184 THE FITNESS OF THE ENVIRONMENT 



vidual chemical substance, that is to say ab- 

 stractly, but also naturally, as automatic 

 processes of cosmic and geological evolution 

 have fashioned it into the principal constit- 

 uent of the face of the globe. Primarily, 

 at any rate, the outcome of such processes is 

 dependent upon the inherent properties of 

 water and upon the quantity of it which is 

 present on the surface of the earth, and the 

 subject is too important to be passed com- 

 pletely by. 



Perhaps the first desideratum in an en- 

 vironment as a source of food is mobility. 

 Any organism which, like the lilies of the field, 

 need not toil for its nourishment, is in most 

 favorable conditions, and such conditions 

 are the principal cause of the enormous wealth 

 of vegetation upon the earth. Now the ocean, 

 apart from the flora and fauna which inhabit it, 

 is perfectly homogeneous ; hence its mobility 

 brings to an organism all that it has to offer, 

 and even sweeps along organic nourishment 

 as well. In the ocean not only plants but 

 many animals may remain motionless and, 

 like the oyster, await the food that will surely 

 be borne to them ; or they may float freely, 

 relying on the mixing of the water to bring 

 them into contact with their food. 



After mobility, richness and variety of 



