viii THE FUNCTIONS OF THE BODY 157 



changes occurring in a specific colloid substratum which 

 is itself a product of such changes and which influences 

 their course and character and is altered by them.' 



/ 



Child writes : 



" The fundamental constituents of protoplasm occur in what is 

 known as the colloid condition ; i.e. they do not form a true mole- 

 ciilar solution, but exist as suspended particles larger than mole- 

 cules in the fluid medium, which in the case of protoplasm is water. 

 Living protoplasm may range in its physical condition from a 

 semi-fluid to a stiff jelly-like substance according to the aggregate 

 condition of its particles. This mixture of substances, protoplasm, 

 is the visible substratum of the living form, and in it the changes 

 which constitute life occur." 



We believe that the reality of the organism is not 

 exhausted by regarding it as a physico-chemical system, 

 that it is also a psycho-physical system. 



