THE EMBRYO 



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pattern of cell divisions in the development of the embryo. The 

 two-celled stage consists of a small lenticular terminal cell and a 

 much larger basal cell (Fig. 173 A). The terminal cell may divide 

 vertically (Fig. 173C) or obliquely (Fig. 173B), and sometimes the 

 first oblique wall is followed by another wall of the same type, 

 resulting in a kind of apical cell (Fig. 173D). The following divi- 



P G H I J 



Fig. 173. Development of embryo of Zea mays. (After Randolph, 1936.) 



sions are quite irregular (Fig. 17 SE). Further growth is limited 

 chiefly to the terminal region, and only a few cell divisions occur in 

 the basal or suspensor region (Fig. 173F-J). 



Carya glabra, Juglans mandshurica (Langdon, 1934), and J. nigra 

 (Nast, 1941) are similar in that the first division wall may be hori- 

 zontal or slightly oblique. The terminal cell does not form any 

 quadrants but divides by two oblique walls and then by a transverse 

 wall to form a group of six cells. The cells on the sides give rise to 



