ON SPECIFIC THERAPEUTICS. 7 



sider to be of the greatest importance, and this 

 is further borne out by the fact that in spite of 

 the most strenuous endeavours we have been 

 unable to find any antigen of a known chemical 

 constitution. 



I believe that the absorption of antigen-like 

 substances by the body is a phenomenon 

 which bears a close resemblance to the assimi- 

 lation of nutritive substances. In the case of 

 the other poisonous substances we find more 

 simple phenomena as causes of localisation, but, 

 in my opinion, the powers which influence the 

 distribution of toxins and kindred substances, 

 belong to the domain of chemical synthesis. 

 There has been a tendency of late to bring the 

 colloid nature of immune substances into the 

 foreground, and thus the impression is conveyed 

 that the whole subject of these phenomena 

 might be explained on the ground of the sub- 

 stances being colloid. Against this view it 

 seems to me to be necessary to insist upon the 

 fact that colloid nature and chemical reactive 

 power do not exclude one another ; for colloids 

 possess, just as other substances do, certain 

 groupings of atoms which render them capable 

 of reactions of a synthetic nature. Thus, one 

 may introduce into certain aromatic nuclei of 



