THE ORIGIN OF ANTITOXIN THE SIDE-CHAIN THEORY 



organs rich in leucocytes, such as the spleen, lymph glands, and 

 bone-marrow. This view harmonizes well with that of Metch- 

 nikoff, which we shall consider subsequently. 



The chief arguments against the origin of antibodies from the 

 cells which are especially acted on are those of Metchnikoff on 

 the production of antispermotoxin, and from the study of other 

 cytotoxins. The first series of experiments are of fundamental 

 importance, and will be discussed here, although the substances in 

 question are not simple bodies like toxins, but have a much more 

 complex structure. The main facts are as follows : The injection 

 of spermatozoa into living animals is followed by the production 

 and appearance in the serum of certain substances which have 

 the power of immobilizing and clumping the spermatozoa of the 

 species from which the spermatozoa used for the injection was 

 taken ; we may call the substances spermotoxin. If the serum of 

 animals which has been prepared in this way is now injected into 

 animals of another species, the result will be the formation of an 

 antispermotoxin analogous with antitoxin, which inhibits the 

 action of the spermotoxic serum in vitro on the spermatozoa. 



Now on Ehrlich's theory we may assume that this anti- 

 spermotoxin is derived from the cells from which the spermotoxin 

 is derived i.e., from the spermatozoa. But Metchnikoff proved 

 that this is not the case, since the substance is developed as the 

 result of the injection of spermotoxic serum into castrated males 

 or into young animals of either sex. Antispermotoxins, therefore, 

 are not necessarily derived from sperm cells. This is certainly a 

 very striking result, and one that tells against the side-chain 

 theory, but it is not conclusive for this reason the cytotoxins are 

 not usually sharply specific. Thus a cytotoxic serum made by the 

 injection of kidney cells has a profound action on the kidney, but 

 it usually has some haemolytic action also, and may affect other 

 cells as well. There do not seem to be any experiments bearing 

 on the point, but it is at least probable that spermotoxins have 

 some action on cells other than spermatozoa, and if this is the 

 case Metchnikoff 's experiments, considered as a proof against the 

 side-chain theory, fall to the ground. 



The mode of formation of the antihaemolysins also calls for short 

 notice in this connection. The haemolysins are, in some cases at 

 least, more sharply specific than some of the cytotoxins, acting 

 apparently almost exclusively on the red blood-corpuscles. It 

 should follow on Ehrlich's theory that the antihaemolysins are 



