EVOLUTION OF THE COLORS OF BIRDS. 75 



ment cells of reptiles and fishes), which are under the 

 volition of an animal. Here, and in many other in- 

 stances which might be cited, it cannot be asserted that 

 the nutrition of use is not under the direct control of 

 the will through the mediation of nerve force. There- 

 fore I am disposed to believe that growth-force may be, 

 through the motive force of the animal, as readily de- 

 termined to a locality where an executive organ does not 

 exist, as to the first segment or cell of such an organ 

 already commenced, and that effort is, in the order of 

 time, the first factor in acceleration." 



All that can be said to the above is that it may be 

 true, but that it has not yet been demonstrated. There 

 is, indeed, a vast difference between the assumption 

 that use can modify a part which already exists, and the 

 assumption that desire or effort can originate something 

 which does not exist. Moreover, even if effort be a 

 valid factor in creation, it cannot, it seems to me, have 

 the general application ascribed to it by Prof. Cope. 

 For example, it could apparentty have no influence upon 

 the origination of new colors. Does the bird desire to 

 be protectively colored? If so, it must decide what 

 colors would be most in harmony with its surroundings 

 and then make an effort of will to have these colors 

 developed; all of which is, on the face of it, inconceiv- 

 able. Or by what imaginable sort of effort could feathers 

 be originated? Effort, then, if it can be shown to have 

 any creative power, must be relegated to a very special 

 field, and cannot be considered as the sole or even 

 principal originator of the fittest. 



What then can be considered the originator of the 

 fittest? This I have attempted to indicate in the discussion 

 of variation. It is an emphasis of the Hilairian rather 

 than the Lamarckian factor. It is rather more in accord 

 with the views of Eimer than Cope, although both are 



