CONCLUSIONS AND SUGGESTIONS 205 



and its adaptations are simply special features of this 

 relation. 



Evolution is not directly concerned with morpho- 

 logical characters, but with the physico-chemical con- 

 stitution of the reaction system, and so with the rate 

 and character of its reactions and the conditions under 

 which they occur. I have called attention elsewhere' 

 to the resemblance between the progress of evolution 

 and the progress of senescence and development in the 

 individual, and have suggested that evolution, like 

 senescence and other processes in nature, may be essen- 

 tially a change from a less stable to a more stable condi- 

 tion in the dynamic reaction system which constitutes 

 the organism. 



The significance of this dynamic conception of the 

 organism for various other biological problems will be 

 apparent without further discussion, and I believe it 

 may possess a certain significance for certain problems 

 of comparative psychology and sociology. It is at 

 least a matter of some interest to be able to trace the 

 fimdamental identity in individuation from the simple 

 unicellular organism to the highest plants in the one 

 direction and to conscious man in the other, and to show 

 that the growing tip of the plant and the brain of man 

 have something in common. Moreover, to find the 

 same principle of individuation in the egg and in the 

 adult organism and again in the single nerve cell and 

 its fiber is at least highly suggestive. The recognition 

 of the fact that individuation in the organism is a rela- 

 tion of dominance and subordination of parts removes 

 much of the difficulty in accounting for the high degree 



^ Child, Senescence and Rejuvenescence, 1915, pp. 144, i93j A^2r^S' 



