3O2 NATHAN FASTEN. 



EXPLANATION OF PLATE 2. 



FIGS. 14 and 15. Nutritive cells, with two nuclei, suggestive of amitosis. 



FIGS. 16 and 17. Early prophases, primary spermatocyte stage. In Fig. 17 

 two darkly staining chromatoid masses can be seen within the cytoplasm. 



FIG. 1 8. Leptotene stage. 



FIG. 19. Synizesis and synapsis stage. In this stage the leptotene threads 

 have a paired parallel arrangement at the synaptic pole of the cell. The chromatoid 

 bodies (k), and the centrosome (c), are also visible in the cytoplasm. 



FIG. 20. Pachytene stage. The paired leptotene threads have united into 

 thick gemini. 



FIGS. 21 and 22. Diplotene stage. 



FIG. 23. Postdiplotene stage. 



FIG. 24. Tetrad formation. In this stage the nuclear wall begins to break 

 down. 



FIG. 25. Tetrads transformed into dumb-bells. The cell is entering the 

 metaphase and the chromatoid bodies, surrounded by clear spaces are seen at 

 opposite poles. 



