ME. G, J. EOMANES OS PHYSIOLOaiCAL SELECTION. 373 



differ from other evolutionists in refusing to suppose that this 

 must invariably, or even generally, be the result of what I may 

 term adaptational causes, when these are producing small (^. e. 

 specific) morphological changes in any part of any organism. 

 Tet, as I have said, I doubt not that such has been the incidental 

 or indirect result of these causes in some minority of cases. But, 

 now, what does this amount to ? It amounts to nothing more 

 than a re-statement of the theory of physiological selection. It 

 merely suggests hypothetically the cause, or causes, of that parti- 

 cular variation in the reproductive system with which alone the 

 theory of physiological selection is concerned, and which, as a 

 matter of fact, however caused, is found to constitute the one 

 cardinal distinction between species and species. Therefore I 

 am really not concerned with what I deem the impossible task 

 of showing how far, or how often, natural selection, or any other 

 cause, may have induced this particular kind of variation in the 

 reproductive system by its operations on other parts of an 

 organism. Even if I were to go the full length that other evo- 

 lutionists have gone, and regard this primary specific distinction 

 as in all cases due to the secondary specific distinctions, still I 

 should not be vacating my theory of physiological selection ; I 

 should merely be limiting the possibilities of variation within 

 the reproductive system in what I now consider a wholly unjusti- 

 fiable manner. For, as previously stated, it appears to me much 

 the more rational view that the primary specific distinction is 

 likewise, as a rule, the primordial distinction, and that the cases 

 where it has been superinduced by the secondary distinctions 

 are comparatively few in number. 



Next, let it be observed that, even in these last-mentioned 

 cases — whether, as I believe, they are comparatively few or com- 

 paratively numerous — where the primary distinction has been 

 superinduced by the secondary, even in these cases my theory is 

 available to show why the two kinds of distinction are so generally 

 associated, or why it is that the primary distinction is so habitual 

 an accompaniment of the secondary distinctions, of whatever 

 kinds or degrees the latter may happen to be. For, according to 

 my theory, the reason of the association in these cases is that it 

 can only be those kinds and degrees of secondary distinction which 

 are able so to react on the reproductive system as to induce the 

 primary distinction that dsmefor this reason preserved, or allowed 

 to become developed as a new specific type. Whether as causes 

 or as effects, therefore, the secondary distinctions are dependent 



