CHAP. XVIII THE PROBLEM OF UTILITY 379 



by so many quotations from Darwin's works, is due to the 

 fact that Darwin was hrmly convinced of the heredity of 

 acquired characters, and especially of the influence of food 

 and climate and the effects of use and disuse ; and this 

 belief must be borne in mind whenever he speaks of 

 specific characters being due to other causes than natural 

 selection. It must also be remembered that Darwin was 

 not acquainted with the evidence we now possess as to the 

 extreme frequency of variation everywhere in nature, its 

 large amount, and its universality in every organ and every 

 character that can be measured or otherwise estimated. 

 Had he known what we now know on this subject, he 

 woTild not so frequently have made the proviso — " if they 

 vary, for without variation natural selection can do no- 

 thing," or have alluded to the possibility of variations of 

 the same kind occurring " perhaps after a long interval of 

 time." We now know that variations of almost every con- 

 ceivable kind occur, in all the more abundant species, in 

 every generation, and that the material for natural selec- 

 tion to work upon is never wanting. Accepting, then, 

 these facts of variation, and always keeping in mind the 

 severity of the struggle for existence, nine-tenths at least 

 of the progeny of the higher animals perishing annually 

 before reaching maturity, thus leading to a systematic and 

 continual weeding out of the less fit — let us endeavour to 

 realise the process of the formation of new species and the 

 nature of the characters which distinguish allied species 

 from each other. 



The Principle of Utility. 



In my article on " Mimicry and other Protective Resem- 

 blances among Animals," first published in 1867, I laid 

 down the principle of utility, perhaps a little too abso- 

 lutely, in the following passage : — " Perhaps no principle 

 has ever been announced so fertile in results as that which 

 Mr. Darwin so earnestly impresses upon us, and which is 

 indeed a necessary deduction from the theory of Natural 

 Selection, namely — that none of the definite facts of or- 

 ganic nature, no special organ, no characteristic form or 



