PLATE VI. 



Fig. 16. Later metaphase, showing peculiar character of spindle, with the man- 

 tle fibers converging at the apical point. Centrosomee are conical in shape. 

 Astral rays connect centrosome and cell membrane. 



Fig, 17. Early telophase of first spermatocyte division, showing the position of 

 the daughter groups of chromosomes. The centrosomes are hemispherical 

 in shape and are flattened against the cell membrane. 



Fig. 18. Later telophase, showing division membrane. The section is cut in such 

 a plane that the persisting spindle remains do not show. 



Fig. 19. Polar view of telophase of first spermatocyte. 



Fig. 20. Telophase showing persisting spindle remains. Mid body in the form of 

 a ring. 



Fig. 21. Metaphase of second spermatocyte division. 



Fig. 22. Telophase of second spermatocyte. The cell-wall shows signs of con- 

 striction. 



Fig. 23. Later telophase. The chromosomes are distributed throughout the 

 nuclear vesicle. Spindle remains persist. Centrosomes still on the cell mem- 

 brane. 



Fig. 2i. Early spermatid. 



Fig. 25. Later stage, showing the protuberance upon one side of the nucleus 

 preparatory to the constriction of the ifomere. 



Fig. 26. Later stage in the protrusion of the itomere. 



Fig. 27. Still later stage, with the itomere in the cytoplasm midway between the 

 nucleus and the cell-wall. 



Fig. 28. Cell, showing the itomere extending from the nucleus to the cell-wall. 



Fig. 29. Stage showing the itomere near the cell-wall. The pathway left by it 

 in its passage through the cytoplasm is plainly visible. 



Fig. 30, Later stage, showing the itomere extruded from the cell. Its course 

 through the cytoplasm is still to be seen. The nucleus is still open at the 

 place of constriction. The centrosome is seen upon one side of the opening. 

 The cell has increased much in size. 



