The account given by GENDRIN (a) of the steps by which the stagnation of the blood in inflammation is produced is very interesting:-"The capillaries around this (irritated) point dilate, and seem to multiply themselves; because a greater number is perceived on account of the presence of red blood, which, in colouring them, renders them more visible. The globules arrive; they are crowded together, their motion is retarded, and at length suspended; they revolve upon themselves, and at last remain entirely at rest. The capillary circulation is then evidently suspended in the point irritated; for some distance around, the retardation of the circulation and dilatation of the capillaries are plainly seen; a little farther off the circulation is more rapid, the capillaries being still dilated, and the globules of the blood less distinct; finally, at the limits of the inflamed areola the circulation is, on the contrary, accelerated, the capillaries dilated, and the blood contains a greater number of globules. All these changes may take place in four or five minutes, and the same space of time is sufficient to allow of the capillary circulation returning to its natural state." (vol. ii. p. 475.) The objection made by EARLE to THOMSON's experiment, that inflammation had not been excited, might perhaps, strictly speaking, be made use of here; but it is quite clear that the experiment had reached the turning point from healthy to diseased action.

THOMSON'S experiments have been repeated and detailed by TRAVERS, in his chapter, Direct Effects of Stimuli and of Wound, and all coincide in producing the same phenomena, excepting that with ammonia; in which TRAVERS's observations are remarkably opposed to those of THOMSON; for "the application of ammonia," says he, "produced an instant increase of velocity, then stagnation, with the deepened tint of colour and enlargement of vessels." (p. 36).

TRAVERS gives a very beautiful account of "the oscillation attending the recovery of the circulation, which seems to be the punctum saliens, or first movement towards the formation of the new circulation.” (p. 166.) * **«The first effect of a drop of stimulant fluid, or of a wound upon a transparent web, (frog's foot,) as seen in the field of a powerful microscope, is," says he, " to arrest the circulation at the part. Around the point of absolute stagnation, the column of blood oscillates, and the particles are seen to separate and congregate in small irregular masses, presenting varieties of shape, some being perfect ellipses, others spherical. The vessels are dilated, and, in proportion, their fulness is increased, and their pink colour heightened. Still more remote from the stagnant centre increased activity of circulation prevails. The point of stagnation, the very slow circulation in the part immediately surrounding it, the current still oscillating in parts, and beyond this the more rapid and vigorous circulation, are manifested for several days. The contrasted appearance of one portion of the web stationary, and another in brisk circulation, is striking. The labour also of the current, the sudden overcoming of the obstacle occasioned by a too crowded passage, and the instant velocity succeeding thereupon, reminds us of the swaying backward and forward, and at length the inrush, of a crowd emerging into an open space from a narrow avenue." (p. 34, 35.)

BENNETT says:-"It is very difficult to determine the cause of oscillation in the column of blood. It may be remarked, however, that this phenomenon has only been observed in the smaller animals which are held fast under the microscope. Even here the oscillation is not invariably seen to precede the stoppage. It is most frequently observed, also, when the animal is very weak, or has fallen into asphyxia. Under such circumstances the energy of the heart and large vessels is evidently diminished, and the blood will be propelled with less force than usual against the capillaries, and either stop for a moment, or flow backwards during the diastole of the heart. It is probable, therefore, that the oscillation does not essentially belong to inflammation, but rather depends upon the general weakness of the animal." (p. 33.)

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The phenomena attending the first steps of the inflammatory process excited in the web of a frog's foot, as seen under the microscope, are well described by WHARTON JONES (b). "Very soon after the irritation," he says, " accumulation and stagnation of the blood in the capillaries, including the terminations of the arteries and radicles of the veins of the part, is observed to take place; but, amidst the obstructed vessels a few here and there may still be seen pervious, and through them the stream of blood is very rapid. The accumulation and stagnation of the blood in the small vessels is always preceded by a retardation of its flow (coincident with dilatation of the vessels ;) this retardation of the flow of blood having or not been preceded by the opposite condition of an accelerated flow (coincident with constriction of the vessels.)" He then proceeds to inquire into "the behaviour of the blood during the retardation of its flow and at (b) Report.

(4) Hist. Anat. des Inflammations.

the time of its stagnation," which he thus describes :-" a. Colourless corpuscles. During the retarded flow of blood immediately preceding stagnation, an accumulation of colourless corpuscles is observed to take place on the inner surface of the walls of the dilated small vessels, similar to what occurs in the healthy state when the velocity of the stream of blood is diminished. b. Red corpuscles. While the accumulated colourless corpuscles may have even become stagnant on the walls of the vessels, the red corpuscles, though in increased quantity, in proportion to the plasma, still continued to float on, but more and more slowly until complete stagnation ensues. They are somewhat more collapsed than natural; hence they appear redder, and their nucleus is less indistinctly seen, a change similar to what takes place in the red corpuscles of newly drawn blood. The red corpuscles appeared to be the agents principally concerned in the stagnation of the blood*** by agglomerating together, and applying themselves here and there flat against the walls of the vessels and adhering to them; whilst other red corpuscles applied themselves to those already adherent." (p. 568, 9.) This view had been already put forward by JONES in 1842; and about the same time was described more at length by EMMERT and by VOGEL. The following is the brief account which JONES gives of their statement. According to EMMERT, the colour of the red globules becomes somewhat deeper, and hence individually they appear less transparent; their surface is less smooth, and the irregularity of their edges is peculiarly distinet: they acquire the property of remaining adherent to each other and to the walls of the vessels when they come in contact with them. When the flow of blood becomes retarded and oscillations commence, the blood-corpuscles apply themselves, according to VOGEL, more to each other; and, though still individually distinguishable, they still touch, and in the smaller capillaries are often pressed close together by their surfaces in the manner of rolls of coin. The space next the walls seems merely filled with plasma; but, in complete stagnation of the blood, it disappears, and the interior of the vessel is completely filled with blood-corpuscles closely aggregated, and forming an apparently homogeneous indistinctly granular mass, in which individual blood corpuscles can scarcely be distinguished: but this fusion is merely apparent; for, if the blood be evacuated by opening the vessels, the individual corpuscles again appear quite distinct." (p. 568.)—J. F. S.]

5. Every injury which acts as an irritant upon any one organic part, may be considered as an incidental cause of inflammation. The necessary intensity of this irritation cannot, in general, be determined; it depends upon the individual susceptibility and condition of the organs. Powerful, young, full-blooded, sanguine, or choleric subjects, are most prone to inflammation; the disposition to which is strongest when the fibrin of the blood is increased in quantity. Inflammation arises most readily in parts which are very sensitive, and in which the capillary-vascular system is much developed. The usual incidental causes of inflammation are, a peculiar condition of our juices differing from the natural commixture, suppression of ordinary discharges, contagious matter, mechanical influences, falls, blows, wounds, and so on, cooling after preceding heat, burning by fire, corroding substances, and so on.

[To these we may also add, with JOHN HUNTER," that fever is often the cause of local inflammation. We see this happen every day. *** These inflammations, in consequence of fever, are commonly supposed to be critical; but I very much doubt the truth of this opinion." (p. 257.)

"Irritating substances," says JOHN HUNTER," when of no specific kind, produce inflammation sooner than other visible causes of inflammation. If of a specific kind, then the time, sort, and violence will be according to that kind. But irritating applications must be continued for some time to produce violent inflammation. These differences are easily accounted for: quick death does not irritate the part killed, and the contiguous living part, not being itself hurt, is only irritated to get rid of the dead part. A wound is a quick irritation of a living part, so that it inflames more readily and more violently, according to the quantity of irritation; but that cannot be of long standing, as nature sets about procuring relief. But when irritating substances are applied, the part inflames quickly, according to their power of irritation; and, if they are continued, nature is not allowed to relieve herself, but is constantly teased, by which means the inflammation becomes also violent." (p. 257.) "All inflammations attended with

disease have some specific quality which simple inflammation has not; and in such cases it is the specific quality which is the disease, and not the inflammation.” (p. 260.) "There are many constitutions which have a tendency to specific diseases, that, when injured by fever or any constitutional complaint, readily produce the specific inflammation in such parts of the body as have the greatest susceptibility for any specific action; or, if such parts are affected by any local violence, the parts affected will not go through the healthy adhesive inflammation, nor will they enter into the healthy suppurative inflammation, but will fall into the specific inflammation peculiar to the habit: such is the case with an erysipelatous habit. Or, if a specific inflammation has already taken place, any violence done to it, when already begun, will increase that disposition and action, which we plainly see to be the case with the scrofula, because this disease can, and often does, arise from such a cause alone." (p. 261.)]

6. The results of inflammation are resolution, exudation, suppuration, ulceration, induration, and various other transformations of organs, softening, and mortification. All these conditions, excepting resolution, are merely different living processes, which are brought about by inflammation, and are still accompanied by it for a long time.

7. In Resolution (Resolutio, Lat.; Zertheilung, Germ.; Résolution, Fr.) the appearances of inflammation subside nearly in the same order as in their development they set in with, and the diseased part reverts to its natural condition. The pain diminishes, or disappears first; in the same degree the temperature and the redness lessen, the swelling alone often remains for a still longer time, till the absorption of the serous or albuminous fluid poured into the cellular tissue is completed.

We may hope for this result when the inflammation has not quickly run on to a great extent, the pain neither particularly severe nor throbbing; and when the fever accompanying the inflammation terminates critically in perspiration and deposit in the urine.

Resolution is distinguished from the disappearance or recession (Verschwinden oder Zurücktreten, Germ.; Délitescence, Fr.) of inflammation, which is in general connected with its simultaneous or speedy development in another organ. This recession depends on the succession of an irritation which is more severe than that which kept up the earlier inflammation. It is often merely a state of changed vital activity, of increased sensibility, which produces the removal of the inflammation, particularly if it be treated with repelling astringent remedies. Certain inflammations, as erysipelas, and critical inflammations, have a peculiar disposition to recede.

[The process of resolution has been well described by Dr. J. H. BENNETT, as follows: Resolution or absorption of the exudation may occur in various ways, and follow any of the transformations of the exudation except the one which converts it into permanent tissue. The early phenomena first disappear; the capillaries recover their contractility; the attraction between the blood and the parenchyma ceases; and the blood within the vessels begins to oscillate, and at length flows in a continuous stream. Secondly, the essential phenomenon disappears, no further exudation takes place, and that already poured out is absorbed. It occasionally, though rarely, happens, that the exudation does not coagulate for some time after it is exuded. Under these circumstances, when the early phenomena terminate, it re-enters the vessels by endosmosis, unchanged. In the majority of cases, however, it coagulates, and, once rendered solid, it could never be absorbed without the occurrence of changes in it by which it is again rendered fluid. This is effected by the formation, ripening and disintegration or decay (moulting process of SCHULZ) of nucleated cells, whereby the coagulated exudation is broken up, made soft, pultaceous, and diffluent, and at length absorbed. By this process exudation poured out into the lung or brain gradually disappears, by the production of inflammatory softening. On the serous surfaces the fluid and broken down corpuscles are absorbed; but that portion which passes into permanent organization, is transformed into fibrous tissue, becomes covered with a smooth membrane, so that the functions of the organ are not disturbed. Abscesses when resolved undergo a similar process. The pus-cells, instead of being evacuated, are brought closely together from the absorption of the more fluid portion (liquor puris.) These are gradually broken down, the cell-walls are dissolved, and the whole is

reduced to a molecular matter, which re-enters the vessels, and thus complete resolution is produced. The disintegration of pus-corpuscles previous to absorption is evidently favoured by the pressure which the abscess receives from the contraction of the filamentous and elastic tissues that form its walls. * * * It is probable also, by increasing the contraction of the integuments, as well as by removing fluid from the neighbourhood of the part, that irritants, blisters and cauteries, are so beneficial in the resolution of abscesses. It is suggested by ZIMMERMAN, that the formation of an acid, as the lactic, in abscesses when fully formed, favours their disintegration. We have seen that acetic acid dissolves the cell-walls and causes the nucleus to appear in the form of granules: if lactic acid be produced, it would probably have the same effect. Alkaline solutions also, it is well known, dissolve pus-corpuscles, a circumstance that may explain the discutient effects of alkaline lotions and washes, and their beneficial operation in removing the incrustations from eruptive pustular diseases." (p. 63-5.)

As to the question "What becomes of the molecular fibrin which thus re-enters the circulation?" BENNETT states that "the observations of several German physicians, more especially of SCHÖNLEIN and ZIMMERMAN, have thrown much light upon it, and determined that the changes which the urine undergoes in acute inflammatory diseases, bear a relation to the absorption of exuded blood-plasma in internal organs. Thus, in a case of pneumonia, SCHÖNLEIN pointed out that the disappearance of dulness was accompanied by a turbid state of the urine, which contained a large amount of molecular fibrin, and was also highly coagulable by heat. ZIMMERMAN has recorded instances where the turbidity and coagulability of the urine bore a marked relation to the diminution of sup purative swellings. In some cases where purulent matter was apparently absorbed, he had observed that the urine was coagulable from the presence of fibrin dissolved in it" (a). Hence it is concluded "that the molecules of the broken-up exudation, after circulating in the blood, are frequently eliminated by the kidneys, and make their exit from the system by the urine, sometimes entire, at others in a state of solution. * * . Occasionally the excess of fibrin may be eliminated by the skin, lungs, and bowels. In all cases it constitutes an important symptom of the crisis." (p. 65.)]

8. Exudation (Exsudatio, Lat.; Ergiessung, Germ.; Exsudation, Fr.) is the outpouring of a larger quantity of serous fluid than the capillary vessels ordinarily exhale into the cellular tissue, into the parenchyma of organs, or into the cavities of the body. For the most part it occurs towards the end of the inflammation, or at least when it is subsiding. The fluid poured out (serum and coagulable lymph) differs in respect to its composition; often thin and transparent, often consistent, mingled with flocculi, and so on. The thicker part of this exudation (the coagulated albumen) not unfrequently unites neighbouring parts, vessels are prolonged into this interstitial substance, and adhesion is effected. If the fluid poured into the cellular tissue be only serous, then dropsical swelling (adema) is produced. The exudation occurs, especially often in serous membranes: not unfrequently also does a similar exudation accompany flammation of the mucous membranes. These exudations may be accompanied by an inflammatory or weakly condition of the capillary vessel.

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in

[The term "exudation," as here explained by our author, is synonymous with "effusion," as generally employed by British practitioners; but the latter, by defining the nature of the matter poured out as effusion of serum, of coagulable lymph, &c., make a distinction which the former does not. Neither of these terms, however, thus used, seem suffici ently pointed; but their employment as proposed by J. HUGHES BENNETT is unobjectionable. Effusions," he says, "no doubt are very common; but, in the great majority of instances, they arise from venous obstruction, altogether independent of inflammatory phenomena. *** In all such cases the fluid is clear, holds no fibrin in solution, and on being evacuated shows no disposition to coagulate. * * * In inflam matory effusions, on the other hand, the fluid is more or less turbid, containing fibrin in solution, and, if allowed to stand, flocculi swim in it, or sink to the bottom of the vessel. * * * Mere effusion, then, cannot itself be considered as characteristic of inflammation. It may be the result of congestions non-inflammatory, or, if otherwise,

(a) Ueber den gerinnbaren Harn; in CASPER'S Wochenschrift, 1843, p. 345.

passes more or less into exudation. In every instance of undoubted inflammatory action an erudation of blood-plasma occurs which may be made visible. *** Where the liquor sanguinis is poured out into shut cavities, the same phenomena occur as when blood is drawn from the body. The fibrin coagulates, and the serum is set free. The former then lines the serous membrane, and is denominated coagulable lymph, whilst the latter is called serous effusion. *** In parenchymatous tissues, however, as in the lungs, liver, brain, &c., the structure of the parts will not allow of this distinct separation. The liquor sanguinis exuded is, of course, at first fluid, and, in this state, insinuates itself among the elementary structure of the organs, filling up every minute space. When it coagulates, the tissues of the part affected are completely blocked up, as if with cement. The blood-vessels, nerves, filaments, &c., are surrounded by a solid mass, in the same manner that the stones in a wall are surrounded by mortar." (pp. 38, 40.)

As to he effusion of serum, TRAVERS observes:-" The first change external to the vessels in inflammation is not a permanent change, and looks like a measure of temporary relief to the over-loaded vessels which surround the inflamed centre. It is an aqueous exudation from the colourless capillaries into the adjoining cellular texture. It would seem to be a passive mechanical effect, as it doubtless often is, but for the precedence of other unequivocal signs of inflammation." (p. 65.)

WHARTON JONES says:-" Immediately after or during the stagnation of the blood, exudation commences. From being at first serous the exuded fluid comes at last to be pure plasma, at least a fluid containing a greater or less quantity of fibrin." He attributes the exudation" to the thinning of the walls of the vessels, from their relaxation and dilatation on the one hand and the pressure from within the vessels on the other:" and he also suggests, as likely to promote exudation," that the plasma will be pressed out from among the aggregating corpuscles, even when the blood would not, if out of the body, present the buffy coat, and that because within the body the fibrin of the plasma does not so readily coagulate;" but, when the blood is so changed that on abstraction the buffy coat appears, "the plasma at the same time that it is more quickly and energetically squeezed out from among the aggregating red corpuscles, will present itself in greater quantity and richer in fibrin, for transudation through the walls of the capillaries." He considers, with WATSON, that the cause of serum alone passing out first, is, as in common ædema, owing to obstruction; the obstruction in inflammation being from the stagnation of the blood;" but how obstruction determines exudation of serum alone, remains a question: to help to a solution of this, it may be stated that, according to KÜRSCHNER, water passes most quickly through animal membranes and saline solutions more quickly than viscid, gummy, and albuminous solutions. With exudation," he says, "is completed the inflammatory process properly so called." (pp. 584, 5.)

"The extravasation of the serum along with the coagulating lymph," says JOHN HUNTER, “is, probably, not a separation of itself, as in a dropsy; but, a part of it being separated from the lymph in the coagulation of that fluid, is squeezed into the surrounding cellular membrane, where there is but little extravasation, and where the cells are not united by it. Thus, the circumference of such swellings is a little cedematous; but the whole of the serum if there be a depending part will move thither, and distend it considerably, as in the foot in consequence of an inflammation in the leg. But, in most cases, there is a continued extravasation of serum long after the extravasation of the coagulating lymph is at an end, so that depending parts will continue œdematous, while the inflammation is resolving, or while suppuration, or even healing, is going on. The whole swelling looks like a part of the body only a little changed, without any appearance of containing extraneous matter; and indeed it is simply formed by an extravasation of fluids without their having undergone any visible or material change, except coagulation." (p. 285.)

GERBER speaks of the exudations after inflammation as watery or serous exudation when merely the serum of the blood is poured out; plastic, when the liquor sanguinis containing fibrin exudes without the blood-corpuscles; and sanguineous, when it is blood-coloured; the colour depending either on solution of the colouring matter of the blood, or the effused liquor sanguinis contains all the components of the blood and even the blood-globules, thus forming the transition to hæmorrhage (p. 42.) He says, also, that in the fluid of serous exudations albuminous granules of albuminous fluids are usually found; that after plastic exudations a yellowish turbid fluid is found in the affected cavity, with fine pale yellow flocculi floating in it, or precipitated upon and perhaps adhering to the walls of the exuding surface. If the exudation of plastic matter go on longer, and the quantity of effused liquor sanguinis, be considerable,

VOL. I.

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