Wonderful as this power of ventilation may be, these singular insects possess a still more extraordinary power, that of increasing heat at will. There are some periods when the temperature of the live is absolutely required to be much higher than at other times. Just when the infant bee is about to burst from its cell, the heat of the hive is considerably raised, as the young bee when it emerges is peculiarly sensitive to cold, its soft, sleek body perspiring most profusely, and covered with moisture. Immediately upon leaving its cell, it instinctively makes its way to the thickest throng of bees, and eagerly seeks for that warmth which is necessary to bring its feeble body to its proper tone, nor is it until after the lapse of some hours that its body attains sufficient firmness to render it independent of the external heat derived from the bees in the live. The necessary amount of caloric is furnished by that portion of the worker-bees called nurse-bees, and the manner in which it is managed is told in the following extract, taken from Mr. Newport's report of his experiments on this subject :- "These individuals," the nurse-bees, " are chiefly young female bees, and at the period of hatching of nymphs they seem to be occupied almost solely in increasing the heat of the nest, and communicating warmth to 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 incubation 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 general, takes its place. Previously to this period the incubation on the cell is performed only occasionally, but becomes more constantly attended to nearer the hour of the development. The manner in which the nurse-bee performs its office, is by fixing itself upon the cell of the nymph, and beginning to respire very gradually; in a short time its respiration becomes more and more frequent, until it sometimes respires at the rate of 130 or 140 per minute." In further experiments on this subject a common humble-bee was confined in a phil containing three cubic inches, and was found by its violent excitement consequent on being thus imprisoned, to have added no less than four degrees of the temperature to the air in the bottle in a space of five minutes. As, therefore, violent excitement produces heat, so inactivity causes heat to be lost, and on that account, the temperature of hybernating bees is very low. According to Mr. Newport, the contradictions of former observers respecting the heat of the hive during winter is easily accounted for by this power of changing the temperature at will. When the hive is at rest, the temperature is usually only a few degrees above that of the external atmosphere, but if the inhabitants are disturbed, the temperature immediately rises. The swarming season, of course, renders the hive extremely hot, as almost every bee, particularly those who intend to form the swarm, is in a violent state of excitement. In one experiment, when the temperature of the external atmosphere was \(34
rac{1}{3}\) degrees, the temperature of an undisturbed hive was found to be \(48
rac{1}{3}\) degrees, while that of a hive whose inhabitants had been thrown into a state of great indignation, by tapping on the exterior, speedily rose to 102 degrees.