Campbell .— Studies on the Araceae. 7 
of the funiculus has begun now to push the nucellus downward, 
and the ovule begins to show the anatropous form found at 
maturity. 
The primary archesporial cell undergoes a transverse division 
resulting, in all the cases seen, in two cells of unequal size, of 
which the upper one seems to give rise at once to the embryo- 
sac, while the lower one may either divide once (Fig. 6), or 
probably in some cases remains undivided. No tapetal cells 
were seen in these young stages, although in the older stages 
a cell was sometimes seen above the embryo-sac which may 
possibly have been a tapetal cell (Fig. 8, t). 
The further history of the embryo-sac offers nothing strik¬ 
ingly different from that of the typical Angiosperms. The 
embryo-sac mother-cell increases in size, and finally destroys 
the smaller sister-cell (or cells) below it. The nucleus is large 
and conspicuous, and after some further enlargement of the 
embryo-sac, which now begins to crowd upon the smaller 
tissue, it undergoes the usual division into two, one of which 
moves to each end of the sac (Fig. 8). The further division 
of these then follows in the usual manner. 
With the rapid enlargement of the embryo-sac the lateral 
cells of the nucellus, which at first form two or three layers 
(Fig. 6), become very much compressed, and the- nuclei and 
other contents show signs of disintegration. Even before the 
nuclear divisions in the young sac are completed, the lateral 
tissues of the nucellus are almost completely destroyed, and 
the embryo-sac is apparently in close contact with the inner 
integument. The apex of the nucellus, however, persists. 
This at first consists of two layers of cells (Figs. 5 , 6), but 
later these may divide by periclinal walls so that there are 
three layers (Figs. 8, 9). The cells of the apex of the nucellus 
become much extended vertically and form a conspicuous cap 
above the apex of the embryo-sac. 
There is but little difference in the appearance of the nuclei 
at the upper and lower ends of the sac. They all stain 
readily and show a small but distinct nucleolus. The arrange¬ 
ment of the cells forming the young egg-apparatus and the 
