62 



Scientific Proceedings (56). 



these plays the more important role in keeping blood in a fluid 

 state cannot as yet be definitely decided. It seems to follow from 

 the results stated above that if hirudin is used in sufficient quantity 

 to prevent platelet disintegration entirely, the antithrombin action 

 will not come into play at all. 



Concerning the physico-chemical mechanism of platelet dis- 

 integration, we can as yet say nothing definite. Ca ions seem to 

 be essential, and on that basis the effect of calcium precipitants 

 (oxalates and fluorides) can be explained. Whether citrate de- 

 creases the ionization of Ca sufficiently to make the remaining 

 Ca ions negligible has, I believe, never been determined quantita- 

 tively. Mn salts do not affect the calcium, but act directly on 

 the platelets, and the possibility suggests itself that the action 

 of citrates may be of the same kind. Gessard 1 reports data which 

 show an antagonism between Ca and Mn ions, i. e., within certain 

 limits additional calcium may overcome the anticoagulant effect 

 of Mn. Regarding the mode of action of hirudin and salts used 

 in "salted plasmas," nothing at all can be said. 



To decide the question whether the platelet preservatives 

 antagonize the disturbing action of calcium on colloidal equilibrium 

 of the lipoids of the cell membrane (i. e., surface layer) as recently 

 suggested by Clowes 2 and West for citrate, would require further 

 experiments. 



The suggestion of Buerker that clotting is the immediate con- 

 sequence of platelet disintegration acquires new interest in the 

 light of the experiments with clay filters. It will be noticed 

 that the material to which the name prothrombin has been given 

 closely coi responds in properties to intact platelets. In that case 

 thrombin would be equivalent to disintegrated platelets; throm- 

 bokinase would be any substance (CaCl2, tissue juices) which 

 accelerates the disintegration of platelets. 



From the above data, it appears clearly that the condition 

 of platelets is of the greatest importance in coagulation. We 

 cannot say that preserving the platelets intact is the only means 

 of keeping blood in a fluid condition, but it does seem that in 

 every case where blood remains uncoagulated, the platelets are 



1 Compt. Rend., 153, 1241 (1911). 



s Proc. Soc. Exp. Biol, and Med., XI, 6, 1913. 



