﻿256 • BOTANICAL GAZETTE [APRIL 



ments during metakinesis, since they are not attached by the 

 ends. But such U's or V's are always double, as is shown in 

 fig. 6 on the left, and n\ fig. 8. Both limbs of the U or V are not 

 necessarily of the same length, for there is every gradation 

 between these forms and straight rods with slightly hooked ends. 



The double character of the U-shaped daughter chromosome 

 is not always very evident. Sometimes the granddaughter seg- 

 ments give the impression that one chromosome is lying just 

 beneath another. Such phenomena were frequently observed 

 by myself during my first investigation of the subject and were 

 interpreted as two different daughter chromosomes, one lying 

 directly below the other. Chromosomes which have the form 

 of fig. 2, c, d, e, will probably yield U- or V-shaped elements 

 as a result of being bent during metakinesis. The X and Y 

 forms [Jig. 2^ g, It) will probably give rise also to V-, rod-, or 

 hook-shaped elements. In fig. 6, the chromosome on the left 

 was attached to the spindle near the middle, and each daughter 

 segment consists of two similar U- or hook-shaped granddaugh- 

 ter elements. This chromosome may have been originally in 

 the form oi fig. 2, b, e, or the two daughter segments may have 

 sustained the same relation to each other as in the figure, being 

 in contact only at one end. In the chromosome at the right 

 [fig, 6), the attachment was. at the end, so that each daughter 

 chromosome consists of two similar rods more or less bent or 

 undulating. 



Fig, 7 shows a typical nuclear figure in the anaphase. Here 

 it is clear that the chromosomes were attached to the spindle 

 by the ends, or very near the ends, so that as a consequence of 

 the second longitudinal fission each daughter chromosome con- 

 sists of tw^o rod-like, straight, or variously bent or hooked 

 granddaughter elements, which adhere at the polar ends, while 

 the equatorial ends diverge. Sometimes the polar ends are so 

 closely adherent or fused that the daucrhter chromosomes may 



I 



o 



appear as continuous V-shaped objects. In such cases it is often 

 impossible to determine in what manner the V-shaped chromo- 

 some was produced, and it is this fact that has led to incorrect 

 interpretations. The close adherence or fusion of the grand- 



