130 BOTANICAL GAZETTE [avcusT — 
mitosis. These spindles show no traces of wall formation. The — 
micropylar daughter cell did not divide here, although the nucleus — 
completed the prophase, even forming the chromosomes. There is — 
just a trace of the disintegrating megaspore nucleus in the sac. The — 
four nuclei in the sac increase in size and divide in the usual fashion ~ 
(fig. 50). The two dark bodies in the lower part of this sac are prob- 
ably the remains of the micropylar daughter cell and the disintegrating 
megaspore nucleus. This division gives eight nuclei in the sac (jig. - 
51). By comparing figs. 51 and 52 it can be seen that one of the four 
nuclei at the lower end passes up toward the center, and the sister 
to the egg moves down in the usual position for the two polar — 
nuclei. The eight nuclei arrange themselves in the usual way—an 
egg apparatus of two synergids and the egg in the micropylar 
end of the sac, three antipodals in the chalazal end, and the two 
polars near the center (figs. 52, 53). Fig. 53 shows a_ pollen 
tube already forcing its way between the integuments, about half- 
way to the sac. 
MICROSPORES AND MALE GAMETOPHYTE 
The pollen in Calopogon is in masses or pollinia, as it is in many 
of the orchids. Each massula is apparently the group of cells result- 
ing from the division of each sporogenous cell (jig. 36). The whole 
sporogenous area probably reaches the mother cell stage at the same 
time (fig. 37). The mother cells divide in the usual way, by the so-called 
simultaneous division, which is thought to be more characteristic of 
dicotyledons than of monocotyledons, although found in both group> 
(COULTER and CHAMBERLAIN 7, p. 121). This gives the tetrad form in 
some cases, but in others the four spores lie in any plane (jigs. 38-42): 
The microspore nucleus divides into the tube and generative nuclel 
while the pollen is still in the sac (fig. 43). Pollen tubes are numerous 
in the ovary, in some cases at least, when ovules are still in the mother 
cell stage, like jig. 5, although no pollen tube was ever seen in contact 
with an ovule at this stage. Figs. 4r and 42 are examples of pollen 
‘tubes within the ovary, before entering the ovules. In these the ge 
erative nucleus had already divided into the two male nuclei, 5° it 
is probable that this division takes place when the pollen grain 8% 
minates. ; 
