More Beetles 



and often with its poisons, each plant tried 

 would be a perilous innovation, to which the 

 insect, repelled by the first mouthfuls, would 

 never consent. How greatly preferable to 

 these dangerous novelties is the invariable 

 dish consecrated by ancient custom! This, 

 no doubt, is why the vegetarian insect is 

 faithful to its plant. 



How is this division of the earth's abun- 

 dance among its consumers effected? We 

 can hardly hope to understand the problem; 

 it is too far beyond our methods of research. 

 The most that we can do is, by experimental 

 methods, to explore this corner of the un- 

 known a little, to seek to discover how far 

 the insect's diet is fixed and to note its varia- 

 tions, if any. This will give us data which 

 the future will employ to carry the problem 

 farther. 



Towards the end of the autumn, I had 

 placed in the vivarium two couples of the 

 Stercoraceous Geotrupes, with an ample heap 

 of provender obtained from the Mules. I 

 had no plans as regards my captives; I had 

 put them there because it was an old habit of 

 mine never to lose an opportunity. Chance 

 had set them within my reach; chance would 

 do the rest. 



218 



