Regeneration . us above ^. Same laid horizontally regenerating near base. E. Same with fruiting head cut at base. E^. Twisted piece regenerating at two points. F. Piece of ray ofhead regenerating near base. F^. Same with distal end of ray cut off. Also regeneratingat base. In the lower plants, such as the mosses, the liverworts, the moulds,and the unicellular forms, regeneration also takes place. Vochtinghas shown that pieces from any part of the thallus of a liverwort ^produce new plants. If a cross-piece is cut off, there appears a small ^ Lunularia vulgaris. GENERAL I
Regeneration . us above ^. Same laid horizontally regenerating near base. E. Same with fruiting head cut at base. E^. Twisted piece regenerating at two points. F. Piece of ray ofhead regenerating near base. F^. Same with distal end of ray cut off. Also regeneratingat base. In the lower plants, such as the mosses, the liverworts, the moulds,and the unicellular forms, regeneration also takes place. Vochtinghas shown that pieces from any part of the thallus of a liverwort ^produce new plants. If a cross-piece is cut off, there appears a small ^ Lunularia vulgaris. GENERAL INTRODUCTION 17 outgrowth from the middle of the anterior cut-edge, as shown inFig. 9, A, A^, that gradually enlarges to form a new thallus. It willbe seen from the figures that the whole anterior edge does not growforward, but a new thallus arises from a group of cells at, or near,the anterior edge. These cells are the least-differentiated cells inthe piece, and have softer cell walls than have the other Fig. 10. —After Pringsheim. A. A piece of seta of sporophore of Hypnum ctipressiforme, sendingout protonema-threads. B. Longitudinal section of a piece of the seta of sporopliore ofBryum ccespitosiim. C. Piece of same oi I/ypnu?n cupressl/orme. Moss-plant arising from newprotonema. B. Piece of same of Hypnum serpens with protonema and moss-plant arisingfrom it. Pringsheim has shown that if a piece of the stalk of the sporan-gium of certain mosses is cut off, it produces at its ends thread-likeoutgrowths which are like the protonema-stage of the moss, and fromthis protonema new moss-plants may arise (Fig. 10, A, B, C, D). Braefeld has obtained a somewhat similar result in one of themoulds, in which a piece of the sporangium stalk gives rise to amycelium from which new sporangia may be produced. i8 RE GENERA TION REGENERATION IN EMBRYOS AND EGGS Regeneration takes place not only in adult organisms, but also inembryos, and larvae of many animals. It is often stated that
Size: 1569px × 1592px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookpublisherlondo, bookyear1901
