COLLECTED STUDIES IN IMMUNITY. 



an immune body derived from a particular species is most surely 

 activated by the serum derived from the same species. From the 

 standpoint of Bordet's theory it would be most puzzling to under- 

 stand why an anthrax immune body derived from a sheep should 

 sensitize the bacilli against just the sheep alexin, one derived from a 

 rabbit against just the rabbit alexin. From the standpoint of the 

 amboceptor theory, however, such a phenomenon does not offer the 

 least difficulty, since it is natural that the amboceptors circulating 

 in every animal species are fitted to their own complements. 



I wish to mention still one more point which plays a great role 

 in Bordet's views. Bordet assumes that the alexin is a simple [ein- 

 heitlich] substance, whereas I maintain that there is a plurality of 

 complements. Some very interesting experiments have recently 

 been published by Bordet which appeared to support the Unitarian 

 view. 



He first determined that a certain serum, e.g. guinea-pig serum, 

 was able to activate two different immune bodies, e.g., a cholera- 

 immune body and a haemolytic immune body. To this guinea-pig 

 serum Bordet added sensitized blood-cells, i.e., blood-cells eager 

 to take up, and susceptible to complement. If now he waited until 

 haemolysis had begun, he found that the guinea-pig serum had lost 

 its property to dissolve sensitized cholera vibrios. The same thing 

 occurred if he reversed the experiment. 



Although it was easy to confirm the experiment of this distin- 

 guished investigator, I found it impossible to accept Bordet's con- 

 clusions. This experiment is only then positive proof for a simple 

 alexin (in this case for the identity of bacteriolytic and hsemolytic 

 alexin) if it can be shown that the two immune bodies in question 

 are acted on by only a single complementophile group and not by a 

 plurality of such groups. Previous investigations, however, have 

 shown that the immune sera artificially produced are not simple 

 in character but are made up of a number of different amboceptors 

 possessing different complementophile groups. 



Nevertheless I consider Bordet's experiments so important that I 

 have once more had this question thoroughly studied by Dr. Sachs 

 and Dr. Morgenroth. These gentlemen were able to establish 

 positive proof for the existence of different complements. Dr. 

 Sachs, for instance, studied these conditions in goat serum, employ- 

 ing for the purpose five different combinations of immune body, 

 each of which could be complemented by goat serum. If goat serum 



