A GENERAL REVIEW OF THE RECENT WORK IN IMMUNITY. 579 



and antitoxin by means of an ingenious method. But even here we 

 are not dealing with a reversible reaction, for it requires certain 

 manipulations to disrupt the neutral combination; thus, in the case 

 of cobra venom, the addition of hydrochloric acid is necessary. The 

 neutral cobra-venom-antitoxin combination therefore behaves like a 

 glucoside, which in itself is entirely stable, but is split up by the addi- 

 tion of hydrochloric acid. 



Besides this, the interesting investigations recently published by I 

 Obermayer and Pick, 1 on the production of immune precipitins by 

 means of chemically altered albuminous bodies, are of particular sig- 

 nificance in connection with the chemical conception of the immunity 

 reaction. These authors succeeded, by iodizing, nitrifying, and 

 diazotizing animal albuminous bodies, in so changing them that, 

 when introduced into the organism of the same or of different species, 

 they excited the production of precipitins which lacked specificity. 

 These precipitins, however, were strictly specific for their respective 

 iodized albumins, xanthoproteids, or diazo-albumins, no matter from 

 what animal species the albumins were derived. 



We see, therefore, that the introduction of a certain chemical group 

 into the albumin molecule completely alters the latter's power to 

 excite the production of antibodies. This certainly corresponds 

 entirely to the view that the production of antibodies is dependent 

 on the chemical constitution of the exciting agent, a view which finds 

 expression in my receptor theory. 



The heuristic value of the receptor idea, the idea which underlies 

 my side-chain theory, can best be appreciated by studying the devel- 

 opment of our knowledge concerning the cytotoxins of blotfd serum. 

 As a prototype of these substances the hffimolysins occupy a promi- 

 nent place in this volume. The view that the hsemolytic immune 

 bodies are amboceptors has been proven to be correct in every case, 

 thus conclusively showing that Bordet's sensitization theory is un- 

 tenable. To begin, the observations of M. Neisser and Wechsberg, 

 that the action of bactericidal sera depends not only on the absolute 

 but on the relative concentration of amboceptor and complement, 

 presented conditions which could not- be harmonized with Bordet's 

 view r s. On the other hand, they were readily explained in accord- 

 ance with the side-chain theory by assuming that the complement 

 was deflected by an excess of amboceptor. But even if this expla- 



1 Centralbl. f. Physiologie, Vol. XIX, No. 23. 



