172 BOTANY. [chap. v. 



the endosperm in the ovule, and surrounding the far 

 tilized oosphere — now the oospore — the latter by re- 

 peated cell-division assumes the form of a tiny plantlet 

 contained entirely within the ovule — now the seed — 

 and called the embryo ; the development of the embryo 

 continues until the most important portions of the vege- 

 tative phase of the plant are formed, namely, a minute 

 stem or plumule, which is continued downwards as the root 

 or radicle, and in addition, either one or two minute 

 leaves or cotyledons. The presence of either one or 

 two cotyledons in the embyro depending on the species 

 examined is so constant that it constitutes one of the 

 most important characters used in breaking up the 

 Angiosperms into two primary divisions — Monocoty- 

 ledons, where one cotyledon is present on the embryo ; 

 examples — palms, grasses, sedges, lilies, etc. ; Dicotyle- 

 dons, where the embryo has two opposite cotyledons ; 

 examples — buttercups, roses, peas, oak, hazel, etc. 



The following arrangement illustrates the primary sec- 

 tions into which the vegetable kingdom is divided : — 



Vegetable Kingdom. 



I. Gryptogamia. 



Asexual reproduction by cell-division, by motile 

 antherozoids, or in the higher groups by highly differen- 

 tiated spores. Sexual reproduction by oospheres that 

 are fertilized by motile antherozoids, water being the 

 agent that enables the antherozoids to reach the oosphere. 

 After fertilization, the oospore does not become dif- 

 ferentiated by cell-division into an embryo previous to 



