July, 1922] 
BAILEY POLLINATION OF MARCGRAVIA 
of pollen and rapidly to become deciduous. As shown in figure 10, the 
multilocular ovary contains a large number of ovules, only a portion of 
which produce embryos (figs. 5, 8). The remaining ovules, presumably the 
unfertilized portion, undergo a curious metamorphosis or process of enlarge- 
ment. Their outer integument becomes greatly thickened by radial elonga- 
tion of its constituent cells, which contain a reddish or amber-colored, 
amorphous substance (fig. 8). The proportion of these aborted ovules 
varied considerably in different fruits, but was no higher in the bagged 
specimens ,than in those which were unprotected. In fact, the former 
frequently contained more embryos or viable seeds than the latter. In 
other words, M. cuyuniensis, instead of being protandrous and cross-pol- 
linated, appears to be self-pollinated and practically cleistogamous. 
(4) 
The objection may be raised at this point that, in dealing with M. 
cuyuniensis , I was concerned with an abnormal or aberrant representative 
of the genus Marcgravia, and that the typical, day-flowering species are 
protandrous and cross-pollinated by birds. Marcgravia purpurea, which 
belongs in an entirely different section of the genus, flowers during the 
daytime, and therefore may be considered to be significant in this con- 
nection. Although I was obliged to leave the Kartabo Station before this 
species flowered. Miss Anna H. Taylor and Dr. and Mrs. Alfred Emerson 
very kindly consented to watch for the flowering season, and were able 
to make a number of important observations. I have already referred to 
the fact that "a humming bird, believed to be the species Topaza pella 
or the long- tailed, crimson Topaz, visited a flower in bloom and sucked 
nectar from the nectary." However, the bird did not approach the in- 
florescence from below, but "hovered from the top, dipping its slightly 
curved or straight bill of medium length into the nectary for a short dis- 
tance." In M. purpurea, as in M. cuyuniensis, dehiscence occurs within 
the calyptriform corolla, and at the time when the capsule falls the stigma 
is already coated with a thick layer of pollen. Furthermore, the stamens 
show a pronounced tendency to wither, and to drop off with the deciduous 
capsules. Dr. Emerson states: 
The caps split at the base and work slowly off. When they fall, they often carry 
a large number of stamens with them. In a few cases, when the caps were about half- 
way off, we could see that many of the stamens had withered at the base and would very 
likely fall with the cap. The pistil is covered with pollen at the time that the cap falls. 
Evidently the day-flowering M. purptirea is self-pollinated like the 
night-flowering M. cuyuniensis. 
Discussion 
Such facts as these raise the question whether the Marcgraviaceae are 
protandrous and whether their curious nectariferous appendages are adap- 
