A treatise on the blood, inflammation, and gun-shot wounds / by John Hunter ; with notes by James F. Palmer.

  • John Hunter
Date:
1840
Catalogue details

Licence: Public Domain Mark

Credit: A treatise on the blood, inflammation, and gun-shot wounds / by John Hunter ; with notes by James F. Palmer. Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    And in most of the cases in which the blood is observed to coagu late the air is commonly in contact with it: this was next presumed to be the cause of its coagulation.* But the air has really no more effect than any other extraneous body, in contact with the blood, that is capable of making an impression upon it; for the blood coagulates more readily in a vacuum than in the open air: nor will either of these supposed causes assist in explaining why it is not found coagulated after many kinds of death, nor in the menstrual discharge. Neither will they account for the very speedy coagu- lation of the blood which usually takes place in all the vessels after death, or when it has been extravasated into cavities, or cellular membranes, where no air has ever been admitted.f coagulation. Hewson had observed that if blood was kept at a temperature of 38° for 24 hours it became thick and viscid, but did not coagulate upon the re- turn of warmth ; which fact is capable of generalization, for whatever keeps the blood fluid for a considerable length of time has a tendency to deprive it of the full power of coagulation afterwards. Thackrah asserts, that blood which has once become frozen does not coagulate in any case, but only forms a grumous mass in which there is no separation of parts. (Op. cit., p. 67.) A very high temperature, as 140°—150°, according to Prater, has the same effect, that is, it renders the blood incoagulable; and, what is very remarkable, dilution with water does not restore this property in one case more than in the other (on the Blood, p. 13). It is sufficient at present to notice these facts, which have been considered by some to bear importantly on the question of the vitality of the blood. I may add, however, what is worthy of remark, as bearing on the same question, viz., that low temperatures, (insufficient to prevent coagulation altogether,) equally diminish the contractility of the clot and of muscular fibre, while the effect of high temperatures is the very reverse. Thus, animals of the order Batrachia im mediately perish and become rigid by being immersed in water at a temperature of 108° to 120°. The muscular structures of warm-blooded animals likewise become more or less contracted by all temperatures above blood-heat.] * Hewson on the Blood, p. 23. f [Hewson merely contended that air promoted coagulation, not that air was essential to the process. It must be confessed, however, that his expressions are sometimes equivocal, as at p. 123, Vol. I., and in some other parts of his In- quiry. Scudamore took two portions of blood from a man slightly indisposed, and placed one of them under the receiver of an air-pump and allowed the other to be exposed in the open apartment. The former cooled in five minutes from 84° to 75°; the latter from 84° to 82.5°. The former, however, was much the most coagulated of the two at the end of this period; although, a3 we have before shown, cold retards the coagulatory process. But if blood be received into a close vessel, so as completely to fill it, and care at the same time be taken to exclude it from the contact of the atmosphere, the process will be considerably retarded. To account for this apparent anomaly, Scudamore not only attempted to prove that carbonic acid is extricated from the blood during coagulation, and that the time required for the concretory process in great measure depends on the quick or slow extrication of this gas, but that its evolution is an essential circum- stance in this process. (Op. cit., p. 103.) With respect to the fact on which this explanation turns, viz., the extrication of carbonic acid gas, nothing can be more discordant than the results of experi- mentalists. One party, as Vogel, Scudamore, Brande, &c, (Ann. de Chimie, torn, xciii. Essay on the Blood, p 28. Phil. Trans. 1818, p. 181,) affirming its existence in arterial and venous blood alike in considerable quantities. Another, as Clanny, Prout and Stevens, (Edin.Med. and Surg. Journ., xxxii. 40. Bridge-