ERRATA 
Page 12, I9th line from top, for mother cell of the embryo sac, 
read embryo sac cell. 
Page 61, oth line from top, for megaspore, read megaspore mother 
cell, ۱ - 
. Page 77, 2d line from bottom, for 10: 252, rea 350: 228 
Page 102, 6th line from bottom, for and, read i”. 
