GENERAL CHEMISTRY OF THE PROTEINS 9 



these groups on the surface or inside the molecule. At first 

 sight it appears that the second example is more complex than 

 the case of the colloidal metal ; but one must not overlook the 

 fact that the various groups which build up the complex com- 

 pound often retain their characteristic properties, and stamp 

 the whole molecule with their physico-chemical behaviour. 

 These properties of compounds of high molecular weight can 

 therefore, in favourable circumstances, throw light on many 

 general colloidal phenomena, as happens in many respects with 

 the proteins. Although we regard the colloid chemistry and 

 the physical chemistry of the proteins as inseparable, we must 

 at the same time emphasise every tendency to a relation between 

 their colloid chemistry and their structure. This connection 

 was the object of our own researches, and is one which will 

 undoubtedly be largely developed in the near future. 



