Ae AI POOP 
. 
hes #! 
Hatal, Mitosis in Nerve Cells. 283 
change occurring in this stage is a disappearance of the nuclear 
membrane. 
Fig. 5 shows the completion of the former stage, present- 
ing sixteen large masses, one of which exhibits a dumb-bell 
shape. The large chromosomes thus formed by the accumula- 
tion of the smaller chromatic granules are disconnected from 
one another. These separate bean-shaped masses next become 
somewhat dumb-bell shaped; then these masses fuse together 
end to end, thus forming again a long continuous strand (Fig. 
6). The number of the internodes composing this strand is 
found to be always sixteen. The connecting pieces of each 
dumb-bell shaped mass are frequently considerably diminished, 
both in length and in diameter; and very often the enlarged 
ends of each dumb-bell are drawn out towards the center of the 
circle. Thus the two neighboring ends form a V-shaped mass 
with the tip towards the center. This case is very well shown 
in Figs. 6 and 7. Still another variation of the figure which is 
met very often, is the intimate union of two dumb-bells. Fig. 
10 isan example of this. The small letter (a) of the figure 
marks the chromosomes where two dumb-bells lie parallel and 
close together, thus giving the appearance of a single rod. This 
union of the two dumb-bell shaped masses into a single rod 
makes it difficult in some cases to count the exact number of 
chromosomes. In this stage the chromosomes stain most in- 
tensely. After the chromosomes combine to form a strand 
composed of dumb-bell shaped masses, the-strand forms a ring, 
the constituents of which are the V-shaped bodies just described 
(Fig. 9). This mitotic figure forms the ‘‘equatorial plate.” 
Fig. 9g is a side view of the germinal cells in this stage. 
Besides the changes of the chromatic substance already men- 
tioned, there are also important changes of the centrosome. 
Correlated with the changes in the chromatic substance is a 
migration of one of the central corpuscles to the opposite pole 
of the nucleus, but in this instance, the migration could not 
be followed. 
From the fragmentary observations of the migration of the 
centrosome, the present writer believes that one of the central 
