The Plant 
45 
Inside, at each end, are a few cells and a nucleus. This 
unites with the nucleus of the pollen tube, after which, the 
united nuclei divide, and then divide again very rapidly, 
filling up the ovule with tissue. The embryo is also 
formed within the ovule, which therefore becomes a seed. 
The tissue is gradually stored with food substances, and 
the whole seed gradually matures. The ovary, which has 
enlarged rapidly, to suit the requirements of the growing 
seed, is now known as the seed vessel, which, when mature, 
splits open, liberating the fully developed seeds. 
