358 



MALE GAMETOPHYTE OF ZAMIA 



be compared with that of Selaginella (Fig. 247, A); the cell^(g) 

 representing the small cell, and the cell (a) corresponding to the 

 large antheridial cell of the gametophyte of Selaginella (Fig. 243, 

 i), while the cell {t) called the tube cell, represents a new depar- 

 ture in the evolution of the male gametophyte. The tube cell 



Fig. 247. Male gametophyte of Zamia: A, stage of germination of the 

 microspore attained in the sporangium. See text for explanation of figures. 

 B, formation of tube for absorbing of food from megasporangium. C, spore 

 end of gametophyte showing the antheridial cell dividing into a body cell, 

 b, and a single wall cell, w. D, the body cell has divided, forming two cells 

 which become the male gametes. E, spore end of male gametophyte, show- 

 ing the spirally ciliated gametes. — After Webber. 



grows out into the tissues of the megasporangium, forming a 

 tubular structure, often branching extensively, and absorbs food 

 for the nourishment of the antheridial cell (Fig. 247, B). This 

 latter cell finally divides, forming a rudimentary antheridium con- 

 sisting of but a single wall cell (w) and a body cell (&). The body 



