1914] ELKINS—MATURATION IN SMILAX 39 
pass through interkinesis in a compact condition, while others 
become vacuolate. In Nephrodium molle (YAMANOUCHI 45) the 
chromosomes become vacuolate, but their identity is not lost. 
ALLEN (1) cites the formation of a spireme during the telophase 
of Lilium canadense. In Pinus and Thuja (Lewis 24) the identity 
of the chromosome is completely lost. NicHots (31) reports a 
similar condition in Juniperus. 
Homotypic piviston.—In preparation for the second division 
the nuclear membrane disappears’ and is succeeded by the forma- 
tion of a spindle whose axis corresponds with the greater axis of 
the daughter nucleus. The daughter spireme is at first spread 
out on the spindle from pole to pole (fig. 21); later the chromatic 
mass contracts (fig. 22) and occupies a position at the equator of 
the spindle. At this time the spireme seems to be resolving into 
chromosomes (fig. 22). Throughout these stages there is no sign 
of a double filament: in fact the whole structure is indistinct. 
Figs. 23 and 24 show fully formed chromosomes which have split 
into daughter chromosomes. A side view of the spindle (figs. 
23, 24) presents chromosomes apparently shaped like dumb-bells. 
A comparison of the above mentioned figures with fig. 25, a polar 
view of the equatorial plate, explains the actual condition. The 
daughter chromosomes are paired in the form of V’s;_ the open ends 
of the V’s are turned outward, the arms of the V’s are nearly at 
right angles to the axis of the spindle. The appearance of the 
chromosomes of figs. 23 and 24, as described above, is due to the 
fact that only the tips of the chromosomes at the open ends of the 
V’s can be seen; the seeming connection between the chromosome 
tips is occasioned by an indistinct view of the apices of the V’s. 
The separation of the daughter chromosomes as in the first 
division is not simultaneous. Fig. 23 shows a chromosome well 
on its way toward one pole before its sister chromosome, or the 
2 LAWSON in a recent paper (23) claims that the nuclear membrane does not 
varias ponies or collapse as _— —, said ase to be the case. On the contrary, 
Changes in the quantity and form 
of the chromatin previous to the metaphase are apparently accompanied by a change 
in the osmotic relations of the karyolymph. As a result of this there is a gradual 
decrease in the volume of the nuclear vacuole until the nuclear membrane closes in 
about the chromosomes; each chromosome becomes a single osmotic system. 
