4 EXPERIMENTAL RESEARCHES 



tution and pharmacological action another and 

 important bond of union exists, which influences 

 the relations between the pharmaco-dynamic 

 agent and the substance on which it is intended 

 to act. This bond of union is the mode of 

 distribution, and represents the sum of the 

 peculiarities of the cells and tissues and of the 

 drug. In this we have to do with a principle 

 so obvious that it should at once be accepted as 

 an axiom, but even when accepted as an axiom 

 it is scarcely ever applied to the study of 

 practical questions. The reason for this, I 

 think, lies partly in a certain disinclination to 

 attempt to master the difficulties of the problem, 

 but mainly in the fact that, in view of the 

 triumphs of synthetic chemistry, per se, the 

 biological factor of the pharmaco-dynamic 

 action is somewhat lost sight of. I may 

 mention that from the beginning, as the result 

 of my studies on dyes, I have endeavoured to 

 point out the necessity of the study of localisa- 

 tion ; in a word, to give pharmacology an 

 aetiologically therapeutic tendency; regarding 

 the details of this I shall speak further in my 

 second lecture. Excepting the case of dyes, 

 which, by reason of their easily appreciable 

 properties allow their distribution in the organism 



