THE NUCLEI OF UROLEPTUS MOBILIS 



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fragmentation of the remaining nuclear parts, resulting in from 

 twelve to fourteen smaller masses (fig. 5) . In all cases, however, 

 after elimination of the chromatin granules, the nuclear fragments 

 fuse to fonn a single elongate and irregularly wound nuclear mass 

 (figs. 6 to 9) . The granular contents condense, with shortening 



Figs. 7, 8, and 9 Stages in concentration of the macronucleus. 

 mitotic nuclei. X 800. 



Three and two 



and loss of the irregularities, until a single, densely granular and 

 massive, nucleus results (fig. 10). It is now ready to divide; it 

 assumes an ellipsoidal form; its chromatin granules become 

 arranged in lines running from end to end (figs. 11 and 12), 

 and it constricts in the center, fonning a typical dumb-bell 

 figure before there is any external sign of cytoplasmic division 

 (figs. 13 and 14). 



