THE BLOOD. 153 



The blood generally coagulates in the living body on escaping 

 from its vessels, and even in its vessels if its motion be prevented 

 by ligatures ; and when it does not, its subsequent escape from 

 the body almost always produces instant coagulation. 1 " It almost 

 always coagulates also in the vessels running through healthy parts 

 to others in a state of mortification, and in large vessels adjoining 

 a pulmonary abscess ; irt which cases, the final cause or purpose 

 prevention of hemorrhage, is evident. The efficient cause, 

 however, in all these examples, is unknown. In all, the blood is 

 still in contact with living parts : in the last two, it is perhaps not 

 at rest till it coagulates. J. Hunter, after mentioning that in a 

 mortification of the foot and leg he found the crural and iliac 

 arteries completely filled with strongly coagulated blood, adds, 

 that this could not have arisen from rest, because the same thing 

 ought then to happen in amputation, or in any case where the 

 larger vessels are tied up. n Besides, coagulation after extrava- 

 sation, or when a quantity is included in a vessel between two 

 ligatures, is not an invariable occurrence. 



These facts, in addition to those stated above, show that 

 fluidity or coagulation iVnot dependent on the simple presence or 

 absence of vitality. Whatever connection coagulation out of the 

 body may have with the escape of carbonic acid gas, there is no 

 proof of it in the case of internal coagulation. 



Some have imagined the globules to be not only endowed, 

 through vitality, with spontaneous motion, but with repulsion, 

 which ceases with life, and thus by their death to run together 

 and produce the phenomenon of coagulation. But M. Raspail 

 contends, as we have noticed, that such spontaneous motion is a 

 microscopic accident, and that, so far from being organised, they 

 are merely minute precipitations of albumen ; and he shows that, 

 when the blood coagulates, the globules are seen under the mi- 

 croscope enveloped in the coagulum, which, therefore, cannot be 

 a mere union of them. He asserts, that fibrin and albumen are 

 identical, and that the fibrin is preserved liquid by the alcalies of 

 the blood, soda and ammonia ; which, if they become saturated 

 by the carbonic acid of the atmosphere and that which forms in 

 blood when exposed to the air, can no longer act as a solvent, 



m J. Hunter mentions the coagulation of blood let out from the tunica va- 

 ginalis, in which it had lain fluid sixty-five days after a wound. On the Bloody 

 p. 25. 



n 1. c. p. 23. 



