88 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
of the division process and concern ourselves chiefly with the fate of 
the chromosomes after their division and separation has been accom- 
plished. 
In my account of the accessory chromosome, I have already men- 
tioned the formation of sacs or vesicles in the telophases of the sperma- 
togonia. In an early telophase, such as is shown in figure 5 (Plate 1), 
the chromosomes are clumped together in a rather compact mass at 
the pole of the spindle. But the distal tips of the larger chromosomes 
may be seen projecting in various directions. Following the clumped 
condition, stages occur during which the chromosomes begin to ex- 
pand and to separate from one another. At the same time there is 
developed about each chromosome a hyaline area, at first small in 
extent, but gradually enlarging as the chromosomes continue to ex- 
pand. These conditions are shown in figures 6-9. Figure 6 is a side 
view and figure 7 a transverse (optical) section of the same stage. 
Figures 8 and 9 are likewise side view and optical section, respectively, 
of a later stage. At this later stage it will be seen that a membrane 
has been formed at the boundary between the hyaline area and the 
cytoplasm. We are therefore probably dealing with sacs or vesicles 
similar to those described by Sutton (’00) for Brachystola. 
What is the origin of these sacs? Does the hyaline region as it 
first appears represent material from the cytoplasm, or from the chro- 
mosomes, or is it an artifact resulting from the contraction of the 
chromatin under the influence of the fixative? That it is not an arti- 
fact, will be apparent, I believe, from the following considerations : — 
(1) The chromosomes themselves, at the stages shown in figures 6 and 
7, are larger than in the earlier stages represented in figures 3 and 4. 
(2) The chromosomes continue to expand and the vesicles expand still 
more rapidly, as will be seen from the later stages (fig. 8 and 9). (3) 
The hyaline region as seen in figures 6 and 7 appears more highly 
refractive than the cytoplasm which would not be the case if it were a 
space produced by shrinkage of the chromatin. 
A comparison of the conditions shown in figures 6 and 7 with those 
shown in figures 10 and 12 will, I believe, show that the expansion of 
the vesicles has been at the expense of the cytoplasm. The relative 
volume of the space within the vesicle as compared with the volume of 
the cytoplasm, is much less in these earlier stages (fig. 6 and 7) than 
in the later stages (fig. 10 and 11). Further, it will be seen that the 
expansion of the vesicles is accompanied by: — (1) an increase in the 
size of the cell-body, (2) a diffusion of the chromatin into a kind of 
reticulum within the space of each sac, (3) the breaking down of the 
