120 
HONEY. 
portant ingredient in those fine ales which are brew- 
ed 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 honev- 
dew. It is believed, generally, to he an exudation 
of the surplus sap of trees, by means of the pores of 
the upper surface of the leaves ; and is most fre- 
quently 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 with- 
out foundation, nor inconsistent with the notion of its 
being originalh' a vegetable exudation. Certain it is 
that, in very sultry evenings, we have observed not 
only the leaves of trees shining with the liquid, hut 
the dry stones also and gravel completely hespotted 
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 atmos- 
phere by the heat of the weather, and falling down 
again in the night with the dews that entangle them. 
Curtis* 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 he found in the insect Aphis, or vine- 
* Linnaean Transactions, vol. vi. page 75. 
