Essays on Life 



was not a Charles-Darwinian ; but what evi- 

 dence other than inferential can from the 

 nature of the case be adduced in support of 

 this, as I believe, perfectly correct judgment ? 

 None know better than they who clamour for 

 direct evidence that their master was right in 

 taking the position assigned to him by Pro- 

 fessor Vines, that they cannot reasonably look 

 for it. With us, as with themselves, modifica- 

 tion proceeds very gradually, and it violates 

 our principles as much as their own to ex- 

 pect visible permanent progress, in any single 

 generation, or indeed in any number of genera- 

 tions of wild species which we have yet had 

 time to observe. Occasionally we can find 

 such cases, as in that of Branchipus stagnalis, 

 quoted by Mr. Wallace, or in that of the New 

 Zealand Kea whose skin, I was assured by 

 the late Sir Julius von Haast, has already 

 been modified as a consequence of its change 

 of food. Here we can show that in even a 

 few generations structure is modified under 

 changed conditions of existence, but as we 

 believe these cases to occur comparatively 



rarely, so it is still more rarely that they occur 



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