File:The cell in development and inheritance (1902) (14596549238).jpg

Identifier: cellindevelopmenwils2 (find matches)
Title: The cell in development and inheritance
Year: 1902 (1900s)
Authors: Wilson, Edmund B. (Edmund Beecher), 1856-1939
Subjects: Cell Physiological Phenomena Cells
Publisher: New York : Macmillan
Contributing Library: Francis A. Countway Library of Medicine
Digitizing Sponsor: Open Knowledge Commons and Harvard Medical School

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106, 107); cf. p. 263. 2 cy; p. 264. ^ It is interesting to note that the botanists of the eighteenth century engaged in the samefantastic controversy regarding the origin of the embryo as that of the zoologists of thetime. Moreland (1703), followed by Etienne Franfois Geoffroy, Needham, and others,placed himself on the side of Leeuwenhoek and the spermatists, maintaining that the pollensupplied the embryo which entered the ovule through the micropyle (the latter had beendescribed by Grew in 1672); and even Schleiden adopted a similar view. On the otherhand, Adanson (1763) and others maintained that the ovule contained the germ which wasexcited to development by an aura or vapour emanating from the pollen and entering throughthe tracheae of the pistil. FERTILIZATION IN PLANTS 219 egg (Fig. 108); and the earlier observers of the angiosperms, includ-ing Strasburger (84, 88) and Guignard (91, i), likewise found thatonly one of the generative nuclei entered the embryo-sac. Guignard // -.
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\ Fig. 107. — Fertilization in the lily. \_D from MOTTIEK, the others from Guignard.)A. Embryo-sac, ready for fertilization. B. Both generative nuclei have entered the embryo-sac ; one is approaching the egg-nucleus, the other uniting with the upper polar nucleus. C. Union ofthe germ-nuclei; below, union of the second generative nucleus and the two polar nuclei. D. Thefertilized egg, showing fusion of the germ-nuclei. E. The fertilized egg dividing; below, division of the endosperm-nuclei, a. antipodal cells; e. endosperm-nuclei; o. the oosphere or ovum;/. polar nuclei; /. t. pollen-tube. and Nawaschin have, however, recently made the remarkable dis-covery that in Lilhiui and Fritillaria both generative nuclei enterthe embryo-sac. One of these conjugates with the egg-nucleus and 220 FERTILIZATION OF THE OVUM thus effects fertilization (Fig. 107). The other conjugates zvith one ofthe polar nuclei (usually the upper), which then unites with the otherpolar nucleus (cf. p. 264). By divis

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