M 



Fig. 72. Development of the embryo in Zea mays 

 A-E, Early stages showing the somewhat irregular segmentation pattern (x 180). 

 F-H, The enlarging club-shaped embryo shows a gradient of cell size and more 

 densely protoplasmic cells begin to be apparent in a median-distal lateral position 

 (x 160). J, K, The shoot apical region {s) and root are beginning to be differen- 

 tiated ( X 140). L, A fully developed embryo showing the scutellum {sc), the coleop- 

 tile (c), the coleorhiza (col), the root (r) and root-cap {re). The scutellar node or 

 median plate can be seen about the middle of the embryo. M, Longitudinal section 

 of caryopsis showing the position of the young embryo relative to the endosperm. 

 (L, after Avery; the others after Randolph.) 



