320 University of Calif ornm Publications in Zoology [Vol.20 



ANAPHASE 



The anaphase is probably of longer duration than is the metaphase, 

 judging by inference from the relative number of individuals of both 

 stages observed. In fact, the majority of dividing nuclei found in the 

 material were in this stage, the next in abundance being the early 

 prophase. 



In most cases, there seems to be little difference in the size and 

 shape of the chromosomes during the anaphase, although occasionally 

 one or two chromosomes may be somewhat smaller in size than the 

 others (pi. 30, figs. 10, 13; pi. 31, fig. 28). The chromosomes range 

 in size from .5/* to 1.5/i. 



As the division of the chromosomes seems to occur before the 

 spindle is formed (lower nucleus in figure 7, plate 29), the separation 

 in the anaphase probably follows the original split, as in Giardiu 

 (Boeek, 1919), and Trichanympha (Kofoid and Swezy, 1919). The 

 separation of the two moieties is not synchronous for the six cliromo- 

 somes, but considerable variation is found between them in almost 

 every case examined. In many nuclei the variations in this respect 

 are striking, some of the chromosomes being well on their way toward 

 the poles before the final parting of the last daughter chromosomes is 

 completed (pi. 30, figs. 10, 11, 15; pi. 31, fig. 19). 



As the chromosomes divide they move toward the poles, as the 

 spindle fibers shorten (pi. 30, fig. 15). Along with this change the 

 nucleus begins to elongate somewhat, becoming less rotund througli 

 its middle and gradually assuming a dumb-bell shape (pi. 30, fig. 16). 



TELOPHASE 



With the migration of the chromosomes to the poles they soon lose 

 their identity and become massed together (pi. 30, fig. 16; pis. 31, 

 figs. 19-21). This process is accompanied by an elongation of the 

 nucleus and its constriction near the middle. The latter change 

 proceeds until the niieleus has become a long, slender dumb-bell (pi. 

 31, fig. 21), which may be drawn out until the sister nuclei come to 

 lie on opposite sides of the cyst. The nucleus parts in the middle, 

 the drawn-out points are retracted and two new spherical nuclei are 

 formed (pi. 30, fig. 17). 



The complete reconstruct iou of the nucleus evidently takes place 

 before the prophase of the next division is entered upon (pi. 30, fig. 

 18). Corresponding steps in the process of mitosis of the nuclei seem 



