chloroplast

n. [ Pref. chloro- + Gr. &unr_; to mold, form. ] (Biol.) A plastid containing chlorophyll, developed only in cells exposed to the light. Chloroplasts are minute flattened granules, usually occurring in great numbers in the cytoplasm near the cell wall, and consist of a colorless ground substance saturated with chlorophyll pigments. Under light of varying intensity they exhibit phototactic movements. In animals chloroplasts occur only in certain low forms. [ Webster 1913 Suppl. ]