1 62 Evolution and Adaptation 



shall appear at the places whence the lateral ribs start, and 

 that here also a definite acute angle shall be preserved." 

 Thus the philosopher in his closet multiplies and magnifies 

 the difficulties for which he is about to offer a panacea. Had 

 the same amount of labor been spent in testing whether the 

 life of this butterfly is so closely dependent on the exact imi- 

 tation of the leaf, we might have been spared the pains of 

 this elaborate exordium. There are at least some grounds 

 for suspicion that the whole case of Kallima is " made up." 

 If this should prove true, it will be a bad day for the Darwin- 

 ians, unless they fall back on Weismann's statement that 

 their theory is insufficient to prove a single case ! 



Weismann has used Kallima only as the most instruc- 

 tive illustration. The objections that are here evident are 

 found not only in the cases of protective coloration, but " are 

 applicable in all cases where the process of selection is con- 

 cerned. Take, for example, the case of instincts that are 

 called into action only once in life, as the pupal performances 

 of insects, the fabrication of cocoons, etc. How is it that 

 the useful variations were always present here ? " Weismann 

 concludes that "something is still wanting to the selection 

 theory of Darwin and Wallace, which it is obligatory on us 

 to discover, if we possibly can, and without which selection 

 as yet offers no complete explanation of the phyletic processes 

 of transformation." Weismann's first step in the solution of 

 the difficulty is contained in the following statement: — 



" My inference is a very simple one : if we are forced by 

 the facts on all hands to the assumption that the useful 

 variations which render selection possible are always present, 

 then, some profound connection must exist between the utility 

 of a variation and its actual appearance, or, in other words, 

 the direction of the variation of a part must be determined by 

 utility, and we shall have to see whether facts exist that con- 

 firm our conjecture." 



Weismann finds the solution in the method by which the 



