MR. NEWPORT ON THE TEMPERATURE OF INSECTS. 
261 
taken to guard against its occurrence. Rengger* observed a distinct temperature 
in Melolonthce when many of them were collected together in an earthen vessel, but 
could not detect a distinct temperature in water-insects, or in Caterpillars. JucH-f~ 
likewise made observations on the temperature of the bee-hive, the ant-hill, and on 
the common Blister-flies. In a vessel containing a large quantity of the latter in 
sects, the Lyttce , he found the thermometer rise several degrees above the tempe- 
rature of the atmosphere. Br. Davy, according to Berthold^:, in making observa- 
tions on several species of insects, Scarabceus pilularis, Lampyris , Blatta, Gryllus , 
and Apis, found only a slight difference, except in the Gryllus, in which the difference 
amounted to five or six degrees, while in the Scorpion and Centipede he found a 
temperature lower than that of the atmosphere. Dr. Burmeister, in his Manual, 
recently translated by Mr. Shuckard, has spoken of the temperature of insects, but 
only of insects in society, and has referred to the observations of Juch, Reaumur, 
&c., and although he believes in the existence of individual temperature in insects, 
has given no observation of his own to prove the fact, while Dr. Berthold, in the 
work just noticed, (experiment 59,) made on a single insect, could not detect it, nor 
could he do so in every species when the observation was made on a number of indi- 
viduals collected together. It is evident, therefore, that although the existence of 
individual temperature is inferred from experiments on insects collected together, 
it yet remains to be proved that every individual insect in a state of activity invariably 
maintains a certain amount of temperature, which is readily appreciable by the in- 
struments we are enabled to employ. 
Before detailing the results of my observations it is necessary to explain the manner 
in which the observations themselves have been made, and to point out those circum- 
stances which seem to have been overlooked by other inquirers in their experiments 
on the temperature of insects. It is only by a careful attention to those circum- 
stances that we are enabled to detect the existence of temperature in single insects, 
and to understand the causes of its variations at different periods. 
The thermometers employed by me on every occasion are of the smallest possible 
calibre, with cylindrical bulbs about half an inch in length, and scarcely larger than 
crow-quills, and are similar to those employed by Professor Daniel for the purpose of 
ascertaining the dew point. They were made by Mr. Newman of Regent Street, and 
are graduated from zero, or from a few degrees below freezing to about 1 10° or 120°. 
Whenever great delicacy of observation is required, in order to observe the varying 
temperature of an insect during a state of partial rest, it is necessary to use the same 
instrument for ascertaining the temperature of the atmosphere as for that of the in- 
sect, otherwise a great difficulty will arise, from the well known circumstance that 
two thermometers, be they ever so delicately constructed, and carefully compared 
* Physiologische Untersuchungen iiber die thierische Haushaltung der Insecten. Tubingen, 1817, p. 39. 
t Ideen zu einer Zoochemie, Bd. 1. 1800, p. 92. 
+ Neue Versucbe, &c. p. 12, 13. 
2 M 2 
