1887.| . BOTANICAL GAZETTE. 241 
To recur now to the mature seed, it will be found to con- 
sist mainly of a much developed embryo-sac, filled with endo- 
sperm and a small embryo. The embryo-sac never entirely 
replaces the nucellus, more or less of the nucellar tissues be- 
ing found on the commissural side, either pressed against 
the flat or concave face of the embryo-sac or embraced in its 
infolding (figs, 12, 13, 14). Important characters have been 
obtained from the commissural face of the seed, based upon 
velops strongly towards the commissure on the two sides, 
resulting in a concave or involute seed-face. This variation 
faces in one and the same plant. 
