THE EMBRYO 



315 



in studies of dormancy and after-ripening. For this stage, the earher 

 studies of embryo development provide most of tlie available informa- 

 tion. 



The beginning of differentiation of cotyledons and axis may be early 

 in some taxa, even as early as the octant stage, but, usually, the origin 

 of these organs is not apparent until the embryo is massive, and it may 



Fig. 118. Beta vulgaris. A, mature, 8-nucleate embryo sac, polar nuclei fused; B, 

 mature embryo in micropylar end of the seed, e, endosperm; eb, body of embryo; 

 ii, inner integument; n, nucellus; oi, outer integument; sus, suspensor. (After Art- 

 schwager. ) 



