. The cell; outlines of general anatomy and physiology. Fig. 144.—Egg from Lilium martagon (after Guignard XVI., Fig?. 80 and 81): A ashort time after the union of the egg- and sperm-nuclei; B a later stage. The fusing ofthe centrosomes is nearly completed. The two nuclei. Fig. 145. — Egg - cellfrom the embryo-sac ofLilium martagon, with itsnucleus undergoing divi-sion. The nuclear plateconsists of twenty - fournuclear segments. (AfterGuignard XVI. Fig. 83.) (Fig. 144) then coalesce, as do also the fourcentrosomes ; these latter unite so as to formtwo new pairs, of which each is composedof one
. The cell; outlines of general anatomy and physiology. Fig. 144.—Egg from Lilium martagon (after Guignard XVI., Fig?. 80 and 81): A ashort time after the union of the egg- and sperm-nuclei; B a later stage. The fusing ofthe centrosomes is nearly completed. The two nuclei. Fig. 145. — Egg - cellfrom the embryo-sac ofLilium martagon, with itsnucleus undergoing divi-sion. The nuclear plateconsists of twenty - fournuclear segments. (AfterGuignard XVI. Fig. 83.) (Fig. 144) then coalesce, as do also the fourcentrosomes ; these latter unite so as to formtwo new pairs, of which each is composedof one element of male and one of femaleorigin. The new pairs are situated on op-posite sides of the cleavage nucleus, andthere develop into the two centrosomes ofthe first nuclear spindle (Fig. 145). In the same way as in animal sexual cells,the nuclein and the number of nuclear seg-ments derived from it are decreased duringthe formation of the pollen-cell and of theegg-cell to one half of the quantity presentin a normal nucleus. For instance, whilstin Lilium martagon the normal nucleus de-velops during its division 24 nuclear seg-ments which split up into 48 daughter- THE VITAL PROPERTIES OF THE CELL 265 segments, in the nuclei of egg- and sperm-cells there are but 1
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