Weismann concludes, therefore, that for his present purpose it suffices to show “that cases exist wherein all natural explanations except that of selection fail us,” and he then proceeds to point out that even the natural selection of Darwin and of Wallace also fail to give us a reasonable explanation of how, for example, the markings on the wings of the Kallima butterfly have come about. The main reason that he gives to show that this is the case rests on the difficulty of the assumption that the right variations should always be present in the right place. Here “is the insurmountable barrier for the explanatory power of the principle [natural selection] for who, or what, is to be our guarantee that the dark scales shall appear at the exact spots on the wing where the midrib of the leaf must grow? And that later dark scales shall appear at the exact spots to which the midrib must be prolonged? And that still later such dark scales 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 imitation 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 Darwinians, 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 instructive 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 concerned. 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 confirm our conjecture.”