Evolution Of Sex In Plants Classic Reprint PDF Download

Excerpt from Fecundation in Plants This volume presents the subject of fecundation in the vegetable kingdom by the discussion of concrete cases, selecting from the great groups of plants certain typical representatives in which the sexual process seems to have been most thoroughly investigated. In the introductory chapter I have discussed typical processes of nuclear division and cell-formation, especially in spore mother-cells, together with a few topics dealing with certain phenomena of the cell and the significance of sexuality. This is considered necessary to a better understanding of sexual reproduction, for problems of sexuality, like problems of evolution, have in late years become reduced to problems of the cell, and, since the nucleus plays by far the most important part in fecundation, I am tempted to say to problems of the nucleus. The processes leading to the development and differentiation of the gametes have been regarded as of prime importance, and they have therefore received emphasis. Whenever the subsequent history of the fecundated egg has been followed to any extent this has been done, as in the Ascomycetes and Floridecae, to show the relation between the real sexual process and the vegetative fusion of nuclei which has been confused with the sexual act, and, as in the Desmids, for the sake of pointing out certain nuclear phenomena that take place during the germination of the zygote with similar phenomena just preceding the sexual act in the Diatoms. Processes which are purely morphological are assumed or dealt with very briefly. In grouping the representative types into the several chapters I have had in mind no particular theory of the evolution of sexuality, but merely the idea of the evolution of the plant kingdom and the corresponding differentiation of the sexual organs and cells accompanying this evolution in the groups of plants themselves. The chapters dealing with the lower plants in which the development of the gametes is not known from a modern cytological standpoint, and in which the behavior of the sexual nuclei in the fusion of the gametes has not been followed - have been made as brief as possible. For a similar reason the mosses and liverworts have been omitted entirely. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works."