322 
MR. NEWPORT ON THE TEMPERATURE OF INSECTS. 
Table XII. (Continued.) 
A Table of the Weight and Rate of Increase and Decrease, with the Faecal and Ga- 
seous expenditure of a Larva of Cerura v inula. 
No. 
Period of Observation. 
1832. Aug. 20a.m. 
A.M. 
A.M. 
A.M. 
P.M. 
P.M. 
P.M. 
P.M. 
P.M. 
P.M. 
P.M. 
A.M. 
A.M. 
A.M. 
9 * 
lot 
lit 
12t 
H 
2t 
3t 
4t 
5t 
6t 
n 
7k 
8t 
9t 
Feeding. 
Fasting. 
Temp, of 
Atmos. 
Insect. 
Difference. | 
Weight of 
larva in 
grains. 
Weight of 
food eaten 
in grains. 
Increase. | 
Gaseous ex- 
| penditure. 
I 
o 
o 
grs. 
65 
76-5 
65-5 
78-1 
3-65 
1-6 
1-55 
b 
66-4 
77-2 
2-4 
1-45 
67 
77-6 
2-55 
•4 
1-2 
68 
76-6 
1-6 
1-25 
69-5 
76-3 
2-5 
1-45 
69*5 
74-95 
2-1 
1-05 
70 
75-9 
4-4 
•95 
21 
70-2 
74-4 
1-75 
]-l 
69-5 
75-05 
2-7 
1-25 
69 
|75-7 
2-1 
•65 
•95 
68-5 
‘69-75 
2-55 
68-7 
‘69-65 
•1 
One hour 
69 
711 
I 
3-7 
1-45 
1-75 
fa o. 
•5 
1-55 
•95 
1 - 35 
1 "35 
2 1 
1-35 
215 
•8 
•5 
4-6 
Remarks. 
This larva was 
fed throughout 
-the whole of 
the observations 
upon stale food. 
Decrease in Weight in 26 hours 5'4 Food eaten 29 - 45 
17-75 11-70 
From this Table we deduce the following facts : — First that the expenditure which 
takes place from the cutaneous surface of the insect and from its respiratory organs 
is greater than its whole amount of faecal expenditure, is more regular and con- 
tinued, and decreases in proportion to the length of time which the insect remains 
fasting, but never entirely ceases. It is greatest while the insect is in motion and 
least when it is lying entirely at rest. Thus in the observations on Sphinx Elpenor, 
Linn., which was fasting during nearly the whole of the period of observation, twenty- 
two hours, the insect lost only ’85 of a grain of faecal expenditure, but 2’45 of grains 
by the respiratory and cutaneous surfaces, and of this expenditure, when the insect 
was lying at rest, only ’05 of a grain per hour, but when in violent motion the loss 
amounted to *15 per hour. This difference of quantity is readily accounted for by 
the quicker circulation of the fluids in the active state of the insect, when its respira- 
tion is greater, and consequently a greater amount of heat is generated, and requires 
to be regulated by the transpiration from the surface of the body. This Table also 
indicates the fact that the whole process of digestion may be completed in the larva 
of the Sphinx in about two hours and a half, and that the average quantity of faecal 
expenditure in the latter period of a moderate sized larva is about one grain per hour. 
But the connection or correspondence between the quantity of respiration, tempe- 
rature and gaseous expenditure in a given time, is beautifully illustrated in what oc- 
curs in the pupa state. On the 3rd of April, 1836, 1 weighed several pupae of Sphinx 
ligustri, and found that one of them which on the 20th of the preceding August, im- 
mediately after it had changed to a pupa, weighed 71 '1 grains, had not expended, 
during the long interval of nearly eight months, or two hundred and twenty-eight days 
inclusive, more than 37 grains in weight, the whole of which must have passed oft 
from the respiratory and cutaneous surfaces. This was the identical specimen which I 
