156 LOUISE B. WALLACE. 



EXPLANATION OF PLATE II. 



FIGS. 19-21. Primary spennatocytes. The spireme loops contract. The acces- 

 sory chromosomes separate again. 



FIGS. 22, 23. Primary spermatocytes. Prophase. Single V-shaped chromo- 

 somes open out into double Vs. 



FIG. 24. Primary spermatocyte. Metaphase. 



FIG. 25. Primary spermatocyte. Division of double V's to form single Vs. 

 Accessory chromosomes passing to one pole. 



FIG. 26. Primary spermatocyte. Anaphase. 



FIG. 27. Primary spermatocyte. Anaphase. Pole view, a.c. split. 



FIG. 28. Primary spermatocyte. Telophase. 



FIGS. 29, 30. Secondary spermatocytes. Rest stage. 



FIG. 31. Secondary spermatocyte. Prophase. Accessor}' chromosomes show 

 precocious, longitudinal split. 



FIGS. 32, 33. Secondary spermatocytes. Metaphase. 



FIG. 34. Secondary spermatocyte. Division of V-shaped chromosomes into rod- 

 shaped chromosomes. 



t" IGS. 35, 36. Secondary spermatocytes. Anaphase. Accessory chromosomes 

 divide equationally. 



FIG. 37. Secondary spermatocyte. Late anaphase, showing twenty-five rod- 

 shaped chromosomes. 



