ee Pe eee ee ese er 
1899] STUDIES ON REDUCTION IN PLANTS 7 
As the chromosomes are drawn to the nuclear plate they lie 
in various positions. At first it was thought that the axis of the 
chromosome, whether a ring, a pair of rods, or plate, lay perpen- 
dicular to the axis of the spindle. I have observed them in this 
position a short time before the spindle is complete. In some 
such cases, the position of the spindle threads suggests that the 
chromosomes are pulled around before division so that the axis 
is parallel with the spindle axis. In other preparations, the 
chromosomes, where they lie close together, tend to fuse to such 
an extent that it isimpossible to determine in what position they 
lie at the nuclear plate, z.e., whether parallel with or perpendicu- 
lar to the axis. In a large number of preparations conditions 
are such as to lead me to believe that the axis of the chromo- 
some is parallel with the axis of the spindle. The chromosomes 
are so numerous and of such size that they cannot all lie at the 
periphery of the plate, but occupy the center of the nuclear 
plate as well, so that an end view of the nuclear plate shows the 
chromosomes quite evenly distributed over this area. In many 
cases a large number of them are fused, and curious figures are 
thus presented. At other times they lie entirely separated, so 
that the individual rings, or pairs of rods, can be seen and 
counted in an end view of the nuclear plate. Where the section 
is cut so as to show an oblique view of the plate, the groups of 
tetrads, or pairs of rods, can be well seen and counted. From 
studies of sections in this direction, it appears that there are 
sixteen groups of tetrads, which would make sixty-four indi- 
vidual chromosomes, thirty-two to be distributed to each daughter 
nucleus of the first division, and perhaps sixteen to each 
daughter nucleus of the second division. A side view of the 
spindles of such preparations, at the nuclear plate stage, shows 
the long axis of the rings or pairs of rods to be parallel with the 
axis of the spindle. Since the chromosomes are distributed 
through the center of the nuclear plate as well, they lie like a 
bundle of chain links. The form of the ring, as suggested 
above, indicates that the axis of the longitudinal cleavage of the 
spirem or of the tetrad lies parallel with the axis of the spindle. 
