ON SPECIFIC THERAPEUTICS. 63 



there would lie enclosed the exceedingly minute 

 disease-producing agents, these agents being in 

 general so small as hardly to be accurately 

 recognisable by the microscope, with the excep- 

 tion of the inclusions in trachoma, where the 

 parasites are clearly visible and bear the stamp 

 of something organised. We may safely as- 

 sume that in all these cases the specific localisa- 

 tion of the parasites in certain distinct kinds of 

 cells, points to the fact that in these cells, 

 notably the epithelium cells in small-pox and 

 trachoma, and the ganglion cells in rabies and 

 fowl pest, such specific auxiliary bodies for the 

 parasites are present, whilst in all the remaining 

 parts the micro-organisms would encounter con- 

 ditions of atrepsy. 



The atreptic immunity, which results as I 

 stated from certain substances not being at the 

 disposal of the parasites, seems to me to play 

 an important role in the study of tumours. 



I may even say, that I first formed the idea 

 of atrepsy as the result of numerous experi- 

 mental observations upon malignant mouse 

 tumours which are of cardinal interest for 

 modern cancer research. I believe that a 

 number of clinical and experimental facts in 

 this sphere of knowledge can only be explained 

 by this hypothesis. 



