuration to take place, then ulceration muft begin firft, fo as to expefe internal Sur- faces for fuppuration ; but in the parts of the Second order, viz. internal canals or dud, it is the Suppurative inflam- mation which moft readily takes place firft ; but it car- ried Surther the adhefive Sollows, as will be more Sully ex- plained hereafter. When it is ari inflammation of the firft order of parts, the fuppurative fucceeds the adhefive, and the ulcerative may be faid to be an adion Superadded ta the Suppurative, arifing out oS effeds produced by the firft, now becoming new caufes, the fuppurative naturally taking place in the time of the firft, and the ulcerative in confe- quence of the Suppurative, which has called forth the ac- Fundamental principles of inflammation. 243 tion of another fyftem of veffels, the abforbents ; all of which may bereckoned as three different modes of adion arifing from the firft irritation or cauSe. The adhefive, as alfo the Suppurative inflammation, ei- ther in the firft or fecond orders of parts, with their varie- ties, may have a principle fuperadeled, which does not in the ieaft alter their inflammatory mode of adion, which Still continues to go on. This principle is fome Specific diSpofi- tion, Srom Scrophula, or poiSons, as the venereal, Smali- por, etc. TheSe three different modes of adion, viz. the adhefive, the Supperative, and the ulcerative, when carried on per- fedly, are gen-rally the effeds oS a good conftitution, Sel- dom attending the unhealthy ; they are what I would call common inflammation. I have already obferved that common inflammation ei- ther takes place in parts that conftitute the largeft part of an animal, which are all the circumScribed cavities, all the cellular membrane, and the fabflance of every part, the two laft oS which are the moft univerSal; or upon internal canals or outlets, wdiich are, in common, only excretory duds. That whatever has a tendency to discharge any extraneous matter,whether already exifting, as matter already Sormed, or a ball lodged, etc. or only preparatory to its formation fuch as inflammation that has a diSpofition to Suppurate, the inflammation is always greateft and extends Sar- theft on that fide next to the fkin ; Sor inftanee, Suppofe a man Shot in the thigh, the ball paffes through to within an inch or two oSthe oppofitc fide ; the ball has not dead- ened any part for an inch or two ofthe laft part of its paff- age fo as to allow this part to unite, we Shall find if that b ill excites inflammation, it will not be along its paffage where we Should (without knowing the principle) have mofefy expeded it, but the inflammation will commence on that fide next to the oppofite Skin that has. not' in the leaft been hurt. If a ball paffes quite through, a piece of cloth is carried in, and lies in die middle between the two orifices; if the paflage is pretty fupcrficial, fey only an inch distant from the Skin where the cloth lies, but which is two or three inches from either orifice, we Hull find that the inflamma- tion, for its exit will not lead to either orifice, but dired- ly acrofv to the fkin. 244 Fundamental principles of inft immatio n. As the adhefive inflammation precedes the Suppurative in every part of the body, except the outlet?, as was ob- ferved, and the Suppurative commonly proceeds the ulce- rative, excepting on an external Surface, the propriety of following, likewife, this order of nature in treating of them will appear evident, efpecially as each Succeeding inflam- mation is in fome meafure illustrated by that which has gone beSore. VII. OF THE DIFFERENT DEGREES, AND DIF- FERENT KINDS OF INFLAMMATION. Inflammation will in general be in proportion to the exciting cauSe, (in which may be included the miSchief done), the conftitution and the nature oS the part; in all which, as there is great variety, So muft there be in the inflammations. The degrees of inflammation will be more in the adhefive than in the fuppurative, for the adhefive may have all the degrees of violence between the molt flight inflammation and Suppurations; but the fuppurative is a more fixed or determined quantity, for when got to a cer- tain point, it takes a new adion, and inflammation ceaSes ; however, we have not always inflammation producing Sup- puration when it has arrived to a certain degree of vio- lence, Sor in Some it oSten goes beyond that point which would produce it in others, and in Such caSes there is no diSpofition Sor Suppuration, and it Seems to become Station- ary, Sor neither has it any diSpofition Sor reSolution. Spontarfeous inflammations which are to Suppurate, are more violent than thoSe inflammations arifing in conSequence oS an operation or accident, which alSo muft produce Sup- puration ; and thoSe inflammations Srom either operations or accidents, if they have not produced death in the part operated upon, are more violent, and of greater extent than thofe where death in the part has been produced. 1 he inflammation of a boil cr abfeefs is more violent, and commonly more extenfive than that in confequence of a cut, or even an amputation of a leg. The inflammation in confequence of a cut or amputation of a leg, will be more violent than that from a gun-Shot wound, or Srom the Fundamental principles of inflammation. 245 application oS a cauftic, which produces death in the part, and even although more parts have been destroyed by theSe means ; neither do Specific diSeaSes, except the gout, pro- duce So violent inflammation, nor are they cornmonnly So painSul as what I have called the common inflammation. It may appear not to be an eaSy matter to account Sor all thofe differences; however it is poSfible that in the Spon- taneous inflammation there is more occafion Sor inflamma- tion than Suppuration ; the inflammation being the only adion which is neceflary to produce the ultimate effed, as Sor inftanee, in the gout; In this difeafe the inflammation is the only thing neceflary for its adion, and the inflammation runs much higher than many others do width produce fuppuration*. The fpontaneous inflammation ariSes oSten Srom diSeaSe, which probably makes the parts more SuSceptible oS in- flammation. When inflammation ariSes from the irritation of death in a part, let the caufe of that effed be what it will, whe- ther mechanical, as in bruifes, gun-Shot wounds, etc. or by chemical means, as cauftic, etc. the inflammation i» late in coming on, and in comparison with the others gen- tle when come on. However, in many bruiSes, even where the death of parts has taken place, we have inflammation quick and vi- olent, but then the living parts have alfo Suffered, and have Suffered much more than iS fimply wounded. In many bruiSes we alSo have inflammations quick and violent, even where death has been produced in a part; but then death does not take place in all the hurt parts, as in many gun-Shot wounds, Such as thoSe attended with Sradured bones, in which the Surrounding parts were only hurt So far as to bring on irritation and not death. If cauftics do not ad with vigour, they will irritate fo as to bring on the inflammation fooner than if they had killed the part quickly. * It is a curious circumftance in the gout, that although it is attended with all the common effects of the adhefive inflamma- tion, as confiderable Swelling, etc. which fwelling muft arife Srom extravafat'on of the coagulating lymph; yet, adhefion? do not Seem to be the intention, Sor none are produced ; the lvmph is in general taken up, and chalk^ltone or tophaceous piatter put in its place. 2±6 Fundamental principles of inflammation. Irritating Subftances, when of no Specific kind, produce ioflammation Sooner than other vifible cauSes of inflamma- tlcu. If of a Specific kind, then the time, Sort, and vio- lence, will be according to that kind. But irritating applications muft be continued Sor fome time to produce violent inflammation. TheSe differences are eafily accounted for ; quick death does not irritate the part killed, and the contiguous living part, not being itfelf hurt, is only irritated to get rid of the dead part. A wound is a quick irritation of a living part, fo that it inflames more readily, and more violently, according to the quantity of irritation ; but that cannot be of long Standing, as nature fets about procuring relief. Eut when irritating fubftances are applied, the part inflames quickly, according to their power of irritation; and if they arc continued, nature is not allowed to relieve herfelf, but is canltantly teazed, by which means die inflammation be- comes alfo violent. I need hardly mention, that fever is often the caufe of local inflammation. We See this happen every day. TheSe cauSes, and of courfe the inflammation, are of two kinds, one which may be called accidental, as inflam- mation arifing in confequence of common fever; the others are more determined, depending upon the fpecies of a fe- ver, which may be called Specific, as the fmall-pox, chicken- pox, etc. Thefe inflammations in confequence of Sever, are commonly SuppoSed to be critical; but I very much doubt the truth of this opinion. The Small-pox and chick- en-pox are, perhaps, the ftrongeft inftances oS an appear- ance in proof of this opinion ; and, perhaps, the mealies, as a critical inflammation, might be produced as another; but, I believe, that it is peculiar to theSe diSeaSes to form inflammation and fores. We muft allow, however, it is not abfolutely neceffary, even in them, that abSceffes Sliould be Sormed, viz. tire pock to leffen or carry off the fever. For the Specific Sever in them cannot exift beyond a certain time, even although no eruption appears. But I think that in die eaSes of the fmall-pox, chicken- pox, and the meaflcs, thefc diSeaSes often prove the con- trary to that which is fuppofed to be the cafe ; Sor we have large abSceffes as often Sormed aSter thoSe diSeaSes as aSter any other, wdiich are commonly SuppoSed to be the fading Fundamental principles of inflammation. 247 of the fever in this part, but which are equally accidental with thofe from common fever, and therefore we cannot fuppofe that thofe abfeeffes are critical in fuch difeafes, be- caufe they are either common abfeeffes, or fcrophulous; for no one difeafe can have two diftind and different criti- cal inflammations. In further confirmation of my opi- nion, thofe inflammations are found no he not in the ieaft of the nature of the difeafe which produces them, So little So in moft cafes, as to be truly fpceific of another kind, viz. the fcrophulous. Now wexcertainly find it difficult to con- ceive one univerfal Specific clifo.rfe, as the Sniaii-pox, etc. producing a local one of another Specific difpofition to cure the firft, or terminating in another difeafe, whole modejof adion is totally different; and the more fo when we feo that the fame local difeafes can and do arife from every kind of fever. To aScertain this fid, dierefore, we are to look out for that difpofition, or that mode of adion common to all fevers which are capable of producing this effec':, with the difpofition of the conftitution, or of the part at the time, and we Shall find that tins kind of inflammation depends upon the conftitution and part at the time, and not upon any peculiarity iji the Sever, as is alSo the caSe with the Small-pox eruptions, viz. diey partake oS the con- ftitution. This common principle in fever, of producing local in- flammation, is the Simple Sever itfelS, abftraded Srom every peculiarity. A Sever in all caSes or of all kinds, is a dis- turbed adion, like inflammation itSelf, which may be join- ed with any Specific mode of adion, and this disturbed ac- tion will always be according to the conftitution, even when joined with any fpecific quality. The inflammatory fever is, perhaps, the moft fimple, becaufe it is a fimple fever on a conftitution having no peculiarity of difpofition. The putrid fever (as it is called) is perhaps no more than the fame fever upon a conftitution that has a peculiarity of ac- tion under that difturbance, and therefore it proceeds ac- cording to that peculiarity. This is well iduftrated in Specific diSeaSes ; Sor inftanee, in the Small-pox. The Small-pox produces a Sever, viz. a disturbed adion, joined with the Specific, and although diis adion is produced by the Same poifon in two different perf ins, yet die one Shall be the true inflammatory, and the other the putrid, the erySepelatous, etc. Now the S.me R r 24$ Ut.ion by the firft intention. poifon can have but one mode of irritating, abftraded from its pcifoncus quality, and this one mode produces Sever ; and it alSo can have but one mode ot irritating in reSped of its poiSonous quality, but that Sever abftraded Srom its poi- sonous quality will be according to the nature of the con- ftitution at the time, the poifon being capable of producing nothing but a fever jefined with its Specific poifon, and that Specific quality takes place equally on every kind oS con- ftitution, the poiSon itSelf having no power of affeding the conftitution in one perfon differently from that of ano- ther, it can only ad in a greater or lefs degree, according to the fufceptibility cf the perfon for fuch irritation. Now Since every fever, whether common or Specific, is equally capable oS producing local inflammation, which may be carried the length of fuppuration ; and as it cannot with any degree of reafon be called critical in fpecific fevers, we have no reafon for fuppofing that thoSe Suppurations are critical in die common fever, cr in thofe fevers, which are of no Specific kind. It was a leading dodriue oS Boerhaave, that inflamma- tion confifted in an obstruction of the minute veflels, in confequence of too great a fpiffitudeof thefluitls, and his pradice confifted in Seeking for attenuants; but thii theo- ry feems to be. almoft entirely exploded. This was certainly too confined an idea of all the caufes cf inflammation, and reduced all inflammations to one Spe- cies. The only diflindion between inflammations, muft have arifen Srom the nature of the obftrudion, if there could be any ; but this could never account for the action of many fpecific difeafes and poifons. It was alfo too mechanical. If they had faid that any obftrudion to the natural actions of a part which could Stop the blood's motion in it, became a caufe of inflamma- tion, they would not have been fo materially wrong ss to a poffible caufe of inflammation. It has been as much laboured on the other hand, to Shew that the caufe cannot on any occafion be obftrudion in the blood's motion through the finally veffels; but I will ven- ture to fay, that any caufe which can obftrud the motion cf the blood, for a given time, will become the caufe of inflammation, for either the caufe ofthe obftrudion itfelf or the blood being retained in the Smaller vefills for a cer- tain time, will cither irritate or unite the parts, or where Fundamental principles f inflammation. 249 it irritates will throw the veffels into fuch adions as natu- rally arife out of an extraneous irritating caufe, but not an increafed motioYi of the blood behind, to drive on the ob- Struded blood through theSe veflels, as has been SuppoSed. It will excite that adion which in the end produces Suppu- ration, in order to get rid oS the extraneous matter, which was the cauSe oS the obftrudion ; Such as preffure on ex- ternal parts, or the obftruding matter itSelf, which is to be reckoned extraneous. But though pure inflammation is ra- ther an effort of nature than a difeafe, yet it always implies diSeaSe or disturbance, in as much as there muft be a previ- ous morbid or disturbed ftate to make Such effort neceS- Sary. All inflammations attended with diSeaSe have Some Spe- cific quality which Simple inflammation lias not; and m Such caSes it is the Specific quality which is the diSeaSe, and not the inflammation ; Sor Such conftitutions or parts as are ca- pable oS Sailing into the true adhefive and Suppurative in- flammation, arc to be looked upon as the moft healthy, and the Srceft Srom diSeaSes oS all kinds. Indeed, even where there is a Specific quality, it often can hardly be cal- led diSeaSe ; Sor in the Small-pox, where the diforder goes through its different operations well, it is exadly fimilar to common healthy inflammation ; Sor if fuch an irritation as above defcribed were to attack a conftitution or parts, in another ftate than that of health, we Should then not have ehher the adhefive, or Suppurative inflammation' taking place, but moft probably Some other, Such as the erySepe- latous cr Scrophulous, according to the nature of the con- stitution or parts at the time. This State oS health in a conftitution is fo remarkable, that we fee in the time of the fymptomatic fever, when nature would feem to be univerfally disturbed, a kindly or benign inflammation going on, and kindly fuppuration ; which Shews that this fever has no Specific tendency to wrong adion, the constitution being only disturbed by Sym- pathizing with a local injury, but not capable of giving or refleding back upon the part inflamed, a difeaSed difpofi- tion or adion. And this is fo remarkable, that Such inflammations as Seem to affed the conftitution by Sympathy only, which is commonly either Srom extent, quantity, or the Seat oS it being a part effential to or connected with parts belonging R r 2 250 Fundamental principles of inftu.nriiathn. to life, go on as kindly as they do in a Small infhivmation, as a boil, which does not affed the conftitution in the le.ift. Indeed fever is a good Symptom when equal to the injury and ofthe fame kind with the local affection, when that kind is good. Let us take an amputation of a leg as an example, which produces Something more than a dilturbed conftitution, for there is a great lofs of a fubftance to that conftitution, which, abftraded from the violence, would probably pro- duce confiderable effects till die conftitution became ac- cuftomed to the lofs ; but even with alt this lofs we often find that a healthy inflammation Shall come upon the ilrnip, and a kindly Suppuration take place while the iymptoma* tic Sever lafts ; in many cafes alSo it Slid keeps its ground even when affeded by many Specific irritations which are foreign to it ; and neatly in the Same manner as when af- Scded by a common irritation, which will only rouSe that conftitution into action, but not alter it, having only the Specific difference added, So that the parts will go readily through the adhefive or Suppurative inflammation ; the Spe- cific being only an attendant on this healthy action ; this wo See plainly to be the caSe in the healthy Small-pox, and , the lues venerea in its firft Stages. But on the contrary, if the conftitution is Such at the time as would readily fall in- to an unhealthy inflammation, from common irritation or accidental violence, then it will alfo fall into that States when irritated- by a Specific irritation Soreign to the confti- tution, Such as the Small-pox, which in this caSe will run into the confluent kind. There are many conftitutions which have a tendency to Specific diSeaSes, that whe#i injured by Sever, or any consti- tutional complaint, readily produce the Specific inflamma- tion in Such parts of the body as have the greateSt'Sufcepti- bility Sor any Specific action ; or iS Such parts are affected by any local violence, the parts affected will go through die healthy adhefive inflammation, nor will they enter in- to the healthy fuppurative inflammation, but will fall into the Specific inflammation peculiar to the habit; fuch is the cafe with f.n eryfepelatous habit. Or if a Specific inflam- mation has already taken place, any violence done to it, when already begun, will increafe that difpofition, and ac- tion, which we plainly fee to be the cafe with the fcrophu- la ; becaufe this difeafe can and often does arife from fuch a caufe alone. Befides the conftitution producing fuch ef- Fundamental principles cf itflcmmeiticn. 251 feds, there are many parts of the body have a greater ten- dency to fome Specific difeafe than the conftitution in gene-; ral ; which particular parts will fall into thefe Specific in-i flanimations moie readily than others, either upon the con- stitution being affected, or a violence committed upon them- Selves ; Sor inftanee, many parts of the body have a great- ■ er tendency to fall into the fcrophula than others, and thefe will Sail into that mode of adion when injured, either by means ofthe conftitution, or from accident ; except the constitutional complaint is fuch as to be a fpecific for the fcrophula, which I can eafily conceive it may ; in the can- cer alSo, if the diSeaSe has previoufly taken place, then the tendency of an injury is to exaSperate and increaSe it. But there are Specific irritations which do not affed ei- ther the part or the conftitution, as a common irritation, but affed them in a way peculiar to the irritation, alter- ing at the Same time both the parts affeded and the con- stitution, Srom an healthy ftate to an unhealthy one of its Own kind. This feems to be the cafe with the plague, perhaps with the putrid and jail-diftempers in a lefs degree ; for what- ever be the kind of conftitution which they attack, they always reduce that conftitution to their own kind ; it iS not a healthy operation going on, and the fpecific fuper- added, as in the healthy fmall-pox etc. However, even the plague has its degrees of power over a constitution, fome being much more eafily, and of courfe more violent- ly, affeded than others. . This change in thefe cafes, efpecially in the firft, is of- ten fo great, that the constitution hardly ever recovers it, So that the patient dies ; which we have obferved above, is not the cafe with many other Specific diSeaSes or poifons, as the fmall-pox, etc. for this difeafe makes no change in the conftitution peculiar to itfelf. . From what has been faid, it muft appear, that the ir- ritations which are capable of producing thofe inflamma- tions may be either fimple, as the adhefive, or producing with it other modes of adion, as either fuppuration or ul- ceration ; and alfo either ofthe above modes of adion may be joined with fome of the fpecific actions. Hence we may conclude, that Irritations of whatever kind, either produce an inflammation peculiar to the con- stitution, or the nature of the parts ; or, according, to the irritating caufe, as in the plague ; and where it is accord" 252 Fundamental principles of inflammation. ing to the conftitution, that many fpecific irritations may be added, without altering the nature ofthe inflammation itfelf, and that they only determine its fituation, extent, duration, etc. according to the fnedfic diSpofition added, provided the conftitution be healthy ; but if the conftitu- tion be unhealthy, whether affeded wirii ■:ryiepc:as, pu- trid fever, or plagac, and the fpecific uifoofie is fupcradded, it will be a mixture oS both, that is, it will be a Specific inflammation, fet down upon a conftitution of a peculiar kind, which partakes of both, ami thofe fpecific properties will not be fo diftind, or fo well formed, as when they appear in a found conftitution. If the conftitution has a fufceptibility to be putrid, and the fmall-pox attacks it, the inflammation will bo the frnall- pox joined with the putrid mode of adion oS the conftitu- tion, which will affect the mode of adion peculiar to the Small-pox, and deStroy the Specific difference ofthe inflam- mation belonging to the Small pox, the puttules will Spread, not Suppurate, and look livid, according to the putrid diS- pofition. TheSe conftant effeds, peculiar to the conftitution, may be changed from one to the other, juft as the conftitution changes, for the fmall pox may begin upon a healthy con- stitution, in which they will be diftind or circumScribed; but if the conftitution becomes diSeaSed, they will Spread; and iS the conftitution takes a healthy turn again, they will begin to contrad to their Specific distance again*. * The knowledge of thefe facts, is of great fcrvice in the cure of many Specific difeafes ; for whatever the fpecific difeafe miy be, we e.ra always to treat the patient in one refpsct ac- cording to the general nature ofthe inflammation ; and if we have a fpecific remedy, we are alfo to join that v. ith the other ; but if we have not a fpecific remeay, w; are then only to take up the di'eafe according to the conftitution. Ifet us iilnltrate the foregoing propositions by example. The firft cafe is explained by the venereal difeafe in th? form of chan- cre- ; the venereal matter produces an inflammation and ulcera- tion according to the nature ofthe fpecific difeafe, and the con- foruiini ; iSth; constitution is perfe.^iy- heal tiiv, then t'te'-f-. fectsaret'ie Suppurative and fo?»cite difeafe joined ; ihe limits of both are confined according to the conftitution and the nature ofthe Specific difeafe. , Knr the inflammation and ulctradon ne- ver extend beyond the fpecific affc&ion ; but if the conftitution is fic!ia3 readily to fill, into the erySepelatous, then it becomes Fundamental prinriftis of inflammation. 253 Many people are much more fufceptible of inflammation than others, even of the common kind, and tliofe probably may be reckoned limply irritable. In fuch it is more violent, and in fuch it is mere apt to Spread, die ijiTcuod- in«- parts being ready to .at or Syinp.ninze with an adion to what they are prune -, continued Sympathy more recoily takes place in Such cafes*; but this is not univerSal, foi* we find many very confiderable inflammations confined to the part irritated, and in fuch inftances continued fynipa-i thy is not great, only the part irritated takes up the action violently. The termor idea of inffamrnarieui may be too genera!, yet it is probable that it may form a genus, in which theri is a number of fpecies, or it may be more con'fined in Itl cfc if fixation, and be reckoned a fpecies containing Several varieties. Thefe ere, however, fo connected among toc:u- tbe eryfepelatons and fpecific joined; and although tl r extent ofthe Specific affection is limited, that ofthe erylepelarou* ii not; the coulequ .nee of which Is, that it Spreads over th« w hole rrepr.ee and ( ften the whole flcin of the penis. i n this dil'eafe, under nich circumftances we are led ro th; method of cure ; for although we have a medicine for ti e vcm> real inflammation, \it bark is to be given Soy the eryfepckiro'js. the quantity to be " n'nen is according to the prcdenunaucy of the one or'the othcrT The effects of this practice are very ftiiking; for as the enfepeiatous inflammation leffens it be- comes more coufmed in its Units, a«,d, as it were, drawn buo the original noint ; and when it becomes truly foppurari-e, and venereal' its limits then are brought within ti e Specific diftance. T". e fecond cafe is explained by the fmall-pox. The vanors maittr in healthy couuuutions produces the Suppurative and fpecific inflammations, the Specific is limited, and directs the fuppurative ; but if d,:. ervfepelatou* comes on, the Suppurativa ceafes it then'fpreads along the Surface, uniting inflammation with inflammation, and producing; the confluent fmall-pox. We have no fjtecilic remedy for the Small pox, nor can we readily have any tor a cif-afe which cures itfelf; o,;r huf nrffj then is to cure the «*nfeptlutous, if toiublc, and have the con- ftitiu ion to cure the fpecific. * Thisone nvcrht illuftrate hv a liece of paper beiror either drv cr damp ; if dr\ t! en ink will not fpie.id, it will he con- 6ned to its point, but if damp, it v ill Spread being allrtcUd by the fai-rov.r;ulngu.>irp lo \rifririt hak mi afi.iv.!>. 15:54 Fundamental principles of inflammation. Telves, that we cannot juftly underftand any one ofthe fpecies or varieties without forming fome idea of the whole, by which means, when treating of any one, we ■ can better contraftit with the others, which gives us a clear- er idea both of the one we are treating of, and of the whole. So Sar as it appears to be neceffary to take notice of the different inflammations, as illustrative, they may be • comprehended in five divisions : although, I mutt own that if we take in all the fpecific difeaSes which produce inflam- mation, Such as the venereal difeafe in its different forms, the gout, etc. they may be without number ; however, ma- sy of them produce very much the fame appearance andef- fecft with thofe which are of no fpecific kind. The fpeci- fic is of no particular kind, but only the caufe, and the ; Specific effect is a Something Superadded. The prefent, viz. the adhefive, with its different effect;., as fuppuration, I Shall confider as one. The cedematous, wLkh comes ; rieareft to the adhefive, Sorms a Second divifion. The crv- ' iepelatous, the carbuncle, and that which leads immec.i- ' arely to mortification, Sorm a third. There is another i:i- ilammation very like chilblain'?, wh;ch is not very livt ly and often in blotches, fome the breadth of a Shilling, others of :he breadth of half a crown, and even broader, etc. This inflammation certainly arifes from irritable debility ; the blotches look more of a copper-colour, and the Skin over them is often difeafed. All, except the firSt, have a kind , of affinity to each other; although I think the cedematoua has the leaft affinity to the three laft, and many vary So as to make it difficult to Say to which Species the varieties belong. There are a great many other inflammations, but which a- riSe Srom Some Specific cauSe, as the gout, fcrophula, etc. or poifons ; but as thefe do not explain, or illustrate by contrail, the adhefive or fuppurative inflammation, I Shall not give the outlines oS them here, except juft to mention the particulars oSthe gout, as an inflammation. The acftion oS the complete gout, has all the characters (while it Lifts) oS the true inflammation, and which may be called the inflammatory acftion of the gout j but it has many Singularities attending it, which attend no other in- flammation, and which of courfe become fome of its Spe- cific characters. The inflammation of the gout is very different from the adhefives and Suppurative in its fenfation. It feldom throbs; Fundamental principles of inflammation. 255 it is a pricking, cutting, and darting pain ; befides which, there is a pain that Seels as if the inflamed parts were all moving, and in that motion there was pain ; thereSore the action, which is the cauSe oS the pain, mult be very diff- erent, and is moft probably Srom the action oS the veffels, not Srom their diltention, as in the Suppurative inflamma- tion. It probably comes on more quickly than any other. Its violence is probably greater. In duration it is probably the moft uncertain ; and its going off is quicker than of any other inflammation. Its Shitting Srom one part oS the body to another, is probably in Some degree peculiar to it- SelS ; and it leaves parts in a State which no other inflam- mation does. Without entering Surther into the nature of this diSeaSe than Saying it is an act: of the conftitution, I Shall defcribe fome of its vifible eflfcts, which of courfe can only be obferved when it falls on an external part, and when it does, it is moft commonly on an extremity, more efpecially on the lower, but Sometimes on the upper, and Still more commonly on the extreme parts oS the extremity in either the upper or the lower ; and its principal Seat in the extremity is a joint. When it Sails on internal parts, it is moft commonly the ftomach, which is only SuppoSed by its effects or fymptoms,; from its being transferred, and from the mode of relief. It attacks alfo the brain, pro- ducing delirium, giddinefs, the loSs oS the natural and zc- cuftomed feel of the body, inceffant SLcpinefs, etc, which is alfo known by the above circumftances. When it falls on other parts, either externally or internally, it is not fo much determined on what part, it is moft apt to fail. It Sometimes Sails either on the lungs or muScles of refpiration, the throat, tefticlcs, urethra, producing a difcharge, etc. on the anus, forming piles ; which can only be known to be gout by collateral circumftances. Why the extremities, the ftomach, and brain, Should be Similar in SuSceptibility to take the gouty action Srom the constitution, is not eafily accounted Sor. I Sliould be inclin- ed to SuppoSe that its effects on the Stomach or brain are not Similar to thoSe on the extremity, or probably it does not advance So Sar in its effects there, becauSe in that caSe it would certainly kill. Its effects on the extremities are> I believe, always more or lets an inflammation, or at leaft it has the common vifible or fenfible effects of inflammation. £> f 2$6 Ftuulimcneid principles of inftammcrtion. It is moft probably what may be called a true fpecific in- flammation, for it produces the fame immediate effects in every conftitution, therefore does not produce an inflam- mation according to the constitution, having the fpecific action added, fimilar to poiSans, but Siom its nature it pro- duces nearly the Same effects in every conftitution. I have feen constitutions whofe extremities were attacked with the cedematous inflammation, attended with a purplifli ap- pearance ; violent pain in fuch cafes comes on, which create, fome apprehenfions of a tendency to mortification ; upon looking at the part, we may Sufpect fuppuration, the inflammation to appearance being of that kind ; but may think it odd that fuch healthy inflammation and fup- puration Should take place in the midft of inflammation of fo contrary a kind, but fliall find no fuppuration ; the in- flammation Shall continue its period and then leave the ex- tremities in a much better ftate than it found them. Al- though the inflammatory action of the gout is attended with great pain, yet I think it is not fo tender as the true inflammation is ; a part may be violently inflamed, and yet it may be handled or Squeezed, the nerves are not in fuch a ftate oS irritation, its conSequent effects are very different from that of the true inflammation, for inftead of entire refolution, it gives the difpofition to the inflamed parts to fill the joint or whatever parts have been affected, as for inftanee, the cellular membrane with chalk. However, chalk is not neceffarily an effect of the gouty inflammation; for in a gouty habit we have chalk formed where there never had been any gouty inflammation, yet it is Singular it Should attack fuch diffimilar parts as the fkin, ligaments, etc. It has not only no tendency to fuppura- tion, as an immediate effect of inflammation, but it leaves the parts in a State not eafily excited to inflammation; the chalk Shall remain for years without producing inflamma- tion, and feldom produces it at all, but from quantity; and when the interior furfaces are expofed, they hardly take on common inflammation and fuppuration, healing more readily than a fore of the fame magnitude from any other caufe ; even a joint Shall be expofed, yet common inflam- mation Shall not come on, nor Shall it fuppurate, only a watery fluid Shall cpnie out, bringing with it the chalk oc- cafionally, and it fliall heal up kindly. It is probable that the gout is not always an act oS the constitution, but that parts may be So SuSceptible, or rather difpoSed Scr this ae- Fundamental principles of inflammation. 257 tion, that they may immediately ru.n into it when de- ranged: if this notion be well founded, then it may be a question, whether this local affection relieves the consti- tution for the time from any fufceptibility for fuch an ac- tion ? It may be difputed, whether the following are all inflam- mations or not. They often rife from the fame caufes ; ac- cident, for inftanee, produces all of them. They have certainly many characters in common, although not always the fame refult. The veflels becoming inlarged, there is an extravafation, pain, and a feparation of the cuticle. but feldom a formation of matter, although there fome- times is, which happens when they have at firft more of die adhefive State; and there is a circumftance which I think is common to them, namely, a red Streak paffing from the inflamed part, generally towards the trunk, al- though not always in this direction. In common language they are called eryfepeiatous, although very different; the eryfepelatous being one of the beft marked inflammations of any. I do not mean to treat of thefe but in a general way, not even when confidering the method of cure. It is probable there is no fpecific distinction between any of thefe inflammations but what arifes from the constitution or the parts, for we find them all proceeding from what may be called the lame accidental caufe, which therefore cannot produce £.ny thing fpecific -, the distinctions in the mode of action of the inh'amed parts being cccaficned by a peculiarity in the conftitution, or the nature of the part it- felf, but probably in the conftitution. It has been fuppofed that the different fpecies or varieties of inflammation arife from the difference in the nature of the part inflamed ; but this is certainly not the cafe ; for if it was, we Should foon be made acquainted with all the different inflammations in the fame perfon, at the fame time, and even in the fame wound ; for inftanee, in an amputation of a leg, where we cut through fkin, cellular membrane, mufcle, tendon, perioSteum, bone, and marrow, the Skin Sliould give us the inflammation of its kind, the cellular membrane of its kind, the mufcles of theirs, the tendons of theirs, the pe- rioSteum, bone, marrow, etc. of theirs 5 but we find it is the fame inflammation in them all; it is the adhefive in them all if the parts are brought together ; it is the fuppu- tlve if parts arc expofed. I fhall ac prefent only take no- « f 2 258 Fun-lamata! principles of inflammation. tioc of the four laft, as I mean to treat more fully of the firft, which cannot be fo completely underftood without feeing die distinctions. What I would call the ©edematous inflammation, is when the extravafated fluid is water; it has very much the ap- pearance of the adhefive, and probably come the neareft to it of any, being of a fcarlet colour ; but much more dif- fufed. The fluid extravafated, being principally the ferum, renders the fwelling more diffufed than even the inflamma- tion itfelf; it is very painful, or rather fore, but there it not fo much of the throbbing fenfation as in the adhefive inflammation ; it appears to be only on the furface, but moft probably goes much deeper; for in fuch cafes the extravaSated fluid is in too large quantity to be furnished by the cells of the cutis alone ; but in this we have not the fame guide as in the adhefive, viz. the fwelling and inflam- mation correfponding with each other. The difference be- tween .this inflammation and the adhefive, arifes, I con- ceive, from the principle of inflammation acting upon a dropfical difpofition, which is always attended with weak- nefs ; whereas a greater degree of Strength would have produced the adhefive inflammation under the Same cauSe, or irritation; and what makes me conceive this, is, that in many caSes oS anaSarcous legs we have exactly this in- flammation come on Srom distention, which adds to the extravaSation oS the Serum, as well as in moft caSes of Sca- rifications oS oedematous parts to evacuate the water. When inflammation takes place it is much more lafting than the adhefive; and, I believe, Seldom, or ever pro- duces Suppuration ; but iS it fhould run into this Stage, it is more general, and the whole cellular membrane in the interftices of parts is apt to mortify and Slough, producing very extenfive abSceffes, which are not circumScribed. The erySepelatous inflammation is very peculiar; and moft inflammations that zrz not of the true adhefive and Suppurative kinds are called So, although probably they do not in the leaft belong to it; and this may ariSe more Srom the want oS terms, than the want oS discrimination. This inflammation oSten ariSes Spontaneously, or in conSequence of a low or debilitating fever. It often arifes from acci- dent, but then it is commonly a fecondary inflammation, although not always j for die firft Shall have gone oif, and Fundamental principles of inflammation. 259 when fuppuration was to take place, it fliall hive come kindly on, but afterwards the erySepelatous fliall take place. This may be called a remote inflammation, and is, in this refpect, fomewhat fimilar to the locked jaw. It is more commonly a cutaneous inflammation than Situ- ated in the deeper feated parts ; although in fome confti- tutions every inflammation, wherever it exifts, will moft probably be of this kind ; however, the Skin appears to be moft fufceptible of it, becaufe it will Spread over a prodi- gious Surface of fkin, while it does not affect even the cel- lular membrane underneath ; at leaft not commonly. There is an inflammation which attacks internal canals, which is claffed with the erySepelatous, but how Sar it is the Same I do not know •, it is certainly not the Suppurative; and as almoft every other inflammation was formerly called eryfi> pelatous ; this has been SuppoSed to belong to this kind of inflammation. The inflammation I am Speaking oS is more common to the throat than any other part, oSten going down the trachea: whatever it is, it may be confidered in fome oS its effects to be in direct oppofition to the adhefive and the fuppurative inflammations ; for where the adhefive moft readily produces adhefions, there the eryfepelatous does not, as in the common cellular membrane ; and where the adhefive feldom takes place, excepting from extreme violence, there this inflammation (if eryfepelatous) has a tendency to produce adhefions, as in canals or outlets; it alfo oppofes, in fome degree, the fuppurative, in being backward in producing fuppuration even in thofe places, where fuppuration moft readily takes place, fuch as canals. and outlets •, for there, as above obferved, it more readily throws out the coagulating lymph. Whatever the inflam- mation may be, it is certainly attended with nearly the fame kind oS constitutional affection. The Sever in both apt pears to be the Same, viz. accompanied with debility, lan- gour, etc. The extravaSation in conSequence oS the ery- Sepelatous inflammarion is not So great as in either the adhe- five, or the cedematous ; nor is it oS that kind which pro- duces adhefions between the parts inflamed, which in this- inflammation would commonly be unneceffary, as it feldow produces Suppuration, but is attended with very bad con- sequences when it does. It appears to Support itSelf by continued Sympathy, for it commonly begins at a point and Spreads, while it fliall be getting well, where it firft began. 260 Fundamental principles of inflammation. This cannot be merely constitutional, for if it was, the parts already inflamed could not recover, if its increaSe in new parts aroSe from the constitution ; but it gives the idea that when the parts have once gone through this action that they loie the difpofition and become healthy. This pro- perty is not peculiar to this inflammation, the ring-worm has this peculiarity, as alfo many cutaneous ulcers*. This inflammation is more common in the fummer than in the winter, more efpecialy in hofpitals ; and I think takes place oftener after wounds on the head than any o- ther. I have often feen it begin round a wound, on the fcalp, extending itfelf over the whole head and face; the eyc-hds being very much Swelled, the ears thickened, and it has advanced to the neck, fhoulders, and body, creep- ing along both arms, and terminating at the finger ends; that which attacks the body often goes along the body to both thighs, down the legs, and terminates at the ends of the toes ; and while this is going on, it is as expeditiously cured behind, and the fkin peels off the cured parts ; how- ever, this is not always the cafe, it often ftops, and where it proceeds fo far, it is commonly becoming milder. This inflammation, when it runs along the fkin, has a determin- ed edge, not lofing itfelf gradually and infenfibly in the Skin beyond, as in the true adhefive, and indeed moft of the inflammations ; the lkin feels as if only a little thicken- ed, and not fo pliable ; for by paffmg the finger along the found firin to tne inflamed, we feel an evident difference. The colour of the fkin is of a darkifh red. When it goes deeper than the Skin into the cellular membrance, it often fuppurates ; but then I fufpect it is not the true eryfepela- tous ; for in fuch cafes it commonly produces mortifica- tion in the cells, by which air is let loofe; this gives a Strange feel, neither of fluctuation nor crepitation, and as there are no adhefions the matter finds an eafy paffage into * There appears to me two ways of accounting for tills ; one is, that the whole Skin is very fufceptible of fuch action, and readily goes oa with it by continued fywipathy, and the part having gone through the action, like the Sinall-pox, etc. lofes the difpofition, and the action ceafes. The other is, that the inflammation is Such as to contaminate while it Spreads, but when it has once acted it is curedvas above obferved. If this lalt be a true fglution, then the right prac- tice would be to Stop its progreSs by 2 Fundamental principles of inflammation. the very cells into which it is extravaSated become dcadi It produces a Suppuration, but not an abSceSs, Somewhat fimilar to the erySepelatous when the inflammation paffes into the cellular membrane, Sor as there are no adhefions, the matter lies in the cells where it was Sormed, almoft like water in an anaSarca; but ftill it is not ditfuSed through the uninflamed cellular membrane, as in the erySepelatous, for it appears to extend no further than the inflammation ; one would almoft imagine that there was a limitation to the ex- tent, beyond which, this fpecies of inflammation could not go, and at thefe limits the adhefive inflammation took place to confine the matter within the bounds of the car- buncle. A diffuSed ulceration on the infide Sor the exit of .the matter takes place, making a number of openings in the fkin; there are generally more carbuncles than one at the fame time, a great number fucceeding each other, which would almoft feem to produce each other in this fuc- ceffion ; they are commonly more on the trunk of the body than any where elfe ; however, I have feen them on th« head, and fometimes on the extremities, although but Sel- dom. They are more commonly on the pofterior part of the body than the anterior. This inflammation attacks more beyond the middle age than at it, and very fewr under it. It is molt common in thoSe that have lived well. I ne- ver Saw but one patient oS this kind in an hoSpital. It ap- pears to have Some affinity to the boil ; but the boil differs in this refpect, that it has more of the true inflammation, therefore Spreads leSs, and is more peculiar to the young than the old, which may be the reaSon why it partake* more oS the true inflammation. As death is produced in a great deal ofthe cellular mem- brane, and I believe, in it only, except the Skin giving way, which I believe is by ulceration principally, it becomes a queftion, whether this mortification arifes from the nature of the inflammation, or rather from the matter being con- fined in the cells of the cellular membrane? I rather fuSpect thelatter; for I find that if thismatter efcapes from thefe cells and comes into uninflamed cells, it produces mortification there. This is like the urine, for whenever the urine e- fcapes into the cellular membrane it there produces morti- fication ; the colour of the Skin is at firft more vivid than afterwards, for it becomes of a purple colour. Fundamental principles of inflammation, 263*1 * « Inflammation often produces mortification or death in die part inflamed. This commonly takes place in old peo- ple that are become very much debilitated, and chiefly in the lower extremities. I fufpect it to be Some what fimilar to the carbuncle, viz. principally in thoSe- who have lived well, although not So much confined to them as the carbun- cle ; however, it takes place in the. young, where great debility has been produced from difeafe, efpecially thofe difeafes that have debility as a principle, fuch as what are commonly called putrid fevers ', but the Situation of thefe is not fo determined, and in fuch, inflammation hardly takes place without an immediate exciting caufe, as the ap- plication of blifters, etc. Death irt a part fomcdmes takes place, almoft immediately without inflammation ; but this is not to the prefent purpofe. Where mortification Succeeds inflammation in the extremties, efpecially in elderly per- sons there is often an early Separation of the cuticle which forms a blifter, filled with a bloody ferum : and we Shall obferve dark brownifh fpots, which confift of extravafated blood in the true cutis, and which Shall at laft blifter, and then the cutis forms a Slough. Such inflammations have little of the adhefive tumefac- tion in them, but more of the (edematous ; are not clear or tranfparent, but rather of a duflcy red ; as the colour ofthe inflamed parts Show fomething of its nature, it is to be obferved that it is different in all thefe inflammations from that of the true adhefive, and as we have reafon to be- lieve that the circulation is quicker in the adhefive inflam- mation than is natural, and that the colour arifes from this caufe, we may fuppofe that the motion of the blood in thefe is languid, and that it affumes the venal appearance, even in the arteries. Inmoft of thefe four inflammations there is an appearance that often arifes, which is a fedifh Streak commonly paff- ing Srom the inflamed parts towards the Source of the cir- culation, but not always in this direction ; Sometimes juft the contrary ; and this is more certain when it happens to take place in.an extremity, becauSe there we know the courSe of all the veffels better ; but it does not always a- rife from the p irt inflamed. I have feen this laft Species >,{ inflammation attack the toes, and red Streaks run up the foat, termln itin^ abiut the ancle, while there were Several ariru-r 01 th: Sore oirt of the log, juft below the knee. T t 264 Fundamental principles of inflammation. They often make a net-work on the leg, and are frequent- ly a forerunner, and an attendant on mortification. They feldom go farther than a blufh in the fkin, feldom thicken, but are more of the ccdematous kind ; however, we Some- times find hard cords running Srom Sores and inflammations, but thefe are commonly deeper Seated, and I have SuSpect- cd them to be veins ; as a prooSoS this, I have Seen the Su- perficial veins of the leg have the fkin red over them, fimi- lar to thofe above deScribed, and the veins have felt hard under the finger. Thefe redifh Streaks are SuppoSed to be abSorbents, becoming inflamed by their carrying a Stimu- lating fluid. I am apt to SuppoSe them to be abSorbents, but I do not conceive that this effect ariSes Srom abSorption. If it arofe from fuch a caufe, it fhould be uniform, the caufe Should always exift when the effect takes place. It is firft to be obferved, that it only takes place in certain conftitutions, in which abSorption, one way or other ex- plains nothing ; and I find, upon observation, that this ef- fect Shall be coeval with the inflammation where no Sup- puratipn has taken place ; I have even Seen it ariSe from accident, prior to the poflibility oS inflammation taking place, viz.- in the time oS the pain arifing Srom the im- mediate effects ofthe accident; this was in the finger, from the prick of a clean needle, which had been for fome time piercing new buck-Skin leather ; the glands in the armpit were fore, ficknefs, attended with its ufual fymptoms, fuch as oppreflion, was nearly as immediate. Its direction from the fource ofthe circulation is another Strong proof of its not arifing from abforption, and its taking place at fome diftance is alfo a corroboration of the fame opinion. Another Strong circumftance in favour of this opinion is, that the morbid poifons do not produce this effect, where we know abforption has taken place. Thus the venereal feldom or ever produces it. The hard cord paffmg from the prepuce along the upper part of the penis, I do not conceive to be pf this kind. In the fmall-pox, after inoculation, it has been obferved, but I imagine it was only in the above-men- tioned conftitutions. I could conceive it to arife in the plague, if there was any local difeafe. I am, therefore, rather apt to attribute this appearance to the irritation run- ning along the lymphatics, more efpecially in fuch consti- tutions ; and as we do not allow the veins to be abforbents^ Fundamental principles of inflammation. t6§ their being affected muft be SuppoSed to ariSe from the fame cauSe. Whenever we See this effect, we may, in fome degree, form an opinion of the kind of inflammation, and that it is not the moft favourable. END OF THE FIRST VOLUME. Med. 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