388 
CLIFFORD H. FARR 
transformed into the prochromosomes of the resting nucleus. After 
nuclear migration has ceased and the nuclei have reached their maxi- 
mum size, they again become much flattened at right angles to the 
direction of the heterotypic spindle (figs. 7 and 22). This is unques- 
tionably in preparation for the homoeotypic karyokinesis (fig. 8). 
The breaking down of the nuclear membrane takes place before the 
disappearance of the nucleoli, and a multipolar spindle is organized 
about the chromosomes. These latter appear to arise directly by the 
enlargement of the prochromosomes and not by the interpolation of a 
spireme stage. Hence the prophase of the homoeotypic division is not 
exactly the reverse of the telophase of the heterotypic. As the multi- 
polar stages progress the nucleoli continue to decrease in size, until by 
the time the bipolar spindles are formed they have completely disap- 
peared. During the homoeotypic karyokinesis there is usually present 
an area of orange-staining homogeneous material on that side of each 
spindle that is toward the equatorial region of the previous division. 
It is often about equal to or wider than the spindle itself and extends 
for varying distances around to the polar side, but is always thicker 
toward the equator. In it no fibers are to be seen and the fibers in 
the region between the two orange areas become fewer and fewer as 
the prophases and metaphases progress. It is not improbable that 
the substance which composed the fibers of the primary heterotypic 
spindle becomes dispersed into the homogeneous orange-staining 
material. Only in rare instances is a fiber found crossing the hetero- 
typic equator during the anaphases (fig. 9). 
After the chromosomes are assembled at the poles in the telophases 
of the heterotypic karyokinesis, a nuclear membrane is formed in the 
usual fashion. No spindle fibers were found to be organized across 
the homoeotypic equator until this membrane appears (fig. 23) . As the 
fibers make their appearance across the heterotypic equator the orange 
area above mentioned slowly vanishes. No orange streak or other 
equatorial differentiation is found in any of the spindles of the second 
mitosis. In fact, no cytoplasmic changes at all are distinguishable 
until the nuclei have enlarged (figs. 11 and 12) and the dispireme has 
gone over into the prochromosome stage. The furrows develop at 
this time (fig. 24). The details of this process will be discussed below. 
The thickening of the wall is not as extreme as in Nicotiana (6), 
but is nevertheless very evident. It has the same staining reaction 
and homogeneous appearance as in the species of Dicotyledons for- 
