Ontogeny and Cytochemistry of the Chalazal Proliferating Cells of Capsella Bursa‐pastoris (L.) Medic.

Summary This paper describes the ontogenic development and cytochemistry of a group of cells which proliferate from the chalaza of the ovule of Capsella bursa‐pastoris. These cells arise from nucellar tissue in the chalaza at the time of embryo development and develop a consistent morphology which seems to protrude into the embryo sac. Azure B staining and intensity of incorporation of nucleic acid precursors indicates a high rate of activity of these cells up to the time that the embryo is in the heart stage. They then begin to disintegrate quickly with but a few cells remaining in the mature seed. The evidence suggests that they may play a physiological role in early embryo development.