1904 | SMITH: NUTRITION OF THE EGG IN ZAMIA 349 
ventral canal nucleus. From this point up to the organization 
of embryos in which the cotyledons were beginning to appear 
the series was fairly complete. 
During the earlier growth of the central cell no jacket is dis- 
tinguishable, and during this time also the contents of the cen- 
’ tral cell are scanty and much vacuo- 
lated. As the central cell approaches 
its mature size and begins to fill with 
nutritive substances, the jacket appears 
and soon becomes very conspicuous, 
“eits single layer of cells being rich in 
protoplasm, but almost destitute of 
starch, while the cells surrounding it 
are nearly filled with large starch grains 
(igi jit 8 condition continues 
during the later growth of the central 
cell, during the growth of the egg, and 
§ even during the earlier 
= ae ee stages in the develop- 
neighboring cells; two of the ment of the embryo. 
prmoeee shown are broken During their entire 
; Haustoria discharging con- period the mode by 
which materials pass 
€8g; 5, starch-containing cells from the jacket into 
Outside jacket; w, thick inner the interior is the 
walls of jacket cells. 
same. All the figures 
are from stages between the formation of the 
ventral canal nucleus and fertilization. 
The inner walls of the jacket cells become : os ’ 
very much thickened (jigs. 1, 3-6, w) and are dite poavate 
pierced by numerous pores of various sizes, AS of inner surface of 
shown in surface view in fig. 2 and in section in jacket showing nu- 
all the other figures. Through these pits the merous pits of vari- 
protoplasm of the egg protrudes into the jacket 
cells, forming haustoria-like processes. After passing through 
the pits, the ends of the haustoria become distended so that the 
Structure appears knob-shaped. The contents of the haustorium 
Es Sa 
ous sizes. 
