THE GYMNOSPERMAE 



Fig. 746. — Ginkgo hiloha. Development of the male gametophyte. A, Antheridial cell. 

 Ab, Antheridial body cell. As, Antheridial stalk cell. Pi and P2, Prothallial cells. 

 T, Tube cell. Note that the extine only partially covers the spore. {After Hirase.) 



Primary root 



Prothallus 



Primary stem apex 



Cotyledons 





W-- 



Fig. 747. — Ginkgo biloba. Longitudinal section 

 through a mature embryo surrounded by 

 prothallial endosperm. Note the unequal 

 size of the two cotyledons. 



