ASPECTS OF KINETIC EVOLUTION 275 



leaders and reformers of the specific organization. For special 

 agricultural purposes mutations are often extremely valuable, 

 but when the desire is for the general improvement of the 

 species or the race, the essentially degenerate nature of muta- 

 tions cannot be left out of account. 



The kinetic theory, if correct, shows that variations, to be of 

 evolutionary value, must take place in the species, or in full 

 contact with society, as it were, and not alone, or in disregard 

 of the condition, interests, and evolutionary direction of the 

 species at large. 



Mutations are physiological phenomena, just as evolution 

 itself is a physiological process ; they will undoubtedly be 

 found to have causes when we are able to appreciate them. 

 They may be thought of as functional reactions from the re- 

 striction of normal heterism and diversity of descent. This ab- 

 normal condition of inadequate symbasis renders the organism 

 unstable and it falls down, degenerates or mutates. 



Inbreeding is to be studied as a condition of existence, and 

 the manner in which the species reacts may be observed with 

 the same propriety as any more purely environmental problem. 

 Mutations may be abnormalities induced by abnormal conditions 

 of descent, but the reaction which produces them need not be 

 considered abnormal, since it is evidently the same tendency 

 which contributes to the maintenance of the normal heterism. 



Indeed, the mutations might restore the normal intraspecific 

 diversity if interbreeding were permitted, as in nature. The 

 very fact that mutations of plants so frequently tend toward 

 dioecism might be accepted as another evidence of their value 

 as a corrective of inbreeding and deficient heterism. 



Coffee mutations are often largely or completely unisexual, or 

 have greatly accentuated proterogyny or proterandry. A condi- 

 tion entirely analogous to a dioecious species could be obtained 

 by the crossing of such staminate and pistillate trees. Never- 

 theless, Professor De Vries has described and named such a 

 unisexual mutation as a new species, without regard to the tax- 

 onomic consequences of the application of this policy to sexually 

 differentiated higher animals. 



If similar results justify the predication of similar causes the 



