THE PROTEIN MOLECULE 95 



that the circulating blood at all times contains 

 the protein poison from the too violent chemism 

 of which the body is normally protected by its 

 combination with an inert body is correct, it will 

 not be difficult to understand that the equilib- 

 rium may be disturbed in a variety of ways with 

 death as a result. The introduction of a little 

 more of the poison or the removal of the protect- 

 ing body may seriously upset the equilibrium. 

 Casein yields about ninety per cent of its 

 weight in protein poison. The calcium is easily 

 removed from casein. An ash-free casein may 

 be prepared by repeated solution in dilute am- 

 monia and reprecipitation with dilute acid. The 

 last trace of calcium is removed by treatment 

 with oxalic acid. The protein poison from 

 casein resembles the globulins inasmuch as it 

 may be wholly precipitated from aqueous solu- 

 tion by saturation with sodium chloride, but dif- 

 fers from globulins inasmuch as it is freely sol- 

 uble in absolute alcohol. 



Blood is rendered poisonous not only by in- 

 cubation with bacteria, agar, starch, kaolin, etc., 

 but as was shown by Kohler as long ago as 

 1877, it becomes poisonous on clotting, killing 

 both homologous and heterologous animals. 

 This phenomenon, which has been confirmed by 

 others, has recently been investigated by Mol- 



