SPERMATOPHYTES 



273 



FIGS. 604-608. The hypophysis in Capsella : 604, cell with nucleus is the cell of 

 the filamentous proembryo next to the terminal one (which has formed most of the 

 embryo); 605, division of this cell into hypophysis (cell next to the embryo) and end cell 

 of suspensor (it is this division that finally differentiates embryo and suspensor); 

 606, division of hypophysis into two cells; 607, division of the outer daughter cell of 

 the hypophysis; 608, final product of the hypophysis (six cells visible, in three tiers), 

 innermost tier completing the periblem (plerome shaded), middle tier (shaded) complet- 

 ing the dermatogen (shaded), and outermost tier starting the root cap. After COULTER 

 and CHAMBERLAIN. 



FIGS. 609-613. Development of embryo of Sagittaria (a monocotyledon): 609, the 

 three-celled filamentous proembryo, the terminal one (z) forming the cotyledon (sy, the 

 undestroyed synergid) ; 610, the same; 611, division of middle cell; 612, 613, later 

 stages; x, enlarged basal suspensor cell; y, middle cell; z, terminal cell. After 



SCHAFFNER. 



Among the Leguminosae there is often developed a conspicuous and 

 very active suspensor, which may almost girdle the sac with its turgid cells. 



C. B. &C. BOTANY 18 



