228 MARY T. HARMAN. 



PLATE II. 



FIG. 13. Early telophase of last spermatogonial division. X, the odd-chromo- 

 some. 



FIG. 14. Beginning of growth period showing the uniting of the chromosomes 

 to form spireme; X is chromatin of the odd-chromosome in all the figures of this 

 plate. 



FIG. 15. Early loose chromatin thread. 



FIG. 16. Early contraction stage. 



FIG. 17. Later contraction stage and the appearance of the nuclear membrane. 



FIG. 18.' Large tangled thread. 



FIG. 19. Beginning of the concentration of the chromatin in various places 

 throughout the thread. 



FIG. 20. Breaking up of chromatin thread into the diploid number of chromatin 

 elements. 



FIG. 21. Further breaking of the chromatin thread and the beginning of the 

 formation of the bivalent chromosomes. 



