Permanence and Evolution. 151 



peacock and others. Now, even if the black- 

 winged peacock is a variation, which is doubt- 

 ful, it is a very slight one, differing, so far as 

 is known, in colour only. Just in proportion as 

 we make the transitions between organised 

 forms sudden, we remove them from the cate- 

 gory of anything that can even be plausibly 

 alleged to be observed. 



In fact, it may be said that Darwin's best 

 work has yet rendered the mutability of 

 organisms more unlikely than before, for while 

 he has deserved splendidly of science in calling 

 attention to the principle of natural selection, 

 it must not be forgotten that natural selection 

 is a principle which by itself accounts for 

 nothing else than the preservation and destruc- 

 tion of various forms of life in no way by itself 

 does it account for the origin of new types, 

 except by supposing in addition an indefinite 

 variability, for which there is no evidence. 

 Natural selection is a fact ; no one can doubt 



