124 PRESENT-DAY RATIONALISM 



indefinite variations, out of which natural selection takes 

 the best ; but, as already stated, naturalists are by no 

 means at one in adopting this view. The one I am 

 advocating in this book is Darwin's alternative to natural 

 selection, vz's., that variations do not occur until external 

 conditions have incited them to appear ; and that when 

 they do, it is in response to, and they are then con- 

 sequently correlated with, the environment ; in other 

 words, the organism becomes more and more adapted 

 to the environment, so that natural selection has 

 nothing to do. 



Darwin would seem to lay much more stress upon 

 the inherent, spontaneous powers of variation than upon 

 the environment as an inciting cause ; for he expresses 

 himself as inclined " to lay less weight on the direct 

 action of the surrounding conditions than on a tendency 

 to vary, due to causes of which we are ignorant." ^ We 

 shall see that he came to modify this view in 1876 in 

 favour of direct adaptation. 



I have always adhered to the opposite view, and 

 regarded the environment as by far the most important 

 "cause" of variation, in that it influences the organism, 

 which, by its inherent but latent power to vary, responds 

 to the external stimulus, and then varies accordingly. 



This view was very strongly insisted upon by Dr. 

 Aug. Weismann, who thus speaks: "A species is only 

 caused to change through the influence of changing 



or? 00 



external conditions of life, this change being in a fixed 

 direction, which entirely depends on the physical nature 

 of the varying organism, and is different in different 

 species, or even in the two sexes of the same species. 

 According to my view, transmutation by purely internal 



' Origin of Species, p. 107. Sixth edition, 1878, 



