DIFFICULTIES OF THE THEORY 163 



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 of the slight analogous differences between 

 true species. 



UTILITARIAN DOCTRINE, HOW FAR TRUE: BEAUTY, HOW ACQUIRED 



The foregoing remarks lead me to say a few words on the pro- 

 test lately made by some naturalists against the utilitarian doc- 

 trine that every detail of structure has been produced for the good 

 of its possessor. They believe that many structures have been 

 created for the sake of beauty, to delight man or the Creator (but 

 this latter point is beyond the scope of scientific discussion), or 

 for the sake of mere variety, a view already discussed. Such doc- 

 trines, if true, would be absolutely fatal to my theory. I fully admit 

 that many structures are now of no direct use to their possessors, 

 and many 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 modifications, lately specified, have all pro- 

 duced an effect, probably a great effect, independently of any ad- 

 vantage thus gained. But a still more important consideration is 

 that the chief part of the organization of every living creature is 

 due to inheritance ; and consequently, though each being assuredly 

 is well fitted for its place in nature, many structures have now no 

 very close and direct relation to present habits of life. Thus, we 

 can hardly believe that the webbed feet of the upland goose, or of 

 the frigate-bird, are of special use to these birds; we cannot be- 

 lieve that the similar bones in the arm of the monkey, in the fore 

 leg of the horse, in the wing of the bat, and in the flipper of the 

 seal, are of special use to these animals. We may safely attribute 

 these structures to inheritance. But webbed feet no doubt were as 

 useful to the progenitor of the upland goose and of the frigate- 

 bird, as they now are to the most aquatic of living birds. So we 

 may believe that the progenitor of the seal did not possess a flip- 

 per, but a foot with five toes fitted for walking or grasping; and 

 we may further venture to believe that the several bones in the 

 limbs of the monkey, horse and bat, were originally developed, on 

 the principle of utility, probably through the reduction of more 

 numerous bones in the fin of some ancient fish-like progenitor of 

 the whole class. It is scarcely possible to decide how much allow- 

 ance 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, 



