126 Arlow Burdette Stout 



in the earl} 7 stages of the equatorial plate the series of double chromo- 

 somes can be traced throughout most of its length. The spirem is more 

 or less twisted so that one chromosome of a pair may lie above the other. 

 As the metaphase stage approaches the spirem is so oriented that when 

 viewed from the poles all of the pairs lie in this position. Juel's figure 

 of this stage for Carex acuta shows fifty-two chromatin bodies, but it is 

 not clear that they are bivalent (Juel, 1900, plate XVI, figure 32). 

 Juel's figures show a suggestion of the serial arrangement of the chromo- 

 somes. His failure to discover the bivalence of the chromosomes in 

 diakinesis and in the equatorial plate was perhaps due to the fact that 

 he did not make a comparative study of the somatic divisions. 



A lateral view of the heterotypic division figure is shown in figure 28. 

 The homologous chromosomes are about to separate. This stage is 

 similar in general appearance to the early metaphase of a somatic divi- 

 sion; but there are, of course, but one half the number of chromosomes 

 in each of the two spirems as they separate and they are here twice as 

 large as the daughter chromosomes of the somatic metaphase. The 

 chromosomes part almost simultaneously throughout the spirem and 

 appear in lateral view in two well ordered ranks. They do not show a 

 split or line of separation for the formation of the daughter chromosomes 

 of the homoeotypic division; this may be due to staining or fixation, 

 though I am inclined to believe from the appearance that the split does 

 not occur at this stage, or that if it does occur, the two halves remain 

 closely joined together. 



For a time during the early anaphases the chromosomes are readily 

 identified and the serial arrangement is more or less in evidence in the 

 polar view. As the poles are reached the chromosomes are loosely massed 

 together so that in early telophases there is an aggregation of the indivi- 

 duals. A nuclear membrane soon forms, and, as the daughter nucleus 

 continues to enlarge, clear spaces show between the chromosomes, a 

 nucleole appears and the serial arrangement of the chromosomes is clearly 

 to be observed (fig. 29). The central spindle which was strongly deve- 

 loped during the early anaphases does not produce any pronounced cell 

 plate. This spindle has largely disappeared when the sister nuclei are 

 completely reorganized. 



The Homoeotypic Division. 



The two sister nuclei reach a completely resting condition, but soon 

 enter on the prophases of the second division. The chromosomes are 

 evidently full-sized throughout this period. At least there is no period 



