FERMENTATION 199 



rermin action is sufficient to produce coagulation 

 when added in the later stages. 



Evidently, in the clotting of milk by rennin 

 two separate phenomena must be distinguished: 

 (1) the chemical transformation of casein by 

 rennin, (2) the precipitation of the transformed 

 casein by the calcium chloride. (This salt favors 

 also the splitting of the casein.) Eennin may 

 therefore be classed with pepsin and trypsin. 



According to Hammarsten the casein is split 

 into phosphorus-free albumose and phosphorus- 

 holding paracasein. Heat is set free. It is the 

 paracasein which precipitates. It is less soluble 

 than casein. 



PRECIPITATION OF FIBRIN BY FIBRIN FERMENT 



Buchanan's Experiment. Press blood clot 

 through a linen cloth. Add the liquid thus ob- 

 tained to a serous fluid, which does not clot spon- 

 taneously, such as ascitic fluid, pleural effusion, 

 hydrocele fluid. 



After some hours a firm, translucent clot will 

 form. 1 



Extraction of Fibrin Ferment. Schmidt's Method. 

 Coagulate one part of serum from the blood 



1 Buchanan : London Medical Gazette, 1835, xviii, p. 51; 

 idem, 1845, xxxvi, p. 617. This discovery was first announced 

 in 1831. 



