PERSPIRATION OF LEAVES. 141 



The above is certainly a very small part of the use 

 of leaves. Yet the observations of this writer, the 

 father of botanical philosophy among the moderns, are 

 so far correct, that if the leaves of a tree be stripped 

 off, the fruit comes to nothing, which is exemplified 

 every year in Gooseberry bushes devoured by cater- 

 pillars; and though the fruit-trees of warm climates, 

 partly naturalized with us, Grapes and Peaches for 

 instance, ripen their fruit sooner perhaps if partially 

 deprived of their leaves ; yet if that practice be carried 

 too far, the fruit perishes, as gardeners who tried it 

 soon discovered. The White Mulberry indeed, culti- 

 vated in the south of Europe 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 fail 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 



ft O 



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 in- 

 sensible perspiration, is proved by the simple experi- 

 ment of gathering the leafy branch of a tree, and im- 

 mediately stopping the wound at its base with mastic k, 



