. The physiology of the domestic animals; a text-book for veterinary and medical students and practitioners. Physiology, Comparative; Domestic animals. 72 PHYSIOLOGY OF THE DOMESTIC ANIMALS. turgescence of certain cells, and has nothing in common with animal motion. The Dionsea muscipula, or Venus' Fly-Trap, furnishes another illus- tration of movement of parts occurring in the vegetable kingdom. The form of the bilobed leaf, which is the movable part of this plant, is shown in Pig. 45. The two lobes stand at rather less than a right angle to each other, and on each of the inner surfaces are t
. The physiology of the domestic animals; a text-book for veterinary and medical students and practitioners. Physiology, Comparative; Domestic animals. 72 PHYSIOLOGY OF THE DOMESTIC ANIMALS. turgescence of certain cells, and has nothing in common with animal motion. The Dionsea muscipula, or Venus' Fly-Trap, furnishes another illus- tration of movement of parts occurring in the vegetable kingdom. The form of the bilobed leaf, which is the movable part of this plant, is shown in Pig. 45. The two lobes stand at rather less than a right angle to each other, and on each of the inner surfaces are three minute filaments projecting inward. The margins of the leaf are prolonged into spikes, into each of which a bundle of spiral vessels enters. When any one of these filaments is touched, even by so slight a pressure as would be produced by contact with a hair, the leaves instantly come into apposition, and the spikes interlock like the teeth of a rat-trap. The upper surface of the leaf is covered with minute glands, which furnish a secretion having the power of digesting organic substances. When insects come in contact with these filaments, the leaves close so as to imprison them, and the insects are digested by the acid secretion stimulated by their contact, and absorbed. In this plant the chief seat of the movement is in the thick mass of cells which overlies the central bundles of vessels in the mid-rib. When any one Fio. 45.—Venus' Fly-Trap (Dioncea muscipula). of these filaments Oil the in- Leaf Viewed Laterally in its Expanded , , r „ ,, , state. (Dariviii.) ternal surface ot the leaves is touched the impulse travels in all directions through the cellular tissue, independently of the course of the vessels, to the cells at the mid-rib. Fluid thus flowing from the upper cells to the lower, the lower cells greatly increase in tension, while the upper ones become relaxed and the leaves come into apposition. Opening of the leaves is accomplished by a reverse process. In
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectphysiol, bookyear1890
