GERMINAL SELECTION. 23 



These genera, now, are by no means all so nearly 

 allied that they could have inherited the leaf-markings 

 from a common ancestral form. They belong to dif- 

 ferent continents and have probably for the most part 

 acquired their protective colorings themselves. But 

 one resemblance they have in common they are all 

 forest-butterflies. Now what is it that has put so 

 many genera of forest-butterflies and no others into 

 positions where they could acquire this resemblance 

 to leaves? Was it directive formative laws? If we 

 closely examine the markings by which the similarity 

 of the leaf is determined, we shall find, for example, in 

 Kallima Inachis, and Parallecta, the Indian leaf-butter- 

 flies, that the leaf-markings are executed in absolute 

 independence of the other uniformities governing the 

 wing. 



From the tail of the wing to the apex of the fore 

 wings runs with a beautiful curvature a thick, doubly- 

 contoured dark line accompanied by a brighter one, 

 representing the midrib of the leaf. This line cuts 

 the "veins" and the "cells" of the wing in the most 

 disregardful fashion, here in acute and here in obtuse 

 angles, and in absolute independence of the regular 

 system of divisions of the wing, which should as- 

 suredly be the expression of the "formative law of the 

 wing," if that were the product of an internal directive 

 principle. But leaving this last question aside, this 

 much is certain with regard to the markings, that they 

 are dependent, not on an internal, but on an external 

 directive power. 



Should any one be still unconvinced by the evidence 

 we have adduced, let him give the leaf-markings a 

 closer inspection. He will find that the midrib is com- 

 posed of two pieces of which the one belongs to the 



