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Show 288 DIONJEA MUSCIPULA. .CHAr. XIII. twenty to thirty polygonal. cells, fille~ with purple fluid. Their upper surface l~ conv~x. rhey stand on very sh or t Pedl.cels ' into wh1.c h spual vessels do not t · hich respect they d1ffer from the tentacles of en er, 1n w · d b h Drosera. They secrete, but only when excite y t e a b sorp t1. on of cer·ta1·n matters. ·' an. d .t hey have the po.w er of absorption. Minute p~·oJect1ons, for~ed. of e1ght divergent arms of a redd1sh-brown ~r orange col_our, and a earing under the microscope hke elegant httlc fl owerps,p are scattered in considerable nu1nbersh over. kth e foot-stalk, the backs of the leaves, and t e srl es, with ·a few on the upper surface of the lobes .. rhese t fid projections are no doubt homologous w1th the ;~;llre on the leaves of Drosera rotundif~lia. Th~re are also a few very minute, simple, po1nted haus, a b ou t -nro_7 0_ 0 (·0148 mm.) of an inch in length on the backs of the leaves. The sensitive fila1nents are formed of several rows of elongated cells, filled with p~rplis~ fluid. They are a little above the '1. 1 0 of an 1nch 1n length; are thin and delicate, and taper to a point. I exa1nined the bases of several, making sections of them, but no trace of the en trance of any vessel could be seen. The apex is sometimes bifid or even trifid, owing to a slight separation between the terminal pointed cells. Towards the base there is constriction, formed of broader cells, beneath which there is an articulation, supported on an enlarged base, consisting of differently shaped polygonal cells. As the filaments project at right angles to the surface of the leaf, they would have been liable to be broken whenever the lobes closed together, had it not been for the articulation which allows them to bend fiat down. These filaments, from their tips to their bases, are ex-quisitely sensitive to a momentary touch. It is scarcely CHAP. XIII. SENSITIVENESS OF FILAMENTS. 289 possible to touch them ever so lightly or quickly with any hard object without causing the lobes to. close. A piece of very delicate human hair, 2~ inches in length, held dangling over a filam nt, and swayed to and fro so as to touch it, did not excite any n1oven1ent. But when a rather thick cotton thread of the same length was similar! y swayed, the lobes closed. Pinches of fine wheaten flour, dropped from a height, produced no effect. The above-mentioned hair was then fixed into a handle, and cut off so that 1 inch projected; this length being sufficiently rigid to support itself in a nearly horizontal line. The extremity was then brought by a slow movement laterally into contact with the tip of a filament, and the leaf instantly closed. On another occasion two or three touches of the same kind were necessary before any movement ensued. When we consider how flexible a fine hair is, we may form some idea how slight must be the touch given by the extremity of a piece, 1 inch in length, moved slowly. Although these filaments are so sensitive to a momentary and delicate touch, they are far less sensitive than the glands of Drosera to prolonged pressure. Several times I succeeded in placing on the tip of a filament, by the aid of a needle moved with extreme slowness, bits of rather thick human hair, and these did not excite n1ovement, although they were 1nore than ten times as long as those which caused the tentacles of Drosera to bend; and although in this latter case they were largely supported by the dense secretion. On the other hand, the glands of Drosera Ina y be struck with a needle or any hard. object, once, twice, or even thrice, with 'considerable force, and no movement ensues. This singular difference in the nature of the sensitiveness of the fila1nents of Dionrea and of u |