272 
MORPHOLOGY 
established when that cell divides and forms the hypophysis. While 
this method of embryo formation may be regarded as characteristic of 
dicotyledons, there are numerous variations, conspicuous among which 
are the following: 
Variations. The proembryo may be a spherical mass of cells (as in 
the water lilies), in which the growing points are organized, but with 
'ittle or no differentiation of a suspensor. 
FlGS. 600-603. Development of embryo of Capsella (a dicotyledon): 600, the 
Ilamentous proembryo, in which the terminal cell has divided and the basal cell has 
become large; 601, later stage, in which the terminal cell has divided to octants; 
602, later stage, in which the dermatogen has been cut off; 603, later stage, in which 
plerome (shaded) and periblem (between plerome and dermatogen) are distinguishable in 
the hypocotyl region; hypophysis (divided to three cells in the figure) completing 
periblem (by inner cell) and dermatogen (by two outer cells). After COULTER and 
CHAMBERLAIN. 
In other cases the proembryo is massive, but of no definite form, filling 
the micropylar end of the embryo sac. 
