| OCR Text |
Show 322 ALDROV ANDA VESIOULOSA. CIIAP. XIV. tainin<Y numerous crustaceans of the genus Cypris, and next ~orning many were found imprisoned and alive, still swimming about within the closed leaves, but doomed to certain death. Directly after reading Prof. Cohn's me1noir, I re-ceived through the kindness of Dr. Ho?ker living plants from Germany. As I can add nothing to Prof. Cohn's excellent description, I will give only two illustrations, one of a whorl of leaves copied from his work, and the other of a leaf pressed flat open, drawn by my son Francis. I will, however, ~ ppend a few re1narks on the differences between th1s plant and Dionroa. Aldrovanda is destitute of roots and floats freely in the water. The leaves are arranged in whorls round the stem. Their broad petioles terminate in from four to six rigid projections,* each tipped with a stiff, short bristle. The bilobed leaf, with the midrib likewise tipped with a bristle, stands in the midst of these projections, and is evidently defended by them. The lobes are formed of very delicate tissue, so as ro be translucent; they open, according to Cohn, about as much as the two valves of a living mussel-shell, therefore even less than the lobes of Dioncca ; and this must make the capture of aquatic arfimals more easy. The outside of the leaves and the petioles are covered with minute two-armed papillre, evidently answering to the eight-rayed papillre of Dionma. Each lobe rather exceeds a semi-circle in convexity, and consists of two very different concentric portions; the inner and lesser portion, or that next to the midrib, * '.rhere has been much discussion by botanists on the homological nature of these projections. Dr. Nitsehke ('Bot. Zeitung,' . 1861, p. 146) believes that .they correspond with the fimbnated scale-like bodies found at the bases of the p~tiolcs of Drosera . . CHAP. XIV. ALDROV ANDA VESIOULOSA. 323 is slightly concave, and is formed, according to Cohn, of three layers of cells. Its upper surface is studded with colourless glands like, but more simple than, · those of Dionrea; they are supported on distinct footstalks, consisting of two rows of cells. The outer FIG. 13. (.Aldrovanela vesiculosa.) Upper figure, whorl ofleaves (from Prof. Cohn). Lower figure, leaf pre!'scd flat open and greatly enlarged. and broader portion of the lobe is flat and very thin, being formed of only two layers of cells. Its upper surface does not bear any glands, but, in their place, small q uadri:fid processes, each consisting of four tapering projections, which rise from a con1n1on y 2 |
