RECENT CRITICISMS AND HYPOTHESES. 565 



with the idea entertained by the late Prof. Owen, who alleged 

 an " ordained becoming " of living things. 



174d. An objection to the Darwinian doctrine which has 

 risen into prominence, is that Natural Selection does not 

 explain that which it professes to explain. In the words of 

 Mr. J. T. Cunningham: 



"Everybody knows that the theory of natural selection was put for- 

 ward by Darwin as a theory of the origin of species, and yet it is only 

 a theory of the origin of adaptations. The question is : Are the dif- 

 ferences between species differences of adaptation ? If so, then the 

 origin of species and the origin of adaptations are equivalent terms. 

 But there is scarcely a single instance in which a specific character has 

 been shown to be useful, to be adaptive." * 



To illustrate this last statement Mr. Cunningham names the 

 plaice, flounder, and dab as three flat fishes in which, along 

 with the adaptive characters related to the mode of life com- 

 mon to them all, each has specific characters which are not 

 adaptive. Xo evidence is forthcoming that these in any way 

 conduce to the welfare of the species. Two propositions are 

 here involved which should be separately dealt with. 



The first is that the adaptive modifications which survival 

 of the fittest is able to produce, do not become specific traits : 

 they are traits separate in kind from those which mark off 

 groups proved to be specifically distinct by their inability to 

 breed together. Such evidence as we at present have seems 

 to warrant this statement. Out of the many varieties of 

 dogs most, if not all, have been rendered distinct by adaptive 

 modifications, mostly produced by selection. But, notwith- 

 standing the immense divergences of structure so produced, 

 the varieties inter-breed. To this, however, it may be replied 

 that sufficient time has not elapsed that the process by 

 which a structural adaptation so reacts on the constitution 

 as to make it a distinct one, possibly, or probably, takes 

 many thousands of years. Let us accept for the moment 

 Lord Kelvin's low estimate of the geologic time during which 



* Address to Plymouth Institution, at opening of Session 1895-6. 

 37 



