558 
MR. NEWPORT ON THE RESPIRATION OF INSECTS. 
ration in insects, as Treviranus has recently remarked *, very much depends upon 
the temperature of the air inspired, and also on the state of quiescence or activity iri 
which the insect has been living - . I made also other trials with other pupae. I in- 
closed one pupa which had remained during the whole winter in the open air, and 
one which had been kept for several weeks in my room, in two stoppered phials, when 
the temperature of the atmosphere was 61° Fahr., and allowed them to remain for 
one hundred and ninety-four hours. During this time the temperature of the atmo- 
sphere varied scarcely more than eight or ten degrees, and both phials were examined 
at a temperature of 59° Fahr. The first specimen, which had remained in my room, 
produced 0*345 of a cubic inch of carbonic acid gas, while the other, which had been 
brought from the open air, produced only 0*310; a difference of thirty five thou- 
sandths less in the insect which had been exposed. Hence it is clear that respiration 
is less perfectly performed in those insects which are only newly aroused from their 
state of hybernation than in those which have been long kept in a state of excite- 
ment. 
The amazing difference which exists in the quantity of respiration of pupae and of 
perfect insects is strikingly exemplified in Centra vinula, Steph. (the Puss Moth). 
This insect, which it is well known is inclosed in a hard and impervious cocoon in 
the open air during its pupa state, is an admirable subject for experiment. On the 
25th of March I inclosed a pupa, which had previously been several days removed 
from its cocoon, and consequently aroused from its hybernation, in a phial at a tem- 
perature of 61°*5 Fahr. At the expiration of one hundred and ninety-four hours it 
had produced only 0*363 of carbonic acid gas, which is considerably less than two 
thousandths per hour. On the 23rd and 24th of April I confined the same insect, 
twenty-four hours after it had escaped from the pupa state, and had become perfect, 
for twelve hours, at two separate times, when the temperature of the atmosphere was 
63° Fahr. In one experiment it produced 0*480, and in the other 0*490 of carbonic 
acid, or at least forty thousandths per hour, and even during part of that time the 
insect was not in a state of activity. 
In will thus be seen that the quantity of air deteriorated by an insect is regulated 
by various circumstances, independently of the natural habits of the species. When 
the pupa is in a state of complete hybernation, the respiration of the insect is at its 
minimum, while in the perfect insect, in a state of great activity, it is at its maximum. 
It is also evident that in making our observations the state of quiescence or activity, 
and the comparative bulk of the insect, in its different conditions, should be particu- 
larly attended to, or we may be led into errors whenever we attempt to compare the 
quantity of its respiration in its different states. 
* As noticed in the Lancet, vol. ii. 1835, p. 456. 
