BEETLES THAT "BLUFF" 225 



the greatest noise succeeded best in finding partners, 

 rugosities on various parts of their bodies were gradually 

 developed by means of sexual selection into true stridulat- 

 ing organs." 



Structures to which we can ascribe a use are commonly 

 supposed to have been evolved for the purpose which we 

 assign to them. The " horns " of Beetles afford a case 

 in point ; but there are many other equally remarkable 

 and extravagant developments among the insects which 

 seem to defy explanation. And they will continue to 

 do so until it is realized that they are but exaggerations 

 of the normal processes of growth, which is not limited 

 to definite areas but may produce extensions and 

 excrescences of an almost infinitely varied character. The 

 only controlling factor is that imposed by Natural Selec- 

 tion when these growth-changes tend to impair the well- 

 being of the organism as a whole. Often such changes 

 confer benefits, giving rise to new organs, and in this 

 case Natural Selection encourages the new departure. 

 Nothing, indeed, " succeeds like success." New departures 

 in one direction may be promptly suppressed, in another 

 they spell fortune : there is no " SociaHsm " in Nature. 

 Often these " new departures " neither help nor hinder, 

 and instances of this kind are commonly afforded by 

 '* ornaments." One of the most singular illustrations 

 of this kind is furnished by that extraordinary Long- 

 horned Grasshopper of India {Schizodactylus monstrosus)^ 

 wherein the wings, when at rest, have their tips coiled 

 up like a watch-spring, while the appendages to the legs 

 are scarcely less remarkable. It is a burrower, driving 

 long tunnels in the banks of rivers. But little is known 

 of its habits, save that it does not emerge from its 

 burrow till night, when it takes long flights. This being 



15 



