296 
MR. NEWPORT ON THE TEMPERATURE OF INSECTS. 
introduced a small thermometer without disturbing the inmates, and found that the 
temperature of the interior of the nest was 83°, but in a few minutes it rose to 85°; 
it was thus evident that the temperature of the nest upon which I had made the pre- 
ceding observations was at about its average temperature in its natural haunts. 
3. Nurse Bees. — Voluntary Power of generating Heat. 
The above experiments on the nest of Bombus terrestris thus confirmed the results 
of my observations made a short time before on individual insects with regard to 
the rapid transmission of heat from the body of the animal when in a state of 
excitement, and also in a less degree when in a state of rest ; but during the time I 
was engaged upon them they also afforded me a new and totally unexpected phe- 
nomenon, and one which is not a little interesting and important as regards its con- 
nection with the origin of animal heat ; — it was the capability which these insects 
possess during the act of incubation on the cells which contain nymphs, of increasing 
their own temperature many degrees above that of the surrounding medium, of in 
fact a voluntary power of generating heat through means of respiration. Huber has 
stated that there are certain individuals in the nests of the Humble Bees, and among 
the bees in a hive, which at a particular season of the year are employed to impart 
warmth from their bodies to the young bees in the combs by brooding over them, 
and these he called Nurse Bees. It gives me great pleasure in being able to bear 
testimony to the correctness of his statement, particularly with regard to those in the 
nest of the Humble Bee, which I had ample opportunity of observing. These indi- 
viduals are chiefly the young female bees, and at the period of the hatching of nymphs 
they seem to be occupied almost solely in increasing the heat of the nest and com- 
municating warmth to the nymphs in the cells by crowding upon them and clinging 
to them very closely, during which time they respire very rapidly, and evidently are 
much excited. These bees begin to crowd upon the cells of the nymphs about ten 
or twelve hours before the nymph makes its appearance as a perfect bee. The incu- 
bation during this period is very assiduously persevered in by the Nurse Bee, who 
scarcely leaves the cell for a single minute ; when one bee has left another in genera! 
takes its place : previously to this period the incubation on the cell is performed only 
occasionally, but becomes more constantly attended to the nearer the hour of develop- 
ment. The manner in which the bee performs its office is by fixing itself upon the 
cell of the nymph, and beginning at first to respire very gradually ; in a short time 
its respiration becomes more and more frequent, until it sometimes respires at the 
rate of 120 or 130 in a minute. I have seen a bee upon the combs perseveringly 
continue to respire at this rate for eight or ten hours, at the expiration of which time 
its body has become of a very high temperature, and on attentive observation the 
insect is often found in a state of great perspiration ; when this is the case the bee 
generally discontinues her office for a time, and another individual will sometimes 
take her place. Very frequently the Nurse Bee respires with much less rapidity, and 
