. Lectures on the evolution of plants. Botany; Plants. THE FERNS 129 phyte may be described as amphibious, inasmuch as it must become aquatic, so to speak, in order that fertili- zation may be effected. The spermatozoid, attracted by the substance ejected from the open archegonium, swims to it and makes its way through the canal in the neck to the central cavity, where it quickly pene- trates the egg- cell and slowly fuses with its nucleus, after undergoing a se- ries of changes. As a result of fertilization the egg begins to grow, having in the mean time secreted a wall about itself, and thus
. Lectures on the evolution of plants. Botany; Plants. THE FERNS 129 phyte may be described as amphibious, inasmuch as it must become aquatic, so to speak, in order that fertili- zation may be effected. The spermatozoid, attracted by the substance ejected from the open archegonium, swims to it and makes its way through the canal in the neck to the central cavity, where it quickly pene- trates the egg- cell and slowly fuses with its nucleus, after undergoing a se- ries of changes. As a result of fertilization the egg begins to grow, having in the mean time secreted a wall about itself, and thus forms what may be called a spore, comparable to the resting-spore of such green algae as CEdogonium, or to the fertilized egg-cell in the moss archegonium. Like the latter it germinates at once instead of passing through a long dormant period, as in most green algse. The early divisions in the young embryo, developed. Fig. 33.— A, the open archegonium of the ostrich- fern, showing the egg-cell, o, within the venter; B, the antheridium of the same species; C, a free spermatozoid, showing the numerous cilia; D, the fertilized archegonium containing the young embryo sporophyte; E, the archegonium of a liverwort,Biccia, with the young sporophyte, showing the close resemblance between the ferns and mosses in regard to the young sporophyte; F, longitudinal section of an older embryo of the ostrich fern, showing the division into stem, St; leaf, L; root, R; and foot, Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Campbell, Douglas Houghton, 1859-1953. New York, London, The Macmillan company
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Keywords: ., bookcentury1900, bookdecade, booksubjectbotany, booksubjectplants
