THE BLOOD l? 



being specifically heavier than the plasma, have time to fall in 

 the fluid before the process is completed. The result of this is 

 that the upper solid layer is considerably decolourized, forming 

 the so-called buffy coat, which, though natural to the blood of 

 the horse, is indicative in other animals of the presence, of an 

 inflammatory process in the system. 



We have here closely followed the account given by human 

 physiologists of the coagulation of the blood in the horse, but 

 the appearance described is by no 

 means invariable. Coagulation in 

 this animal is often complete in less 

 than five minutes, when, of course, 

 no buffy coat forms, and we are 

 inclined to believe that rapid coagu- 

 lation and non-buffy coat are the 

 rule rather than the exception ; we 

 have repeatedly observed the blood 

 of the horse clot so rapidly as to be 

 almost instantaneous. One thing in Fig. 7. — Diagram of Clot 

 connection with horse's blood is un- ^^ BuFFY CoAT (Stewart). 



doubted, and that is that COagU- v. Lower portion of clot with 



lation is more easily slowed or red corpuscles ; w, white cor- 

 prevented by cold and neutral salts ^^K 

 than it is in the blood of any other clot ; s, serum, 

 warm-blooded animal. May it not 



be that some confusion has thus arisen, and we have come to 

 regard this abnormally easy slowing of clotting by cold and 

 salts, as if it were markedly a characteristic of horse's blood as it 

 clots naturally ? 



According to Nasse, the average time occupied in coagulation 

 is as follows : 



Pig - - - - - - £ to i£ minutes. 



Sheep - - - - - I „ i£ 



Dog 1 „ 3 



Ox 5 „ 13 



Horse 5 „ 13 



In our experience the extreme time mentioned for the horse is 

 exceptionally long. 



If the clot be examined microscopically, it is found to consist 

 of fine fibrils, entangled in which are the blood corpuscles ; if the 

 fibrin produced be washed completely free from blood, its appear- 

 ance is well described by its name. 



If instead of allowing the blood to clot spontaneously it be 

 whipped with a rod or bunch of twigs, or, as we say, is ' defibri- 

 nated,' the fibrin separates rapidly and coats the rod, while no 



2 



