66 Darwin, and after Darwin. 



Now, rudimentary organs of this kind are of such 

 frequent occurrence, that almost every species presents 

 one or more of them usually, indeed, a considerable 

 number. How, then, are they to be accounted for ? 

 Of course the theory of descent with adaptive modifi- 

 cation has a simple answer to supply namely, that 

 when, from changed conditions of life, an organ which 

 was previously useful becomes useless, it will be suf- 

 fered to dwindle away in successive generations, under 

 the influence of certain natural causes which we shall 

 have to consider in future chapters. On the other 

 hand, the theory of special creation can only maintain 

 that these rudiments are formed for the sake of ad- 

 hering to an ideal type. Now, here again the former 

 theory appears to be triumphant over the latter ; for, 

 without waiting to dispute the wisdom of making 

 dwarfed and useless structures merely for the whim- 

 sical motive assigned, surely if such a method were 

 adopted in so many cases, we should expect that in 

 consistency it would be adopted in all cases. This 

 reasonable expectation, however, is far from being 

 realized. We have already seen that in numberless 

 cases, such as that of the fore-limbs of serpents, no 

 vestige of a rudiment is present. But the vacillating 

 policy in the matter of rudiments does not end here ; 

 for it is shown in a still more aggravated form where 

 within the limits of the same natural group of or- 

 ganisms a rudiment is sometimes present and some- 

 times absent. For instance, although in nearly all the 

 numerous species of snakes there are no vestiges of 

 limbs, in the Python we find very tiny rudiments of the 

 hind-limbs. (Fig. 8.) Now, is it a worthy conception of 

 Deity that, while neglecting to maintain his unity of 



