376 STUDIES, SCIENTIFIC AND SOCIAL chap. 



environment, instead of merely furnishing the material 

 which is required for that adaptation. In our view, the 

 fundamental laws of growth and development, through 

 the agency of rapid multiplication and constant variability, 

 provide the material on which natural selection acts, and 

 by means of which it is enabled to keep up the adaptation 

 to the environment (which alone renders continuous life 

 and reproduction possible) during the constant, though 

 slow changes, whether inorganic or organic, by which, 

 in the course of ages, the effective environment of each 

 species becomes more or less profoundly modified. Thus, 

 and thus alone, we believe, are new species produced in 



/ strict adaptation to the new environment. So far as 

 rendering possible and actually leading to growth, re- 

 production, and variation, the fundamental laws are 

 supreme. In securing the development of new forms in 

 adaptation to the new environment, natural selection is 



V supreme. Hence arises the real distinction — though we 

 may not always be able to distinguish them — between 

 specific and non-specific or developmental characters. 

 The former are those definite, though slight modifica- 

 tions, through which each new species actually became 

 adapted to its changed environment. They are, there- 

 fore, in their very nature, useful. The latter are due to 

 the laws which determine the growth and development 

 of the organism, and therefore they rarely coincide 

 exactly with the limits of a species. The more important 

 of these latter characters are common to much larger 

 groups, as families, orders, or classes, while others, de- 

 pending partly on complex and fluctuating influences, 

 are variable even within the limits of a species. Of 

 this last kind are the finger-prints, which, like many 

 other minute details of form or structure, vary from 

 individual to individual. 



I have now, I think, shown that the two most recent 

 efforts to establish new " methods of organic evolution " 

 as either complete or partial substitutes for natural selec- 

 tion — that is, for the survival of the fittest among the 

 individual variations annually produced — have completely 

 failed to establish themselves as having any relation to the 



