GERMINAL SELECTION. 25 



incidence of an Indian butterfly with the leaf of a 

 tree now growing in an Indian forest as fortuitous, 

 as a lusus nature. Assuming this seemingly mechan- 

 ical force, therefore, we should be led back inevitably 

 to a teleological principle which produces adaptive 

 characters and which must have deposited the direc- 

 tive principle in the very first germ of terrestrial or- 

 ganisms, so that after untold ages at a definite time 

 and place the illusive leaf-markings should be devel- 

 oped. The assumption of pre-established harmony 

 between the evolution of the ancestral line of the tree 

 with its pre-figurative leaf, and that of the butterfly 

 with its imitating wing, is absolutely necessary here 

 a fact which I pointed out many years ago, 1 but 

 which is constantly forgotten by the promulgators of 

 the theory of internal evolutionary forces. 



For the present I leave out of consideration alto- 

 gether the question as to the conceivable extent of the 

 sphere of operation of natural selection ; I am primar- 

 ily concerned only with elucidating the process of se- 

 lection itself, wholly irrespective of the comprehensive- 

 ness or limitedness of its sphere of action. For this 

 purpose it is sufficient to show, as I have just done, 

 that cases exist wherein all natural explanations ex- 

 cept that of selection fail us. But let us now see 

 how far the principle of selection will carry us in the 

 explanation of such cases natural selection, I mean, 

 as it was formulated by Darwin and Wallace. 



There can be no doubt but the leaf-markings readily 

 admit of production in this manner, slowly and with 

 a gradual but constant increase of fidelity, provided 

 a single condition is fulfilled: the occurrence of the 



1 Studien zur Descendenztheorie, Leipsic, 1876. Vol. II, 

 pp. 295 and 322. 



