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 u 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 u 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 u 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. 
