382 CHEMISTRY OF THE PROTEIDS CHAP. 



to 56, or is precipitated by acetic acid, or is acted upon by the fibrin- 

 ferment. 



The process of fibrin formation is represented by Halliburton l in 

 the following tabular way : 



From the colourless corpuscles a nucleo- 

 proteid is shed out, called : 



In the plasma a proteid sub- Prothrombin. 



stance exists, called : By the action of calcium salts prothrom- 



Fibrinogen. bin is converted into fibrin-ferment, or 



Thrombin. 



I 



Thrombin acts on fibrinogen in such a way that two new substances are formed. 



I I 



One of these is unimportant, viz. The other is important, viz. 



a globulin (fibrino-globulin) which fibrin, which entangles the cor- 



remains in solution. Its amount is puscles, and so forms the clot, 

 very small. 



This fibrin - globulin has the same solubilities as have other 

 globulins, the same precipitation-limits for ammonium sulphate as has 

 fibrinogen, and a coagulation -temperature of 64. The percentage 

 composition of fibrinogen, fibrin, and fibrin -globulin is somewhat 

 different. Serum always contains fibrin-globulin. 



Lilienfield, 2 Frederikse, 3 Schmiedeberg 4 and Heubner 5 are of the 

 opinion that coagulation depends on a hydrolytic dissociation of 

 fibrinogen into fibrin and fibrin-globulin ; Hammarsten at one time 

 also believed in this view, but now he believes 6 that fibrinogen is com- 

 pletely changed into fibrin by the fibrin -ferment, but that only a 

 portion of the fibrin is precipitated, while the rest remains in solution. 

 All investigations into this matter are very difficult, as fibrin carries 

 down other albumins with it when it is being formed. According to 

 Hammarsten, 6 77 to 80 per cent of fibrinogen is converted into fibrin, 

 while Heubner gives lower figures. 



Kamsden, in a paper not yet published, states that fibrinogen- 

 solutions, free from fibrin-ferment, can be made to yield ' mechanical 

 surface aggregates' indistinguishable from typical fibrin, and that 



1 Halliburton, Handbook of Physiology, 1904, p. 414. 



2 L. Lilienfeld, Zeitschr. f. physiol. Ghem. 20. 89 (1894). 

 a J. J. Frederikse, ibid. 19. 143 (1894). 



4 0. Schmiedeberg, Arch. f. experiment. Pathol. und Pharmak. 39. 1 (1897). 



6 W. Heubner, ibid. 49. 229 (1903). 



6 0. Hammarsten, Zeitschr. f. physiol. Chem. 28. 98 (1899). 



