25-1 Uiiivefsity of California Publications in Zoology [Vol. 16 



adequatel.y provided for in the peripheral material. Often there are 

 found prophase stages in which the karyosome, both polar mas.ses and 

 their connecting portion, are granular (pi. 20, fig. 55). The chromatin 

 masses of the karyosome are large and loose and some of the chromatin 

 granul&s in the chromatic polar masses are in an unbroken line with 

 those on the fibers (pi. 20, figs. 41, 55, 56). Those nearest the polar 

 mass stain dark and there is a slight decrease in staining capacity 

 toward the equator. This seems to indicate that part of a chromosome, 

 and a large part at that, comes from the karyosome. Also the late 

 division stages and nuclear reorganization indicate the same thing. 

 During the anapha.se the chromosomes become fu.sed (pi. ]8, figs. 8, 14) 

 and a chromosome ma.ss is clearly distinguishable in every stage after 

 that until the nucleus is reorganized (pi. 20, figs. 43, 46, 50, 51) and 

 the chromosome mass and chromatic polar masses are fused in the 

 central karyosome. 



Extrusion of chromatin from the region between the polar ma.ss 

 and the chromatin mass, begins in the telophase (pi. 18, fig. 15). Cer- 

 tainly all of the chromosome chromatin is not given out, from the later 

 reorganization stages (pi. 20, figs. 43, 46, 58, 61). For that matter 

 none of it may be given off, but .some from the polar mass, or from both, 

 or none at all. may be given off. The last assumption, however, would 

 leave out of account the stainable peripheral granules unless the.se were 

 later given off by the karyosome. From the .slight decrea.se in the 

 relative sizes of the chromatic masses, polar and chromosome, in re- 

 organization, it seems probable that some must be given off from the 

 chromosome mass (pi. 20, figs. 50, 51, 53. 57) to the peripheral 

 chromatin. 



(h) Mitosis and Amitosis 



Stages have been found which correspond to some of those 

 figured by Hogue (1914) as amitosis, but on careful analysis have 

 proved to be stages in mitosis. As described by Hogue (1914, pi. 

 16, figs. 5-7) amito.sis is most often unequal. "The two parts of 

 the karyosome always bend up into a u-shape. " In the "unequal 

 division" the small part is the chromosome mass, the large part the 

 chromatic polar mass, the narrowed portion the connection between 

 the two, and the appearance of a pinehed-in nuclear membrane is 

 given by the extruding peripheral chromatin (pi. 20, fig. 57) as 

 found in a nucleus reorganizing after division. The case in which 

 Miss Hogue 's amitotic division is "equal" corresponds to the prophase 

 in which the karyosome has become dumb-bell shaped before the 



