INFLORESCENCE AND FLOWERS FRUIT AND SEED. 131 



In a few weeks the ovary and its cupule have in- 

 creased considerably in size, and the one successful 

 ovule, with the rapidly developing embryo in the em- 

 bryo-sac in its interior, occupies nearly the whole of its 

 cavity; the remains of the two aborted chambers and 



Fio. 36. Sections of acorns in three planes at right angles to one another 

 A. transverse ; B, longitudinal in the plane of the cotyledons (F) ; C ? 

 longitudinal across the plane of the cotyledons ; c, cotyledons ; t, 

 testa ; p, pericarp ; , scar, and r, radicle ; pi, plumule. The radicle, 

 plumule, and cotyledons together constitute the embryo. The em- 

 bryonic tissue is at r and pi. The dots in A, and the delicate veins 

 in B and C, are the vascular bundles. 



the five unsuccessful ovules being traceable as tiny, 

 shriveled remnants in one corner. The walls of the 

 ovary then gradually change into the polished brown 

 walls (pericarp) of the fruit ; the walls of the ovule be- 

 come the coat (testa) of the seed ; and the embryo de- 

 veloped from the fertilized egg-cell fills up the interior 

 of the latter, as described in Chapter II. 



The ripe fruit is the acorn, and we may regard it 

 apart from the cupule ; it contains the seed. 



