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FIBRINE OF LYMPH. 159

mining different extravasations, or blood drawn from a vein. The fibrine of lymph has this special peculiarity, that under ordinary circumstances it coagulates within the lymphatic vessels neither during life nor after death, whilst blood in many instances coagulates even during life, and regularly does so after death, so that coagulative power is attributed to blood as being one of its regular properties. In the lymphatics of a dead animal or human corpse, no coagulated lymph is met with, yet the coagulation takes place directly the lymph is brought into contact with the air, or has changes imparted to it by some diseased organ.

The explanation of this peculiarity has been attempted in very different ways. For my own part, I must still adhere to the view that there is, properly speaking, no perfectly developed fibrine contained in lymph, but that it becomes perfect either by contact with the atmospheric air, or in abnormal conditions by the introduction into it of altered matters. Normal lymph contains a substance which is very readily converted into fibrine, and is, when it has once coagulated, scarcely to be distinguished from fibrine, but which, as long as it continues to circulate with the ordinary stream of lymph, cannot be regarded as really perfect fibrine. This is a substance, of which I had demonstrated the presence in various exudations, especially in pleuritic fluids, long before my attention had been drawn to its occurrence in lymph.

In many forms of pleurisy the exudation long remains fluid, and a number of years ago a peculiar case came under my notice, in which on puncturing the thorax a liquid was evacuated which was perfectly clear and fluid, but in a short time after its evacuation had its whole mass pervaded by a coagulum, as is often enough the case with fluids from the abdominal cavity. After I had removed this coagulum from the liquid by stirring it, in order to convince myself of its identity with ordinary fibrine, the next day a fresh coagulum displayed itself, and this took place also on the following days. This coagulative power lasted fourteen days, although the operation had been performed in the midst of the heat of summer. This therefore was a phenomenon essentially differing from the ordinary coagulation of the blood, and somewhat difficult to explain upon the supposition that real fibrine existed completely developed in the fluid, but it seemed to indicate that it was only under the influence of the atmospheric air that the fibrine was produced from a substance which must indeed have been nearly related to fibrine, but yet could not be real fibrine. I therefore proposed to give it the distinctive name offibrinogenous substance, and when I afterwards had come to the conclusion that it was the same substance which we find in lymph, I was enabled to extend my view so as to include the proposition, that in lymph also fibrine is not contained in a perfect form.

This same substance, which is distinguished from ordinary fibrine by its requiring to be a longer or shorter time in contact with atmospheric air before it can become coagulable, is also found under certain circumstances in the blood of the peripheral veins, so that even by an ordinary venaesection perfonned on the arm blood may be obtained, distinguished from ordinary blood by the slowness of its coagulation. Polli named this coagulative substance braille f brine. Such cases occur especially in inflammatory diseases of the respiratory organs, and most frequently give rise to the formation of a buffy coat (crusta pleuritica, crusta phlogistica). You all know that the ordinary crusta phlogistica forms in the blood of pneumonia or pleurisy the more readily the greater the wateriness of the liquor sanguinis, and the poorer the blood is in solid constituents, but it is an essential requisite that the fibrine should coagulate slowly. If the duration of the process be noted watch in hand, the conviction will soon be acquired that a

FIBB.INOGENOUS SUBSTANCE IN THE BLOOD. 161

very much longer time passes than is requisite for ordinary coagulation. From this frequent phenomenon, as it is met with in the ordinary formation of a crust upon the surface of inflamed blood, gradual transitions are observed to a greatly increased prolongation of the period during which fluidity is retained.

The most extreme instance of this kind as yet known occurred in a case observed by Polli. In a vigorous man, suffering from pneumonia, who came under treatment in the summer, at a time which does not offer the external conditions most favourable to slowness of coagulation, the blood, which flowed from the opened vein took a week before it began to coagulate, and not until the end of a fortnight was the coagulation complete. In this case, too, occurred the other phenomenon which I had observed in the pleuritic exudations, namely, that decomposition (putrefaction) took place in the blood at an unusually late period in proportion to this lateness of coagulation.

Now since phenomena of this kind are observed to occur with especial frequency in chest affections, a frequency so especial indeed that the buffy coat was long since designated Crusta pleuritica, there would seem to be some grounds for inferring from this, that the function of respiration has a definite influence upon the occurrence or non-occurrence of the fibrinogenous substance in the blood. At all events, the peculiarity possessed by the lymph is under certain circumstances transmitted to the blood, so that either the whole of the blood partakes of it, and that in a higher degree, the greater the disturbance under which the respiration labours; or, in addition to the ordinary, quickly coagulating matter, a second which coagulates more slowly is found. It frequently happens, namely, that two sorts of coagulation subsist side by side in the same blood, one early and the other late, especially in the case, in which direct analysis shows an increase of fibrine, a hyperinosis. These hyperinotic conditions appear therefore to indicate that in them an increased supply of lymphatic fluid is introduced into the blood, and that the matters which are afterwards found in the blood are not the products of an internal transformation of its constituents, and that therefore the original source of the fibrine must not be sought for in the blood itself, but in those parts from which the lymphatic vessels convey the increased supply of fibrine.

In explanation of these phenomena, I have ventured to advance the hypothesis, somewhat bold perhaps, though I consider it perfectly able to sustain discussion, namely that fibrine generally, wherever it occurs in the body external to the blood is not to be regarded as an excretion from the blood, but as a local production; and I have endeavoured to introduce an important change in the views entertained with regard to the so-called phlogistic crasis in relation to its localization. Whilst it had previously been the custom to regard the altered composition of the blood in inflammation as a condition existing from the very outset, and especially denoted by a primary increase in the fibrine, I on the contrary have shewn the crasis to be an occurrence dependent upon the local inflammation. Certain organs and tissues have inherent in them in a higher degree the power of producing fibrine and of favouring the occurrence of large quantities of fibrine in the blood, whilst other organs are by far less adapted for its production.

I have, moreover, pointed out the fact, that those organs which with especial frequency exhibit this peculiar combination of a so-called phlogistic state of the blood with a local inflammation are generally abundantly provided with lymphatic vessels and connected with large masses of lymphatic glands, whilst all those organs which either contain very few lymphatics, or in which these vessels are scarcely known to exist, do not exercise any influence

TRANSUDATION OF FIBRINE. 1G3

worth naming upon the amount of fibrine in the blood. Former observers had already remarked that there were inflammations occurring in very important organs, as for example, in the brain, in which the phlogistic crasis was, properly speaking, not at all met with. Now it is precisely in the brain that we have scarcely any evidence of the existence of lymphatics. In those cases, on the contrary, in which the composition of the blood is earliest altered, namely in diseases of the respiratory organs, we find an unusually abundant network of lymphatics. Not merely the lungs are pervaded by, and covered with, them, but the pleura also has extremely numerous connections with the lymphatic system, and the bronchial glands constitute almost the greatest accumulations of lymphaticgland substance possessed by any organ in the whole body.

On the other hand, we are acquainted with no fact which shews it to be possible that, in consequence of a simple increase of the pressure of the blood, or of a simple change in the conditions which influence its circulation, an exudation of fibrinous fluids could in any organ take place into its parenchyma, or upon its surface, from the blood. It is certainly generally imagined that, when the current of the blood attains a certain strength, fibrine begins to appear in the exudation, but this has never been proved by experiment. Nobody has ever been able, by the production of a mere change in the force of the current of the blood, to induce the fibrine to transude directly as it is wont to do in certain inflammatory processes; for this some irritation is always required. The greatest obstructions may be induced in the circulation, exudations of serous fluids may be experimentally produced upon the largest scale, but that peculiar fibrinous exudation which the irritation of certain tissues provokes with so much ease, never ensues upon these occasions.

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