portant ingredient in those fine ales which are brewed in Scotland; and certainly it must add not a little to the nutritive qualities of that wholesome beverage.
It will not, perhaps, be considered out of place to take notice here of the Honey-dew. When the close of summer happens to be hot and sultry, and the air calm, the bees find a large supply of food on the leaves of certain plants and trees. This is the honey-dew. It is believed, generally, to be an exudation of the surplus sap of trees, by means of the pores of the upper surface of the leaves; and is most frequently found in the oak, the elm, the plane, the lime, and the beech, and also in many fruit-trees and ever-green plants. The idea has been entertained of its falling from the atmosphere; and perhaps the supposition is, in a certain sense, not altogether without foundation, nor inconsistent with the notion of its being originally a vegetable exudation. Certain it is that, in very sultry evenings, we have observed not only the leaves of trees shining with the liquid, but the dry stones also and gravel completely bespotted with it, as if it had fallen in a gentle shower or dew. White of Selbourne regarded it 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. Curtis[1] is of opinion that it is neither an exudation of the sap of trees, nor falls from the atmosphere, but that the true and only source of this saccharine matter is to be found in the insect Aphis, or vine-
- ↑ Linnæan Transactions, vol. vi. page 75.
