Growth 



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 



FIG. 79. Germination of zygote 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.] 



transverse division precedes or follows the second 

 longitudinal division, it separates the cotyledonary and 



1 Coulter 

 196-198. 



and Chamberlain, "Morphology of Angiosperms, " pp. 



