T/te Blood. 



37 



free from blood, its appearance 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, the fibrin 

 separates rapidly and coats the rod, whilst coagulation in 

 the remaining fluid is absolutely prevented. The power 

 of spontaneous clotting lies then in the production of 

 fibrin. 



These changes may be graphically represented thus : 



Blood. 



Blood. 



Plasma. 



Clotting. 

 I Serum. 



\ Fibrin. \ 



(Red. 

 .Corpuscles. -J White. 



( Mood platelets./ 



Clot. 



(Halliburton.) 



Plasma. 



pit 



.Corpuscles. 



When Whipped. 

 l Fibrin. 

 \ Serum. 

 rRed. 

 \ White. 

 (Blood tablets. 



j Defibrinated blood. 



Fibrin is a yellowish-white, stringy-looking bulky mass ; 

 it may be dissolved by hydrochloric acid forming acid 

 albumin or syntonin ; also by dilute alkalies with the 

 production of alkali albumin. Its general appearance 

 would lead to the belief that it exists in blood in large 

 quantities, it is found, however, to be by weight relati 

 small ; in human blood its proportion is 2 per cei 

 sheep, -2 to S per cent. ; ox, o to -4 per cent. ; hon 

 •4 per cent. ; pig, -4 to '5 per cent. (Colin). 



Fibrin is produced by the action of the fibrin ferment 

 on fibrinogen, the whole of the latter being used up in the 

 process. The ferment does not exist in living blood, but 

 is produced by the disintegration of the white corpuscles 

 immediately the blood is shed. Schmidt's view that 

 fibrin can only be produced by the action of the fibrin 



