GINKGO ALES 



211 



The cells of the micropylar two-thirds of the proembryo divide very 

 little or not at all, but the cells of the antipodal one-third form a 



245 246 



Figs. 242-246. — Ginkgo biloba: archegonium and embryogeny; fig. 242, longi- 

 tudinal section of the neck of the. archegonium, showing the two cells; X160; fig. 

 243, transverse section of the same; X160; fig. 244, archegonium shortly before 

 fertilization, showing ventral canal cell (v) and egg nucleus (»); X66; fig. 245, free 

 nuclear stage of the proembryo; X66; fig. 246, later stage, showing that the tissue 

 of the proembryo has resulted from a segmentation of the entire egg; X66. — After 

 Strasburger (4). 



small-celled meristem which grows vigorously (fig. 247). This 

 growing region invades the endosperm as a broad, blunt cylinder, 

 the micropylar end of the proembryo being forced back through the 



