426 



PART IV. CLASSIFICATION. 



FIG. 250. Later stages in the embryogeny of the sporopbyte of Picea excclsa (after 

 Btrasburger). A Optical section of young embryo borne on the end of the suspensors ( x 240) : 

 B older embryo, with suspensor and embryonal tubes ; nt this stage the growing- points of 

 primary root and stem are already differentiated : C half-grown embryo in surface-view: 

 D longitudinal section of a half-grown embryo : E surface-view of the apex of the ehoot of 

 this embryo (x27): F longitudinal section of a fully developed embryo in a ripe seed; e 

 cotyledons; h hypoctyl; pi apex of the plerome in the root; cp root-cap; m pith; op pro- 

 cambial ring. 



