12 ABSORPENF VESSERLS: SCT. 7.

feen to bleed out haftily a milky juice, and at once evinced both the abforbent and artertal fyftem.

Many fimilar experiments were made by M. Bonnet, by placing parts of the fterm or roots of various vegetables, as of kidney-beans, peach-tree, and elder, in dilute ink; in all thefe the vefñels of the bark were uncoloured, and thofe of the pith; but thofe beneath the bark, which he terms woody, were coloured black, which I fuppofe to have been the circlé of abforbent veflels above mentioned. Ufage de Feu- illes, Plate XXIX.

3. T'hefe abforbent vefels have been called bronchia by Malpighi and Grew, and fome other philofophers, and erroneoufly thought to

e air-veflels; in the fame manner as the arteries of the human body were fuppoled to convey air by the antients, till the great Harvey by more exa€t experiments and jufter reafoning evinced, that they were blood-veffels. This opinion has been fo far credited becaufe air 1$ feen to iflue from wood, whether it be green or dry, if it be covered with water, and placed in the exhaufted receiver of an air- pump; and thefe veflels have therefore been fuppofed to conftitute a vegctable refpiratory organ; but it will be fhewn hereafter, that the leaves of plants are their genuine lungs, and that the abforbent veflels

and arteries become accidentally filled with air in the dead parts of vegetables.

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For as the veffels of vegetables are very minute, and have rigid coats, their fides do not collapfe when they are cut or broken, as their juices flow out or exhale; they muft therefore receive air into them. This may be readily feen by infpettins with a common lens tbe end of a vine-ftalk two or three years old, when cut off hori- Zontally. At firft the veffels, which are feen between the partitions radiated from the center, appear full of juice; but in a minute or lefs this juice either pañles on, orexhales; andthe vefels appear empty, that is filled with air. This experiment I have twenty times repeated

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