Helen Dean King 361 
During the late anaphase of the first maturation mitosis, the chromo- 
somes become greatly crowded together and appear to fuse into an amor- 
phous mass in which the outlines of the separate chromosomes are com- 
pletely lost (Fig. 53). Whether there is a true fusion of the chromo- 
somes at this time I have been unable to determine. Kingsbury has 
found a similar massing of the chromosomes at the poles of the first 
maturation spindle in the spermatocytes of Desmognathus, and he be- 
lieves that the chromosomes do not lose their identity at this time 
although they become inclosed in a nuclear membrane. Division does 
not take place simultaneously in all of the spermatocytes of a cyst; some- 
times only a single cell will be found dividing while all of the other 
cells of the cyst are in the early or late prophases of mitosis. 
As in Salamandra and Triton, there is no resting nucleus formed 
between the two maturation divisions. Sometimes the centrosomes divide 
for the second mitosis during the early anaphase of the first mitosis 
(Fig. 50), but as a usual thing division does not take place until much 
later. As in the prophases of the former divisions, each centrosome is, 
for a time, the centre of a small aster (Fig. 54). As the spindle for 
the second mitosis forms, the asters disappear and in the fully formed 
spindle the fibres converge sharply to minute centrosomes which show no 
traces of a radiation. 
During the formation of the second maturation spindle, the chro- 
mosomes remain massed together, as shown in Fig. 54, and the changes 
taking place in them cannot be determined. In rare instances this 
amorphous mass of chromatin may be found at the equator of the fully 
formed spindle (Fig. 55), but as a rule the chromosomes are separated 
at this time. Part of an equatorial plate of the second maturation 
spindle is shown in Fig. 56. Nine dumbbell-shaped chromosomes are 
seen which, as one might expect, are very much smaller than those 
found on the first spindle. The fact that at this stage also the chromo- 
somes are of different sizes seems to indicate that the chromosomes main- 
tain their individuality during the period between the two maturation 
divisions when they are apparently fused into an irregular mass. The 
second division must take place much more quickly than the first, as I 
have not been able to find more than two or three dividing cells in sec- 
tions of the testis containing hundreds of cells in earlier or slightly later 
stages of development. In all of the spindles that I have seen, the 
chromosomes were invariably in the form of dumbbells in the meta- 
phase (Fig. 56). In the anaphase, each dumbbell is separated into two 
nearly spherical portions (Fig. 5%) which are inclosed in a membrane 
29 
