THE COAGULATION OF THE BLOOD 73 



body, but only in certain proportions. Pekelharing considers 

 that its action depends upon hindering the formation of pro- 

 ferment, i.e. kinase, from the corpuscles of blood, but this is 

 improbable, since in hirudin-blood all the corpuscles are par- 

 ticularly well preserved, and on cooling the plasma no 

 separation of any granular precipitate can be noticed. The 

 differences between hirudin-, peptone-, oxalate-, and fluoride- 

 plasma can be seen in the following table, from which it may 

 be concluded that in the case of hirudin this substance does 

 not remove lime nor neutralise any kinase : 



Hirudin, therefore, exerts its effects by neutralisation of any 

 thrombin which may appear. Fuld and Spiro have also shown 

 that no neutralisation-ratio exists between thrombo-kinase and 

 hirudin. Schittenhelm and Bodong do not hold this view, since 

 a solution of fibrinogen containing calcium salts is not prevented 

 from clotting by hirudin, and in the case of hirudin-blood the 

 action is set aside by a definite amount of thrombo-kinase. These 

 authors also draw attention to the fact that a suspension of 

 blood-platelets, which after a time spontaneously gelatinises, 

 does not pass into this state when hirudin is present. Hirudin- 

 blood has also been shown to be markedly resistant to putre- 

 factive change, possibly owing to the liberation of alexines from 

 the leucocytes. 



Among snake-poisons, the anti-coagulant effect of cobra- 

 virus is set aside by the anti-venom prepared by Calmette, 

 and Morawitz has shown that the action of the venom is 

 dependent on the existence of an anti-kinase. 



1 Depends on the amount of thrombin produced in relation to amount of 

 hirudin present. 



