Cytological Investigations of Pisum sativum

Abstract

1. Each theca of the anther of Pisum sativum contains many microspore mother cells. 2. Cell plates are formed on the cytoplasmic strands midway between the nuclei of the tetrad. 3. The microspore cell divides to form a two-celled pollen grain. 4. The tube nucleus disintegrates before germination of the pollen grain. 5. The generative cell divides within the pollen tube to form two male gamete cells. 6. Each ovule usually contains one primary sporogenous cell; two or three cells have been observed in some instances. 7. An apical hypodermal archesporial cell divides to form a primary sporogenous cell and a primary parietal cell. 8. The primary sporogenous cells function as megaspore mother cells. 9. Usually four megaspores are formed as a result of the meiotic divisions. 10. The chalazal megaspore develops into an eight-nucleate, seven-celled megagametophyte; the other megaspores disintegrate. 11. One megagametophyte is usually found in an ovule; occasionally two are present. 12. The mature ovule is half an...