HYBERNATION OF INSECTS. 461 
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. J*acts, 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- 
ter was never lower at night than 48°, while in the first 
week of August it was twice as low as 46°, and never 
higher than 50°.? 
As a last resource, the advocates of the doctrine I am 
opposing, may urge, that possibly insects may even have 
@ Since the publication of the first edition of this volume, I have 
had an opportunity of making some observations which ‘strongly cor- 
roborate the above reasoning. The month of October in the pre- 
sent year (1817) set in extremely cold. From the first to the sixth 
piercing north and north-west winds blew ; the thermometer at Hull, 
though the sun shone brightly, in the day-time was never higher than 
from 52° to 56°, nor at night than 38°; in fact, on the first and 
third it sunk as low as 34°, and on the second to 31°: and on those 
days, at eight in the morning, the grass was covered with a white 
hoar frost ; in short, to every one’s feelings the weather indicated De- 
cember rather than October. Here then was every condition fulfill- 
ed that the theory I am opposing can require ; consequently, accord- 
ing to that theory, such a state of the atmosphere should have driven 
every hybernating insect to its winter quarters. But so far was this 
from being the case, that on the fifth, when I made an excursion pur- 
posely to ascertain the fact, I found all the insects still abroad which 
I had met with six weeks before in similar situations, 
