ASPECTS OF KINETIC EVOLUTION 295 



The difficulties which attend the presentation of the kinetic 

 theory arise, no doubt, largely from this fact, that it breaks 

 with the Darwinian traditions and recants the whole doctrine 

 of selection as the actuating cause or principle of evolution. 

 It seeks for the laws and causes of evolution, not in the environ- 

 ment, nor in a "hereditary mechanism" of the organisms 

 themselves, but in the association of organisms into specific 

 groups of interbreeding individuals, which are the units of 

 evolutionary motion. The reader is therefore duly warned 

 that, unlike most of the suggestions made since the time of 

 Darwin, kinetic evolution does not come as an amendment to 

 natural selection. 



Those who may wish to experiment with the new method of 

 biological locomotion had best unload beforehand all their pre- 

 possessions regarding natural selection as an evolutionary cause. 

 This does not mean that selection is to be permanently aban- 

 doned, but it can be taken up later, and put to a much more 

 useful purpose than before. Indeed, the material analogy may 

 be carried a step further by saying that the supposed evolu- 

 tionary properties of selection have been due to an unsuspected 

 admixture of kinetic implications, the selection idea in itself 

 being quite inert, and incapable of actuating even a logical 

 conception of evolutionary motion. 



Theories which located the causes of evolution in natural 

 selection or other forms of environmental reactions have con- 

 sidered the species normally stationary until acted upon by the 

 external forces. Theories which located the causes inside the 

 organisms have thought of evolutionary motion as proceeding 

 in definite directions without regard to environmental influences, 

 except as they might work the extermination of types poorly 

 fitted to the conditions they happened to encounter. The kinetic 

 theory, in appreciating the fact that the evolutionary change 

 goes forward in a network of descent woven by the free inter- 

 breeding of the individual members of the specific group, 

 reaches the conception of a highly composite, indeterminate 

 motion carried along without any environmental causation, but 

 at the same time capable of being deflected through selective 

 influence into channels of adaptation. 

 Proc. Wash. Acad. Sci., January, 1907. 



