Nostoc
prop. n.
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A genus of algæ. The plants are composed of moniliform cells imbedded in a gelatinous substance.
Nostoc commune is found on the ground, and is ordinarily not seen; but after a rain it swells up into a conspicuous jellylike mass, which was formerly supposed to have fallen from the sky, whence the popular names, fallen star and star jelly. Also called witches' butter.
