DIVERGENCE NOT ALWAYS ADVANTAGEOUS. 2G, 
the snails he has found in similar stations not far distant; but what is 
his surprise to find only different species, all allied to, but quite dis- 
tinct from, those he has previously known! ‘Twenty miles from the 
first valley he renews his investigations, finding the forms of all the 
different groups still more divergent, though all the conditions of the 
environment are, so far as he can observe, the same. 
He finally perceives that he must give up the theory that the cause 
of this divergence is exposure to different environments. 
(3) When the environment is the same in two districts occupied by 
allied species or varveties, it 1s evident that the differences that distinguish 
the latter can not be advantageous, even though their differences include 
strongly contrasted habits. For in order that these differences should 
be advantageous, it is necessary not only that they should relate to 
the performance of vital functions, and, therefore, be differences of 
adaptation, but it is necessary that these differences of adaptation 
should relate to differences in the environment, so that the forms 
would be at some disadvantage if they should exchange districts. 
Advantageous differences are always adaptational; but adaptational 
differences are not always advantageous, and in such cases the diver- 
gence can not be primarily attributed to diversity in the action of 
natural selection in the different districts. Under the protection of 
isolation, diversity of selection may arise which helps in producing 
divergence; but when the environments are the same, the divergence 
is in no sense advantageous; for, if a given combination of characters 
is an advantage in one district, so would it also be in the other dis- 
trict, and the difference or divergence is no advantage. 
A familiar example will perhaps put the distinction between the 
causes of survival and transformation and the causes of divergent sur- 
vival and transformation in a clearer light. The forms of language 
are growths that are governed by the laws of utility as fully as the 
forms of varieties and species. Each language and each part of a 
language exists and persists only asitisfound to beofuse. The ‘‘sur- 
vival of the fittest’’ is alaw that is perhaps as conspicuous in the 
domain of language as in the organic world. Again, every language, 
like every organic species, is in many respects determined by the 
environment. A language, for example, developed in Java will pre- 
sent names for many plants and animals that will not be represented 
in a language developed in Greenland. But, granting all this, does it 
follow that linguistic differences are necessarily advantageous? The 
Polynesian system of counting by fours, and the Eskimo system that 
proceeds by scores, are undoubtedly useful systems; but is there any- 
thing advantageous in the difference? I think not, for each system is 
