PHYSICO-CHEMICAL PROPERTIES. 91 



can give many good reasons for doing so. As is evidenced 

 by the studies of H. MEYER and OVERTON on the theory 

 of narcosis, and by the work of STRAUB on the tenability 

 of the law of mass action for the distribution of certain 

 poisons in the organism, so our work, too, has clearly 

 shown that only the use of physico-chemical methods 

 renders possible a deeper understanding of medicinal 

 effects. To this there comes the well-founded feeling 

 that in this way explanations of the nature of the im- 

 portant phenomena accompanying constitutional changes 

 may also be obtained, a problem which has long been 

 a favorite one with the internal clinicist. 



This paper will be limited to a discussion of the r61e 

 of ions, those electrically charged dissociation products 

 of acids, bases, and salts which are produced when these 

 substances are dissolved in water. We know that the 

 mineral constituents of the body are, in the concentration 

 in which they are present, almost completely dissociated. 

 This is true also of the metallic and alkaloidal salts 

 which are introduced into the body for medicinal pur- 

 poses. Other pharmacologically active substances which 

 scarcely ionize on solution in water, such as the esters, 

 may be converted into ionizable compounds in the body. 

 Because of this many-sided importance of the omni- 

 present ions, it seemed of value first of all to get an 

 experimentally demonstrable conception of the mode of 

 action of the ions in the animal body. Of all the con- 

 stituents of the protoplasm, the proteins show the most 

 intimate relation to the salts. Their most varied changes 

 in state, such as solution, precipitation, and coagulation 

 through heat, are all connected with the cooperation of 

 salts, and it seemed necessary therefore to obtain first 



