290 Lang.—Development of Cycadean Sporangia . 
filled with starch, is still enclosed within the wall of the 
megaspore. Just beneath the pollen-chamber its surface is 
depressed, to form a single cylindrical cavity about 2 mm. in 
diameter with vertical or slightly overhanging sides. At the 
base of this archegonial depression (Fig. 19) the necks of from 
two to four archegonia were distinguishable. 
Only a single unfertilized archegonium was met with ; it is 
represented in Fig. 20. From this the close agreement between 
Stangeria and other Cycads, as regards the structure of the 
archegonium, will be evident. The neck consists of two cells 
projecting above the general level of the surface of the pro¬ 
thallus, and the cap-like ventral canal-cell bears much the 
same relation to the large ovum as in Cycas. The nucleus of 
the ovum was situated towards the upper end, while in a central 
position a small irregular area of less granular cytoplasm was 
to be seen. The thick wall of the ovum is strongly pitted, 
several pits being present opposite each cell of the layer of 
the prothallus, forming the wall of the venter. Sometimes 
the pair of neck-cells was met with, although the lower cell 
had not developed into an ovum ; such a case is represented 
in Fig. 21. The structure of the prothallus does not call for 
special remark; its cells, with the exception of those around 
the archegonia, and the limiting layer, which presents the 
structure described by Warming 1 in Zamia , being filled with 
starch. 
Having considered the general structure of the pollinated 
ovule of Stangeria , there remain, for more detailed considera¬ 
tion, two classes of facts, those relating to the changes in the 
pollen-chamber after pollination, the germination of the pollen- 
grain, and the mode of fertilization, and those relating to the 
development of the embryo. On both of these questions, 
although the material did not afford a complete series of 
stages, it has been found possible to draw sufficient conclusions 
to bring Stangeria into relation with those Cycads in which 
the phenomena of fertilization and embryogeny have been fully 
studied. 
1 Warming, loc. cit., 1877. PI. Ill, Fig. 30. 
