128 THE PLANT CELL. 



them. Thus, from the epibasal cell are subsequently produced 

 the young stem, first leaf, and the cotyledons (or cotyledon, in 

 the case of monocotyledons) ; whilst from the hypobasal cell, the 

 root, and, in some cases, the foot (an absorbent organ), and the 

 so-called hypocotyledonary portion of the stem arise. The 

 manner in which these tissues arise is, briefly, by the formation 

 of octants of cells, from which, by subsequent synclinal and 

 anticlinal divisions, the rudimentary tissues are developed. 



Before the embryo-plant (spore-forming or asexual generation) 

 thus formed is completed, the endosperm (or secondary prothal- 

 lium, so-called : see section on " Homology ") has increased to 

 a great extent, and cells with definite cell-walls have arisen. 

 At first the endosperm nuclei lie free in the shell of cyto- 

 plasm lining the embryo-sac, and no walls are formed until 



Fig. 97a. ~ A Single Celi, from the Endosperm of CcUlha paiuMris, 

 showing: — w, cell- wall; n, nucleus; ^, protoplasmic "bridles" passing 

 through the cell- wall ; v, vacuoles. 



a considerable number of nuclei have been produced. After 

 a time, however, the cytoplasm grows in thickness, and 

 fresh nuclei are produced centripetally. Ultimately cell-walls 

 are formed simultaneously between a large number of nuclei, 

 there being a peculiar formation of radiating inter - nuclear 

 achromatic spindles, across which walls are formed. (In Caltha 

 palustris, very beautiful preparations of the developing endo- 

 sperm may be made, which show this internuclear wall- 



