504 PATTEN— COOPERATION AS A FACTOR IN EVOLUTION. 



although one has had the same length of time for development, and 

 the same opportunities in the world at large, as the other. On the 

 other hand, the prevailing methods of cooperative action between the 

 plant kingdom and the animal kingdom are essential factors in the 

 evolution of life as a whole, and in the creation of the highest prod- 

 ducts of both kingdoms. Hence our estimates of values will vary 

 with our visual angle ; that is, according as we consider each method 

 or individual by itself, and as an end in itself, or as several different 

 methods, or individuals, acting together for a larger end. 



As the vertebrate has progressed farther in the same time and in 

 the same general surroundings than the plant, or than the starfish, 

 or the snail, it is well to inquire what are the basic methods of struc- 

 ture and organization on which this progress depends. 



In such an inquiry, we may confine our attention to the internal 

 structure of the individual organism, ignoring, for the time being, 

 its external environment ; for, in the main, the external environment 

 is a common factor, affecting all kinds of life in the same way ; any 

 special response of the individual to its environment is due to the 

 special structure and special internal life of that individual. 



The external environments, for example, of the dog and his 

 master, of father and son, of the bee and the flower, may be essen- 

 tially the same, but these environments will not affect all their resi- 

 dents in the same way. The things in them that cooperate with the 

 life of one may have no existence in the life of the other because the 

 inner structure and response of the one to the other is different. 



Thus while the initial source of our knowledge of living things 

 is external, as our knowledge of these things deepens, it tends to ex- 

 press itself more and more in terms of their inner mechanism of 

 response and in the cooperative action of their various internal parts. 



The older school of naturalists laid too much emphasis on the 

 external environment of the completed individual, and of necessity 

 ignored its complex inner mechanism of response to the outer 

 world, because that mechanism was inaccessible to them. The more 

 modern school of genetics lays too much stress on the beginning of 

 individual life, on the assumption, expressed or imphed, that at the 

 beginning of things, the solution of vital problems is simpler and 



