PLATE 4 



EXPLANATION OF FIGURES 



29 Primary spermatocyte anaphase, oblique view showing 12 chromosomes 

 at either pole. The dotted line a-h separates the two groups; the m chromosome 

 is the last to divide; white. 



30. Same stage as figure 29; negro. 



31 and 32 Primary spermatocyte telophase. In figure 31 12 chromosomes 

 may be counted at the left pole of the spindle. The chromosomes at the other 

 were fused and indistinct. 



In figure 32 a large plasmosome may be seen near the lower pole of the spindle; 

 white. 



33, 34, 35 Characteristic interkinesis stages, showing chromatin nucleoli 

 which suggest the X and Y elements. In figure 35 the X element lies above the 

 Y element which is not shown; white. 



36 Interkinesis stage showing 2 chromative nucleoli which very likely are 

 the separated X and Y ; negro. 



37 Secondary spermatocyte metaphase plate showing 12 chromosomes; white. 



38 and 39, Secondary spermatocyte plate, showing 12 chromosomes; negro. 



20 



