THE COAGULATION OF THE BLOOD. 

 SUPPLEMENTARY NOTE. 



SINCE the paper with the above title was written for 

 the January number of this volume, an important 

 paper on the subject by L. Lilienfeld 1 has appeared. The 

 paper is a long one, as it includes a historical account of 

 this vexed question, and also contains in full the experi- 

 ments on which the author has based several previous 

 preliminary communications. The main argument may be 

 stated as follows : The active agent in coagulation is re- 

 garded as a nucleo-albuminous substance which is called 

 nucleo - histon. It is considered to originate from the 

 leucocytes, especially from their nuclei and from platelets. 

 The nuclein of the nucleo-histon hastens, while the histon 

 moiety hinders coagulation ; the separation into nuclein 

 and histon may be effected by lime water or barvta water. 

 Nuclein alone, and calcium chloride alone, do not cause 

 coagulation in solutions of Hammarsten's fibrinogen ; but 

 if acetic acid is added to a solution of fibrinogen, a sub- 

 stance is precipitated therefrom which is coagulated by 

 nuclein with calcium salts, or by calcium salts alone. This 

 substance is termed thrombosin ; and fibrin is regarded as 

 a calcium compound of thrombosin. The constituent of 

 fibrinogen, which remains in solution when thrombosin is 

 precipitated by acetic acid, „ is like peptone in some of its 

 properties, particularly in its hindering influence on coagula- 

 tion. Nuclein, or rather nucleic acid, acts just like acetic 

 acid in precipitating free thrombosin from fibrinogen (not 

 a nucleic acid compound of thrombosin). This is stated to 

 hold good both for intravascular and extravascular blood ; 

 nucleic acid first splits up the fibrinogen molecule, and 

 then one of its components, thrombosin, unites with a 

 calcium salt to form fibrin. The fibrin-ferment is described 

 as a globulin, which is a product, and not the cause of 

 coagulation. 



1 Zeit. Physiol. Chem., vol. xx., pp. 89-163, 1894. 



