STUDIES, SCIENTIFIC AND SOCIAL 



Again, after referring to cleistogamic flowers and de- 

 graded parasitic animals, he says : — 



" We are ignorant of the exciting cause of the above 

 specified modifications; but if the unknown cause were 

 to act almost uniformly for a length of time, we may infer 

 that the result would be almost uniform ; and in this case 

 all the individuals of the species would be modified in the 

 same manner " {Origin, p. IV 5).-^ 



Now these passages, merely as stating a possibility or a 

 probability, appear to me to be wanting both as regards 

 logic and in the absence of any appeal to the actual facts 

 of variation. For the argument is, briefly, that the same 

 causes will always produce the same or closely similar 

 results. But this is only true when the same causes act 

 upon identical materials and under identical conditions. 

 Now the very foundation of the Darwinian theory is, that 

 the materials — the individuals of a species — are not 

 identical, but that they vary indefinitely and in many 

 directions even under closely similar conditions. How 

 then can any external or internal causes produce an 

 identical result — a definite new variation — in all the in- 

 dividuals of a species, born as they are of varying parents, 

 of different ages, and subject to ever fluctuating con- 

 ditions ? It seems to me, therefore, that the a priori 

 probabilities are all against Darwin's supposition. 



Now let us see how far the facts of variation give any 

 support to the theory of useless specific characters. If 

 there is one thing better established than another it is that 

 the individual variations which are constantly occurring 

 in all common species are indefinite in their character 

 and very unequal in their amount. Some species are 

 much more variable than others, and Darwin has shown 

 reasons for believing that any change of conditions induces 

 variability, but not that it causes definite variations. 

 The two things are radically distinct. So far as I am 

 aware, no evidence has been adduced of any special con- 



^ In my Darwinism, p. 141, I have stated my opinion that Darwin 

 did not believe in the production of useless characters in all the 

 individuals of a species. I had overlooked the passages quoted by 

 Mr. Romanes and given above, which certainly show that he did 

 believe it. 



