D. W. CUTLKR 165 



Figures 11 — 27. Spermatogenesis of hybrids. 



Fig. 11. Spermatogonia! division of dark coloured hybrids. 



Figs. 12, 13. Spermatogonia! divisions of !ight coloured hybrids. 



Figs. 14, 14 a. Spermatogonia! equatorial plates of darli coloured hybrids showing in 

 Fig. 14 probably 20 chromosomes, and in Fig. 14a 19 or 20. 



Fig. 15. Spermatogonia! equatorial plates of light coloured hybrids, showing pro- 

 bably 19 chromosomes on the left, and 20 on the right hand figure. 



Fig. 16. Spireme stage of darlc coloured hybrids. 



Figs. 17, 18, 19. Stages in synapsis of dark coloured hybrids, showing the concen- 

 tration of the threads to one side of the nucleus. 



Pig. 20. Three large chromatin masses in the primary spermatocytes of light coloured 

 hybrids. 



Figs. 21, 22, 23. Irregular number of chromatin masses in the primary spermato- 

 cytes of light coloured hybrids. 



Figs. 24 — 27. Irregular number of chromatin masses in the primary spermatocytes 

 of dark coloured hybrids. 



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