SYNAPSIS AND CHROMOSOME ORGANIZATION 479 



of the nucleus, is here removed a considerable distance, and 

 separate from the deeply stained loop (5), to which it is usually- 

 attached. This deeply-staining thread is found in the later 

 stages to be that of chromosome 5 (see plate 1) and it very com- 

 monly lies near, and often attached to, the accessory. This 

 association may be seen in figures 1, 4, and 6. 



Figure 6 represents a nucleus at about the same stage as cell 

 A on plate 1 and shows the separate spireme segments. Each 

 of these has but one longitudinal split, but each represents a 

 tetrad. The segments are numbered according to the arrange- 

 ment on plate 1. A series of successively older stages may 

 therefore be recognized, beginning with figure 1, extending 

 through figure 6 on plate 3, and continuing through cells A to H 

 on plate 1. 



The series of stages just mentioned constitute, it seems to 

 me, a sufficient body of evidence to indicate that in Chorthippus 

 parasynapsis is the rule. 



d. Chromatid movements. Attention may be directed to the 

 different rates of change in the chromatid relationships experi- 

 enced by different chromosomes in the . same cell and by the 

 same chromosome in different cells. The typical form of the 

 metaphase chromosome " of the telomitic type seems, in this 

 species, to be the rod extended parallel to the spindle axis. Such 

 a form is taken by chromosomes 1, 2, 4, and 6 of cell G on plate 1. 

 Although number 5 has not been pulled out in the direction of 

 the mitotic poles sufficiently to make it a rod, it is readily ap- 

 parent that only a small amount of movement of the oppositely 

 directed pairs of chromatids would produce the forms seen in 

 chromosomes 4 and 6. As an example of the different degrees to 

 which the chromatid movements have brought about an ap- 

 proach to the extended-rod condition of the metaphase, atten- 

 tion may be called to cell E, where chromosome 4 seems to be 

 lagging much behind the other chromosomes, though in cells F, 

 G, and H, such is not the case. In cell D, on the other hand, 

 chromosomes 2 and 5 seem to be farther advanced toward the 

 metaphase-rod condition than any of the others. 



