(ENOTHERA MUT. EATA AND (E. MUT. SEMILATA. 571 
Fig. 48. — Similar to fig. 47, but here 0 whole chromosomes are 
moving to one pole and probal)ly 8 to the other. In the former group 
is a chromosome which has left behind a long trail of chromatin, while 
the latter group contains a small fragment of chromatin. At tlie 
periphery of the spindle is a nucleolus. 
Fig. 49. — A similar case of degeneration and loss of chromatic sub- 
stance ; two chromosomes are behaving as in figs. 47, 48, and are losing 
their chromatic substance. The spindle is cut, and the full number of 
chromosomes is not present. The chromosomes are also much smaller 
than normal. 
Fig. 50 a and b . — Late homotypic prophase of the two nuclei in a 
pollen mother-cell. In fig. 50 a there are 7 chromosomes just going on 
the sx)indle, while the sister nucleus in fig. 50 b shows 8 chromosomes. 
Nearly all these chromosomes show the longitudinal split. 
Fig. 51. — One nucleus of a pair at the homotypic metaphase, showing 
8 chromosomes in a group, and a ninth which is outside the nucleus and 
will probably degenerate. 
CE. lata. 
Fig. 52. — Normal heterotypic spindle in profile, showing 15 chromo- 
somes On the periphery of the nucleus are two nucleoli which have 
persisted up to this late stage. 
CE. lata to semilata. 
Fig. 53. — Metaphase of one of the nuclei of the homotypic division, 
showing 7 chromosomes, the two halves of one of which are widely 
separated. 
Fig. 54. — Homotypic metaphase, showing both nuclei in polar view. 
In the left-hand group are 7^ chromosomes, and in the right-hand 
group 6| chromosomes. Between the groups are fragments which 
together constitute the fifteenth chromosome, which was probably left 
behind on the heterotypic spindle. 
The half- chromosomes are marked S 
