The upper surface of leaves, which I suppose to be their organ of respiration, seems to require light as well as air; since plants which grow in windows on the inside of houses are equally sollicitous to turn the upper side of their leaves to the light. Vegetables at the same time exsude or perspire a great quantity from their leaves, as animals do from their lungs; this perspirable matter as it rises from their fine vessels, (perhaps much finer than the pores of animal skins,) is divided into inconcievable tenuity; and when acted upon by the Sun's light appears to be decomposed; the hydrogene becomes a part of the vegetable, composing oils or resins; and the Oxygene combined with light or calorique ascends, producing the pure part of the atmosphere or vital air. Hence during the light of the day vegetables give up more pure air than their respiration injures; but not so in the night, even though equally exposed to warmth. This single fact would seem to shew, that light is essentially different from heat; and it is perhaps by its combination with bodies, that their combined or latent heat is set at liberty, and becomes sensible. See additional note, XXXIV.] [_Electric torrents pour_. l. 463. The influence of electricity in forwarding the germination of plants and their growth seems to be pretty well established; though Mr. Ingenhouz did not succeed in his experiments, and thence doubts the success of those of others. And though M. Rouland from his new experiments believes, that neither positive nor negative electricity increases vegetation; both which philosophers had previously been supporters of the contrary doctrine; for many other naturalists have since repeated their experiments relative to this object, and their new results have confirmed their former ones. Mr. D'Ormoy and the two Roziers have found the same success in numerous experiments which they have made in the last two years; and Mr. Carmoy has shewn in a convincing manner that electricity accelerates germination. Mr. D'Ormoy not only found various seeds to vegetate sooner, and to grow taller which were put upon his insulated table and supplied with electricity, but also that silk-worms began to spin much sooner which were kept electrified than those of the same hatch which were kept in the same place and manner, except that they were not electrified. These experiments of M. D'Ormoy are detailed at length in the Journal de Physique of Rozier, Tom. XXXV. p. 270. M. Bartholon, who had before written a tract on this subject, and proposed ingenious methods for applying electricity to agriculture and gardening, has also repeated a numerous set of experiments; and shews both that natural electricity, as well as the artificial, increases the growth of plants, and the germination of seeds; and opposes Mr. Ingenhouz by very numerous and conclusive facts. Ib. Tom. XXXV. p. 401.