PLATE XXV 



PRIMARY SPERMATOCYTES 



Fig. 17. Early leptotene nucleus, showing xx and y 



Fig. 18. Trifle later stage than Fig. 17, xx and y in close apposition. 



Figs. 19-20. Nuclei of syndetic cells, xx and y connected. 



Figs. 21-22. Diplotene nuclei, showing separation of xx and y-elements. 



Figs. 23-24. Early strepsistene nuclei, showing reunion of xx and y. 



Figs. 25-26. Later strepsistene nuclei, showing fusion of xx and y. 



Fig. 27. Late strepsistene, showing the formation of the nucleolar spherule 

 (nl) 



Figs. 28-29. Primary spermatocytes, metaphase plates, polar view, showing 

 12 chromosomes. 



Figs. 30-33. Primary speratocytes metaphase, lateral view, showing xxy-hexad 



Fig. 34. The twelve chromosomes of a primary spermatocyte metaphase. 

 xxy on extreme right, taken from a section. 



Fig. 35. Same stage as figure 34, except that it was taken from a smear slide. 



Fig. 36. Various forms of the xxy-hexad, as seen in metaphases and anaphascs 

 of primary spermatocytes viewed laterally, y-element shown above in each case 



