THE 13LUUJJ. 



Fibrin- ferment is a term used simply for convenience and prob- 

 ably is a misnomer. It is a proteid of the globulin group whose 

 substance does not seem to be used up in the process nor to enter 

 into the fibrin formed ; a small quantity of it serves to break up an 

 immense amount of fibrinogen. 



Calcium is needed only in the formation of fibrin-ferment, and 

 is not needed for the action of the fibrin-ferment on fibrinogen. 

 This is shown in the schema below. 



Plasma 



Thrombogen or 

 Prothrombin 



Thrombin or 



Fibrin-ferment 



Lime Salts 



I 



-Thrombin 



Cell 

 Thrombokinase 



Metathrombin 



Alkali 



Thrombin 



This schema gives the method of the formation of thrombin or 

 fibrin-ferment according to Morawitz. The active substance in the 

 tissues is thrombokinase. Thrombogen is assumed to exist in cir- 

 culating blood, and is formed from the blood-plates and the white 

 corpuscles. The pre-existence of thrombogen in blood is shown by 

 the venous injection of the juices of tissues producing coagulation. 

 Thrombokinase is intra- and extra-vascular, and is formed from the 

 white corpuscles. Thrombokinase can be obtained from all tissues 

 as a general protoplasmic product, whilst thrombogen is not found 

 in the tissues. Thrombokinase is thermolabile, but stands more heat 

 than fibrin-ferment. It is easily destroyed by autolysis and alcohol. 

 In the plasma of the circulating blood is found all the necessary 

 factors for coagulation, fibrinogen, lime salts and thrombogen; the 

 only thing wanting is thrombokinase. Thrombokinase comes from 

 the extra-vascular formed elements of the blood, which by contact 

 with foreign bodies gives the thrombokinase to the plasma. If 

 blood is received under oil or in a paraffined glass, then it remains 

 fluid for a long time, since no adhesions and no irritant by a foreign 

 body acts upon the formed elements. 



When blood flows from a cut it rapidly clots, owing to the 

 thrombokinase supplied by those tissues over which it runs. 



The formation of an active fibrin-ferment from the action of 

 thrombogen, thrombokinase and lime salts cannot be chemically 



