Inconsistencies of Utilitarianism. 131 



lated in different areas of the same environment, will be 

 necessarily subjected to the same influences from natural 

 selection, and will inevitably maintain the same characters 

 and, of course, the same habits. That he believes divergent 

 habits may arise, when the divergent groups are occupying 

 the same area^ and are prevented from crossing simply by the 

 divergence of habits, will be seen by the case of the varieties 

 of wolves mentioned on p. 105 and by some of the cases 

 mentioned on pp. 108 and 117; also by the statement, on 

 p. 119, that " When one portion of a terrestrial species takes 

 to a more arboreal or a more aquatic mode of life the change 

 of habits itself leads to the isolation of each portion," and by 

 a similar statement at the bottom of p. 145. That he believes 

 there can be no change either of habits or structure when 

 portions of the same species are isolated in different areas 

 under the same environment appears from the statement on 

 p. 149 that " If the average characters of the species are the 

 expression of its exact adaptation to its whole environment, 

 then, given a precisely similar environment, and the isolated 

 portion will inevitably be brought back to the same average of 

 characters." And this he maintains will be the case even " if 

 we admit that, when one portion of a species is separated 

 from the rest, there will necessarily be a slight difference in 

 the average character of the two portions." 



Does the difference in the Environment increase 

 icith each successive Mile ? 



If the divergences presented by the Sandwich-Island land- 

 molluscs are wholly due to exposure to different environments, 

 as Mr. Wallace argues on pages 147-150, then there must be 

 completely occult influences in the environment that vary pro- 

 gressively with each successive mile. This is so violent an 

 assumption that it throws doubt on any theory that requires 

 such support. Of all the suggestions made by Mr. Wallace 

 concerning possible and inevitable differences in the environ- 

 ments presented in the successive valleys, it seems to me not 

 one meets the requirements of the case or throws any light on 

 the subject. The one suggestion which is quite applicable 

 as an explanation is the one already quoted, that " the isolated 

 portion is at once in a different position as regards its own 

 kind." This is, I believe, a most potent difference, which (as 

 Mr. Wallace's language seems to indicate) is directly intro- 

 duced by isolation, and (adhering to the meaning usually 

 given to environment) is not at all due to difference in the 

 environments presented in the different areas. 



