309 



also may be taken as a type. After fertilization there is 

 developed a row or filament of cells, called the proembryo, 

 invested at the be- 

 ginning, as a rule, 

 with the endosperm. 

 The apical cell of the 

 proembryo divides 

 longitudinally, and 

 there are then cross 

 and longitudinal divi- 

 sions, either occurring 

 first, thus producing 

 a stage with 8 cells of 

 the embryo proper, 

 the remaining fila- 

 mentous portion being 

 designated suspensor. 

 The following com- 

 plete description of 

 the embryonic growth 

 from Coulter and 

 Chamberlain l i n d i- 

 cates the differentia- 

 tion of the important 

 regions of the young 

 plant. 



"Whether the 

 transverse division precedes or follows the second 

 longitudinal division, it separates the cotyledonary and 



Coulter and Chamberlain, "Morphology of Angiosperms," pp, 

 196-198. 



FIG. 79. Germination of aygote and em- 

 bryology of Lepidium : fertilized egg (A) ; 

 proembryo (B) with suspensor (S) and 

 apical embryo cell (e) ; later stages (C, D, 

 E, F) showing development of stem, root, 

 and cotyledonary parts. [After Curtis.] 



