EXAMPLE OF DIVERSITY OF OPERATIONS. 175 



caterpillars, feed upon the leaves ; others upon the 

 flowers, or on the fruit ; a few will eat nothing but 

 the bark ; while many derive their nourishment only 

 from the internal substance of the trunk. Every 

 part of the tree is thus seen to supply food " in due 

 season" to all these diversified tribes. If we examine 

 further, new modifications of habit are discovered. 

 Those insects, for instance, which feed upon leaves, 

 do not all feed in the same manner, or upon the 

 same parts : a few devour only the bud ; others spin 

 the terminal leaves together, forming them into a 

 sort of hut, under cover of which they regale, at 

 leisure, upon the tenderest parts ; some, apparently 

 even more cautious, construct little compact cases, 

 which cover their body, and make them appear like 

 bits of stick, or the ends of broken twigs ; some eat 

 the outside of the leaf only, while others, — like the 

 caterpillars of New Holland, mentioned by Lewin, 

 — bore themselves holes in the stem, into which 

 they carry a few leaves — sally out during the 

 night for a fresh supply, and feed upon them at 

 their leisure during the day. It seems, in fact, 

 impossible to conceive greater modifications than 

 are actually met with, even among insects which 

 feed only upon leaves ; while other variations are 

 equally numerous in such tribes as live upon other 

 portions of the tree. Hence it is apparent, that in 

 accurately determining the habits and economy of 

 insects, no less than of animals generally, the greatest 

 nicety of observation is absolutely essential. 



(119.) If we look to the feathered creation, we 

 shall find an equally remarkable diversity of habits, 

 even among those tribes whose food consists en- 



