CHEMICAL CONSTITUTION' AND PHARMACOLOGICAL ACTION. 429 



for example, with phenacetin, in which by the introduction of the 

 methyl radical and of the acetyl group the powerful OH and NH 2 

 groups of paramidophenol are occupied. 



All this has led me to conclude positively that Low's theory of 

 the substituting action of therapeutic substances is untenable. 



By this I do not in the least wish to say that groups capable of 

 reacting, such as Low presupposes to exist in the living protoplasms, 

 cannot occur there. It must be borne in mind, however, that 

 condensation phenomena are not produced merely by the presence 

 of two substances capable of condensing, but that the combining 

 affinity must usually first be increased through appropriate means, 

 such as increase of temperature, the addition of substances abstract- 

 ing water, etc. Even in the practice of the synthetic chemist, who 

 allows the substances to act on one another either directly or in con- 

 centrated solutions, such direct condensations are not especially fre- 

 quent. The number of these, however, is still more limited if the 

 synthesis is to occur under conditions corresponding to those in the 

 living organism, i.e. in dilute solutions, at low temperature and in 

 the absence of suitable auxiliary substances. Dimethylamidoben- 

 zaldehyde unites with indol, for example, even in dilute solutions, 

 at room temperature, forming a red dye, but only when the solution 

 contains small amounts of f ee mineral acid. If this is absent, or if 

 the solution is even faintly alkaline, no combination of any kind 

 occurs. 



VI. 



These considerations lead at once to the view that in certain 

 cases apparently it still is possible to effect a substitution within the 

 organism by the introduction of chemical substances. In order to 

 accomplish such a synthesis the selection of suitable substances will 

 be prerequisite, and these substances must be of such a chemical 

 constitution that they can exert chemical influences of the most 

 powerful kind. I have made extensive experiments with many 

 hundreds of different combinations, and in all of these I have only 

 discovered one substance to which I am inclined to ascribe such 

 a substituting action on protoplasm. This substance, vinylamin, 

 discovered by Gabriel and described by him in a masterly manner, 

 is formed by abstracting bromine from bromethylamine by means of 

 potassium. 



