Nucleus

1. The Madreporite. 2. Embryonic shell which forms the umbo of adult molluscan shells. 3. Compact ma formed, in Tunicates, of the digestive and generative glands. 4. Cytoblast or cell-nucleus which may be a solid or vesicular body containing chromatic bodies (nucleoli) and a chromatic and an achromatic reticulum. It undergoes interesting transformations during cell-multiplication or cell-reproduction. See INDIRECT CELL-DIVISION. -In Botany, protoplasmic body of oblong or spherical form, occurring in cells of plants; also central portion of the ovules, and center of a starch-grain. series; the example given will form squares, as,