8 Darwin- Wallace Celebration. 



a good and precise answer to this question, and one which is 

 of somo psychological interest, I will, with your permission, 

 briefly state what it is. 



On a careful consideration, we find a curious series of 

 correspondences, both in mind and in environment, which led 

 Darwin and myself, alone among our contemporaries, to reach 

 identically the same theory. 



First (and most important, as I believe), in early life both 

 Darwin and myself became ardent beetle-hunters. Now 

 there is certainly no group of organisms that so impresses 

 the collector by the almost infinite number of its specific 

 forms, the endless modifications of structure, shape, colour, 

 and surface-markings that distinguish them from each other, 

 and their innumerable adaptations to diverse environments. 

 These interesting features are exhibited almost as strikingly 

 in temperate as in tropical regions, our own comparatively 

 limited island-fauna possessing more than 3000 species of 

 this one order of insects. 



Again, both Darwin and myself had, what he terms " the 

 mere passion of collecting," not that of studying the minutiae 

 of structure, either internal or external. I should describe 

 it rather as an intense interest in the mere variety of living 

 things the variety that catches the eye of the observer even 

 among those which are very much alike, but which are soon 

 found to differ in several distinct characters. 



Now it is this superficial and almost child-like interest in 

 the outward forms of living things, which, though often 

 despised as unscientific, happened to be the only one which 

 would lead us towards a solution of the problem of species. 

 For nature herself distinguishes her species by just such 

 characters often exclusively so, always in some degree 

 very small changes in outline, or in the proportions of ap- 

 pendages, as give a quite distinct and recognisable fades to 

 each, often aided by slight peculiarities in motions or habits ; 

 while in a large number of cases differences of surface- 

 texture, of colour, or in the details of the same general 

 scheme of colour-pattern or of shading, give an unmistakable 

 individuality to closely allied species. 



