THE ELEMENTS OF ORGANIC EVOLUTION. 85 
where. Possession and not abstract fitness has deter- 
mined the nature of the island faune, lake faune, and 
isolated faunz and flore generally. This is shown by 
the rapidity by which the species composing these be- 
come extinct when brought into competition with the 
more persistent forms which the continent has developed. 
But as all this represents a natural adjustment pro- 
duced by natural relations as distinguished from artifi- 
cial selection produced by the act of man, we may still 
include it under the head of natural selection. What- 
ever result is brought about in the struggle for exist- 
ence by the action of natural forces without human aid 
is natural selection in the sense in which Darwin used 
the term. 
The term “fitness” as used in these discussions 
means, of course, only the power to win in the peculiar 
kind of contest that may be in question, no moral ele- 
ment and no element of general progress being necessa- 
rily involved. 
In the question of fitness or unfitness the question 
of goodness or badness is only incidentally concerned. 
To be fit, in the biological sense, is not necessarily to 
be good, except as in the long run altruism promotes 
individual power and strength. 
The struggle for existence appears under a three- 
fold form: the struggle of creatures with like creatures, 
the struggle with unlike forms, and the struggle with 
the conditions of environment. In general, when the 
environment is most favourable, the competition of in- 
dividual with individual will be most severe. Where 
this environment is alike favourable for many different 
forms or species, the struggle between species and spe- 
cies becomes intensified. Where conditions are adverse, 
the number of forms able to maintain themselves will 
be smaller, but those which acquire adaptation, not 
