DARWINISM DEFENDED. 165 



attacks on the species-forming capacity of natural selection, 

 which are based on ( I ) the slightness and inutility of the 

 fluctuating Darwinian variations, and (2) the improbability 

 of the right variations appearing at the right time to make 

 possible the development of .specialisations of qualitative 

 and coadaptive character. In a discussion of some length 

 (pp. 32-77), mostly quite fair and unprejudiced, he brings 

 out the best and strongest arguments that the faithful Dar- 

 winians have to offer to reduce the force of at least, if not to 

 answer satisfactorily, even for themselves, the most effective 

 attacks on the capacity of selection. In very condensed form 

 I present in the following paragraphs the essential points 

 in these defensive arguments. 



In regard to the first objection, namely, that the very 



slight or small differences in organs and functions which 



result from the fluctuating or Darwinian varia- 



to the tightness tions cannot be sufficiently advantageous or 



of Darwinian disadvantageous enough to afford "handles" 



variations. . . , f ... 



for natural selection, that is, cannot be 01 liie- 

 and-death-determining value, Darwin devoted, in his "Origin 

 of Species," a whole chapter of discussion and argument 

 to show that in many cases even the slightest of differences 

 may conceivably (it is of course a matter practically incapa- 

 ble of proof by observation or experiment) be sufficient to 

 turn the scale, in a rigorous competition, one way or the 

 other. In many other cases such differences could not, even 

 to Darwin, appear sufficient to be of a life-and-death advan- 

 tage or disadvantage. But Darwin too often, Plate admits, 

 confounded mere usefulness 2 with life-and-death-deciding 

 usefulness (or non-usefulness). 



However, for many cases Plate maintains that the slight 

 Darwinian variations can serve as handles for selection, 

 particularly in periods of unusual rigour of competition 

 or fierceness of struggle (either active or passive) : ex- 

 amples are, slight differences in the speed of preyed-on 



