458 HYBERNATION OF INSECTS. 



last fact in particular, on their theory, admits of no 

 satisfactory explanation. We may say, and truly, that 

 the sensation of fatigue causes man to lie down and 

 sleep ; but we should laugh at any one who contended 

 that this sensation forced him first to make a four-post 

 bedstead to repose upon. 



In the second place, if we grant for a moment that it 

 is cold which drives insects to their hybernacula, there 

 are other phenomena attending the state of hybernation 

 which on this supposition are inexplicable. If cold led 

 insects to enter their winter quarters, then they ought to 

 be led by the cessation of cold to quit them. But, as has 

 been before observed, we have often days in winter milder 

 than at the period of hybcrnating, and in which insects 

 are so roused from their torpidity as to run about nimbly 

 when molested in their retreats ; yet though their irrita- 

 bility must have been increased by a two or three months 

 inactivity and abstinence, they do not leave them, but 

 quietly remain until a fresh accession of cold again in- 

 duces insensibility. 



In short, to refer the hybernation of insects to the 

 mere direct influence of cold, is to suppose one of the 

 most important acts of their existence given up to the 

 blind guidance of feelings which in the variable climates 

 of Europe would be leading them into perpetual and fa- 

 tal errors — which in spring would be inducing them to 

 quit their ordinary occupations, and prepare retreats 

 and habitations for winter to be quitted again as soon 

 as a few fine days had dispelled the frosty feel of a May 

 week ; and in a mild winter's day, when the thermome- 

 ter, as is olten the case, rises to 50" or dB"", would lure 

 them to an exposure that must destroy them. It is not. 



