THE BLOOD. 21 



COAGULATION OF THE BLOOD, IN THE VESSELS, AFTER 



DEATH. 



The coagulation, or death, which we have described as 

 occurring in blood abstracted from the system by venesection, 

 takes place likewise, the vital influence which maintains the 

 circulation being removed, in that which is still contained 

 within the vessels of the body, although in a manner less 

 marked and appreciable. 



As also in the case of the blood withdrawn from the system, 

 the time occupied in the coagulation of that which is still 

 enclosed in its own proper vessels, varies very considerably. 

 This difference depends partly upon the circumstances under 

 which the patient has died, whether he has been exhausted or 

 not by a previous long and wasting illness, and partly upon 

 temperature and, perhaps, certain electric states of the 

 atmosphere. In all instances, however, a much longer period 

 is required for the production of coagulation in blood not 

 removed from the body, than in that which has been with- 

 drawn by bleeding ; this change in its condition being seldom 

 effected, in the former instance, in a shorter period than from 

 twelve to twenty-four hours subsequent to decease ; although 

 occasionally, but rarely, it may occur at periods either earlier 

 or later than those named. 



Signs of Death. It has already been stated, that blood 

 once coagulated is rendered unfit for the purposes of life, 

 and that no known means exist capable of restoring to 

 coagulated blood its fluid state, so as to render it once again 



frequently observed to precede the formation of the buffy coat, and the 

 existence of which he states to be quite characteristic of inflammatory 

 blood. This appearance is produced in the following manner : after the 

 lapse of a minute or two a peculiar heaving motion of the threads or rolls 

 formed by the union of the red corpuscles with each other is observed to 

 take place ; this results in the breaking up of the rolls, the corpuscles of 

 which now collect into masses, leaving, however, intervals between them, 

 and which become filled with fibrin ; now it is the contrast in colour 

 between this fibrin and the masses of red corpuscles which occasions the 

 blood in coagulating to assume the mottled aspect referred to. 



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