260 PROTEIN POISONS 



the refractory state in sensitized guinea-pigs by these 

 methods. He accomplishes a similar result by giving the 

 reinjection while the animal is deeply narcotized with either 

 ether or alcohol. He finds that in this state many animals 

 survive the reinjection made at any time and by any 

 method, and that after recovery they are completely, but 

 only temporarily, refractory. Of these methods he prefers 

 the rectal injection, or better still, the subcutaneous injec- 

 tion of a less than fatal dose. For the reinjection he prefers 

 the cerebral method. Since these investigations, made by 

 Besredka, are of the highest importance both theoretically 

 and practically, we must study them more in detail. They 

 are of theoretical importance because he holds that mixed 

 proteins contain not only sensitizing and toxic substances, 

 but also a vaccinating body and the last mentioned of 

 these he claims vaccinates sensitized animals, thus ren- 

 dering them immune to reinjections. This part of his 

 study he has carried out most thoroughly with milk, and 

 along this line we will follow him. Milk heated for fifteen 

 minutes at 120 still sensitizes and kills on reinjection, but 

 when heated for fifteen minutes at 130 it neither sensitizes 

 nor kills sensitized animals on reinjection, but does render 

 sensitized animals refractory to reinjections of milk heated 

 to only 120. From these results he concludes: (1) That 

 the sensitizing and toxic components of milk behave alike 

 under the influence of the temperatures mentioned. (2) That 

 the vaccinating component can be separated from the other 

 two. In other words, the milk heated to 130 vaccinates or 

 immunizes against anaphylaxis, while it can neither sensi- 

 tize fresh animals nor kill sensitized ones. In order to 

 determine the nature of the vaccinating substance he coag- 

 ulates the milk with Bulgarian lactoferment and separates 

 the coagulum from the whey by the centrifuge or by filtra- 

 tion through paper. The whey immunizes sensitized 

 animals, but is without toxic action. The whey is neutral- 

 ized with soda and the flocculent precipitate which forms 

 is separated from the supernatant fluid by decantation of 

 the latter, and then made into a gelatinous mixture with 



