THE FACTORS OF ORGANIC EVOLUTION. 773 



Verification of the reasons above given for the paucity of this 

 direct evidence is yielded by contemplation of it, for it is observable 

 that the cases named are cases which, from one or other cause, have 

 thrust themselves on observation. They justify the suspicion that it 

 is not because such cases are rare that many of them cannot be cited, 

 but simply because they are mostly unobtrusive, and to be found only 

 by that deliberate search which nobody makes. I say nobody, but I 

 am wrong. Successful search has been made by one whose compe- 

 tence as an observer is beyond question, and whose testimony is less 

 liable than that of all others to any bias toward the conclusion that 

 such inheritance takes place. I refer to the author of the Origin of 

 Species, 



Now-a-days most naturalists are more Darwinian than Mr, Darwin 

 himself. I do not mean that their beliefs in organic evolution are 

 more decided ; though I shall be supposed to mean this by the mass 

 of readers, who identify Mr. Darwin's great contribution to the theory 

 of organic evolution, with the theory of organic evolution itself, and 

 even with the theory of evolution at large. But I mean that the par- 

 ticular factor which he first recognized as having played so immense a 

 part in organic evolution, has come to be regarded by his followers as 

 the sole factor^ though it was not so regarded by him. It is true that 

 he apparently rejected altogether the causal agencies alleged by ear- 

 lier inquirers. In the Historical Sketch prefixed to the later editions 

 of his Origin of Species (p. xiv, note), he writes : — "It is curious how 

 largely my grandfather. Dr. Erasmus Darwin, anticipated the views 

 and erroneous grounds of opinion of Lamarck in his ' Zoonomia ' (vol. 

 i, pp. 500-510), published in 1794." And since, among the views thus 

 referred to, was the view that changes of structure in organisms arise 

 by the inheritance of functionally - produced changes, Mr. Darwin 

 seems, by the above sentence, to have implied his disbelief in such in- 

 heritance. But he did not mean to imply this ; for his belief in it as 

 a cause of evolution, if not an important cause, is proved by many 

 passages in his works. In the first chapter of the Origin of Species 

 (p. 11 of the first edition), he says respecting the inherited effects of 

 habit, that " with animals the increased use or disuse of parts has had a 

 marked influence ; " and he gives as instances the changed relative 

 weights of the wing bones and leg bones of the wild duck and the 

 domestic duck, " the great and inherited development of the udders in 

 cows and goats," and the drooping cars of various domestic animals. 

 Here are other passages taken from the latest edition of the work. 



" I tliink there can be no doubt that use in our domestic animals has strength- 

 ened and enlarged certain parts, and disuse diminished them; and that such 

 modifications are inherited " (p. 108). [And on the following pages he gives five 

 further examples of such effects.] " Habit in producing constitutional peculiari- 

 ties and nse in strengthening and disuse in weakening and diminishing organs, 



