THE WHITE LILY 



191 



in size, and the increase in the number of the nuclei 

 keeps pace with its growth (see Fig. 88). For a long 

 time no cell-walls are formed between them. They lie 

 scattered in the undivided protoplasm. Only after 

 hundreds of free nuclei have been produced does tissue- 

 formation begin. Then for the first time cell-walls 

 make their appearance between the nuclei, so that the 



Cr- 



FIG. 91. Longitudinal section of the ripe seed of a Lily. 

 t, testa ; m, micropyle ; e, endosperm, in which the 

 embryo is embedded ; r, radicle of embryo ; g.p, growing 

 point of stem; c, cotyledon. Magnified 6 diameters. (R.S.) 



protoplasm is partitioned up into as many distinct cells 

 as there were free nuclei before. The endosperm tissue, 

 as we may now call it, at first forms a single layer 

 lining the sac. Growth and cell-division, however, 

 go on continuously, until by the time the seed is ripe 

 the whole cavity of the sac, except the small part 



