554 
MR. NEWPORT ON THE RESPIRATION OF INSECTS. 
by Dr. Hall # , is more decidedly the case in the hybernating Mammalia; and it is 
exactly like these in insects, in which, as will presently be shown, respiration is al- 
most entirely suspended at certain periods. 
It generally happens, that while we are making observations upon larvae they are 
in constant activity, and consequently they then consume the greatest amount of 
oxygen ; while the perfect insect, independently of its being two thirds smaller in 
bulk, is generally in a state of complete inactivity, at rest or sleeping, and then con- 
sumes only its smallest proportion of oxygen. Besides this, it is probable that the very 
confinement of the perfect insect in a given quantity of air, insulated from external 
currents and sudden changes of temperature, may induce a more complete state of 
rest, and thus be the means of reducing the respiration still lower than it would 
otherwise have fallen, and still further prevent the necessity for a renewal of atmo- 
spheric air in the phial. A female specimen of Bombyx Caja, whose cubic bulk was 
about ‘09, confined in a phial of 1*14 capacity at a temperature varying from 63° to 
71° Fahr., was still living and vigorous at the expiration of eighty-four hours; but 
during this time the insect was almost constantly in a state of inactivity. There is 
the same disposition in perfect butterflies ( Papiliones ) as in moths to become inactive 
when placed in confinement. After having been confined for a few minutes, and en- 
deavouring to escape, they gradually become quiet, and their respiration is diminished. 
In order to prove distinctly that the quantity of respiration depends upon the degree 
of activity or quiescence of the individual insect, I confined a female Bombus tdrrestris, 
Steph. (Table I. No. 28.), immediately after the insect was captured, in a glass-stop- 
pered phial of about two cubic inches capacity, at a temperature of 60° Fahr. It 
continued in a state of violent activity, and in one hour evolved CP345 of a cubic inch 
of carbonic acid gas ; while the very same insect, when confined at nearly the same 
temperature (59° Fahr.) for twenty-four hours on the following day, during the whole 
of which time it was in a state of perfect rest, evolved only 0-305 of a cubic inch, 
which was not one twentieth part of the amount produced in a state of activity, 
although the insect had been fed immediately before commencing the observation. 
The quantity of air deteriorated by an insect diminishes in proportion to the num- 
ber of its respirations, and these diminish in frequency in proportion to the length of 
time it has remained in a state of quiescence. I had full proof of this during the 
above observation on the quantity of respiration of Bombus terrestris. Before noting 
the number of its respirations, the insect was allowed to remain at rest for about half 
an hour. At the expiration of that time the respirations were only fifty-eight per 
minute, and these were deep and laboured. At the expiration of one hundred and 
forty minutes, during the whole of which time the insect had remained at rest, its 
respirations were at the rate of only forty-six per minute : these were laborious and 
feeble, like those of an animal sinking into profound sleep. At the expiration of one 
hundred and eighty minutes, the respirations were no longer perceptible. Now in 
* Philosophical Transactions for 1832, Part I. 
