562 Chapter XVII 



readiness with which the leucocytes react against all kinds of 

 poisons, microbial or other toxins, as well as against organic and 

 mineral poisons, such as the alkaloids and the arsenical combina- 

 tions. However, in spite of so many data which speak in favour 

 of the phagocytic origin of antitoxins, it has been impossible to 

 support this view by rigorous facts easy of interpretation, such as 

 those which science possesses in support of the phagocytic origin of 

 fixatives. 



The antitoxins have acquired a very great importance in the 

 artificial cure of toxo-infective diseases, the aim in these cases being 

 to paralyse the action of the toxins already produced by the micro- 

 organisms and absorbed by the diseased animal. But their function 

 is less in the protection against diseases where the object to be 

 obtained is a reaction against the micro-organisms before these 

 are able to inundate the animal with their toxic secretions. It is 

 for this reason that the immunity against toxins must, in the study of 

 immunity, occupy a less preponderant place than does the immunity 

 against micro-organisms. 



As the micro-organisms placed in the refractory animal ultimately 

 undergo a digestion by chemical substances elaborated by the phago- 

 cytes, so also the toxins undergo a chemical modification due to the 

 presence of substances in the production of which the living elements 

 of the animal play a large part. The direct action of antitoxins on the 

 toxins, so well demonstrated, especially by Ehrlich's investigations, 

 does not, however, exclude the intervention of living cells, which, 

 though sometimes not very manifest, is in other cases very marked. 



The reaction of the living elements against the microbial toxins 

 and their allies leads to the production, and even the over-production 

 of antitoxins. According to Ehrlich, these elements are the receptors, 

 or side-chains, which, to a certain extent, pre-exist in the cells 

 which are capable of elaborating the antitoxins. On entering into 

 combination with the toxin molecules, the side-chains, which are 

 indispensable for the nutrition of the cells, are reproduced in very 

 large numbers. After having saturated, so to speak, the productive 

 elements of the antitoxin, the superfluous side-chains escape from 

 the cell and pass into the plasmas of the body fluids. This theory 

 may be brought into harmony with the other theory, which maintains 

 that certain elements of the animal, capable of acting on the complex 

 molecules of microbial toxins and their allies, produce special soluble 

 [587] ferments, which digest the toxins whose introduction frequently 



