HYBERNATION OF INSECTS. 4-55 



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 14-th 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 il 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 llth 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, thnt regulates their move- 

 ments, as the lower degree which may have obtained 

 for a few nights previously, and which ma}' 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- 



