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 Rh for the food of silkworms only, bears wonderfully the loss of its foliage three or four times a year. How far the fruit is injured nobody thinks it worth while to inquire, as it is never eaten, but it certainly does not fall off prematurely.

That Leaves imbibe and give out moisture has been long known, this being one of the most obvious facts belonging to them. Dr. Hales thought they might probably imbibe air; but since his time more certain discoveries have been made concerning this point, as well as the effects of light upon leaves, which also did not escape the consideration of that great philosopher. All these subjects we shall mention in their turn.

That Leaves give out moisture, or are organs of insensible perspiration, is proved by the simple experiment of gathering the leafy branch of a tree, and immediately stopping the wound at its base with mastick, wax, or any other fit substance, to prevent the effusion of moisture in that direction. In a very short time the leaves droop, wither and are dried up. If the same branch, partly faded, though not dead, be placed in a very