228 COOK 



Nature abounds in striking evidence of the alternative kinetic 

 view that species are normally in motion, and that the individual 

 organisms of which they are composed have a normal and 

 necessary intraspecific diversity, quite independent of environ- 

 mental influences. Moreover, there is reason to believe, from 

 the prevalence of sexual and other diversities inside the specific 

 lines, and from the degeneration which follows attempts at 

 maintaining a stable and uniform type, that diversity among 

 individuals of a species is not only universal and normal, but 

 necessary and advantageous. The prevalent doctrine that evo- 

 lution is caused or actuated by natural selection has been char- 

 acterized as a static theory because species are thought of as 

 normally at rest, that is, as stationary or constant in characters 

 and tending to be uniform as far as external conditions will 

 permit. The causes of variation and of evolution were sought 

 in the environment and not in the species itself. The problem 

 was to show how the external causes produce the internal effects, 

 but the task was hopeless from the beginning, for the variations 

 which the environment causes are not those through which 

 evolution goes forward. 



It is apparent, therefore, that the abandonment of the static 

 point of view, and the placing of a new interpretation upon a 

 large class of familiar facts calls for a new plan for the study 

 and discussion of the phenomena familiarly called variations, 

 in the older and looser sense of the term, meaning all the differ- 

 ences to be found among the individuals of a species. Differ- 

 ences not caused by environmental influences were, of course, 

 quite unconsidered in static theories and classifications. There 

 was not even a scientific term for this universal phenomenon of 

 intraspecific diversit}-. 



A complete treatment of the subject would involve the rear- 

 rangement of a large part of the data which have figured in the 

 evolutionary literature of the last half-century. The scope of 

 the present statement permits only a brief and imperfect outline. 

 It is not possible even to adequately describe and illustrate the 

 details of the facts of original observation to which reference is 

 made. Particular instances are not given, therefore, with any 

 idea that they are adequate to demonstrate the truth of the inter- 



