PROTEIN SENSITIZATION OR ANAPHYLAXIS 223 



they proposed to call it "anaphylactin." But ammonium 

 sulphate alters the chemical nature of proteins, and Armit 1 

 has shown that after precipitation with this reagent the 

 poisonous group in it cannot be extracted by the method 

 of Vaughan and Wheeler. It is probable therefore that 

 the "anaphylactin" of Gay and Adler contains the poisonous 

 group, but so combined that it is not set free either in vitro 

 or in vivo. 



Besredka has pointed out that in anaphylactic experiments 

 with milk the fluid should be boiled for about twenty 

 minutes, the injections should be made into the peritoneal 

 cavity, larger guinea-pigs of from 300 to 400 grams' weight 

 should be used, and a period of from sixteen to twenty 

 days allowed to elapse between the sensitizing and test 

 injections. When these conditions are complied with, an 

 exquisite sensitization with uniform results is secured. 

 Besredka was not able to sensitize guinea-pigs with milk 

 given by mouth or rectum. We have found rabbits, espe- 

 cially young ones, easily sensitized by either of these avenues. 

 In our work we have observed that hungry rabbits will 

 eat milk when mixed with other food and seldom are sensi- 

 tized, but when the milk is introduced into the stomach of 

 a fasting rabbit through a tube, or injected into the rectum, 

 the milk can soon be detected in the heart's blood, and the 

 animal becomes sensitized. Evidently when the milk is 

 taken normally into the stomach, it is digested; when 

 forcibly fed through a tube, it is in part, at least, absorbed 

 undigested. Like the blood, milk as between different 

 species of animals shows a strictly specific action. Animals 

 sensitized to woman's milk do not react when treated with 

 cows' milk, and vice versa. By this method we have iden- 

 tified the source of milk stains deposited on wood for 

 months. The evidence concerning the difference between 

 the proteins of the milk and those of the blood of the same 

 animal is somewhat conflicting. Besredka 2 found that 



1 Zeitsch. f. Immunitatsforschung, 1910, v. 703. 



2 Compt. rend. Soc. biol., Ixiv, 888; Ann. de 1' Institut Pasteur, 1909, xxiii. 



