1898 ] COMPARATIVE MORPHOLOGY OF PISTILS 301 
while the apex of the pistil is directed so as to form an angle of 
about 90° with the axis of this papilla (fig. zz). Even at this 
stage the outer part of the pistil is flattened above (figs. 12, 13). 
This flattening progresses until a longitudinal groove is formed 
in the upper surface of the carpellary leaf, extending back to the 
axillary placenta. The apex of the carpel now begins to bend 
upward, while the ovule begins to grow downward. By the 
time that the ovule has bent 45° from its original position, the 
archesporium appears. The outer part of the pistil has also 
changed its direction by 45°, thus bringing the ovule partly 
within the cavity formed by the laminae which connect the axil- 
lary placenta with the apex of the carpel (fig. rg). At the time 
that the first traces of the single integument appear, the arche- 
sporium has divided into two cells and the ovule points directly 
down, 7. ¢., in its curving it has described an arc of about 145°. 
The apex of the carpel has in the same time described an arc of 
only 125°, so that it lies parallel to the receptacle (fig. 75). 
For some time further the pistil does not change much except 
in size. The ovule, on the other hand, is active in its changes. 
By the time that the megaspore furthest from the micropyle has 
by its enlargement destroyed the others (two or three in num- 
ber), the ovule has curved go? more (figs. 16,17). This process 
continues until at the time that the embryo sac is ready for fer- 
tilization the ovule lies with its axis parallel to that of the 
receptacle, a change in direction of about 325° (fig. 78). To 
accommodate the ovule thus bent upon itself the lower part of 
the pistil elongates somewhat, so that the fibrovascular bundle 
of the median line of the carpel, after leaving the receptacle 
and giving its branch to the ovule, passes first downward, then 
outward, and finally upward. The bundle going to the ovule 
passes first upward, then outward, then downward, and finally 
inward to the base of the nucellus. From this time on until the 
seeds drop, the position of the nucellus remains the same, so 
that by making longitudinal sections of the flower, it is easy 
to obtain longitudinal median sections of all the ovules, from 
one hundred to two hundred in number. As in Ranunculus, the 
