SPECIES AND THEIR ORIGIN 319 



of weak links in his own argument which he candidly 

 avowed. These became more emphasized as time 

 went on, and a host of investigators continually 

 added to the facts that were most difficult to explain 

 by the theory of Natural Selection. We have space 

 for but a few of these objections. (1) The basis of 

 elimination or preservation is the usefulness of 

 the organ whose variations serve as the criterion 

 for selection, but there are thousands of very 

 stable characters which must be of wholly indifferent 

 value to the organism. One of the largest groups 

 of the ground-beetles is divided into two sub-groups 

 containing hundreds of species by the invariable 

 distinction of the possession of one microscopic hair 

 above the eye or of two. (2) Again, while it may be 

 recognized that the emphasis on a certain structure 

 may be, so to speak, of selection value, yet the 

 minute differences of fluctuating variations can hardly 

 count one way or the other. Thus one author calls 

 attention to the polar bear, whose white coat must 

 be of great utility to him in stealing upon his 

 prey unobserved. Without doubt, this species has 

 evolved from a type of the more usual coloration, 

 but " did the fortuitous appearance in his coat of a 

 spot of white hairs as large as a dollar or a pancake 

 give some ancient brown bear such an advantage 

 in the struggle for existence as to make him or her 

 the forerunner of a new and better-adapted sort of 

 bear ? " Darwin recognized this difficulty, but 

 thought that the struggle for existence was so keen 

 that the slightest difference, however slight, might 



