NATURAL THEOLOGY. 317 



couple of sparrows hatched in an oven, and kept 

 separate from the rest of their species, would pro- 

 ceed as other sparrows do in every office which 

 related to the production and preservation of their 

 brood. Assuming this fact,'" the thing is inexpli- 

 cable upon any other hypothesis than that of an 

 instinct impressed upon the constitution of the 

 animal. For, first, what should induce the female 

 bird to prepare a nest before she lays her eggs ? 

 It is in vain to suppose her to be possessed of the 

 faculty of reasoning ; for no reasoning will reach 



"3 There can be very little doubt of this assumption being ac- 

 cording to the fact. Nevertheless, as the experiment has proba- 

 bly not been actually made, there is no harm in mentioning one 

 or two examples of the same import, and which are ascertained 

 by repeated observation. When caterpillars bred upon a tree are 

 shaken off and fall for the first time upon the ground, they imme- 

 diately regain the tree by crawling up as quick as they can. 

 Again — it is a very general law of insects, that the grub feeds 

 upon a food which the parent does not eat, and yet the latter 

 makes provision for the grub. Thus the solitary wasp deposits 

 its eggs, each in a hole, and then collects a certain number of 

 green worms, which she rolls up and deposits in the same hole, 

 over the egg. When the grub is hatched, it feeds upon these 

 worms until transformed into a young wasp. And here two 

 things are remarkable : first, the wasp itself never feeds upon the 

 worm, or indeed on any animal food ; and next, M. Reaumur 

 found that she provides just enough of the worms to sustain the 

 grub till it becomes a fly, and changes its food. Our author 

 dwells afterwards upon the application to the argument of the fact 

 that the parent insect never sees its young. The arcliitecture of 

 bees affords perhaps the most striking illustration ; for those which 

 have been taken without ever having any communication with the 

 former race, build precisely in the accustomed manner. See the 

 next note. 



27* 



