278 
MR. NEWPORT ON THE TEMPERATURE OF INSECTS. 
the early part of the spring and summer, at a temperature of at least 10° lower than 
the present, would have perished within forty-eight hours. Hence it is not diminished 
temperature alone that induces a state of hybernation. Now during the confinement 
of these individuals I examined other specimens of the same species, and found the 
abdomen in each of them well filled with fat, while the respiratory organs appeared 
to be diminished in calibre, and somewhat compressed by its accumulation. This 
was particularly the case with one specimen which I examined, and the circumstance 
became the more interesting to me from a knowledge of the fact that both the amount 
of respiration and the quantity of heat evolved by the insect are at this period dimi- 
nished. But without going further with the causes of hybernation of insects, and 
which do not directly belong to this subject, it may be inquired how it happens that 
if the sleep of the hybernating insect be induced by a plethoric condition of body, 
that there are certain species, as, for instance, the Anthophora retusa, Steph., which 
assume the perfect form and begin to hybernate during the summer, even at the end 
of August, but do not leave their abodes until April or May in the following spring, 
although the morning sun shines brightly on their dwellings, and sometimes raises the 
exterior surface of the bank in which they are deposited to a temperature of 80 ° Fahr. 
or upwards ? Unto this it may be replied that the bodies of those insects, having so 
recently changed from the larva to the perfect state, are still provided with a full 
supply of nourishment ; that the soil in which they are nidificating has not its tempe- 
rature increased to a sufficient depth to arouse them into activity, and that even if 
its temperature be sufficiently increased for a day or two, it does not continue at the 
same standard, but gradually declines with the approach of autumn ; while on the 
other hand, on the approach of spring the mean temperature of the atmosphere is 
daily augmented, and the insect becomes aroused from its long slumbers by the 
steadily increasing warmth of its dwelling ; its respiration is then excited, its fluids 
circulate more quickly, and the nutriment stored up within its body when it entered 
its sleeping condition having become exhausted, it is soon stimulated by the calls of 
hunger*, which the more perfect aeration of its fluids and the activity of all its func- 
tions induce within it ; it makes a powerful effort to escape from its prison house, 
and pioneers its way through the soil to a new life, a life of activity, — directed in 
its proper course by the less consolidated state of the earth, in the passage to its 
abode, with which, many months before, the careful parent bee had securely closed 
the entrance, to protect her delicate offspring from the intrusion of enemies. I have 
seen this insect at the moment of its first leaving its abode. It always takes several 
very deep and powerful inspirations before it first takes wing, and its temperature is 
then scarcely more than a degree or two above that of the nidus it has just left. The 
comparative amount of the temperature of this insect in its different states during the 
period of hybernation, as compared with the temperature of the soil in which it is 
living and with its temperature in the perfect and active period, is very interesting, 
and will best be shown in the accompanying Table. 
* Dr. M. Hall on Hybernation, Philosophical Transactions, 1832, Part I. p. 22. 
