IOO E. L. SHAFFER. 



PLATE II. 

 (Figs. 13 to 27.) 



FIG. 13. Telophase nucleus of spermatogonium, showing chromosomes spinning 

 out into delicate threads. 



FIG. 14. Characteristic resting nucleus of spermatogonium. 



FIGS. 15, 16, 17. Stages in the condensation of the chromatin from the resting 

 stage to the formation of the chromatic blocks. 



FIGS. 18, 19. Early growth stages. Evidences of parallel pairing of leptonete 

 threads. 



FIG. 20. Contraction (synezesis) stage. 



FIG. 21. Pachytene threads released from synezesis stage. 



FIG. 22. Strepsistene nucleus. Chromatin threads unanalyzable. 



FIG. 23. Various forms of diplotene and strepsitene threads. 



FIG. 25. Early prophase of ist spermatocyte. Tetrads beginning to form. 



FIG. 26. Cell in prophase simulating synezesis; due to faulty fixation. 



FIG. 27. Cell in stage similar to Fig. 26 from well-fixed material. 



