CONCLUDING REMARKS. 435 



sion — which constitutes his most prominent factor, 

 really explains those variations, and imposes a definite 

 limit to them. 



If the theory that variations are due to Reversion ;* 

 that the improvements arising under domestication are 

 due to the reappearance of characters lost or reduced 

 under nature; and that the variations or increments of 

 development which are preserved and accumulated by 

 Natural Selection, under nature, are but the regain of 

 what was lost by the respective species, at some former 

 period ; be true, then Darwinism, and every theory of 

 Biology, of Psychology, and of Sociology, which is 

 based upon the assumption of the unlimited accumu- 

 lation of those slight increments of development, 

 known as Variations, must be false. 



But is the' theory of Reversion true ? 



* Of course, the positive features which are due to Reversion, and 

 which are essential to the integrity of a species, do not comprise patho- 

 logical characters where (for instance) inorganic, or foreign, or mis- 

 placed, organic processes of integration have effected a coalescence 

 with the normal forces of growth. Nor do they include the features 

 of local hypertrophy, or other monstrous growths. 



The perfect type, of any species, is not the sum of all the modifica- 

 tions of which all the characters of such species, are susceptible, but 

 it is the sum of all the positive characters of a species, as those charac- 

 ters are when fully and normally developed. These words, " fully and 

 normally," do not here beg the question as they would were the 

 theory dependent upon its mere agreement with the facts; for, we 

 have the crucial test of self-fertilization, or of close-interbreeding, by 

 which to determine what is normal and what abnormal. That which 

 is abnormal will ever manifest itself in the evil attendant upon self- 

 fertilization or close-interbreeding. 



There is one of the features of species, which may occasion doubt. 

 Reference is had to color. It is difficult, frequently, to tell what color, 



