set up a kymograph and attach a few registering instruments can 

 claim to be a pharmacologist. Such an one will not travel far beyond 

 the region of mere routine, a region chiefly of pedagogical interest. 



Thoughtful pharmacologists have also made it the object of their 

 investigations to understand more fully the chemical and chemico- 

 molecular phenomena that underlie and accompany the coarser 

 changes to which reference has already been made. The principles of 

 physics and chemistry must furnish the pharmacologist with pro- 

 visional or permanent explanations of these phenomena. Like the 

 physicist, he is well aware, however, of the "futility of attempting an 

 ultimate explanation of natural phenomena," and fully recognizes the 

 limitations of his method. At present we make use of a hundred 

 terms which convey anything but a clear idea to the mind. Take so 

 old a drug as ethyl alcohol, for example, and endeavor to explain 

 why it is not a dynamogenic substance for muscle-tissue. We hide 

 behind such expressions as "protoplasm poison" and the like. We 

 know that alcohol is oxidized in the tissues and that liberation of 

 energy folloAvs, but a more careful study of the subject shows that 

 oxidizability and the liberation of energy are not alone the measure 

 of dynamogenic value. A closer study of the intermediate steps in 

 the oxidation and of the chemico-molecular processes which are in- 

 itiated by these products and by the alcohol itself will alone clear up 

 a problem of this sort. 



Knowledge of the "chemical architecture" and constitution of a 

 given drug often enables the pharmacologist to trace it in its passage 

 through the body, and in studying its chemical fate and final dis- 

 position, valuable facts bearing on the synthetic, oxidative, reductive, 

 or splitting powers of various tissues and organs have been brought 

 to light. In this way, too, intermediate products of metabolism are 

 discovered and glimpses of hidden chemical processes are obtained 

 which throw light on deep problems of pathology and clinical medi- 

 cine. The results of the study of the relation of chemical constitution 

 to physiological action as yet apply only to certain families of chem- 

 icals. They have not led to any principles of universal application. 

 Recently a clearer statement of the action of whole series of drugs 

 and poisons has been given in the language of physical chemistry. 

 Thus, this or that feature of the pharmacologic action of many acids 

 is in proportion to the concentration of their hydrogen ions and de- 

 pends to a lesser degree on the specific properties of their anions. The 

 toxic or disinfecting action of a series of dilute metal hydroxides stands 

 in relation to the concentration of the OH ions. The theory of electro- 



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