Elementary text-book of zoology, tr Elementary text-book of zoology, tr. and ed. by Adam Sedgwick, with the assistance of F. G. Heathcote elementarytextbo01clau Year: 1892-1893 REPRODUCTION BY SPORES. SKXL'AL REPRODUCTION. layers are repeated in the commencing buds, and from them the organs are differentiated. The reproduction by spores is characterised by the production within the organism of cells, which develop into new individuals in situ or after leaving the organism. But this conception, of spores, which is taken from the vegetable kingdom, can only be applied to the Protozoa and coinci
Elementary text-book of zoology, tr Elementary text-book of zoology, tr. and ed. by Adam Sedgwick, with the assistance of F. G. Heathcote elementarytextbo01clau Year: 1892-1893 REPRODUCTION BY SPORES. SKXL'AL REPRODUCTION. layers are repeated in the commencing buds, and from them the organs are differentiated. The reproduction by spores is characterised by the production within the organism of cells, which develop into new individuals in situ or after leaving the organism. But this conception, of spores, which is taken from the vegetable kingdom, can only be applied to the Protozoa and coincides with endogenous cell-division. The cases of so-called spore-formation amongst the Metazoa (germinal sacs of Trematodes) are probably identical with egg formation, and are to be reduced to a precocious maturation and spontaneous development of ova (Parthenogenesis, Psedogenesis). The digenous or sexual reproduction depends upon the production of two kinds of germinal cells, the combined action of which is necessary for the de- velopment of a new or- ganism. The one form of germ cells contains the material from which the new individual arises, and is known as the egy-cell, or merely eyy (ovum). The second form, the sperm-cell (spermato- zoon), contains the ferti- lising material, semen or sperm, which fuses with
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