MR. NEWPORT ON THE TEMPERATURE OF INSECTS. 
323 
had watched from the egg, and whose rate of pulsation is noticed on Table IX. At the 
time of entering into the pupa state in August, it weighed, as above stated, 7 IT 
grains. At the present time it weighed 67‘ 4 grains. This diminution was during the 
period of hybernation, and is in beautiful accordance with the greatly diminished 
quantity of respiration during this state, respiration being reduced to its minimum 
in this condition of the insect, as shown in my previous observations. On the 24th 
of May, fifty-one days after the first weighing, the perfect insect was developed 
from this pupa, and then weighed only thirty-six grains, and when weighed again on 
the following day, only thirty-four grains, Table V. A, being an amazing diminution 
of nearly one half of the whole weight of the pupa in the short space of fifty-three days. 
Now it will be remembered that, as shown in the Tables on the Respiration* of the 
pupa of Sphinx ligustri in the month of April, that the quantity of respiration at 
that period is gradually increasing, and is in proportion to the degree of animation 
in the insect ; and the degree of animation is proportioned to the quantity of stimuli, 
external temperature, &c., so that, as shown by Reaumur in the pupae of the common 
Cabbage Butterfly, if the pupae be kept in a very low temperature, as in that of an 
ice-house, development into the perfect state is greatly retarded ; and as now shown, 
respiration, owing to the absence of a proper amount of external stimulus, being 
reduced to its minimum, the circulation of blood is almost suspended, the develop- 
ment of heat scarcely, if at all perceptible, and the expenditure of solid matter from 
the body of the insect in a gaseous form is so insignificant that the powers of life are 
in no way injured by retarded development, and the insect revives in its full vigour 
whenever the natural stimuli of life are sufficiently increased. At the moment of 
weighing the above pupa in April, I weighed several others which had entered the 
pupa state about the same time. One of them at the expiration of fifty-three days, 
on the 26th of May, had lost thirteen grains, another eight grains, a third nine 
grains, and a fourth ten grains, and the respiration of these had increased in the ratio 
of their loss of weight. 
There may, perhaps, be some difficulty in ascertaining with certainty the chemical 
constituents of this gaseous expenditure from the body of the insect in its different 
stages, since a large proportion appears to be aqueous vapour, but I am satisfied that 
sometimes there is also a quantity of carbonic acid. However, I could not discover 
the carbonic acid in a quantity of vapour expelled from the bee hive and condensed 
during the night, but I very readily detected it in the pupa, in my earlier observations 
on the respiration of insects, in April 1829. A pupa of Sphinx ligustri, after being 
carefully washed to prevent the adhesion of air to the surface of its body, was placed 
for a few hours in a glass stoppered phial, completely filled with perfectly clear lime- 
water, and at the expiration of two or three hours, I had the satisfaction of detecting 
carbonate of lime deposited both within the entrance of the spiracles and also in the 
minute punctures which are distributed over the whole body of the pupa ; a certain 
* Philosophical Transactions, 1836, Part II. p. 552, Table I. No. 3 to 10. 
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