CHANGES WROUGHT IN PATHOLOGY. 125 



charge, at another time an opposite charge, is evidenced 

 by a large number of facts. With this conception of 

 the role of amphoteric substances, LANDSTEINER has 

 made the first rational attempt to explain the specificity 

 of the immune substances. 



The chemistry of the colloids also allows us to 

 assume a freer position regarding the hypotheses 

 governing investigations in immunity. We can, how- 

 ever, touch upon this subject only briefly here, and 

 must limit ourselves to the question of toxins and anti- 

 toxins. 



Every one is familiar with the dominating influence 

 which those views have at present attained that EHRLICH 

 has developed under the name of the side chain theory, 

 views which have not, of course, remained without con- 

 tradiction. The opposition which this theory has encoun- 

 tered has evidenced itself silently in the fact that a number 

 of investigators have continued to work independently 

 and without using it, and audibly through the ex- 

 pressions of various authors, more particularly MAX 

 GRUBER, who delivered an address in Vienna several 

 years ago. 



As already stated, EHRLICH has, among others, utilized 

 the fact that the affinity of toxin for antitoxin and the 

 toxicity of toxin may vary independently of each other 

 to support the idea that two different groups, a hapto- 

 phore and a toxophore, exist in a toxin. These are 

 supposed to furnish the material substrate for the different 

 reactions of which one and the same substance is capable. 

 EHRLICH has at the same time distinguished between 

 different varieties of a toxin, originating in part from the 

 bacteria themselves, such as the toxones, and in part the 



