j 
THE FLOWER 295 
DEVELOPMENT OF THE Empryo (DicoTyLepons).—In the 
development of the embryo of a typical Dicotyledonous type, as 
seen in Brassica (the mustard genus), the odspore, lying within 
the embryo sac, undergoes division and redivision to form a sev- 
eral celled filament. At the end of the filament farthest away 
from the micropyle of the ovule, unequal growth and differentia- 
Fic. 223.—Successive stages, 1, 2, 3, 4, 6, 8, in the development of the embryo 
of Brassica. 1. Proembryo. 2. Octant stage. x, Octant. 7, i, Suspensor. 
3. Formation of dermatogen. 4. Differentiation of periblem and plerome. 6. Last 
cell or hypophysis, (v), of suspensor completes the dermatogen by division. 
8. Inner part of v. d!, d?, Completes periblem. 2, Region of stem apex. A, A, 
Bases of cotyledons. D, Dermatogen. Pe, Periblem. Pl, Plerome. (From 
Small, after Kny.) 
tion takes place which eventually produces the body or main part 
of the embryo. Just below this region, the cells of the filament 
develop into a suspensor whose basal cell is larger than the rest 
and directed toward the micropylar end of the embryo sac. 
The body of the embryo is formed as follows: The upper end 
cell of the axis of the young developing embryo divides to form 
2 rows of four cells each. The upper row of 4 cells by unequal 
growth and repeated division form the terminal epicotyl and 2 
