Active Causes of Organic Evolution 199 



of special plants and animals by man in no way differs funda- 

 mentally from the selection of a special host-root by a sapro- 

 phytic fungus; or of a particular host tissue — e. g., roots of 

 the beech by the beechdrops (Epiphegus virginiana) — through 

 action of an invading parasite; or the concealment of one species 

 of animal by another that is more perfectly provided with 

 defensive apparatus; or the housing and rearing of aphides 

 by ants as a means of nourishment for the latter. 



The difference in degree here, though not in kind, is merely 

 due to man's more highly organized cogitic activities, as com- 

 pared with those even of the highest apes. To speak therefore 

 of artificial and natural selection as distinct lines of inquiry 

 simply obscures the advancing continuity of a great law, by 

 raising false barriers of nomenclature. 



Darwin in formulating and expanding the law of Selection 

 spoke of it as "the survival of the fittest." This expression 

 ''the fittest" has often been criticized or explained by succeeding 

 investigators. In the writer's estimate the expression "sur- 

 vival of the best adapted" would more exactly designate alike 

 the static and the dynamic ramifications of the law, in its 

 positive as in its negative phase. For selective survival is 

 very largely dependent on the sum total of environal action 

 and of proenvironal response. Organismal adaptation there- 

 fore is usually intimately bound up with selective survival. 



We would define the law thus: ''Continued organismal sur- 

 vival in an individual or in its progeny, due to the sum-total of 

 conditions possessed by such, imparting sufficient integrating or 

 resistant reaction to environal agents as to prevent disintegration 

 or death, while other organisms not so conditioned are extermin- 

 ated. " 



On its positive side the law may operate to effect one of two 

 results: (1) uniform continuity of existence, or (2) progressive 

 advance; both of which conduce to the survival of the individual 

 and of the species. On its negative side the law only effects 

 degeneration, and, if such be progressive, it effects ultimate 

 destructive elimination. The consideration of one example 

 of each of these may not be inappropriate here. 



