2l8 



MORPHOLOGY 



deep into the endosperm by the rapidly and extensively elongating 

 suspensor. In the organization of the embryo two cotyledons appear, 

 as in all the preceding groups of gymnosperms. Torreya is peculiar 

 in the irregular growth of its endosperm (female gametophyte), which 



Figs. 482-484. — Embryo of Torreya: 482, the stage of four free nuclei; 483, the 

 completed proembryo (filling the egg), the cells approximately in three tiers; 484, upper- 

 most tier of proembryo elongating to form suspensor. — ■ After Coulter and Land. 



encroaches upon the surrounding nucellar tissue in such a jagged way 

 as to give the appearance in the seed called rumination, which may 

 be seen also in sections of nutmegs. 



Conclusions. — The Taxaceae have not been traced with certainty 

 below the middle of theMesozoic, so that it seems to be a comparatively' 

 modem group among gymnosperms. It has made a decided advance 



