22 INTRODUCTION. 
or it may have had this form at an earlier stage. The chromosome at 
the right in this figure (Fig. 9, C), was attached to the spindle end- 
wise, and the retreating granddaughter segments will probably form 
V’s. If the chromosome on the left were rotated 45°, so that the seg- 
ments would be seen in profile, we might have the picture of two 
double V’s or U’s about to separate, for, as shown in the figure, the 
free ends of the pairs of granddaughter elements tend sometimes to 
diverge. The two chromosomes in this figure, which belong to the 
same spindle, show clearly how figures of the same shape may be pro- 
duced in different ways. In the one on the right the chromosome was 
probably attached to the spindle by the end, and the V’s are formed by 
the divergence of the free ends, while that on the left was fastened near 
the middle of each segment, and the V- or U-shape of the retreating 
segments is the result of a bending. 
In such chromosomes as Fig. 8, G, H, I, the retreating elements 
may retain their present form, or they may be bent during metakinesis 
into U’s or V’s. When the daughter segments of such chromosomes 
are separated, they must untwist, and it is reasonable to suppose that 
the force necessary to separate them when twisted will be sufficient to 
bend the segments into a U- or V-like figure. 
‘THE ANAPHASE. 
*The pairs of granddaughter segments, as they pass toward the poles, 
are in the form of contiguous, straight, or undulating rods, V’s or U’s, 
or, in case one limb of the last two named figures be much longer 
than the other, as is sometimes observed, the retreating elements will 
be in the form of hooks. Even in those cases in which both grand- 
daughter segments are nearly straight or undulating rods of equal 
length, each is often slightly bent or hooked at the end fastened to the 
spindle fibers, or the segments may be bent at both ends. 
The daughter chromosomes in Podophyllum and Tradescantia 
show with great clearness their double character during the anaphase 
(Fig. 9, E), The granddaughter segments generally lie close side by 
side, although cases in which they are slightly separated are now and 
then to be observed. There are in these genera also variations in the 
forms of the chromosomes which may be explained in the same man- 
ner as in Leléum. 
The retreating chromosomes and the structure of the spindle suggest 
that the segments are conveyed to the poles by a pushing and pulling 
action of the spindle fibers. 
