31 J. E. WODSEDALEK. 



PLATE II. 



FIGS. 10 AND ii. Last spermatogonial cells showing thirty-six ordinary chromo- 

 somes and the large sex-chromosome. 



FIG. 12. Last spermatogonial cell taken from stale tissue showing the per- 

 sistence of the segregation of the chromosomes in this stage. 



FIG. 13. Spireme stage of the primary spermatocyte showing the large sex- 

 chromosome. 



FIGS. 14-18. Polar views of metaphase stages of division of the primary 

 spermatocytes showing eighteen bivalent chromosomes and the sex-chromosome 

 which is usually at the periphery of the plate. 



