GTXKGOALES 



vides unequally, the smaller daughter cell, in contact with the 

 persistent vegetative cell, being the primary spermatogenous 

 cell or generative cell (Fig. 32, B, a), the larger daughter cell 

 being the tube cell (Fig. 32, J5, t). The gametophyte is in this 



C 



FIG. 32. GinTcgo biloba, development of male gametophyte: A, pollen grain collected 

 April 24th, showing third nuclear division and the persistent vegetative cell (p), 

 x. 500; B, a later stage, showing persistent vegetative cell (/>), generative cell (a), 

 and tube nucleus (2), x 500; f, later stage, July 10th, the generative cell almost 

 spherical, x 500; D, division of nucleus of generative cell into nuclei of stalk and 

 body cells, July llth, x 500; F, division of the body cell, the blepharoplasts being 

 faintly visible, x 120; E, the two male cells produced by the body cell, September 

 12th. x 22rt. After HIRASE. 



three-celled stage when pollination takes place, during the last 

 of April or early in May. 



From this stage on the sequence is exactly as that described 

 for Cycas. The generative cell divides to form the stalk and 

 body cells (Fig. 32, D), which lie side by side, only the body 

 cell functioning further. In the body cell the two blepharo- 

 plasts (Fig. 32, F) appear, and division occurs, resulting in 

 the two male cells, lying side by side, and each containing 

 a blepharoplast. Each male cell then directly develops as a 



