The term +honey-dew+ is applied to those sweet clammy drops that glitter on the foliage of many trees in hot weather. The name of this substance would seem to import, that it is a deposition from the atmosphere, and this has been the generally received opinion respecting it, particularly among the ancients; it is an opinion still prevalent among the husbandmen, who suppose it to fall from the heavens: +Virgil+ speaks of "Aërii mellis cœlestia dona:" and +Pliny+ expresses his doubts, "sive ille est cœli sudor, sive quædam siderum saliva, sive purgantis se aëris succus." The Rev. +Gilbert White+, in his Naturalist's Calendar, regards honey-dew as the effluvia of flowers, evaporated and drawn up into the atmosphere by the heat of the weather, and falling down again in the night with the dews that entangle them. But if this were the case, the fall would be indiscriminate, and we should not have it confined to particular trees and shrubs, nor would it be found upon green-house and other covered plants. Some naturalists have regarded honey-dew as an exudation or secretion from the surface of those leaves upon which it is found, produced by some atmospheric stroke, which has injured their health. +Dr. Darwin+ stands in this class. Others have viewed it as a kind of vegetable perspiration, which the trees emit for their relief in sultry weather; its appearance being never observed in a cold ungenial summer. Dr. +Evans+ is of this opinion, and makes the following comparative remark: "As the glutinous sweat of the negro enables him to bear the fervours of his native clime, far better than the lymph-perspiring European; so the saccharine dew of the orange, and the fragrant gum of the Cretan cistus, may preserve them amidst the heats even of the torrid zone." Mr. +Curtis+ has given it as his opinion that the honey-dew is an excrementitious matter, voided by the aphis or vine-fretter, an insect which he regards as the general cause of what are called blights. He assures us that he never, in a single instance, observed the honey-dew unattended with aphids.