130 THE FITNESS OF THE ENVIRONMENT 



of adsorption in biology is not to be briefly 

 presented, but it may be found in almost 

 endless profusion in such works as those of 

 Freundlich and Bechhold. 1 



It must not be supposed that the phenomena 

 of adsorption in biology are simple and exactly 

 understood. What is certain is that they 

 are universal, and that surface tension lies 

 at the root of the matter. This is because 

 all living things are colloidal, and I am in- 

 clined to think that most physiologists will 

 admit that life without colloids is probably 

 unthinkable, even in a world very differently 

 constituted from our own. Colloidal struc- 

 tures are, in fact, the first and greatest factors 

 in physical complexity of organization, and 

 the principal force, unless it be in exceptional 

 cases an electrical charge due to ions, which 

 operates upon the colloidal structures is sur- 

 face tension. This, then, is another striking 

 fitness of water above all other things. 



Such are the facts which I have been able 

 to discover regarding the fitness of water for 

 the organism. The following properties ap- 

 pear to be extraordinarily, often uniquely, 



1 Freundlich, " Kapillarchemie." Leipzig, 1909. Bech- 

 hold, "Die Kolloide in Biologie und Medizin." Dresden, 

 1911. 



