362 



THE FRUIT 



FIG. 62. Development of embryo. A, embryo sac shortly after 

 fertilisation. The secondary nucleus has divided many times 

 and the sac is rapidly filling with the endosperm tissue ; food 

 is coming in through the vascular bundle of the ovule (arrows) . The 

 fertilised egg (zygote) has divided to form the suspensor and the 

 embryonal cell. B, sac full of endosperm, into which the embryo 

 is being pushed by the elongation of the suspensor. C, growth 

 of embryo (cells not shown) : the free end develops two lobes (the 

 rudiments of the cotyledons). D, older embryo ; cot., cotyledons ; 

 hyp., hypocotyl; r, radicle ; susp., suspensor. E, ripe endospermic 

 seed showing embryo with two thin cotyledons closely appressed 

 with epicotyledonary bud (epic.) between, hypocotyl (hyp.), 

 radicle (rad.) ; also endosperm, perisperm (per.), testa, and 

 micropyle. Note B-E are drawn on progressively smaller scales, 

 the size of the seed and embryo having very greatly increased. 



