GROUP IV. PHANEROGA3VIIA : QTMKOSPERMa, 



475 



Ephedra), there is a two-sided apical cell in the growing-point at 

 its first development. 



The cotyledons vary in number : one, in Ceratozamia, and some- 

 times in other Cycadaceae ; two, in the CycadaceaB generally, in 



the Cupressineaa 

 generally, in some 

 Araucarias, in the 

 Taxoideae, and in 

 the Gnetaceae ; in 

 the Cupressinese 

 sometimes 3-5 ; in 

 the Taxodineae 4-9 ; 

 in the Abietineae 

 5-15. The cotyle- 

 dons are generally 

 epigean: they are 

 hypogean in the Cy- 

 cadaceae, as also in 

 Araucaria (sect. 

 Colymbea) and in 

 Ginkgo among the 

 Coniferae: in the 

 Cycadaceae, and in 

 Ginkgo, the two hy- 

 pogean cotyledons 

 are closely coherent 

 at the apex, whereas 

 in these Araucarias 

 the cotyledons are 

 free. 



The growing- 

 point of the root is 

 in all cases differen- 

 tiated endogenously, 

 at some distance 

 from the posterior 

 end of the embryo. 



THE GAMETOPHYTE. 

 As the Gymno- 

 sperms are hetero- 

 sporous, the sexual 



FIG. 300. Germinating seeds of Pinus Pinea: I first 

 stage, in longitudinal section : II second stage, with pro- 

 truding radicle ; A external view; B view after removal of 

 half the seed-coat ; C longitudinal section, without seed- 

 coat; D transverse section, without seed-coat; III ger- 

 mination is here completed, the cotyledons having expanded, 

 and the hypocotyl elongated : s seed-coat; e endosperm; w 

 radicle ; c cotyledons ; y micropyle ; r red membrane (re- 

 mains of nucellus) ; x the embryo-sac. 



