432 COLLECTED STUDIES IN IMMUNITY. 



and propargylamin, which contains the acetylen group, 



C-H 



NH 2 



All of these substances were found to possess the evanescent 

 general symptoms together with an absence of permanent organic 

 injuries. Hence I believe that the chemical avidity of the double 

 and triple combinations is insufficient to effect substitutive reac- 

 tions with the protoplasm. I am strengthened in this view by the 



CH 



fact that prussic acid, which owing to its threefold combination ||| 



N 



can be classed with the most active substances known to chemistry, 

 is nevertheless not anchored in the animal body, as can be seen from 

 Geppert's findings already referred to. 



If we consider that substances which possess double or triple 

 bonds are usually much more poisonous than the corresponding 

 saturated combinations, 1 and if we bear the above considerations in 

 mind, we shall ascribe this increased toxicity not to a combining 

 capacity but to the fact that the unsaturated groups possess auxotoxic 

 properties, i.e., that they are able to increase the toxicity when they 

 enter into complexes which in themselves already possess certain 

 toxic properties. 



I must emphasize the fact that all observations thus far made 

 &re only to be applied to organic substances foreign to the body 

 We must, however, assume that all substances which enter into the 

 construction of the protoplasm are chemically fixed by the proto- 

 plasm. A distinction has always been made between substances 

 capable of assimilation, which serve the nutrition and enter into a 

 permanent combination with the protoplasm, and substances foreign 

 to the body. No one believes that quinine and similar substances 

 are assimilated, i.e., enter into the composition of the protoplasm. 

 The foodstuffs, however, are bound in the cell, and this union must 

 be regarded as a chemical one The sugar molecule cannot be ab 



1 Neurin is twenty times as toxic as cholin (trimethyiethylammonium 

 hydroxide); allylalcohol fifty times more toxic than propyl alcohol; ct also 

 Low, Natiirliches System der Giftwirkungen 1893, page 95. 



