336 Darwin, and after Darwin. 
but depends upon the variations being supplied by 
some other means. For, it is said, all that natural 
selection does is to preserve the suitable variations 
after they have arisen. Natural selection does not 
cause these suitable variations; and therefore, it is 
argued, Darwin and his followers are profoundly 
mistaken in representing the principle as one which 
produces adaptations. Now, although this objection 
has been put forward by some of the most intelligent 
minds in our generation, it appears to me to betoken 
some extraordinary failure to appreciate the very 
essence of Darwinian doctrine. No doubt it is per- 
fectly true that natural selection does not produce 
variations of any kind, whether beneficial or other- 
wise. But if it be granted that variations of many 
kinds are occurring in every generation, and that 
natural selection is competent to preserve the more 
favourable among them, then it appears to me 
unquestionable that this principle of selection deserves 
to be regarded as, in the full sense of the word, a 
natural cause. The variations being expressly re- 
garded by the theory as more or less promiscuous}, 
1 The degree in which variability is indefinite, or, on the contrary, 
determinate, is a question which is not yet ripe for decision—nor even, 
in my opinion, for dicussion. But I may here state the following general 
principles with regard to it. 
(1) It is evident that up to some point or another variations mzest be 
pre-determined in definite lines. Men do not gather grapes from thorns, 
figs from thistles, nor even moss-roses from sweet-briars. In other words, 
“the nature of the organism” in all cases necessitates the limiting of 
variations within certain bounds. 
(2) But when the question is as to what these bounds may be, we can 
only answer in a general way that, according to the gencral theory of 
evolution, they must be such as are imposed by heredity, coupled with 
the degree to which external conditions of life (and possibly also use- 
inheritance) are capable, in given cases, of modifying congenital 
