28 



THE BLOOD. 



1. As a condition preliminary to coagulation, there is either an increase 

 in the formation of fibrin-ferment or an appearance of ferment in the blood, 

 due to changes in certain of the leucocytes. The red corpuscles are probably 

 not directly concerned in coagulation, and there is nothing definite known of 

 the action of the blood-plaques in this process. 



2. The fibrin-ferment unites with fibrinogen and forms fibrin, which is 

 the coagulating substance. Paraglobuline (or metalbumen) is little if at all 

 concerned in this process. 



3. The processes described as incident to the coagulation of blood take 

 place also in the coagulation of lymph and chyle. 



In accordance with the views stated in connection with the composition 

 of blood-plasma, paraglobuline, or metalbumen, fibrinogen and, finally, fibrin 

 are products of decomposition, are abnormal formations, and are not normal 

 constituents of the blood. 



It is possible that the statement just given of the mechanism of the coagu- 

 lation of the blood may be modified in the future in accordance with the most 

 recent views of Schmidt, who claims that all the so-called fibrin-factors result 

 from decomposition of the leucocytes, a great number of which, it is said, 

 are dissolved soon after blood is drawn from the vessels. There are, in- 

 deed, many experimental and pathological facts in support of this view ; but 

 it can not be adopted without reserve, until the experiments of Schmidt shall 

 have been supplemented by more extended observations. Schmidt maintains 

 that in certain classes of animals, dissolved red corpuscles are also concerned 

 in the production of fibrin-factors. 



Leech-drawn blood remains fluid in the body of the animal. Richardson 

 has observed, also, that the blood flowing from a leech-bite presents the same 

 persistent fluidity, which explains the well-known fact that the insignificant 

 wound gives rise to considerable haemorrhage. 



The existence of projections into the caliber of vessels, or the passage of 



a fine thread 



through an ar- 

 tery or vein, will 

 determine the 

 formation of a 

 small coagulum 

 upon the foreign 

 substance, while 

 the circulation is 

 neither inter- 

 rupted nor re- 



Fio. 10.- -Coagulated fibrin (Robin) tarded In the 



Fibrinous clot, without red corpuscles, and containing leucocytes, thrown off 



in the form of a whitish pseudo-membrane in a case of lilceration of the present state of 

 neck of the uterus with haemorrhage. 



knowledge, ex- 

 planation of these facts is difficult if not impossible. The process, under 

 these conditions, can not be subjected to direct experiment as in the case 

 of blood coagulating out of the body. 



