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XVI NoTE XXXVII. VEGETABLE RESPIRATION. q4srt

deipht the ſtems and middle rib of the leaves are ſometimes na-

erte; turally coloured reddiſh, and hence the colour of the mad-

umd der ſeemed to paſs further into the ramifications of their

Me 4 leaf-arteries, and was there beautifülly viſible with the

made, returning branches of milky veins on each ſide.

WR 11 3. From theſe experiments the upper ſurface ofthe leaf

„135 WE] appeared to be the immediate organ of reſpiration, be-

mum)| Cauſe the coloured fluid was carried to the extremities

unter of the leaf by veſſels moſt DILEIEN on the vpper ſur-

walhe]; face, and there changed into a milky fluid, which is the

1,9: blood of the plant, and then returned by concomitant

middle veins on the under ſurface, which were ſeen to ooze when

divided with ſciflars, and which, in Picris particularly,

btn|. render the under ſurface of the leaves greatly whiter than

9 from the upper one. 4 er fide 4. As the upper ſurface of leaves conſtitutes the organ|] nf che of reſpiration, on which the ſap 13 expoſed in the termi-| eſel nations of arteries beneath a thin pellicle to the adtion of, j ww the atmoſphere, theſe ſuriaces in many plants ſtrongly re-| ere pel moiſture, as cabbage-leaves, whence the particles cf j 08 Of rain 1ying over their ſurfaces without touching them, as

| gloyr obſerved by Mr. Melville(Eflays Literary and Philoſoph.

lüb Edinburgh) have the appearance of globules of quick-

AC ſilver. And hence leaves laid with the upper ſurfaces on

0“ water, wither as ſoon as in the dry air, but continue green jen many days, if placed with the under ſurfaces on water, as je| appears in the experiments of Monſ. Bonnet(Uſage des ae|“4,:'

Feuilles.) Hence ſome aquatic plants, as the water-Iily

„u(Nymphaea) have the lower ſides of their leaves Qoating on

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