9<> PHYSICAL CHEMISTRY IN MEDICINE. 



on the other, which are inherent in the nature of such a 

 method itself. 



When we speak of the great analogy between changes 

 in state in organic colloids and life phenomena, we are 

 dealing, to use the words of MAXWELL, " with that 

 partial similarity between the laws of one series of phe- 

 nomena and those of another, in consequence of which 

 the one comes to illustrate the other. " Besides a limited 

 identity, extensive differences may therefore exist, many 

 of which are still beyond our understanding. This holds 

 also for the great differences known to exist in the toxicity 

 of ions in animal experiments. We are at present still 

 much inclined to attribute, qualitatively at least, great 

 importance to the value of animal experiments for settling 

 such a question as the one before us. This we do un- 

 justly, I believe. Clinical therapeutic experience must be 

 gotten by itself. The animal experiment brings in this 

 case also only an analogy; at the best it serves only to 

 stimulate further work. 



5. On the Relation between Physico-chemical Properties 

 and Medicinal Effects.* 



IN the consideration of questions in pharmacody- 

 namics, from the point of view of physical chemistry, a 

 scarcely measurable field lies before us, into only a small 

 part of which, however, paths lead at present. If under 

 these conditions I attempt to speak before a body of 

 clinical men on some questions which belong in this 

 realm and which have interested me for several years, I 



* From Verhandlungen des XXI. Congresses fiir innere Medicin 

 in Leipzig, 1904, 



