44 CONTROLLED NATURAL SELECTION 



Fig. 1 is a pictorial representation of this 

 conception ; ~E V E 2 , E 3 , &c., are the factors 

 of the environment, shaded, to show their 

 serial nature ; the area enclosed by dark lines 

 is the environment of the species. Fig. 2 is 

 a simplified illustration. The environment of 



E.i. 



E.2. 



E.3. 



E.4. 



E.s. 

 E.e. 



FIG. 1. 



FIG. 2. 



a species can be classified into common and 

 specific. The common environment is shared 

 with other species (many animals breathe air 

 and drink water) ; its specific environment it 

 occupies, solus. 



If, as has been considered, structure means 



