1898] KARKYOKINESIS IN THE ROOT TIPS OF ALLIUM CEPA 233 
2. The continuous spirem shortens and thickens and is 
looped into a definite number of loops, the heads of which, in 
typical cases, point toward the two poles of the spindle. The 
nucleoli and nuclear membrane disappear and the dome-shaped 
spindle becomes more pointed by the outward extension of the 
poles. This stage ends with the breaking of the chromatin 
loops into separate chromosomes, and it may appropriately be 
called the looped mother skein (figs. 11-19). 
Il. METAPHASE, 
3. After the nuclear membrane disappears, the separate 
chromosomes are drawn down, with their heads toward: the 
center, into the equatorial plane, while the spindle continues to 
become more pointed (figs. 20-25). This constitutes the /oose 
mother skein stage. 
4. When the chromosomes have come into the equatorial 
plane, there is a pause resulting from the seeming pull of the 
spindle fibers in opposite directions, which holds the chromo- 
somes rigidly until the longitudinal splitting of the chromo- 
somes is complete, when separation of the daughter chromo- 
somes begins (figs. 26-28). This constitutes the mother star stage. 
III. ANAPHASE. 
5. After the longitudinal segmentation of the chromosomes 
which, as a general rule, does not begin until the chromosomes 
are in the equatorial plane, the daughter chromosomes are grad- 
ually pulled apart, the separation beginning at the heads of the 
loops. The centrosomes usually divide during this stage, though 
in some cases the division may be considerably earlier. This 
Stage is appropriately known as metakinesis ( figs. 29-31). 
6. The daughter chromosomes having been completely 
pulled apart, now travel to the poles and arrange themselves in 
Star-shaped figures around the poles, while the central spindle 
appears between the two stars. The radiations around the cen- 
trospheres, which now contain two separate centrosomes, become 
more prominent (figs. 72, 37). This is the daughter star stage. 
