THE COAGULATION OF THE BLOOD 



6 7 



vascular clotting. Outside the body the morphological con- 

 stituents of the blood, and in particular the blood-platelets, yield 

 kinase when these are brought in contact with non-living matter. 

 The first phase of the coagulation process is thus initiated by 

 the co-operation of thrombogen, calcium ions, and kinase. 



BLOOD 



Plasma 



I 

 Thrombogen 



Calcium 



\ I 

 a-Thrombin 



Cells 



I 

 Thrombo-kinase 



,-->: • p i7> 



converts fibrinogen 

 into fibrin. 



Thrombin 

 Thrombogen 



SERUM 

 Metathrombin 



I by alkali 



^-Thrombin 



The following table shows the accepted constituents of 

 various plasmata on the suggested hypotheses of Morawitz, 

 Fuld, and Spiro : 



Of the substances concerned in the production of thrombin, 

 as described in the account just given, it would appear that very 

 definite knowledge as to the sources or nature of thrombo- 

 kinase and thrombogen in coagulable liquid does not exist. It 

 is possible that kinase corresponds entirely or in part to the 

 nucleo-proteid which apparently enters into the composition of 

 the blood-platelets. Fluids such as goose-plasma, fluoride- 

 plasma, or hirudin-plasma are devoid of kinase, while in oxalate 

 or peptone-plasma this is present. On cooling these plasmata 

 a granular precipitate occurs only in those which possess kinase, 

 and this deposit is recognised in part to be nucleo-protein. 

 As to the source or sources of thrombogen in blood there is 



