2 24 COCK 



as a theory, but the facts have refused to sustain it. Subsequent 

 efforts by Naegeli, Weismann, De Vries, and others to supple- 

 ment or supplant selection as an evolutionary cause have failed 

 to command general confidence, largely because they provided 

 no logical or adequate solution of the fitness problem, and 

 undertook to deny adaptation or to explain it away as a mere 

 coincidence. The best that could be done under the static 

 hypothesis was to suppose that if the new types happened to 

 differ from the old in characters of greater adaptive utility they 

 could survive, and, it might be, exterminate their parents. No 

 means not wholly hypothetical were suggested whereby the 

 environment could exert a definite influence upon the course of 

 evolution. 



The kinetic theory more than makes good these deficiencies. 

 It removes all need or temptation to minimize the extent of 

 adaptation or the obviously very important role of selection in 

 evolution. Though providing more generously than Darwinism 

 itself the materials for selection to work upon, it does not carry 

 us upon the dangerous ground of supposing that selection itself 

 is an evolutionary cause, or that evolution is limited to adaptive 

 characters. Darwinism assumed too much and explained too 

 little. It predicated an important causal relation where none 

 existed, and could still explain the evolution of adaptive char- 

 acters only. Kinetic evolution assumes less and explains more. 

 In recognizing the fact that the species are normally in motion 

 it allows for the development of useless as well as of useful 

 characters, and explains also how selection can contribute to 

 adaptive specialization. 



SUMMARY OF INFERENCES REGARDING FITNESS. 



The problem of fitness is a crucial defect in the doctrine of 

 evolution by selection, because in this theory selection does not 

 become effective until enough fitness has been obtained to give 

 a character selective value. The fact that organisms are often 

 able to adjust themselves to different environments has been 

 taken to prove that the environment causes variations of selective 

 value. Environmental selection of these adjustment characters 

 yielded the logically complete idea of an evolution initiated and 

 actuated by environment. 



