CONTRIBUTIONS TO THE STUDY OF IMMUNITY. 51 



toms may not, however, at once be ascribed to an absence of affinity 

 between cells and the poisonous substance. 



The formation of an antibody, according to the side-chain theory, 

 follows only from the binding of the haptophore group which excites 

 the immunity, to the corresponding side-chain, and hence is not 

 directly dependent on the toxophore group. 



As to which cells will be able to produce an antibody depends, 

 therefore, on the possession of a receptor for the haptophore group 

 in question. A highly toxic action of the substance bound by the 

 cell is not at all essential, and, is in fact, often injurious, as has been 

 emphasized especially by Knorr. 1 This action, as Ehrlich 2 has 

 shown in his experiments on toxoids, is produced by a molecular 

 group entirely distinct from the haptophore group and having no- 

 relation to the antitoxin. 



If this law applies even to the true toxins, we shall all the more 

 have to assume that it applies where compound substances, such as' 

 hsemolysin, epitheliotoxin, or spermotoxin are concerned. In these 

 the toxophore group is only loosely combined with the haptophore 

 group; it is nothing but the complement, which, according to my 

 researches, 3 can be bound by all kinds of cells, even independently 

 of the immune body, and can, under certain conditions of affinity, 

 be separated from the immune body. 



We see, therefore, that the assumption by Metchnikoff , that the 

 spermotoxin is related exclusively to the spermatozoa, is incorrect. 

 As against it I have here shown that a toxin obtained by immuniza- 

 tion with epithelial cells is able to destroy the red blood-cells in the 

 same manner as a true hsemolysin. 



In the following short communication I can bring forward an 

 additional instance in which the development of a hsemolytic immune 

 body results although the co-action of the red blood-cells is com- 

 pletely excluded. Even this demonstration proves that the assump- 

 tion on which Metchinkoff based his objections to the side-chain 

 theory is contrary to the facts. The phenomenon that even in 

 castrated rabbits an antispermotoxin is formed is therefore readily 

 explained according to the side-chain theory by assuming that re- 



1 Miinch. med. Wochenschr., 1898, Nos. 11 and 12. 



2 Klin. Jahrbuch, 1897, Vol. VI, and Deutsch. med. Wochenschr., 1898, 

 No. 38. 



3 See page 41. 



