EXPLANATION OF PLATE XXIV. 



Fig. 21. — Late prophase of first spermatocyte showing the quadrivalent 

 character of the chromosomes. 



Figs. 22, 23. — First spermatocyte metaphases. Note the constancy in 

 form and number of the chromosomes. 



Figs. 24, 25, — Succeeding metaphases following the stage shown in fig- 

 ure 23. 



Figs. 26, 27. — Anaphases of first spemiatocyte. 



Fig. 28. — Telophase of the first spermatocyte. The homogeneous condi- 

 tion of the accessory chromosome is characteristic. The bivalent 

 character of the chromosomes is apparent. 



Fig. 29. — Later telophase of the same. The polar granules are seen in 

 the polar ends of the dyads. 



Fig. 30. — Metaphase of the second spermatocyte showing twelve dyads. 



Fig. 31. — Same stage. A lateral view of the mitotic figure. 



Fig. 32. — Anaphase of the second spermatocyte resulting in the separa- 

 tion of chromatids. 



Fig. 33. — An early stage in the developing spermatid, (a) The spindle 

 fiber remains. Note also the small round bodies staining like homo- 

 geneous chromatin within the nucleus. 



Fig. 34. — A later stage in the developing spermatid, (a) Middle-piece 

 staining like the chromatin bodies in the nucleus of figure 33. 



