1918] OTTLEY—IMPATIENS 305 
to find all the microspores of an anther in an apparently resting 
stage and showing distinctly 7 chromatic masses. 
The microspore divides and forms a more or less vacuolate 
2-celled pollen grain (figs. 31, 32). The tube nucleus is normally 
spherical and lies more or less near the center of the developing 
pollen grain (figs. 32, 34, 35). The generative cell occupies various 
positions within the cytoplasm of the tube cell, and at all times its 
nucleus is smaller and its reticulum is much less delicate than that 
of the tube nucleus. The pollen grain grows and its cytoplasm 
becomes densely filled with food granules. At this time the genera- 
tive cell may either be attached to the wall of the pollen grain or 
lie free in the cytoplasm (figs. 34, 35). 
When the anther is ready to dehisce, it is impossible to dis- 
tinguish the cytoplasm of the generative cell, and its nucleus has 
changed from nearly spherical to a very slender lunate form (fig. 36). 
At first it was thought to be a sperm nucleus, but while these 
crescent-shaped nuclei are very characteristic of the developing 
male gametophyte, no more than one to each pollen grain was 
ever found. When the nucleus is in this condition it contains 
several chromatic masses in the center and stains a diffuse yellow 
at either end. In all cases where the nucleus could be seen clearly 
throughout its entire length 7 chromatic masses were visible 
(fig. 36). The mature pollen grains, in longitudinal section, present 
an almost rectangular appearance and possess 4 germ pores, one 
at each corner. No instances of the division of the generative 
cell while still within the anther were discovered, and it is doubtful 
whether this division takes place until some time after pollination. 
Ovule after pollination 
The pollen tube enters the embryo sac after the chalazal 
haustorium has developed. Many of the embryo sacs of a given 
ovary were found containing the pollen tube contents in their 
micropylar region. While no experiments were made to eliminate 
all chance of cross-pollination, the conditions under which these 
plants were grown in the greenhouse render it very probable that 
many of the flowers were self-pollinated. The pollen tube enters 
the embryo sac at one side of the filiform apparatus and either 
