INFLORESCENCE AND FLOWERS FRUIT AND SEED 131 



all the available nourishment to itself. Consequently 

 the advancing ovary is soon filled by one avule the 

 other five and two of the chambers being pressed to one 

 side by it. 



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 



A B. C. 



* t 



FIG. 36. Sections of acorns in three planes at right angles 

 to one another. A, transverse ; B, longitudinal in the 

 plane of the cotyledons (7) ; C, longitudinal across the 

 plane of the cotyledons ; c, cotyledons ; t , testa ; p, peri- 

 carp ; s t scar, and r, radicle ; pi, plumule. The radicle, 

 plumule, and cotyledons together constitute the embryo. 

 The embryonic tissue is at r and pi. The dots in A, and 

 the delicate veins in B and c are the vascular bundles. 



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

 its cavity; the remains of the two aborted chambers 

 and the five unsuccessful ovules being traceable as tiny, 

 shrivelled 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 

 become the coat (testa) of the seed; and the embryo 



K 2 



