334 JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES VOL. 11, NO. 14 



probably enter cells because they are more or less lipoid-soluble, for 

 example, mercuric chloride, cadmium chloride and copper chloride. 

 Perhaps for that reason they are so very toxic and antiseptic. 



Perhaps the best summing up of the relative importance of chemical 

 and physical factors in determining the action of toxic agents has been 

 given by Barger and Dale in one of their papers upon the active 

 principles of the ergot of rye: "but it by no means follows that the 

 peculiar distribution of the action of nicotine or of the sympatho- 

 mimetic amines depends on the existence of specific chemical re- 

 ceptors in the cells primarily sensitive to them, as supposed by Langley. 

 Stimulation may be a chemical process but the fact that certain cells 

 are preferentially stimulated by a certain group of substances such as 

 our amines may mean that in those cells these substances readily reach 

 the site of action; a supposition which is in accord with the view 



advanced by Straub." "On the whole then the least unsatisfactory 



view in the present state of knowledge seems to us to be that which 

 regards the existence of stimulant activities as dependent on the 

 possession of some chemical property, the distribution, and, in the 

 main, the intensity of the activity as due to a physical property. "^^ 



This thought will help us to understand the reasoning that is used 

 in the production of synthetic drugs, that is, the science known as 

 chemo- therapy. Chemo-therapy is the name given to that phase of 

 pharmacology which deals with the production of drugs for special 

 and specific purposes. Sometimes its aim is defined more narrowly 

 as the search for chemical agents that will cure infectious diseases, 

 that is, agents that will act as internal disinfectants for the diseased 

 body. Since such substances are usually more or less poisonous for 

 the body cells as well as for the parasite, much of chemo-therapeutic 

 research aims to so modify the molecular structure of the toxic sub- 

 stance as to render it appreciably more toxic to the parasite than to 

 the body cells of the host." 



We can then divide the aims of investigators in the field of chemo- 

 therapy into two groups ; those that endeavor to influence the physical 

 properties of drugs and therefore their intensity and place of action 

 in the organisms, and those that endeavor to influence the chemical 



attribute to the lipoid only a part of the observed phenomena. Schulemann, for example, 

 attributes a large role to phagocytosis, a phenomenon undoubtedly largely dependent 

 upon surface tension effects. 



3" Cf. also W. Schulemann, op. cit. 



3' G. GiEMSA, op. cit. p. 190-191. 



