THE SPERMATOGENESIS OF LEPIDOSIREN PARADOXA. 17 
ones, however, are one bivalent ring* (6), one pair of recently 
separated univalents ( 5 ), and a number of free univalents. In 
the univalents the transverse constriction is beginning to 
develop. 
In PI. 3, fig. 20 a synizesis has almost broken up, but there 
are still some chromosomes hidden away among the main clump. 
At least thirty free ones can be made out, and of these one 
is a bivalent ring ( b ). One pair of very long chromosomes is 
also seen still united by a thin thread (6*). Owing to the 
fact that the transverse constrictions are beginning to 
develop, it is not in every case easy to determine the valency 
of the chromosomes. 
The pair of long chromosomes ( l ), which are seen united by a 
thread only at s in this figure, can be traced from now ou wards 
to the end of the second maturation division. They can also 
be seen in the spermatogonial mitoses (PI. 1, fig. 7) and 
probably also in the somatic nuclei. 
In PI. 3, fig. 21 synizesis has quite broken up and the 
separation of the ex-conjugants is complete. O 11 the other 
hand the shortening and transverse constriction of the chromo- 
somes has not proceeded so far as in the preceding figure. 
The somatic number of univalents can be easily seen. The 
wide separation of the “homologous” chromosomes is well 
seen in the case of the large pair; it will be noticed that 
several chromosomes are lying between them. Although this 
nucleus, unlike the others figured of this stage, has been 
grazed by the razor, the wide separation of this pair of 
chromosomes cannot be due to dislocation by the knife, as 
they lie towards the untouched surface of the nucleus, and the 
section is a celloidiu one, mounted without dissolving out the 
celloidin. 
The nucleus shown in PI. 3, fig. 22, is further advanced 
in that the transverse constriction of the univalents is much 
more marked, but the dissociation of the ex-conjugants is not 
so complete. The chromosomes can be easily counted, and 
we find nine bivalents and twenty univalents (= 38 uni- 
VOL. 57, PART 1. NEW SERIES. 
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