states or INSECTS. 265 



sun when he waked ; and an ardent astronomer would 

 probably commit himself with scientific joy to a repose as 

 long and as sound as that of the seven sleepers, for the 

 chance of viewing his predicted return of a comet, on 

 stepping out of his cave : but ordinary mortals would 

 consign themselves to the perils of so long a night with 

 reluctance, apprehending a fate no better than what be- 

 tel the magician, who ordered himself to be cut in small 

 pieces and put in pickle, with the expectation of becom- 

 ing young again a . 



The duration, then, of an insect's existence in the 

 pupa state, depends upon its bulk, upon the temperature 

 to which it is exposed, and upon a combination of these 

 two circumstances. This experiment appears very sim- 

 ple. We seem to ourselves to have accomplished what is 

 so often undertaken in vain — to have found an entrance 

 into the cabinet of Nature, and to have made ourselves 

 masters of the contents of one of the pages of her sealed 

 and secret book. We deceive, ourselves, however : this 

 book, when it seems most legible, is often interlined with 

 sympathetic inks, if I may so speak, which require tests 

 unknown to us for their detection. If you lay up a con- 

 siderable number of the pupae of a moth now called Erio- 

 gaster lanestris, the larva of which is not uncommon in 

 June on the black-thorn, selected precisely of the same 

 size, and exposed to exactly the same temperature, the 

 greater number of them will disclose the perfect insect 

 in the February following ; some not till the February of 

 the year ensuing, and the remainder not before the same 



* This is a legend of Virgil, of which an account is given in The 



Lay of the Last Minstrel, Note xv. 12mo ed. 1822, p. 257. 



