Essays Upon Heredity and Kindred Biological Problems: By Dr. August Weismann ... Ed. by Edward B. Poulton ... Selmar Schonland ... and Arthur E. Shipley...Authorised Translation
Essays Upon Heredity and Kindred Biological Problems: By Dr. August Weismann ... Ed. by Edward B. Poulton ... Selmar Schonland ... and Arthur E. Shipley...Authorised Translation
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1889 Excerpt: ...structure de 1'ovaire et la formation des oeufa chez les Pballuaiadees.' Ibid., 9 avril, 1883. 3 Balbiani, ' Sur 1'origine des cellules dn follicule et du noyau vitellin de I'ffinf chez les Geophiles." Zool. Anzeiger, 1883, Nos. 155, 156. 1 Will, 'Ueber die Entatehung des Dottera und der Epithelzellen bei den Amphibien ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1889 Excerpt: ...structure de 1'ovaire et la formation des oeufa chez les Pballuaiadees.' Ibid., 9 avril, 1883. 3 Balbiani, ' Sur 1'origine des cellules dn follicule et du noyau vitellin de I'ffinf chez les Geophiles." Zool. Anzeiger, 1883, Nos. 155, 156. 1 Will, 'Ueber die Entatehung des Dottera und der Epithelzellen bei den Amphibien and Insecten.' Ibid., 1884, Noa. 167, 168. separates from the female germ-cell, reminds us, in every way, of the polar bodies of animal eggs. Furthermore, the spermatozoids in the mosses and vascular cryptogams throw off a small vesicle before performing their functions1. On the other hand the equivalents of ' polar bodies ' (the 'ventral canal-cells') are said to be absent in the Cycads, although these are so nearly allied to Conifers. Furthermore, 'no phenomenon occurs in the oospheres (ova) of Angiosperms which can be compared to the formation of polar bodies.' Strasburger therefore concludes that the separation of certain parts from the germ-cells is not in all cases necessary for maturation, and that such phenomena are not fundamental, like those of fertilization, which must always take place along the same morphological lines. He further concludes that the former phenomena are only necessary in the case of the germ-cells of certain organisms, in order to bring the nuclei destined for the sexual act into the physiological condition necessary for its due performance. I am unwilling to abandon the idea that the expulsion of the histogenetic parts of the nuclear substance, during the maturation of germ-cells, is also a general phenomenon in plants; for the process appears to be fundamental, while the argument that it has not been proved to occur universally is only of doubtful value. The embryo-sac of Angiosperms is such a complex stru...
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