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PLATE EL

Fic. x. reprefents the umbilieal veffels fpread on the lobes of a bean, when it begins to vegetate, as mentioned in Seét. I. 7. but more particularly defcribed in Seët. III. 1. 3; which are believed to confift of a fyftem of abforbent veffels, and another fyftem of placental veffels, for the purpofe of acquiring nutriment, and of oxygenating the vege- table blood. The plate is copied from Grew, Tab. I. f 14. a the plumula, à the cor- culum, cc the lobes. See Se&. I. 7. and III. 1.3.

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Fic. 2. is copied from Malpighi, Tab. II. Fig. 6, and reprefents the longitudinai fibres of the bark of willow, which adhere tosether, and feparate from each other alter- vately, with horizontal apertures between them; which are believed to be air-veffels, for the purpofe of oxygenating the blood of the embryon buds, like the air-bag at the broad end of an egg. b b b are the longitudinal filaments of the bark, a a a are the ho- rizontal perforations.

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Duhamel obferved by a microfcope fimilar apertures of different diameters in the bark of oak; the fmaller ones he believed to be the excretory duéts of the perfpirable matter, and larger ones I fuppofe to be air-veffels. The extremities of fome of thefe in the birch- tree ftood above the level of the cuticle. Phyfique des Arbres, Plate I. Fig. 7. and 15, See Seét. I. 7. and IT, 4. of this work.

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