402 



GYMNOSPERMS 



and they continue, sometimes giving the impression of amitotic 

 divisions, until nearly all of the cells become uninucleate (fig. 377). 



!'"'■ 377- — Welwitschia mirabilis: A, late free-nuclear stage of female gamctophyte: 

 H, cell of nucellus; nt, megaspore membrane; B, early cellular stage, with most of the 

 cells still multinuclear; at/, nuclear fusions have taken place until the cells are uninu- 

 clear;/, at bottom, shows that cells may divide after the fusions; a, in the middle cell at 

 the left, shows that nuclei may divide before fusion; C, four of the cells,/, have become 

 uninuclear and nuclear fusions are advancing in the rest, nt; A, X30s«»; B and C, 

 X350.'"'* — After Pearson. 



The cells of the lower part of the gametophytc contain more nuclei 

 than those in the micropylar end, the former often containing a 

 dozen, while the latter contain two or three, or sometimes half a 

 dozen. Fusions are completed earlier in the micropylar region, but 



