458 HYBERNATION OF INSECTS. 
The authors who have treated on these phenomena 
have generally? referred them to the Ss of cold 
upon the animals in which they are witnessed, but act- 
ing in a different manner. Some conceive that cold 
combined with a degree of fatness arising from abun- 
dance of food in autumn, produces in them an agreeable 
sensation of drowsiness, such as we know, from the ex- 
perience of Sir Joseph Banks and Dr. Solander in Terra 
del Fuego, as well as from other facts, is felt by man 
when exposed to a very low temperature; yielding to 
which, torpidity ensues. Others, admitting that cold is 
the cause of torpidity, maintain that the sensations which 
precede it are of a painful nature; and that the retreats 
in which hybernating animals pass the winter are selected 
in consequence of their endeavours to escape from the 
disagreeable influence of cold, 
I have before had occasion to remark? the inconclu- 
siveness of many of the physiological speculations of very 
eminent philosophers, arising from their ignorance of 
Entomology, which observation forcibly applies in the 
present instance. ‘The reasoners upon torpidity have 
almost all confined their view to the hybernating qua- 
drupeds, as the marmot, dormouse, &c., and have thus 
lost sight of the far more extensive series of facts supplied 
by hybernating insects, which would often at once have 
* Here must be excepted my lamented friend the late Dr. Reeve 
of Norwich, who, in his ingenious Lssay on the Torpidity of Animals, 
has come to nearly the same conclusion as is adopted in this letter ; 
but, by omitting to make a distinction between torpidity and hyber- 
nation, he has not done justice to his own ideas, ~ 
‘> Vot, I. 4th Ed. 32. 
