Development of the embryo-sac of Hybanthus concolor 
FRANK M. ANDREWS 
The embryo-sac of Hybanthus concolor (Forst.) Spreng. (Cu- 
belium concolor Raf.) begins its development as an hypodermal 
cell. At first this cell is not different apparently from the other 
cells about it, but soon it becomes very grumous and is then easily 
distinguishable (Fic. 1). 
The mother-cell of the embryo-sac next divides by a transverse 
wall into two cells unequal in size (Fic. 2). The terminal one of 
these two cells becomes somewhat more granular than the others 
and gives rise to the primary tapetal cell. By the rapid and nu- 
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Figures 1-8. Development of the embryo-sac of Hybanthus concolor. The 
figures are magnified 420 diameters. See text for explanations. 
merous transverse divisions of this primary tapetal cell the embryo- 
sac when completely formed and sometimes even before maturity 
is covered by many layers of cells. Vertical as well as transverse 
divisions of the cells of the tapetal region also occur, so that fre- 
quently several quite regular rows of cells above the embryo-sac 
are produced (FIGs. 3, 4, 5,6). Sometimes this regularity of these 
477 
