ON SPECIFIC THERAPEUTICS. 27 



behaves absolutely differently from these. It 

 is not unnecessary to lay special stress upon 

 this point, for repeated attempts have been 

 made recently by Michaelis and Rona to draw 

 a parallel between the process of lecithid-for- 

 mation and certain phenomena of colloid- 

 absorption ; however, the tertium comparationis 

 of such conclusions consists solely of analogies 

 of the most formal kind, and the above-sketched 

 important fundamental fact is absolutely un- 

 touched. The study of the lecithids from the 

 chemical point of view has shown that in them 

 we have a field in which the phenomena of 

 immunity and those of pure chemistry meet, 

 and the hope can therefore be cherished that 

 we may thus obtain a nearer insight into the 

 chemical peculiarities of antigens and anti- 

 bodies. Already the large mass of facts col- 

 lected shows how fruitful the investigation into 

 chemical structure, and the questions which 

 arise therefrom as to distribution, are for the 

 analysis of immune substances and their re- 

 actions. 



As to the biological factor in the formation of 

 antibodies, it has been shown, by the recent 

 investigations of Pfeiffer and Wassermann, that 

 a part of the process takes place in the obscure 



