Appendix II. 323 



" I have made these remarks only to show that, if we are un- 

 able to account for the characteristic differences of our several 

 domestic breeds, which nevertheless are generally admitted to 

 have arisen through ordinary generation from one or a few 

 parent stocks, we ought not to lay too much stress on our 

 ignorance of the precise cause [i.e. whether natural selection 

 or some other cause] of the slight analogous differences between 

 true species. ... I fully admit that many structures are now 

 of no use to their possessors, and may never have been of 

 any use to their progenitors ; but this does not prove that 

 they were formed solely for beauty or variety. No doubt the 

 definite action of changed conditions, and the various causes 

 of modification, lately specified, have all produced an effect, 

 probably a great effect, independently of any advantage thus 



gained. It is scarcely possible to decide how much 



allowance ought to be made for such causes of change, as 

 the definite action of external conditions, so-called spontaneous 

 variations, and the complex laws of growth ; but, with these 

 important exceptions, we may conclude that the structure of 

 every living creature either now is, or formerly was, of some 

 direct or indirect use to its possessor \" 



Here again, if we remember how "important" these 

 " exceptions " are, I cannot understand any one doubting 

 Darwin's opinion to have been that a large proportional 

 number of specific characters are useless. For that it is 

 " species " which he here has mainly in his mind is evident 

 from what he says when again alluding to the subject in 

 his "Summary of the Chapter" — namely, "In many o'Csxx 

 cases [i.e. in cases where natural selection has not been 

 concerned] modifications are probably the direct result of 

 the laws of variation or of growth, independently of any 

 good having been thus gained." Now, not only do these 

 "laws" apply as much to species as they do to genera; 

 " but," the passage goes on to say, " even such structures 

 have often, we may feel assured, been subsequently taken 



• Descent of Man, pp. 159-60. 

 Y a 



