370 
PROCEEDINGS OF SOCIETIES. 
temperature in individual insects had been ascertained by himself prior to these 
observations; the results of which observations, together with other facts 
connected with the physiology of insects, he subsequently communicated to 
Dr. M. Hall. 
Since the time when the author has been engaged in the prosecution of this 
inquiry, some observations on the same subject have been published by Dr. 
Berthold, of Gottingen, who expresses it as his opinion that insects ought not 
to be regarded as cold-blooded animals, but who does not appear to have detected 
the existence of a temperature higher than the surrounding medium in any in¬ 
dividual insect. The author also notices the observations on this subject made 
by Hansmann, Juch, Rengger, Dr. John Davy, and others, some of whom 
have detected, while others have not observed, the existence of an increased 
temperature in this class of animals. He then gives a detailed account of the 
precautions to be taken for insuring accuracy in making observations of this 
kind; and remarks that greater reliance is to be placed on those made on the 
external than on the internal temperature of the animal, seeing that comparative 
results are all that can be obtained, and that the injury inflicted on the insect by 
its mutilation very materially interferes with the correctness of the conclusions 
as to the degree of internal temperature. 
After premising these introductory remarks, the author gives a detailed account 
of his observations on the temperature of insects in their several states of larva, 
pupa, and imago, from which it appears that those which possess the highest 
temperature are always volant insects, and are chiefly diurnal species, residing 
almost constantly in the open air. He shows that the larva has a lower tem¬ 
perature than the imago, and that the energy of its respiration is also less, 
regard being had to the activity of the insect, and to the size of its body. In 
iepidopterous insects the average elevation of temperature above that of its sur¬ 
rounding medium, is in the larva from 0° *9 to 1° *5 ; while in the imago it is 
from 5° to 10°. Among the Hymenoptera it is from 2° to 4° in the larva, and 
in the imago from 4° to 15° or even 20°; but in all cases the amount of this 
elevation is shown to depend on the degree of activity, and the quantity of air 
respired during a given period. The author then inquires into the influence of 
various circumstances, such as inactivity, sleep, hybernation, and inordinate 
excitement, on the temperature of insects, and shows that the evolution of heat 
gradually diminishes in a degree corresponding to the length of time during 
which the insect remains in a state of repose, but that it is immediately increased 
as soon as the insect is roused into action. He adverts also to the remote cause 
of hybernation, which he ascribes, in every state of the insect, to accumulations 
of adipose matter, or of nutrient fluid, which, being stored up in the system, 
induce a plethoric state, from which the animal is aroused when this store of 
