282 
MR. NEWPORT ON THE TEMPERATURE OP INSECTS. 
meter pressed against its abdomen until it had become perfectly quiet, the mercuiy 
rose only to about one degree above that of the surrounding medium. These experi- 
ments appeared to indicate that the quantity of heat evolved is in the ratio of the 
degree and activity of respiration. 
On the 9th of June 1834 three female specimens of Bombus terrestris, B. lapidarius, 
and B. muscorum, all of which had been captured about three hours previously, were 
submitted to experiment, great caution being taken to prevent anything from inter- 
fering with the correctness of the observations. The temperature of the atmosphere 
and of the phials employed on this occasion was 68° Fahr., and the time occupied in 
each observation was five minutes. Bombus terrestris raised the temperature of the 
phial to 72 ° Fahr., and maintained it at that height during the whole of the experi- 
ment, while the temperature of its own body was 77° Fahr. That of B. lapidarius at 
the end of the observations was 71°'5, and of B. muscorum 7 2° - 2 Fahr. In the first of 
these observations the temperature of B. terrestris was gradually raised from the tem- 
perature of rest, or only two or three degrees above that of the atmosphere, 68° Fahr., 
to 77°- During the whole five minutes the insect continued in violent motion, and 
maintained the temperature of the stoppered phial at 72°, or 4° above the temperature 
of the phial at the commencement of the observation, while that of the insect itself was 
raised to 9°, or 5 0, 5 above that of the medium around if, which it had itself raised 4°. 
At that time I imagined that this great amount of temperature, nearly 10° Fahr., 
was very nearly or quite the maximum amount of temperature that a single insect 
can generate, since a little more exertion, or longer continuance of excitement, would 
have made the insect perspire copiously. The occurrence of this phenomenon in in- 
sects, as in vertebrated animals, must be looked upon as the natural cooling process, 
and beyond which the temperature of the animal cannot be raised in a state of health. 
The second specimen, B. lapidarius, was feeble, and only in a moderate state of ac- 
tivity, and consequently did not raise the temperature of its body above the usual 
standard. The third specimen, B. muscorum , was very much excited, and its tem- 
perature rose to 72 °’ 2 , or 4° above that of the atmosphere. On the 9th of July 1834, 
atmosphere 69 0, 8 Fahr., I placed a single specimen of B. Jonella immediately after it 
was captured in the stoppered phial employed in the previous experiments. The phial 
was closed, and the insect continued in a highly excited state for six or eight minutes. 
When it had become quiet a thermometer was very carefully introduced to the bottom 
of the phial without touching the insect, and the mercury rose to, and was main- 
tained at 74°’7, or 5 0, 8 above that of the atmosphere and of the phial at the com- 
mencement of the observations. The insect then became excited, and the thermo- 
meter was held near enough to touch the tips of its wings. The temperature of the 
air in the phial immediately sunk to 72°'5, being a diminution of 2 0, 2. This observa- 
tion was several times repeated with the same results, so that while confirming the 
previous conclusion respecting the evolution of heat, it shows also another interesting 
fact, viz. that the vibration of the wings tends to cool the body of the insect during 
