HIBERNATION OF INSECTS. 455 



to the constitution and wants of different species, in 

 which they quietly wait the accession of torpidity and 

 pass the winter ? In my opinion, certainly not. 



In the first place, if sensations proceeding from cold 

 lead insects to select retreats for hybernating, how comes 

 it that, as above shown, a large proportion of them enter 

 these retreats before any severe cold has been felt, and 

 on days considerably warmer than many that preceded 

 them? If this supposition have any meaning, it must 

 imply that insects are so constituted that, when a certain 

 degree of cold has been felt by them, the sensations which 

 this feeling excites impel them to seek out hybernacula. 

 Now the thermometer in the shade on the 14th of Oc- 

 tober 1816, when I observed vast numbers thus employ- 

 ed, was at 58: this then, on the theory in question, is 

 a temperature sufficiently low to induce the requisite 

 sensations. But it so happens, as I learn from my me- 

 teorological journal (which registers the greatest and 

 least daily temperature as indicated by a Six's thermo- 

 meter), that on the 31st of August 1816 the greatest 

 heat was not more than 52, or six degrees lower than 

 on the 14th of October : yet it was six weeks later that 

 insects retired for the winter ! 



But it may be objected, that it is perhaps not so much 

 the precise degree of cold prevailing on the day when 

 insects select their hybernacula, that regulates their move- 

 ments, as the lower degree which may have obtained 

 for a few nights previously, and which may act upon 

 their delicate organization so as to influence their future 

 proceedings. Facts, however, are again in direct oppo- 

 sition to the explanation ; for I find that, for a week 

 previously to the 14th of October 1816, the thermome- 



