. Animal physiology. Physiology, Comparative. GERM-CELLS :—FERTILIZATION OF GERM. 559 from other cells by the nature of their contents, though they are usually recognisable by the peculiar nuclei they present; each cell is known as the germinal vesicle (fig. 302, d), whilst its nucleus (e) is designated i\ germinal sjM.—The act of fertiliza- tion appears to consist in the contact of one or more spermato- zoids with the exterior of the germinal vesicle; the sperma- tozoids, ceasing to move, undergo a sort of liquefoction; and the product of their dissolution, being received by absorp- tion i
. Animal physiology. Physiology, Comparative. GERM-CELLS :—FERTILIZATION OF GERM. 559 from other cells by the nature of their contents, though they are usually recognisable by the peculiar nuclei they present; each cell is known as the germinal vesicle (fig. 302, d), whilst its nucleus (e) is designated i\ germinal sjM.—The act of fertiliza- tion appears to consist in the contact of one or more spermato- zoids with the exterior of the germinal vesicle; the sperma- tozoids, ceasing to move, undergo a sort of liquefoction; and the product of their dissolution, being received by absorp- tion into the interior of the germinal vesicle, mingles with its contents, to form with them the basis of the new structure.— When, as usually happens, tlie gei-m-cells are developed in a. Fig. 302.—Section of Ovarium of Fowl: (I, fibrous substance of the ovary; b, yolk; c, yolk-bag; d, germinal vesicle; e, germinal spot. special and distinct organ, this organ, which is termed the Ovary, has very commonly among the lower animals a glan- dular character, the mature ova being discharged by the ovi- duct, just as the products of secretion pass-ofi' through the ducts of their respective glands : but among the Yertebrata the ovary has a much more solid texture, and the germ-cells, developed in the very midst of its fibrous tissue {fi<^. 302, a), have to find their way to its surface, and to burst fortli from it; being then received into an oviduct, wdiose trumpet-shaped mouth embraces the ovary, so as to prevent the liberated germs from falling (as they would otherwise do) into the visceral cavity of the body. 733. AVith the "germ-cell" there is always associated in Animals, as in FloAvering Plants, a store of nutriment that serves for the early development of the germ; this consists of a mixture of albuminous and oily matter, known as the yolk (fig. 302, h); and it is inclosed in a membranous envelope c,. Please note that these images are extracted from scanned page
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