II. The Ovule of Stangeria paradoxa. 289 
length, by more than 8 cm. in diameter at the widest part. 
At first, in the hope of obtaining a series of successive stages, 
one or two sporophylls were removed at intervals of a week 
or more. When, however, it was ascertained that even on 
July 4 embryos were present, this plan was abandoned and 
all the remaining ovules of one cone removed and fixed. The 
method is mentioned here, since, though useless in the present 
case, it would, if adopted early enough, enable all the main 
stages of fertilization and embryogeny to be studied on 
a single cone; the careful removal of sporophylls did not 
appear to injure the remainder of the cone in any way. 
Besides the seeds a number of aborting ovules were borne on 
the pollinated cone. As Fig. 17, which represents a scale 
bearing an aborted and a healthy ovule, shows, the former 
do not undergo the enlargement which normally succeeds 
pollination. The prothallus in the aborted ovules was either 
absent or represented by shrivelled remains, but the examina¬ 
tion of these ovules was of use in affording pollen-tubes 
arrested at an earlier stage of their development than those in 
the seeds. 
The seeds varied somewhat in size, but averaged about 
2*5 cm. long by 2 cm. broad : the differences mainly depended 
on the variable thickness of the fleshy layer of the integument, 
which is especially thick at the micropylar end of the seed. 
Within the succulent layer, of a bright purplish pink colour, 
is the sclerotic layer, which is continued outwards as a pointed 
projection surrounding the inner fourth of the micropylar 
canal (Fig. 18). Within this is a brown layer of papery 
texture including the internal system of vascular bundles. 
Below the level of separation of nucellus and integument no 
distinction of these regions can be made in the internal layer. 
As Fig. 18 shows, the eight vascular bundles of the inner 
vascular system bifurcate once or twice but no anastomosis 
takes place. The remains of the nucellus form a thin cap 
over the micropylar end of the prothallus. In the centre of 
this, the pollen-chamber with its conical apex is to be seen. 
The prothallus, now of a white colour owing to its cells being 
