THEORIES OF IMMUNITY. 



Another point in favor of the chemical nature 

 of the reaction is brought forward by Ehrlich in 

 the case of the action of the red corpuscles and 

 the alkaloid (?) ricine. By injections of the latter 

 he was able to secure a resistance to it by the 

 red corpuscles of the animal injected, an anti- 

 ricine is formed, apparently of the same nature as 

 the antitoxine in diphtheria, and this serves to 

 protect the red corpuscles against a further 

 action of the ricine. j^ow, he says, if the union 

 is not of the nature of a chemical reaction, a 

 new physiological function must be ascribed to 

 the red-blood corpuscles, which are not usually 

 looked upon as anything but acting as carriers 

 of oxygen. This supposition, however, goes on 

 the ground that there never will be any new 

 function ascribed to them, which is of course 

 inadmissible. 



A great deal of experimental work has been 

 brought forward in support of Ehrlich's theory 

 of a purely chemical relationship between the 

 substances active in the various reactions, and 

 much also that has been interpreted as support- 



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