Ueber das Verhalten des Pollens und die Befruchtungsvorgänge bei den Gymnospermen

Abstract

THIS forms the fourth part of Prof. Strasburger's “Histologische Beiträge,” and it is largely taken up with an examination of segmentation in pollen-grains of the gymnosperms, and the contents of, and processes in, the pollen-tubes. Recent discoveries had led Strasburger to doubt the correctness of his former interpretation of the contents of the pollen-tubes, and his further researches have “confirmed in a surprising manner” the results obtained by Belajeff in his paper on Taxus baccata, entitled “Zur Lebre von den Pollenschläuchen der Gymnospermen.” Strasburger is also essentially in accord with Belajeff's generalisations therefrom. Two double plates illustrate division in the pollen-grain, the development of the pollen-tube, and the further processes of fertilisation in various gymnosperms, including Taxus, Pinus, Ginkgo, and Welwitschia. An unusual condition is shown of cell-division in a pollen-grain of Ginkgo. Usually two or three “prothalliurn cells” are formed, and in part disappear before the protrusion of the pollen-tube and the division of the “generative cell” but occasionally they persist somewhat longer, and Strasburger figures a pollen-grain in which the three prothallium cells are intact, and the first of them has a partition at rightangles to the walls of the other cells. In this work Strasburger also gives the results ofsome experiments on the colour-reactions of the male and female nuclei. Rosen discovered that, as in animals, the male nucleus of phanerogams is kyanophilous and the female nucleus erythrophilous. Strasburger found that the small nuclei of the cells formed in the pollen grains of gymnosperms were kyanophilous, whether the cells were vegetative or destined for generation; but the nucleus of the pollentube was more or less decidedly erythrophilous. The second and larger portion of this “Beitrag” is devoted to swarmspores, gametes, vegetable spermatozoids, and the nature of fertilisation.

Ueber das Verhalten des Pollens und die Befruchtungsvorgänge bei den Gymnospermen.

Von Eduard Strasburger. (Jena: Gustav Fischer, 1892.)