File:The natural history of plants, their forms, growth, reproduction, and distribution; (1902) (14596746539).jpg

Identifier: naturalhistoryof01kern (find matches)
Title: The natural history of plants, their forms, growth, reproduction, and distribution;
Year: 1902 (1900s)
Authors: Kerner von Marilaun, Anton, 1831-1898 Oliver, Francis Wall, 1864- Macdonald, Mary Frances Ewart Busk, Marian Balfour, Lady
Subjects: Botany
Publisher: London, Blackie
Contributing Library: NCSU Libraries
Digitizing Sponsor: NCSU Libraries

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twenty days. Although PLANTS WHICH EXHIBIT MOVEMENTS IN THE CAPTURE OF PREY. 151 the larger live articulated animals—earwigs, millipedes, and dragon-flies—caughtupon the upper surface of the leaf, cause the lobes to slam together, they are ableto slip out if part of their bodies projects beyond the toothed margin, for the teethare flexible and yield to strong pressure. But small creatures are hopelessly lostwhen the lobes have closed over them. They are at once suffocated in the liquidwhich is poured out copiously by the glands and are then dissolved and absorbedwith the exception of their claws, leg-bones, chitinous rings, &c., which are incapableof being digested. In spite of the identity of aim and of result, the mechanism of a Dioncea leafdiffers very materially from that of the sun-dew leaf described above. Division oflabour is carried much further in the Fly-trap. The pre-eminently sensitivestructures, viz., the six filaments situated upon the upper surface of the leaf,
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Fig. 29.—Aldrovandia vesiculosa. do not act also as digestive glands. Again, the long sharp teeth at the edgeof the leaf, which correspond in position to the marginal tentacles of a sun-dew leaf,carry no glands, and only serve to close the trap securely when an animal has beencaught. Accordingly in Bioncea there exist special structures for three differentfunctions, namely, stimulation, seizure, and digestion, whilst in the case of Droseraall these functions belong to the gland-bearing tentacles alone. The stimulus actingon the sensitive filaments on the leaf of the Fly-trap is liberated in the form of arapid motion of the lobes and a discharge of digestive fluid from the glands, andthis discharge of secretion ensues therefore through the mediation of cells wdiichhave not themselves been directly excited. The process here again is much morestriking than in the sun-dew leaf. The transmission of stimulus, though as a factidentical in the two plants we are comparing, proceeds at any ra

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