136 BOTANICAL GAZETTE [aucust 
forming the boundary of the group of cells which we may call the 
“spongy tissue,” using STRASBURGER’s term. These flattened cells 
of the periphery were first seen in the young ovule (fig. 8). The 
“spongy tissue” may perhaps be referred to the mass which originated 
in a single archesporial cell, but the lack of sufficient material prevents 
me from drawing conclusions. 
By the time the embryo sac nucleus has divided, the “spongy 
tissue” shows differentiation. Next to the embryo sac membrane 
3 the cells (a) are larger, 
more vacuolated, and often 
bulge into the sac as 
pressure is released on this 
side. Occasionally these 
cells are broken apart and 
the walls are very indis- 
tinct. The next rows (0), 
often eight or ten in num 
ber, are made up of smaller 
cells, therefore seeming t0 
be closely packed and often 
dividing in such planes that 
they form rows radiating 
from the center of the sac 
The nuclei and cells them 
selves stain deeply, co 
trasting both with the inner layers mentioned and with the flattened 
peripheral rows (c). Quite often a spindle is seen in these cells, 8° 
that this is by no means a degenerating tissue. The cytoplasm 1D the 
preparations has separated from the walls a little, and the walls “ 
“so transparent that the nuclei seem to be floating in cytoplasm 
(3), but I am convinced that this is due to a slow passage of the 
killing fluid into the tissue and the consequent shrinkage. Fig. 16 
shows the two embryo sac nuclei at the poles, and fig. 17 has “oe 
nuclei in one section, one of which has not yet passed to the periph- 
eral position. The interior of the sac in these sections has a beau! 
ful vacuolate structure, and the “spongy tissue” has not change 
appreciably. 
Fic. 16.—Polar position of embryo sac nuclei. 
93°. 
