No. 851.

LONDON, SATURDAY, DECEMBER 21, 1839.

COURSE OF LECTURESON THE

PHYSIOLOGY AND PATHOLOGYOF THE BLOOD,

AND

THE OTHER ANIMAL FLUIDS,DELIVERED IN THE SESSION OF 1839 - 40,

AT THE

School of Anatomy adjoining St. George’sHospital,

BY HENRY ANCELL, ESQ., SURGEON.

LECTURE VI.

The liquor sanguinis or plasma.-The coagu-lation of blood: consists in the separation of.fibrin from the liquor sanguinis, and itsconeretiora.-The clot, a mixture of serum,fibriii, and red corpuscles.-The less obviousphenomena attending coagulalion.-O/’igin(if the fibrin,-Causes assigned.- Vital1lO!eel’ the true cause: : coagulation takes]/lace ollly so long as blood is licing.-Theordinary influences on coag ulation air ; ;form a1HI material of the ’Cessel; mass agi-tution or ?’est; tempe/’ature.-Necessity of1)(tyi?i- due Te{!;ard to their effects.GEXTLEix?;:—We have already seen that

the living blood, as it Sows in its vessels,presents the appearance of cei,puseles floatingin a tJ’anspamd fluid, My last lecture com-prised a considerable part of tbe microsco-pical history of the former. I propose tocall your attention to-day to the fluid in

question, and to those vital changes whichtake place in blood after its extravasation,occasioning its separation into a vapour orhalitus, a fluid called serum, and a moresolid clot.

It is remarkable that so many years shouldhave elapsed, and so many observations havebeen made, since Boyle first introduced theexperimental method into our investigationsupon the blood, and the microscopical disco-veries of Malpighi and Hewson, before anyvery decided distinction was made betweenthese two fluids. The living liquid was fre-quently meant when the word serum was

employed by physiologists. Miiller on the

continent, and Dr. Babington in this country,were, I believe, the first to describe theformer, under the term liquor sanguinis, andSchultz has employed the word plasma, tadesignate the same thing. For the purposeof illustrating the distinction between thesetwo fluids, I shall repeat one or two simpleexperiments from Hewson’s inquiry, andDr. Babington’s original paper.Exp. I.-Hewson abstracted blood from a

patient labouring under phthisis. It lowedin a full stream, and soon filled the bason.The surface was then observed to become

transparent, and the transparency went

deeper and deeper, the blood being stillfluid. The coagulation was observed tobegin first on the surface, forming a thinpellicle in contact with the air, and the re-moval of this was soon succeeded by another.A part of the clear liquor was then taken upwith a viet teaspoon, and put into a phial,with an equal quantity of water; a secondportion was kept in the teaspoon, and bothwere found to coagulate, and to separateserum.

Dr. Babington repeated this experimentwith blood from a patient suffering underacute rheumatism. He collected the liquorin quantity, and transferred it to anothervessel. It became opalescent, somewhatviscid, and perfectly homogeneous in ap-pearence. After standing sometime, it se-

parated into two parts-a clot of fibrine,which had the precise form of the vessel inwhich it was gathered, and a clear fluid,with all the properties of serum. Hence itmay be inferred that blood, as observed tobe the case microscopically, has only twoconstituents-the corpuscles and the liquorsanguinis; and that in this and similar in-stances, it remains fluid long enough to per-mit the heavier corpuscles to subside, afterwhich the fluid separates by a general anduniform coagulation and contraction into twoparts, and a portion of the solid part throughwhich the corpuscles have time to fall, formsa coating of pure fibrine, while the portioninto which they descend forms the colouredclot.To obviate the objection that the blood

was diseased in these experiments, Dr. Ba-

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bington placed the healthy fluid under con- yellow colouring matter of the blood. Rhl1’ditions which enable its red corpuscles to barb renders it of a deeper yellow, aud it,

settle more quickly than would otherwise colour is heightened or modified in jaundice,happen, by According to the present state of our kIl’,1B".

Exp. 2.-Take two similar jars, each ca- ledge, it appears, therefore, that the liquorpable of holding four or five ounces, and fill sanguinis exerts its influence principally iuone of them with olive oil. Draw the blood nutrition and secretion, and the corpu;c1e;of a healthy subject into them. That which on the nervous, respiratory, and musculur i,.flows through the oil, will have its coagula- tems, the former being closely related to thetion retarded a sufficient length of time for organic or vegetative part, and the latter tothe formation of a layer of liquor sanguinis the animal part of the living system.on its surface, which will produce a buffy When blood is drawn from the vessels oicrust; there being none in the other jar. a living animal in a state of health, ancl al-

Hence, healthy blood is similarly constituted lowed to remain at rest, under ordinary cir.to that disposed to form a distinct fibrinous cumstances, it undergoes the wen-knowncoating, the obvious difference being that process of spontaneous coagulation. Thethe former coagulates more quickly than the halitus is given off immediately, a thin tilllatter, is formed on its surface, near the edge of the

I have already stated, that when the containing vessel, in a very few minutes, andliquor sanguinis has separated a coagulum, its state of fluidity is rapidly converted mtoits shape is precisely the same as that of the that of a thin jelly. Subsequently its more

containing vessel. It -has also a similar solid parts concrete, and it separates into

density throughout. We may, therefore, two portions-an albuminous liquid, calledconclude that the coagulation takes place the serum, and a soft solid, known as theuniformly from every part of the fluid, that clot or crassamentum, which may eitherit is homogeneous, :and that it is not a mere float or sink in the former, and which fre-mixture of serum and fibrine. It may thus quently presents a fibrous or irregular net.be inferred, that fibrine and serurn do not work appearance. The coagulation of L-11-exist as such in the liquor sanguinis, or any man blood is generally effected in from threeother part of the circulating blood. Dr. Bab- to eight minutes; the subsequent concretionington goes so far as to say that, although and effusion of serum take place mainlytheir separation may take place in the body in from one to three hours; but the processunder diseases, it can never do so consis- goes on as long as the fibrine retains anytently with healthy action. There is no dif- degree of vital contractility, which may beference between the fluid described by Müller several days. The whole phenomena of co-and Babington, and the plasma of Schultz, agulation and concretion vary greatly in dif-except that the first-mentioned physiologist ferent animals and in different individuals.regards it as a chemical solution of fibrine and they are greatly modiiied in differentin serum, the second has made his obsei’va.- states of the constitution, in diseases; and bytions more particularly on the transparent the influence of various external causes.part of the living blood after its extravasa- Various explanations of the phenomenation from the vessels, and accordingly during just described have been advanced ar dif-the changes which take place while it is ferent times. The opinion of Mr. Hewson.losing its vitality, and the last refers to the that it depends on the contraction of iibrine.same fluid viewed microscopically as it cir- is now generally received. One of theculates in the living body. No purpose but strongest proofs of the correctness of thisthat of confusion would be served by em- opinion, is the fact, that when this animalploying two names for one and the same principle is removed from blood immeoiatelything. I, therefore, propose to adhere to the after its extravasation, the coagulation of thedesignation used by our own countryman, fluid is entirely prevented. The physiuio-when I refer to this part of the living blood. gical properties of fibrine corroborate this

There can be very little doubt that the proof.liquor sanguinis is the true nutritive part of The chemical qualities of fibrine, as an

the blood, from which all the organs of the animal proximate principle, have alreadybody are nourished, since the red corpuscles been detailed. The physiological properties.are never known, as corpuscles, to leave the in a moist condition, wiih a great proportioncapillary vessels. Schultz describes it as a of water, or the elements of this fluid in itstenaceous plastic liquid, and believes it to composition, are those which concern us atbe formed from the corpuscles, and that the the present moment. It was first described.latter are accordingly indirect organs of nu- as it appears, in an isolated state, by iIal-trition. According to this physiologist, also, pighi, and the terms hepar, insina, gfuten,foreign matters introduced into the circula- lymph, coagulable lymph, coagulating lymph,tion, and deposited in the organs, or excreted, coagulum, coaguline, and clot, have been fre-are contained in the liquor sanguinis, and quently employed by authors to designate.do not go to the corpuscles. Thus, indigo not only the coagulum of blood, but the prin.gives it a greenish tint, resulting from the ciple on which its coagulation depends.mixture of the blue of this substance and the When deprived of extraneous matter by

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washing, we have seen that this substance by organised matter, as meshes and ramifi-has the appearance of white strings, laid in cations intermingled, anastamosing in a

striae and resembles in form and distribu- variety of ways." The same phenomenontion the planes of muscle which encircle the may be studied by means of water holdingbladder. It is distinguished from all other a small quantity of salt in solution, whichanimal substances, and especially from al- latter substance, like sugar, does not dis-

bumen, as follows :-1. It always presents a solve the corpuscles, but promotes their se-fibrous or filamentous texture; albumen paration from the liquor sanguinis. Thenever does. 2. It resists considerable pres- circumstances and experiments detailed,sure, being firm and elastic; albumen when leave no reasonable doubt on the minds of

coagulated is readily broken down between physiologists, that the coagulation of bloodthe fingers into a pulpy mass. 3. It becomes after its extravasation from the living Yes-solid spontaneously when blood is separated sels, depends on the fibrine and its power offrom the living vessels; albumen has no such contraction, and that the clot is formed

property. 4. The chemical properties differ essentially of this coagulating and contract-slightly, as shown in Table III. and IV., and ing principle, inclosing within its meshesin the commentaries made upon them. the blood corpuscles.The following experiments, by Müller, on A great deal of doubt hangs over the less

the formation of fibrine, are extremely in- obvious phenomena of coagulation. I mean

teresting. He collected blood from the as to what actually takes place during itsheart and vessels of a frog into a watch- progress, from the period at which the bloodglass, and observed the commencement of is drawn, till the perfect concretion of thesmall transparent clots before the whole clot. We have seen that the fibrine contractsmass coagulated; he then examined a drop and encloses the blood corpuscles within itsdiluted with serum, under the microscope ; meshes, and that the liquor sanguinis re-the corpuscles were widely separated, but solves itself into serum and fibrine thpre canthe construction of a coagulum which con- be very little doubt. The following ques-nected them together could be discerned, tions have arisen:—What other substanceshowever wide the intervals between them, are contained in the clot besides fibrine andand, bv placing a needle between any two blood corpuscles ? What are the relationscorpuscles, and moving it about, he could of coagulation with respect to caloric ? Whatset the whole mass in motion. Müller also gases are absorbed or given off?adopted the method of filtering frog’s blood I. When we examine blood recently coa-before it coagulates. The large elliptical gulated, we find, as originally observed bycorpuscles remain behind on the filter, and Boyle and Hewson, that the crassamentum,the limpid liquor sanguinis passes through, under ordinary circumstances, bears to theA small glass funnel and common white serum the proportion of from one to two-filtering paper, with the blood of one frog, thirds of the whole quantity. On examiningare sufficient for this experiment. The filter the chemical tables, we find only 80 to 130must be moistened, and the blood, when parts out of a thousand assigned to the clot.placed on it, should be diluted with a little This arises from chemists, for their especialwater. In a few minutes, a coagulum forms purposes, regarding all the water and saltsin the filtered liquor sanguinis, but, owing as belonging to the serum. We must beto its transparency, it must be drawn out of particularly guarded not to admit this asthe fluid with a needle, to be remarked. any other than the chemical constitution ofThis coagulum gradually contracts, and the blood. With respect to the salts, therebecomes whitish and fibrinous, it then ac- is no proof that some of them are not, inquires, as viewed under the microscope, a minute quantities, essential constituents offinely granulated aspect, the red corpuscles ; and, with regard to theThe fibrine, and its property of coagula- fibrine of the clot, a portion of the water, if

ting, may likewise be observed by means of not of the salts, undoubtedly belongs to it,a beautiful experiment with sugar and but at present the clot is usually regardedwater. Cast blood, either arterial or venous, as a mixture of serum, fibrine, and recl cor-immediately after it is drawn, and before puscles.coagulation commences, into water holding II. Since fluids give out caloric, on be-about one-sixteenth part of sugar in solu- coming solid, it might be inferred, a priore,tiun; the coloured corpuscles are by this that the coagulation of blood is attended withmeans precipitated, and the fibrine remains an evolution cf heat; but there are severalsuspended through the whole mass of fluid, exceptions in nature to this general law,forming " a sort of rude cellular structure, and innumerable experiments have beenby the interlacement of its fibres, represent- made to determine the point as regards theing a rare and loose coagulum. If we blood, with contradictory results. Theimagine these distended cells contracted on affirmative was originally maintained bythe corpuscles, we have the regular clot. Fourcroy ; in,one experiment he found theOn examining the fibrine thus coagulated, thermometer rise 11°! Dr. Gordon watchedunder the microscope, a regular conforma- the effect on moving a thermometer, duringtion is seen, resembling the forms assumed the formation of the clot, first into the coa-

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gulated, and then into the fluid part, by facts already detailed, much discussion haswhich he detected a difference of 6°, and taken place respecting the origin of fibrine;this remained perceptible for 20 minutes more especially Home, Prevost, Dumas, andafter the process of coagulation had com- some others, have contended that it is de.menced. On repeating the experiment with rived from the nuclei of the red corpusclesblood drawn from a person labouring under But the following facts prove this to be an

inflammatory fever, the rise of the thermo- error:—1st. When blood is defibrinated itmeter was 12° ! Other experiments have becomes uncoagulable, as already described,been made, by comparing the rate of cooling but the corpuscles remain entire. 2ndly,of the blood with that of other liquids. The The nuclei are not soluble in acetic acidresult of Sir C. Scudamore’s experiments after the dissolution or rupture of their en.is also on the affirmative side of this ques- velopes. 3rdly. The lymph and chyle,tion ; he found a slight rise of the thermo- which contain a considerable quantity ofmeter at the moment of concretion. Hunter, fibrine and very few corpuscles, are sponta.Davy, M. Edwards, Thackrah, and Raspail, neously coagulable. 4thly. The buffy coat,

dispute the fact. One thing is certain—if a constituted entirely of fibrine, according to

rise of temperature takes place, anything the experiments of Lassaigne and M’uiier,approaching in degree to that mentioned by occurs in blood which furnishes an abun.Dr. Gordon, it is totally inexplicable on the dance of this principle. These consrdera.chemical theory of latent heat, the quantity tions, and the experiments before related,of fibrine being so small that its solidifica- show incontestably that it is derived fromtion could scarcely affect the thermometer the liquor sanguinis. A further questionin any sensible degree. We can only, then, has arisen as to whether fibrine pre-exists,conclude that there is great reason to believe, either suspended or dissolved, in this liquid,but it is not yet proved, that a quantity of or whether it is formed from it by a chemicalcaloric is extricated during the coagulation of or vital process, under particular circum.

fibl’i?le. stances ? I cannot agree with Denis, Dugés,III. We have already seen that carbonic Berzelius, Gruilhuisen, Burdach, and Wag-

acid, and, perhaps, other gases, may be ner, that the above facts prove the existenceabstracted from the blood by certain of the fibrine in a state of solution in theprocesses of experiment, and it has been blood; nor can I concur with Schultz andasserted that the extrication of the elastic Magendie, that it forms as a chemical pro-fluid mentioned is essential to coagulation: duct after death. The process in questionbut, according to Dr. Davy, a slight com- does not take place in the true sepum, it

pressing force, which would not interfere occurs only in the liquor sanguinis beforewith coagulation, is capable of preventing its death. I regard coagulation, and thethe separation of any gas whatever. Sir contraction of the clot, in the light of an or-C. Scudamore performed a series of experi- ganic process, as shown by the coagulatedments (the results of which will be laid be- fibrin having an organized texture, alreadyfore you in a future lecture) by which it ap- so beautifully described in a quotation frostpeared that carbonic acid was given off Magendie himself.during coagulation. It is also urged, "that Many causes have been assigned for thethe period of time in which the blood coagu- formation and contraction of the fibrin, andlates depends in a great measure on the the consequent coagulation of the blood, 1.

quick or slow extrication of carbonic acid Rest. Spallanzani stated that he saw the bloudgas. Its evolution takes place most freely coagulate in an animal in which the circula-as the blood begins to concrete, and ceases tion was arrested, and liquify anew whenwhen the process is completed. It is evi- this was re-established, but contradictorydently an essential circumstance, as the facts were afterwards brought forward.same causes which retain it delay coagula- Hunter gave an instance of the blood reo

tion." But Sir Charles’s experiments were maining fluid sixty-five days in the tunicamade on diseased blood, and a few by Mr. vaginalis, and coagulating after extrav a,;a.

Thackrah, made upon healthy blood, fur- tion. Hewson proved that rest alone is notnished negative results. Moreover, Dr. its cause, by tying the jugular vein of a livingDavy has rendered it highly probable that dog in two places. After a considerablethe gases of the blood are greatly modified time, although still coagulable, the blood wasby diseased states of the system. There not coagulated. 2, Cold. By freezing blood,can be no doubt that gases are given-off and then thawing it, without producing coa-with the halitus of the blood, but, as well as gulation, Hewson proved that it is no moreI can determine, it is not proved that the ex- owing to cold than to rest. Coagulablebloodtricati;n of an elastic fluid is a circumstance remains liquid in cold-blood ed animals, or itsessential to coagulation. circulation could not be maintained. 3, Air,

This remarkable phenomenon is of so much Hewson regarded this as the most powerfulimportance in theoretical and practical medi- coagulating cause ; but air is not essential tocine, that I am desirous not to omit any con- the process, since it frequently takes place insiderations which are calculated to elucidate the vessels and cavities of the body afterits true nature. Notwithstanding the strong death, and even, as in fibrinous concretion;;

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during life. Air has been found, after death, temperature. Whatever credit may be duein the blood-vessels with fluid blood. Expe- to these statements, we shall find, as W2 pro-riment also proves, that the admission of air ceed, that the process may be accelerated byfrequently fails to induce coagulation, and the same agents which excite contractions inits exclusion to prevent it. Air is, therefore, irritable muscular fibre. Small quantities ofnot the cause of coagulation. 4, The Escape chloride of sodium, or of ammonia, both pow-of Gas. According to direct experiment, erful stimuli to irritable muscular fibre, forcoagulation takes place without the escape instance, hasten the coagulation of the blood.of carbonic acid or any other elastic fluid. Muscular fibre does not contract by the effect5, Loss of Nervous Influence. By this, most of stimuli, when kept at a temperature oflikely, is to be understood, all the vital pro- 32°; nor does blood coagulate ; but the irri-perties of which the blood is possessed. Mr. tability of both is evinced when they areThackrah says " the vital or nervous influ- again raised in temperature. Muscles, likeence;" according to this view, coagulation blood, have a tendency to contract on expo-is the death of the blood. But, as remarked sure to the air-their sudden convulsive

by Dr. Elliotson, the blood is often com- snatchings, when just dead, are familiar topletely dead, and remains fluid ; hence it is every one. Not that the two things are

clear that coagulation cannot be looked on identical, for the state of relaxation and re-as the death of the blood. 6, Evaporation of_ pose exhibited by muscular fibre, are in noAqueous Particles. This is open to the ob- way evident in the contraction of fibrin.jection urged against carbonic acid gas, and John Hunter seems to have erred, by endea-is totally inadequate as a cause. 7, A Last vouring to establish too close an identityEffort, or Loss of the Vital Actions of the between them. When a limb is withdrawnCorpuscles. Fibrin is not derived from the from a living body, it exhibits vital effects forcorpusles, and coagulation takes place in the a time, but they are fewer in number thanliquor sanguinis, completely isolated from before its separation, for we do not imaginethese bodies. 8, Vital Power. Hunter de- it to retain any degree of animal sensatiau.scribes it as a process similar to union by the Extravasated blood exhibits fewer vital phe-first intention, or to that of the contraction of nomenon than detached muscle. In propor-muscles after their separation from the living tion to the number and vigour of its vital

body. He terms it " an inherent power of effects, we say, a substance has a highself-coagulation." If this is not correctly or low degree of vital power. Fibrin,expressed, it undoubtedly points to the true then, has a low degree of vital power. Mr.cause of the coagulation of the blood. Prater has directed attention to the existenceEvery attempt to explain this phenomenon, of a closer analogy between the fibrine of

on chemical or mechanical principles, has blood and the muscular fibre of the bladder

signally failed. I believe I may say, that the than that of any other muscle in the body.numerous experiments and the strenuous efforts 11 If an animal just dead, in which this organwhich have been made for the purpose, is empty, be opened, it is not found con-

prove it to be impossible, and although the tracted on itself, but after exposure to theemployment of the term vital power may air it is seen gradually to diminish very muchappear to be a mere expression of our igno- in size ; this contraction may he hastened, asrance, yet if we can convince ourselves of it in the case of the blood, by more powerfulas a fact, we, in truth, advance our know- stimuli than air; if the organs be removed,ledge greatly, by ceasing to compare this from the body, after its contraction is onceremarkable process with mere inorganic complete, there is no tendency to relaxationagencies and effects, and by studying it ana- as in other muscles, and in this respect it

logically and deductively, in connection with resembles the contraction of the coagulum ofvital phenomena. blood." Mr. Lane has made a similar re-In the coagulation of the blood we have mark to me with respect to the persistance

clearly developed the principle of contractility. of contraction in the descending colon, whichDuges compares it to a post-mortem rigidity, he has observed to remain contracted to one-so that blood, once coagulated, can no longer third of the diameter of the rest of that intes-be considered as living; and he regards the tine, till the commencement of decomposition.subsequent contraction and separation as a Thus the irritability of the blood seems to admitphysico-chemical effect. Dnges describes of abetter comparison with some of the musclesthe comparison made by Aristotle and of the body than with others. Another proofHunter, between this process and muscular of the existence of vital power in the blood,irritability, as erroneous, since we have no after its extravasation, much insisted uponexample of the retum of the blood to a liquid by Mr. Prater, is the following. Variousstate after its coagulation. Yet some of the agents produce widely different effects uponexperiments of Spallanzani seem to prove the it, before and after its coagulation. Thus,reality of such an occurrence; and Mr. the proper chemical effect of bi-chloride ofCornish, as quoted by John Hunter, found mercury is to coagulate the albumen of deadthe blood of the bat, in its torpid state, in blood, but six grains of this salt added toa certain degree coagulated, but soon re- two ounces of sheep’s blood, before coagula-ew erinti its fluidity on motion and increase of tion ; prevent the process altogether. So,

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also a heat of 140° - 150° applied to blood the blood exercises in the living economy,immediately after it is drawn, keeps it per- that it behoves us to acquaint ourselves withmanently fluid, while the same temperature every thing which is known on the subject.

, coagulates, or rather consolidates, a mixture I have already cautioned you against red.

of clot and serum, rubbed up together, so as soning by analogy from dead to living blood.to resemble, as much as possible, the state of but the circumstance that its vitality ib re.the fluid during life. We have, at present, no tained for some time after its extravasation.evidence of any other vital properties in the enables us to investigate the vital effect: uffibrine but those of contractility and irrita- many influences upon it. Here, also, the

bility ; but, as that eminent physiologist, analogy between the living blood at rest,

Magendie, says, although it must be confessed with its volatile constituents rapidly disper:.that he is frequently inconsistent with him- ing, and all its parts in a state of incipientself, " It is neither by a chemical action, nor transition from life to death, and the sameby a process analogous to crystalisation; " ever-moving, ever-changing" nuid of life. sothere is something more than this in the for- beautifully described by Dr. Wilson, is bymationof the net-work of the clot; there is no means very close. Yet both are living,something in it which tends to live." and if we can expect to obtain any knowledgeMany things in the history of the blood are of the effects of agents upon the living blood

explained by this undoubtedly correct view as it flows in its vessels, by observations andof its coagulation. This process will not take experiments made on blood after its abstrac.place at all times and under all circumstances; tion from the system, it must be previous to,coagulation will, in fact, take place only so long or during coagulation, or before the vitalas blood is living. If you kill the blood the principle is extinct. The following are thefibrine will never coagulate, and this is true, general influences to which I have ’alluded:-whether its vitality be destroyed before its I. Atmospheric Air. Hewson mixed air withabstraction from the living system, as fre- blood in the jugular vein of an animal, andquently happens in sudden death, or after- found the coagulation promoted, and hewards. Many substances added to the accordingly inferred that it is the mo3t pow-blood after its extravasation, by destroying erful agent in the process. Prater repeatedits vitality, prevent its coagulation. Many the experiment with the same results. So,substances injected into the veins of also, from the following experiment by Dr.living animals, by destroying its vitality, Scudamore, we know that coagulation isprevent its coagulation. Many agents retarded when the atmosphere is simply ex-in the system, as causes of disease and eluded. Two stoppered bottles were filleddeath, and many powerful therapeutical with blood, the stopper was inserted into one,agents, destroy the vitality of the liquor and left out of the other; after five minutes,sanguinis and hence the contractility of the that in the closed bottle remained nearlyfibrine, or by acting upon its vitality, suspend, fluid ; that in the open bottle was coagulated,hasten, or destroy, the coagulation of the the temperature of each being 82°. Air ad.blood, mitted to blood at rest hastens the effect

Before these last-mentioned effects can be of rest itself. Mr. Thackrah’s experimentsstudied, we must make ourselves acquainted tend to show, that although the exclusion ofwith those of certain influences to which air retards the commencement of coagulation,blood is necessarily subjected, when apart it favours its completion, since, on comparingfrom the living system. The best practi- blood 24 hours after it is drawn, the exuda-tioners have always been aware of the im- tion of serum is much more complete whenportance which attaches to its coagulation in the atmosphere has been excluded.certain diseases, although the consideration It is no doubt to the action of the air thatof this quality, as relates to other maladies, the influence of extent of surface is, for thein which it is equally important, has been most part, to be referred. When extrava-too much overlooked. Dr. Wilson, however, sated blood presents a large surface, theat all times urged this subject most forcibly period at which coagulation takes place is

upon the pupils of this school. Even in shortened, but the separation into serum anddiseases, and classes of diseases, upon which clot is retarded. This is frequently observ-volumes have been written during the last ed when blood is received into cups stand.half century, without even so much as men- ing on a plate ; no separation takes placetioning the blood at all, Dr. Wilson ap- in the portion spilt on the plate, providedpreciated this most important consideration, the layer be thin. So, also, when bloodIn his own words- as respects the influence Iiows down the arm during venesection,exercised by the very existence of this prin- or trickles over a considerable surface,;iple, we know that a range of time and coagulation ensues almost immediate-degree exists, for we have registered it in ly. A fast or slow stream, in venesection.faintingsand inflammations. Many sensa- influences the process in the same man-

tions in hysteria and other diseases may de- ner. Sydenham, Huxham, Hey, and Hun-pend on incipient coagulation." So univer- ter, particularly, observed that inflammatorysal is the range, and so powerful is the in- blood differs in appearance according to thefluence, which the state of coagulability of degree of rapidity with which it flows.

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When the stream is weak and slow, espe- strong as to destroy vitality altogether, thecially as before said, when it trickles down coagulation of the blood is hastened, but thethe arm, it coagulates quickly. When the subsequent contractile power of the fibrine isstream is strong or rapid, coagulation is debilitated or exhausted.

proportionally retarded. Flowing from the III. Mass.—The greater the quantity ofsame vein, one portion in a full stream into blood, the later the coagulation. Hunterthe receiver, another portion trickling down thus expresses it : "the contact of blood withthe arm, several minutes elapse before coa- blood retards coagulation." This is, in somegulation begins in the former, whereas, in measure, the reason why a deep mass isthe latter, it begins immediately. This is longer in coagulating than a shallow one,particularly observable when the quantity is and has something to do with the quicksmall. When the surface exposed is coli- coagulation which is observed after a slowsiderable, but not so great as to prevent stream. A curious appearance connectedentirely the separation of parts, the natural with the mass of coagulating blood, has beenprocess is greatly disturbed. Sometimes noted by De Haen and Hewson. The latterwhen the separation of serum from clot is having bled a person into four cups, at 10

prei-elited, there is a tendency in the corpus- o’clock in the morning, on looking at theeles to subside from the serum and fibrin, blood at five in the afternoon, the serum inleaving behind a diluted buffy coat. The the first cup was found not separated fromexplanation of all these circumstances, ac- the clot, but the clot felt as if it contained a.cording to the principles already explained, fluid in a bag. Upon pressing it, the fluidis this --The atmospheric air acts as a strong gushed out, and, in a few minutes after ex-stimulus to the vital properties of the liquor posure to the air, it coagulated. The ex-

sanguinis, so as to promote coagulation planation of this phenomenon seems to be,under ordinary circumstances, but when it is that the fluid in contact with the air and theapplied too suddenly, or too extensively, it sides of the vessel, coagulated first, and pro-exhausts or weakens those vital powers, so tected the enclosed liquor sanguinis fromas to lessen the contractile energy in the lat- external influences ; the vitality of the wholeter stages of the process. mass being sufficient to maintain its fluidity,

II. The Form and ?6Tuterial of the Vessel. just as a quantity of blood may be foluid—Mr. Hey first made the observation that fluid and still coagulable in the heart of ai-i

the material of which the vessel is com- animal twelve or fourteen hours after death.posed, into which living blood is received, This subject is too intimately connected withinfluences its coagulation. Mr. Thackrah that of vital influences on the coagulationmade experiments on the influence both of of the blood, to be further pursued in thisthe shape and material of the vessel. Blood place.coagulated sooner in metallic than in glass IV. Agilation or Rest.-It is well knownand glazed earthen vessels, and the quantity that the agitation of blood, immediately afterof serum separated is smaller in the former. it is drawn, preserves it apparently fluid,In one specimen of blood divided into five and this process has been frequently adoptedparts, the proportion of serum to clot was as for culinary purposes. Hey and others,folloms :- from a superficial examination, inferred, in

Vessel. Serum. Clot. these cases, that the coagulation of the

Copper ............ 10 to 18.9 fibrine was prevented; but Thackrah andSilver.............. 10 ...... 22.6 Prater performed the following experiment,Glass.............. 10 ...... 2-1.4 from the result of which it appears that thisGallipot............ 10 ...... 37.3 3 fluid appearance is fallacious. Blood,whichPewter ............ 10 ...... 175. had been kept fluid by agitation, was after-But these results were, in part, influenced wards placed in a filter, and the fibrine was

by the shape, and accordingly, by the extent left behind in shreds. Strong agitation,of surface. However extraordinary that in therefore, does not prevent coagulation; itthe pewter vessel may appear, Mr. Thackrah merely divides the coagulum, and moderateasserts it to be correct. Upon the whole, agitation appears to promote the process.according to the experiments by the last- Prater, Davy, and Scudamore, confirm this,mentioned physiologist, the form and mate- although the effect is but slight, and therial seemed to produce irregular effects. former explains it by the stimulus of a largerThis has been referred to the electrical con- surface of inanimate matter, the last by itsdition of the different vessels. Scudamore favouring the escape of carbonic acid gas.attempts to account for it upon the principle Exp. Blood received into a gallipot wasof a difference in the conducting power of moderately stirred with a stick for two mi-the material, metals being better conductors nutes; it coagulated in three minutes and a.of caloric than glass and earthenware. half. Another portion of the same stream,However this may be, on examining the re- treated in the same manner, coagulated insults of experiments, I see nothing contra- four minutes. Another portion remaining atdictory to the principle that when the liquor rest had no appearance of coagulation in sixsanguinis is more powerfully acted upon by minutes, and at the end of eight was much.external stimuli, provided they are not so less firm than the two first portions.

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V. Temperature.-The coagulation of blood, process may, in fact, be hastened, retarded,and its separation into serum and clot, are or entirely prevented, by different degrees ofgreatly influenced by the temperature to heat. These effects will be seen in thf-which it is exposed after extravasation. The following-

TABLE XIV.Results of Experiinents on the influence of Degrees of Temperature, on the Coagulation of the

Blood, and the Contraction of the Coagulum; with Authorities.

Favourable to coagulation. This, and a few de-grees lower, the standard usually referred to....

Coagulation is accelerated in blood raised to thistemperature immediately after extravasation....

Accelerates very considerably. Italso acceleratesthe contractions of the clot ...................

Suddenly raised to this degree, coagulability is per-manently destroyed. If previously coagulated,it destroys the contractility of the clot .........

Becomes solid almost instantly from the solidifica-tion of albumen, but not from the separation offihrine and its contraction, or coagulation of

blood, properly so called .....................

Retards coagulation ..........................

Considerably retards..........................

Considerably retards. Human blood kept at 45°remained fluid for full 16 minutes .............

Remained fluid 20 minutes after being cooled tothis degree, and did not coagulate for an hourand ten minutes.............................

In one experiment kept at this temperature for 22hours, coagulability permanently destroyed ....

Kept at this temperature for an hour, remains fluid,but coagulates after removal to a higher. Keptat the same degree for 36 or 40 hours, coagula-bility permanently destroyed .................

Blood freezes. If kept frozen a short time, andthen thawed, it coagulates. If kept so for 24hours, coagulability is permanently destroyed.In blood previously coagulated the contraction

goes on at the freezing temperature............

It appears from these results, that a very above results corroborate those of Hesonhigh or a very low temperature is capable of and Hey. The fact that blood can be

destroying the vitality of blood, and of pre- frozen without destroying its coagulability,venting altogether the phenomena of coagu- has been adduced as the strongest argumentlation. Hewson had observed that blood against its vitality, more especially the vitaldrawn from a vein, divided into portions, organisation of the fibrine. But the inter-and exposed to different degrees from GOo esting experiments of Mr. Prater completelyto 105°, coagulates in about the same time, supersede this objection. The most inter.and that, at 108° it coagulates and separates esting circumstance of all is, perhaps, thesooner than at 55° ; and Hey found that cold following:—that high degrees of temperature,- did not prevent, but suspended the separa- not sufficient to destroy the vitality of thetion of serum, and that a temperature of 45° liquor sanguinis, or of the clot, act as

or 46° greatly interrupted the process. The stimuli to vital contractility ; on the con.

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trary, lower degrees of temperature thanordinary from the abstraction of stimulus,retard both coagulation and contraction.The same degree of heat which destroys thepower of coagulating also destroys the

power of the coagulum to contract. Thevital character of the contraction of the clotis well exemplified by the following experi-ment from Prater:—" Two equal portions ofthe same blood were poured into similar ’,vessels ; one was immersed in water at 120°,the other into cold water ; the former con-tracted two-eighths of an inch in one hour,the latter only one-eighth ; the former beingnow taken out of the water, was found,when examined at the end of ten hours, tohave contracted another eighth of an inch.This further effect proves that the contrac-tion caused by the heat was not the resultof any decomposition or disorganization."Although blood is not coagulated, as a fluidit is rendered more dense and viscid by cold.

Air, temperature, motion, or rest, the formand material of the vessel, and the circum-stance of mass, are then the known ordinaryinliuences which affect the coagulation ofextravasated blood. They must be takeninto account in every observation which ismade on this process, with a view to elicitinformation as to the state of the living sys-tem. Of these influences, one acts far lesspowerfully than two or more, so that whenwe only in part, as it were, place blood inunnatural circumstances, its tendency to

coagulate is much less than if we place itmore decidedly in such a state. Rest pro-duces a great tendency to coagulate; thencomes the admission of air : combined,their individual powers are much increased.These agents, we have seen, are not causes,and they have more or less effect, accordingto the weakness or strength of the vital

power of the fluid upon which they act.Many experiments have been made uponthis interesting process ; these we shallhave to consider, as also the subjects of theperiod of coagulation, the proportion anddensity of the clot, and the influence ofstates of the living system, at our next

meeting. You will be fully apprised thatnone of these circumstances could be cor-rectly estimated, without due attention tothose which have already been discussed.John Hunter remarks, "Life could not

go on without the property of coagulatingin the blood ; for, as all the solid parts areformed from the blood, this could not takeplace if there did not exist such a power ofcoagulation;" and Dr. Wilson has statedin this theatre, that " the tendency of bloodto coagulate without actual coagulation, isno doubt modified, if not suspended, by theimpressions constituting disease, whetherreceived from the air, from the food, or frompoisons. Some medicines may producetheir effects on the system, by influencingthe same principle of coagulability in the

blood ; for medicines act by the same meansas air, food, poisons, and other impressions."Thus, gentlemen, we are not only linealdescendants, but virtual disciples of theSchool of the HUNTERS.

COURSE OF LECTURESON THE

DISEASES OF THE EYE,Delivered in 1839-40,

AT THE

ROYAL SCHOOL OF ANATOMY AND MEDICINE,

MANCHESTER,By JOHN WALKER, Esq., Surgeon.

LECTURE III.

CONJUNCTIVITIS PURIFORMIS; OR, PURULENTOPHTHALMIA.

THE next variety of conjunctival inflam-mation I shall treat of is, conjunctivitis puri-formis; or, purulent ophthalmia, so named‘from the appearance of the discharge pouredout from the conjunctival surfaces. Thisvariety is also frequently termed Egyptianophthalmia, and sometimes contagious oph-thalmia. The former of these appellationshas been assigned to it on account of itspresumed origin; the latter, from the mode in.

which it is supposed to be communicated.Ofconjunctival inflammation, there is noform so severe or dangerous as that to whichI now invite your attention. Conjunctivalinflammation in this form is, indeed, one ofthe most important of all the affections o4the eye ; and it is even probable that a greateinumber of individuals are deprived of visioufrom this disease than from any other cause.Hence purulent ophthalmia has justly ex-cited, particularly of late years, the earnestattention of surgical practitioners; and to noclass of the profession are we more indebtedfor information concerning its nature, andthe means of treating it, than to the intelli-gent and highly respectable class attachedto the military service of the country.There are many affections, as well of the-

eye as of other organs, which may be safelytrusted to the unaided efforts of nature.-Purulent ophthalmia, however, is not oneof them; for if there be a disease whichmore than another requires the vigilant at-tention of the ophthalmic surgeon, it is this,,as will, I think, be fully proved by whatI intend to lay before yon.

In presenting my remarks on purulentophthalmia, I shall imitate the example set-by authors, in general, of first treating of theordinary purulent ophthalmia of adults;-next of gonorrhoeal ophthalmia; and, lastly,of the purulent ophthalmia of infants ; andI shall do so, not because there is any mate-rial difference in the nature or treatment of