PLATE 3 



EXPLANATION OF FIGURES 



17, 18, 19 and 20 Primary spermatocyte, metaphase plate, negro, showing 

 12 chromosomes. In figure 20 oi and a^ are the halves of a divided chromosome. 

 In figures 18 and 19 in has divided into m-i and Wo. 



21 and 22 Primary spermatocyte, metaphase side view, showing A'l' ele- 

 ments divided longitudinally liefore the other chromosomes; negro. 



23, 24 and 25 Primary spermatocyte, metaphase side view. In figure 23, 

 the XY element has divided. In figure 24 none of the chromosomes have divided, 

 c is a large bivalent chromosome out of plane with the majority of the chromo- 

 somes. In figure 25 hi and 62 are parts of a divided chromosome probably not 

 the XY; white. 



26 Primary spermatocyte metaphase side view showing at Ci, c-i, di and d^ 

 the halves of two chromosomes already dividing. These may or may not be the 

 products of the XY chromosome; negro. 



27 Primary spermatocyte anaphase showing most of the chromosomes di- 

 vided; white. 



28 Primary spermatocyte anaphase showing the divided XY element at 

 either pole and away from the other chromosomes; negro. 



18 



