^2,^ 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 ihat 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^, 



^ The degree in which variability is indefinite, or, on the contrary, 

 determinate, is a question which is not jet ripe for decision — nor even, 

 in my opinion, for dicussion. But I may here state the following general 

 principles with regard to it. 



(i) It is evident that up to some point or another variations must 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 genTal theory of 

 evolution, they must be such as are imposed by heredity, cou]iled with 

 the degree to which external conditions of life (and possibly also use- 

 inheritance) are capable, in given cases, of modifying congenital 



