284 Lang.—Development of Cycadean Sporangia . 
a smaller upper segment; other ovules have been seen with 
a row of three uncrushed cells (Fig. 5). From the comparison 
of these two stages, it would appear to be almost certain that 
it is the upper cell of the two resulting from the first division 
that divides again ; only the examination of the cells in the 
process of division can, however, settle this question definitely. 
In slightly older ovules the two cells of the row nearest to 
the micropylar end of the ovule are found crushed and 
flattened, the lowest cell, which is the young megaspore, 
being still uni-nucleate (Fig. 6). While these changes have 
taken place in the embryo-sac mother-cell, the ovule has 
undergone considerable alteration in size and form. This 
will be evident from Fig. 7, which represents the median 
longitudinal section of an ovule with the embryo-sac in the 
condition last described. As this figure shows, the indication 
of the division of the integument into three layers is becoming 
apparent. The margin of the integument has closed in some¬ 
what, narrowing the micropyle, and the bluntly conical apex 
of the nucellus does not quite reach the level of the integu¬ 
ment. The sporogenous mass is very distinct, and exhibits 
a difference between its more peripheral cells and those im¬ 
mediately around the embryo-sac. The cytological character, 
upon which this difference mainly depends, is, as the detailed 
drawing of the sporogenous tissue around the embryo-sac in 
Fig. 4 shows, the vacuolization of the more central cells. 
This is most marked in those which immediately surround 
the embryo-sac. These cells are also noteworthy for con¬ 
taining in their cytoplasm certain spherical bodies, the nature 
of which it has been impossible to determine with certainty 
from the material investigated. Since they also occur in the 
embryo-sac mother-cell it appears to be advisable to record 
their occurrence. Most frequently two of these spherical 
bodies are present in each cell; they are situated in the 
cytoplasm at a greater or less distance from the nucleus, and 
stain similarly to the cytoplasm, though more deeply. As 
the figure shows, one of these bodies remains in each of the 
first two segments of the mother-cell, but it has not been 
