Page:An introduction to physiological and systematical botany (1st edition).djvu/214

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184
PERSPIRATION OF LEAVES.

crop is produced, and longer, as in the Fir, the Arbutus, and the Bay. It is reported that in hot climates, where there is almost perpetually a burning sun, scarcely any trees lose their leaves, because they require them for shade." Cacsalpinus goes on to show that leaves proceed from the bark, with some remarks on the pith, (in which we may trace the origin of the Linnæan hypothesis of vegetation,) but which are now superseded by more accurate inquiries.

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 caterpillars; 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, cultivated in the south of Eu-