288 THEOPHILUS S. PAINTER 



one finds short strands of chromatin (fig. 5, just above the 

 deeply staining X-elements) which may represent micro- 

 chromosomes. 



The tetrads, which condense into the prophase chromosomes, 

 are for the most part ring-shaped, at least this is true for three 

 of them. These rings subsequently divide so that a V-shaped 

 element goes to each pole, but I have not determined which 

 plane the line of splitting cuts through. Among the rings the 

 conspicuous bipartite X-body can readily be seen. 



When the first maturation division spindle is formed, one sees 

 in equatorial plate view (figs. 7 and 8) six large macro-chromo- 

 somes and eleven micro-chromosomes. Among the macro- 

 chromosomes the small 'b' chromosome can always be identified, 

 the ' c' chromosome is frequently seen, but it not so easy to mark 

 the 'a' chromosome in polar view. The presence of six macro- 

 chromosomes in the first maturation division indicates that 

 the twelve spermatogonial chromosomes have united, and the 

 presence of eleven micro-chromosomes (there are twenty-two 

 in the spermatogonia) indicates that the same thing holds true 

 for these smaller bodies. 



Side views of the first maturation division show several 

 points of considerable interest (figs. 9 to 14). First of all, one 

 can nearly always identify four chromosomes in such views. 

 The large 'a,' the small 'b,' the intermediate 'c' chromosomes 

 show up in all such views, and in addition a bipartite chromosome 

 is observed (marked X) which has spindle fiber attachments at 

 one pole only of the cell. The micro-chromosomes (figs. 10 to 

 13) show up as small dumb-bell-shaped bodies, which are doubt- 

 less small tetrads. 



As the first maturation division goes forward, one finds here 

 and there cells in which the bipartite chromosome (marked X) 

 is passing undivided to one pole. Figures 9 to 14 show six such 

 cells. A close study of the chromosomes has shown that it is 

 the same chromosome which shows this movement in the different 

 cells, and, further, that this bipartite element is not half of one 

 of the tetrads which has divided early, the other half remaining 

 in the spindle. Tliis bipartite element is believed to be the same 



