矮生菜豆胚珠和胚囊的发育

本文观察了矮生菜豆（Ｐｈａｓｅｏｌｕｓｖｕｌｇａｒｉｓｖａｒ．ｈｕｍｉｌｉｓ）胚珠和胚囊的发育。通常大孢子母细胞减数分裂形成三个直线排列的细胞，合点端大孢子具功能，功能大孢子发育成蓼形胚囊。成熟胚囊中，三个反足细胞已消失。两助细胞分别在受精前后退化。两极核受精前融合或不融合。卵细胞的细胞质中有少量淀粉粒。珠孔端及合点端的胚囊壁均具发达的壁内突。成熟胚珠为弯生型、双珠被、厚珠心。四核胚囊形成后，淀粉粒依次出现在珠被组织，珠心组织及中央细胞中，至开花前２～３天达到高峰。开花前一天，珠心和中央细胞中淀粉粒开始减少。

EMBRYO SAC AND OVULE DEVELOPMENT IN PHASEOLUS VULGARIS VAR. HUMILIS

Embryo sac and ovule development in Phaseolus vulgaris var. humiliSwere investigated.The meiosis of a macrospore mother cell usually forms three lineally arranged cells, and thechalazal macrospore develops into a polygonal embryo sac. Antipodal cells are ephemeral.One synergid degenerates before fertilization, the other does after fertilization. The centralcell is full of starch grains. The nuclear membranes of two polar nuclei fuse each other ordon't before fertilization. The egg cell contains a few starch grains. There are wallingrowths in the embryo sac wall. The mature ovule is campylotropous, bitegminous andcrassinucellate. After the formation of 4--nuclear embryo sac, the starch grains gradually appear in integument, nucellus tissue and the central cell, and about 2 days before floweringthey are most.