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152 VEGETABLE RESPIRATION. Norz XXXVII NN the water, while the upper ſurfaces remain dry in the 9 alr. pu 5. As thoſe inſe&s, which have many ſpiracula, or iv breathing apertures, as waſps and flies, are immediately zun ſuffocated by pouring oil upon them, I carefully covered€ with oil the ſurfaces of ſeveral leaves oſPhlomis, of Por-| u tugal Laurel, and Balſams, and though it would not re-| wer gularly adhere, I found them all die in a day or twO. füh) Of aquatic leaves, ſce Note on Trapa and on Fucus, dept

;n Vol IL. to which muſt be added that many leaves are au furniſhed with muſcles about their footſtalks, to turn their( in upper ſurfaces to the air or light, as Mimoſa and Hedyſa- Im rum gyrans.» From all theſe analogies I think there can re be no doubt but that leaves of trees are their lungs,| p giving out a phlogiſtic material to the atmoſphere, and| abſorbing oxygene or vital air.| d 6. The great uſe of ligat to vegetation would appear| to! from this theory to'be by diſcngaging vital air from the ſüß water which they perſpire, and thence to facilitate its| te) union with their blood expoſed beneath the thin ſurface wi of their leaves; ſince when pure air is thus applied, it 1S MT probable, that it can be more readily abſorbed. Hence a in the curious experiments of Dr. Prieſtley and Mr. Ingen-" houz, ſome plants purified air leſs than others, that 18, they m perſpired leſßs in the ſunſhine; and Mr. Scheele found en that by putting peas int0 Water, which about half-covered|: 0 them, they converted the vital air into fixed air,„or.Car-" bonic acid gas, in the lame manner 2s in animal relpira- A tion. See Note XXXIV.| >. The circulation inche lungs or leaves of plants 15 mi

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