FIG. 99. Median longitudinal sections of young ovules, a, Showing primary arche- 

 sporial cell ( x 260) ; b, after its first division ; c, tetrad stage ; d, inner cell of 

 tetrad after the collapse of the three outer cells. Outlines of the two ovular integu- 

 ments are shown (b, c, d x 350). 



FIG. 100. Egg apparatus and fusion- 

 nuclei (June 12) (><35o). 



FIG. 101. Embryo-sac before fertilisation 

 (June 12) (x 280). 



