. Texte-livre de botanique, morphologiques et physiologiques. La botanique. 444 cryptogames vasculaires. Mais enfin. Lorsque le antherozoids sont formés dans leur mère- cellules, l'exospore éclate à l'apex, l'endospore est bombé comme une vessie hyalines, qui enfin éclate et permet à l'échappement de l'antherozoids (Fig. 310, B). Le prothalle femelle est formé au sein de la papille apicale de la macrospore à partir d'une petite partie de son protoplasme, et seulement partiellement émerge à une période ultérieure à partir de la cavité, mais reste unie avec ce dernier, il clôture par sa surface basale, dans le but

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. Text-book of botany, morphological and physiological. Botany. 444 VASCULAR CRYPTOGAMS. but finally becomes detached. When the antherozoids are formed in their mother- cells, the exospore bursts at the apex, the endospore swells up as a hyaline bladder, which finally bursts and allows the escape of the antherozoids (Fig. 310, B). The Female Prothallium is formed within the apical papilla of the macrospore from a small part of its protoplasm, and only partially emerges at a later period from the spore-cavity, but remains united with the latter, closing it by its basal surface, for the purpose of using up the food-materials (starch-grains, fatty oil, and albuminous substances) which are stored up there. The separate stages in the first formation of the prothallium are still in many respects not clear; but it is certain that it arises from a collection of protoplasm in the cavity of the papilla; this protoplasm, immediately breaks up into several cells, which, according to Hanstein in Marsilia and Pilularia1 and according to Juranyi in Salvinia, become clothed only at a later period with cell-walls and thus form a tissue. The further. FIG. rp.x.—Sal'vinia nutans {after Pringsheim). A longitudinal section through (he macrospore, prothallium, and embryo in the median line of the prothallium (X about 70), a wall of the sporangium, b epispore, c proper wall of the spore, e its prolongation, d the diaphragm mentioned above which separates the prothallium from the spore-cavity, pr the prothallium already broken through by the embryo, /, // its two first leaves, xthe scutiform leaf; B an older seedling with the spore sp and prothalliumpr (X20), a the caulicle, b the scutiform leaf, /, //first and second single leaves, L, V aerial leaves of the first whorl, -w submerged leaf of the first whorl. processes seem to me, according to the statements of Pringsheim, Hanstein, and Hofmeister, compared with my own observations on Marsilia Salvairix, to be briefly these:—the tissue o

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• bookcentury1800
• bookdecade1880
• booksubjectbotany
• bookyear1882