1909] | PACE—GAMETOPHYTES OF CALOPOGON 129 
cell is still in the spirem stage. This does not appear so often as the 
other in my material. At this division of the daughter cells the walls 
begin to form in the usual way (figs. 14, 18, 19), though in a few 
instances no evidence of wall formation was seen (figs. 17, 20). But 
the walls all disappear, if they were ever found in these cells (jigs. 20, 
28), for no case of a wall at this stage was seen, though hundreds of 
examples like those figured were found. After this division the 
micropylar nucleus from the inner daughter cell begins to disintegrate 
(jigs. 21, 22), although it may sometimes divide (fig. 24). Fig. 23 
shows both daughter cells divided, with one megaspore nucleus in 
each case disintegrating. While apparently two of the megaspores 
are active, one of them is already in advance of the other, judging 
by size of nucleus and cell. Fig. 24 shows the micropylar daughter 
cell with the nucleus in metaphase, while jig. 25 is’only late spirem. 
Probably the former would have completed the division. Figs. 24 
and 25 are also interesting as the only cases seen in which the mega- 
spore nucleus that usually disintegrates in the sac shows evidence of 
further development. In the first it has divided, while in the second 
it is in the spirem stage, yet in both cases it is evidently disintegrat- 
ing. The megaspore that is to form the sac in fig. 25 is in mitosis with 
the spindle well formed. 
EMBRYO SAC 
As the walls disappear, or never develop, in the division of the 
daughter cells, the two megaspore nuclei are left in the embryo sac. 
The micropylar nucleus apparently always disintegrates, as does the 
cytoplasm about this nucleus (figs. 21, 22, 23, 48). This leaves only 
one megaspore nucleus, probably one might say only one megaspore, 
to enter into the organization of the embryo sac. This nucleus 
divides, giving a sac with two nuclei (jig. 46). The three other 
bodies in the sac are probably the three disintegrating megaspore 
nuclei. The two nuclei of the sac divide simultaneously (fig. 47), 
giving a four-nucleate sac (fig. 48). This figure is interesting be- 
Cause the three disintegrating megaspore nuclei are easily identified - 
at this late stage. Fig. 49 shows about the same stage, except that 
the sac has increased in size and the nuclei are preparing for the ae ee 
division, although there are still traces of the spindles of the preceding 
