THE COAGULATION OF THE BLOOD 75 



Nolfs 1 recent contributions can scarcely be said to simplify 

 the coagulation question. Besides the salts of calcium, he 

 recognises three protein bodies which are concerned in the 

 formation of a clot : 



1. A protein derived from the leucocytes, termed leuco- 

 thrombin. 



2. One found in the liver — hepatothrombin. 



3. Fibrinogen, which is formed by the activity of the cells of 

 the same organ. 



The interaction of the first two with calcium yields fibrin- 

 ferment. Thrombin arises by the formation of an envelope of 

 hepatothrombin around fine particles of leucothrombin, which 

 appear early in a clear, spontaneously coagulable liquid. This 

 process is followed by gelatinisation of the plasma, owing to 

 the further aggregation of another layer of fibrinogen upon the 

 thrombin. Fibrin, therefore, originates from an agglutination 

 process which becomes established in a liquid plasma which 

 at first shows no morphological constituents, and the whole 

 phenomenon of coagulation is to be regarded as one of aggluti- 

 nation which takes place in a perfectly clear plasma which is 

 originally devoid of any morphological constituents. 



1 Archiv Internat. de Phys. iv. 1906. 



