The Struggle for Existence 
existence, as many of the statements contained 
in recent books on evolution seem to us to be 
based upon a mistaken conception of this 
important factor. 
As usual, Darwin’s disciples have failed to 
improve upon the account he gave of the nature 
of the struggle for existence. This is set forth in 
Chapter III. of the Origin of Spectes. 
“The causes,” writes Darwin (new edition, 
p-. 83), ‘which check the natural tendency of 
each species to increase in number are most 
obscure. Look at the most vigorous species ; 
by as much as it swarms in numbers, by so much 
will it tend to increase still further. We know 
not exactly what the checks are even in a single 
instance.” This is perfectly true. Nevertheless 
elaborate theories of protective and warning 
colouration and mimicry have been built up on 
the tacit assumption that the checks to the multi- 
plication of all, or nearly all, species are the 
creatures which prey upon them. Possibly no 
Wallaceian asserts this in so many words, but it 
is a logical deduction from the excessive pro- 
minence each one gives to the various theories of 
animal colouration; for, if the chief foes of an 
organism are not the creatures which prey upon 
it, how can the particular shade and pattern of 
its coat be of such paramount importance to it? 
We shall endeavour to show that there are 
checks on the increase of a species far more 
347 
