272 OF THE BLOOD: ITS VITAL PROPERTIES, 



fibrin, the longer is it before it changes its state. Thus the coagulation of 

 sthenic inflammatory blood, which produces a clot of remarkable firmness, 

 is much longer in taking place than the coagulation of ordinary blood; 

 whilst the coagulation of the blood of cachectic subjects, which takes place 

 very rapidly, is feeble and imperfect. The plastic effusions poured out from 

 the blood in these two opposite conditions, partake of the character of the 

 blood itself; those of the inflammatory blood of a previously healthy sub- 

 ject being converted into fibrous membranes of considerable firmue'ss, which 

 are subsequently penetrated by bloodvessels, and become regularly organized 

 tissues; whilst those proceeding from the blood of cachectic subjects fre- 

 quently undergo a certain degree of organization with great rapidity, but 

 do not go on to the same perfection, and speedily degenerate. 1 



207. Instances occasionally present themselves, in which the blood does 

 not coagulate after death, or coagulates very imperfectly. It was affirmed 

 by Hunter 2 that no coagulation occurs in the blood of animals hunted to 

 death, or of those killed by lightning, by electric shocks, or by blows upon 

 the epigastrium; and this statement has been generally received upon his 

 authority. It is far, however, from being constantly true; for Mr. Gulliver 

 has made observations, and collected numerous cases in which coagulation 

 was found to have taken place in the blood of animals killed in each of 

 these modes; in some of them, however, the coagulation was very imperfect. 3 

 It is not improbable that some of the instances of apparent absence of coagu- 

 lation were really cases of retarded coagulation ( 208); and Dr. Polli goes 

 so far as to maintain, that the complete absence of coagulating power is a 

 phenomenon which has no real existence. He states that he has never met 

 with an instance in which the blood, when left to itself, and duly protected 

 from external destructive influences, did not coagulate before becoming pu- 

 trid ; and that he has more than once found blood to coagulate, which had 

 been taken in a fluid state from the vessels thirty-six or forty-eight hours after 

 death. 4 Still there seems no reasonable doubt that non-coagulation may 

 occur, when the blood has been previously subjected to conditions which 

 affects its vitality. Such appears to be the case, for example, when death 

 occurs from Asphyxia, as by hanging, drowning, or breathing of irrespir- 

 able gases; 5 and the same has been observed in cases of poisoning by hydro- 

 cyanic acid, in which asphyxia was probably the immediate cause of death. 

 In certain diseased states, again, we have seen that the coagulating power 

 seems to be completely deficient ( 200). 



208. The rapidity of Coagulation, and the degree in which the clot solid- 

 ifies, vary considerably ; in general, they are in the inverse proportion to 

 each other. Thus, if a large quantity of blood be withdrawn from the 

 vessels of an animal at the same time, or within short intervals, the por- 

 tions that last flow coagulate much more rapidly, as originally proved by 

 Hewson, but much less firmly, than those first obtained. In blood drawn 

 during Inflammatory states, again, the coagulation is usually slow, but the 

 clot is preternaturally firm ; especially at its upper part, where the Buffy 

 coat ( 199) or colorless stratum of fibrin gradually contracts, and produces 



1 Sec especially Mr. Dalrymplo's Memoirs, On the Rapid Organization of Lymph 

 in Cachexia, in the Med.-Chir. Trans., vol. xxiii ; and On the Early Organization 

 of Coagula and Mixed Fibrinous Eti'usions under certain Conditions of the System, op. 

 cit., vol. xxvii. 



' The Works of John Hunter, edited by James F. Palmer, vol. iii, pp. 34, 114. 



3 See Edinh. Med. and Snrg. Journ., O'et. 1848, pp. 3G7, 418, and his Edition of 

 Hewson's Works, pp. '20, 21. 



4 Annali Universal!, 1845; and Ranking's Abstract, vol ii, p. 337. 



6 See Dr. J. Davy's Physiological and Anatomical Researches, vol. ii, p. 191. 



