334 cook 



If the environments controlled the character-units and thus 

 moulded the characters of organisms we should expect to find 

 that each environment would have its own organisms, or that 

 all the individuals of the same species in the same environment 

 would be alike, or at least more alike than individuals from 

 different environments, but these results have not been attained. 

 Sexual and other analogous differences which have been de- 

 veloped among the members of the same species in the same 

 environments are vastly greater than any of the diversities 

 which differences of environments can cause or induce. More- 

 over, there are nowhere in nature any constant environments 

 which suppress or tend to extinguish the potential of adjustment. 

 Vicissitudes are ever at hand, ready to make selections in direc- 

 tions of adjustability. The highest types of organic life, those 

 which have been able to travel farthest on the evolutionary road, 

 are those which have responded most effectively to their oppor- 

 tunities for learning the arts of adjustment. Neither are these 

 responses mere passive mouldings ; the powers of individual ad- 

 justment, no less than the general adaptive characters of the 

 species have been attained by the putting forth of variations, the 

 steps by which species travel. 



Heredity, the name we have given to the mysterious power 

 of plants and animals to follow accurately the developmental 

 pathway of the species, and even to repeat the individual pecu- 

 liarities of the parents, is more similar to memory than to any 

 other biological phenomenon. Professor Lankester's concep- 

 tion of the facts implies that the hereditary memory is imposed 

 from without, that it is stamped or moulded upon the species by 

 the environment, and that its strength is, or should be, propor- 

 tional to the time during which the environmental impression is 

 continued. It is true that new or recent environmental reac- 

 tions, or direct adaptations, are not inherited, and do not replace 

 the older responsive characters of the species, but this fact lends 

 no support to the doctrine of environmentally moulded heredity, 

 for other character-modifications do appear suddenly, and do 

 immediately and definitely replace the earlier type of the 

 species, as shown in numerous and well established instances 

 of genetic variation and mutation. These modifications of 



