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Spore (sp&ō;r), n. [Gr. &unr_; a sowing, seed, from &unr_; to sow. Cf. Sperm.] 1. (Bot.) (a) One of the minute grains in flowerless plants, which are analogous to seeds, as serving to reproduce the species.
&hand_; Spores are produced differently in the different classes of cryptogamous plants, and as regards their nature are often so unlike that they have only their minuteness in common. The peculiar spores of diatoms (called auxospores) increase in size, and at length acquire a siliceous coating, thus becoming new diatoms of full size. Compare Macrospore, Microspore, O&ö;spore, Resting spore, Sphærospore, Swarmspore, Tetraspore, Zo&ö;spore, and Zygospore.
(b) An embryo sac or embryonal vesicle in the ovules of flowering plants.
2. (Biol.) (a) A minute grain or germ; a small, round or ovoid body, formed in certain organisms, and by germination giving rise to a new organism; as, the reproductive spores of bacteria, etc. (b) One of the parts formed by fission in certain Protozoa. See Spore formation, belw.
Spore formation. (a) (Biol) A mode of reproduction resembling multiple fission, common among Protozoa, in which the organism breaks up into a number of pieces, or spores, each of which eventually develops into an organism like the parent form. Balfour. (b) The formation of reproductive cells or spores, as in the growth of bacilli.