SENSITIVE PLANTS. The best known is 3firnosa pudica. A knock upon the ground at a short distance from the plant is sufficient to produce an influence on its leaves. Bichloride of mercury, sulphuric acid, caustic potash, etc., applied to the knots of the joints set the leaves in 'notion. The removal of the plant to a higher temperature, as well as exposing it to a lower temperature or a draught of cold air, produce the• mine result. They are destroyed by the application of chloro form and other anmsthetic agents. Its leaflets rapidly fold together and droop when touched, and its leaf-stalk, to its base, droops downwards. On the approach of evening, the foliage of this plant assumes the same appearance. Besides M. pudica, the AI. sensitiva, M. viva, 3f. casta, M. aspemta, M. quadrivalvis, 3f. Pernambucana, M. pigra, 31. hut-Lillis, 3f. peltata, 31. dormiens, possess the same property, though not in so re markable a degree. Species of other genera of the Leguminosm exhibiting these movetnents are Smithia sinsitiva, tEschynomene Indica, ./E. pumila, and Desmanthus stolonifer. The locust tree, when its branche,s are roughly shaken, closes up its leaves, and tho same has been ob served of Gleditschia triacantha. Oxalis sensitiva, mlled by De Candollc, on account of its sensitive properties, Biophyturn, has long been known to possess this property. Oxalis strieta, if hit smartly on a warm day, will contract its leaves and assume a position as in the ordinary sleep of the leaves of these plants; aud the same movements occur in O. acetosella, O. corniculata, and ninny other species.
The movements in these plants consist in the folding up of their leaves, so that the two halves of the leaf approach each other by their upper surface. The midrib is also slightly bent, so that its inferior surface presents a convexity ; and the petioles of the leaflets bond downwards, so that the leaf, when irritated, becomes dependent. Averrhoa bilimbi and A. cammbola fold their leaves on the application of a sthnulus. The leaves of Dioncea muscipula or Venus fly-trap contract upon insects that nifty happen to alight upon their surface. The surface of their leaves is covered with long hairs, which secrete a viscous matter. When any insect settles upon the leaf, it is entangled with the viscous secretions, and before it has tirne to escape, the hairs exhibit a eonsidemble degree of irritability, ruid, curving round, en the animal down on the surface of the leaf. ther instances of vegetable irritability occur in the Berberis vulgaris, aud Stylidium. In the Destnodium gyrans, one of the Fabacere called the telegraph plant, a native of the Ea.st Indies, the large terminal leaflet when exposed to the bright light of the sun, forms a direct and continuous line with its leaf-stock, but is inanifestly depressed if placed in the shade for a few minutes. Its position varies with the in crease or decrease of light durino. the day.— Bulletins de l'Academie Royale de Bruxelles, vi. in Eng. Cyc.; Chambers' Journal, 1863.