File:The structure and development of mosses and ferns (Archegoniatae) (1918) (14782633154).jpg

Identifier: structuredevelop00camp3 (find matches)
Title: The structure and development of mosses and ferns (Archegoniatae)
Year: 1918 (1910s)
Authors: Campbell, Douglas Houghton, 1859-1953
Subjects:
Publisher: New York, Macmillan
Contributing Library: The LuEsther T Mertz Library, the New York Botanical Garden
Digitizing Sponsor: The LuEsther T Mertz Library, the New York Botanical Garden

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magnified; B, an archegonial branch, X40; C, cells from the margin ofthe archegonial branch showing the oil bodies (0), X300. to grow equally, when the thallus shows a marked forking(M. furcata), or one of the branches grows more strongly thanthe other, which is thus forced to one side and appears like alateral branch (Aneura pinnatiiida, Fig. 41, B). In certain species of Pallavicinia and Symphyogyna, andespecially in Hymenophyton (Fig. 38, B), the gametophyteshows a differentiation into a prostrate rhizome-like sterj, 88 MOSSES AND FERNS CHAP. from which arise upright flattened shoots which are repeatedlyforked, so that there is a remarkably close superficial resem-blance to the fan-shaped leaves of certain Ferns, especiallysome of the smaller Hymenophyllacese. This resemblance isheightened by the very distinct midrib traversing each thallus-segment. Sexual Organs. The sexual organs in both Aneura and Met2geria are borneon short branches, which in the latter arise as ventral struc-
Text Appearing After Image:
FiG. 40.-^Aneura pinnatiUda. A, Horizontal section of the apex of a young antheridialbranch, X565; x, the apical cell; (^, antheridia: B, transverse section of a youngarchegonial branch, passing through the apical cell (x); J, young archegonia,X525; C, longitudinal section of a nearly ripe archegonium, X262; D, E,spermatozoids of Pellia calycina, X1225 (D, E, after Guignard). tures, but in Aneura are simply ordinary branches that arechecked in their growth by the production of the sexual or-gans, and not infrequently may grow out into ordinarybranches after the formation of the sexual organs has ceased.In A. pinnatifida (Fig. 39, B), archegonia and antheridia areusually produced upon separate branches, but may occur to-gether. The origin of the antheridia can be readily followed in Ill THE JUNGERMANNIALES 89 sections made parallel to the surface of the male branch. Theapex is occupied by an apical cell of the usual form, and thecell divisions in the young segment arc extremely regular

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