CHEMICAL ACTIONS: PROTOPLASM 



will one day be combined. The hypothesis of 

 Arrhenius is more satisfactory for the scientific 

 chemist. The theory of Ehrlich is founded upon a 

 sound atomistic basis, and has proved of great 

 heuristic value. 



When toxin and antitoxin solutions are mixed, 

 no change can be seen in the solution. With other 

 anti-bodies it is quite different. It was found 

 that the blood serum of animals which had been 

 injected with bacteria of typhoid fever or cholera 

 asiatica gave a strong precipitate with the limpid 

 filtrate from cultures of the same bacteria. Even 

 this effect is quite specific. Further, it was shown 

 by a series of experiments that similar results are 

 obtained by injection of different proteids into the 

 venous system of animals. The blood serum is 

 then able to precipitate the proteid which was 

 injected, and exclusively this proteid, from its 

 solutions. All these reactions were called Pre- 

 cipitin Reactions. They are in many respects 

 most interesting. In the first place, they show 

 that comparatively primitive protein-bodies cause 

 the same anti-reaction as enzymes or cytotoxins. 

 But only protein-bodies are known to give the 

 reaction, no other organic compounds. When the 

 proteid is decomposed by pepsin and hydrochloric 

 acid the precipitin reaction cannot be obtained 

 again. The simple amino-acids which are formed 

 from protein in digestion do not give the precipitin 

 reaction. But the reaction is also satisfactorily 



