NATURAL SELECTION SINCE DARWIN 81 



the anterior wings, but as soon as the creature is 

 alarmed, it spreads all four wings, and now both eyes 

 stand boldly out on the red posterior wings and alarm 

 the assailant, as they give the impression of the head 

 of a much larger animal." 1 



And this is not an isolated case; there is no struc- 

 ture, no function, which Weismann can not account 

 for by attributing to it some plausible purpose. Such 

 hypotheses necessarily presuppose an anthropomor- 

 phic view of the world; a man might be frightened 

 when suddenly confronted by the head of a large un- 

 familiar animal; but would the butterfly's foe, with 

 its life habits and its mentality, have the same feeling? 

 Fear in man and in animals is due to widely different 

 causes. Why should a bird, for example, be afraid" 

 of a horned devil? 



The~defects of this conception are glaring. Once 

 more we see finalist explanations smuggled into a 

 domain in which Darwin had had the merit of replac- 

 ing them by purely causal explanations. Another 

 ever present danger is that our mind, too easily satis- 

 fied with fictitious explanations, may be induced to 

 discontinue its investigations. 



Let us now consider characters whose usefulness is 

 apparent and incontestable. Would usefulness in 

 any degree suffice to make the presence or the absence*^ 

 of one certain structural character a question of life or 



i The Evolution Theory, Vol. I, p. 69. 



