134 PHYSICAL CHEMISTRY IN MEDICINE. 



what I intended to offer in the line of experimental 

 facts. 



If I have succeeded, as I hope, in convincing you also 

 that the application of colloidal chemistry to physiology 

 and pathology justifies great expectations, it might be well, 

 in conclusion, to seek in the development and the present 

 state of the colloid problem a measure for our faith in 

 its future contributions. 



As is well known, the difference between crystalloids 

 and colloids appeared to be so radical a one to GRAHAM 

 that to characterize it he wrote the following oft- quoted 

 sentence : 



" The difference between these two kinds of matter is 

 like that which exists between the material found in a 

 mineral and that found in an organized mass." 



The discoverer of the colloidal world has since been 

 reproached, and certainly unjustly, for having so strongly 

 emphasized the differences between crystalloids and col- 

 loids. For every discovery depends primarily upon a 

 recognition of the most apparent differences between the 

 new phenomenon and the facts well known at the time. 

 This contrast is the most powerful stimulus to investi- 

 gation. It is the source of the problem, which is not 

 solved until the apparent contradictions to it have been 

 set aside and those fine threads have been unravelled 

 which connect the newly found with the old. Our prob- 

 lem also developed in this way, and we have seen how 

 the connection between colloids and crystalloids was 

 established through a recognition of their principal 

 characteristics and their gradations. One is almost 

 inclined to believe that the possibility of explaining 



