Meiotic Mitoses of Osmunda. 165 
chromosomes proceed to the poles, fission almost completely separates 
them into the daughter chromosomes which will separate on the homotype 
spindle (Fig. 84). 
In anaphase (Fig. 85) these daughter univalent chromosomes persist (see 
Text-fig., Nos. 25 and 26), and as telophase advances each daughter chromo- 
some further splits into two threads (Fig. 86). This apparently additional 
secondary fission may be accounted for by the fact that entire univalent 
chromosomes, instead of half univalent chromosomes, have passed to the 
spindle poles, as in all other spindle figures. 
The daughter chromosomes become resolved into paired beads and 
parallel threads (Figs. 87 and 88), and the identity of the chromosomes is 
lost to view. 
5. Second Meiotic Division. 
The homotype prophase follows speedily on the heterotype telophase, 
and with no intervening rest. The threads derived from the splitting of the 
daughter halves of the univalent chromosomes of the heterotype anaphase 
come together in pairs, and concentrate into chromatic masses (Fig. 89). 
These are in excess of the reduced number of chromosomes, and this is only 
to be expected, since double the reduced number of chromosomes split 
apart in anaphase, owing to the splitting of the daughter univalents (see 
Text-fig., Nos. 25-28). 
Throughout the homotype prophase the daughter chromosomes are 
more or less separate, and they pass on to the spindle as individual entities 
(Fig. 94) (see Text-fig., Nos. 29-35). As the daughter univalent chromo- 
somes proceed to the spindle poles, each one becomes almost completely 
divided into longitudinal halves (threads) (Fig. 95). This is the reappearance 
of that fission seen in the daughter chromosomes of the heterotype telophase 
(Fig. 86). The fission closes up temporarily during the homotype anaphase 
(Fig. 96), and then reappears during telophase, thus splitting the chromo- 
somes into halves (threads) (Fig. 98). These threads are at first homo- 
geneous and then become beaded. The parallel threads gradually diverge 
from one another (Fig. 99) and form a reticulum, thus giving rise to the 
resting stage of the several tetrad nuclei (Fig. 100). 
6. The exact correspondence of the two spiremes as they come 
together in pairs is exceedingly striking. This phenomenon is character- 
istic, not only of the associating pairs of threads or half univalent spiremes 
of the somatic and presynaptic prophases (PI. VIII, Figs. J 1, 14, 16 ; PI. IX, 
Figs. 41, 46, &c.), which combine to form the entire univalent spireme 
filament, but also of the conjoining pairs of filaments or entire univalent 
spiremes of the post-synaptic stages which unite to form the bivalent 
spireme (PI. X, Fig. 69). In both cases the paired spiremes are taut and 
strained, and the spireme of each pair is precisely similar to its fellow, even 
to the beading. If their previous history had not been traced, the spiremes 
