Explanation of Plate VIII. 



Fig. 17. Two cells in metaphase — a pole view of one and an oblique view of 

 the other. The accessory chromosome does not show in the former, the cell 

 being such a one as is represented in figures 14 and 15. 



Fig. 18. Pole view of another cell, showing but sixteen chromosomes. 

 Fig. 19. Early anaphase of the first spermatocyte, with the accessory chro- 

 mosome already at one pole. 



Fig. 20. Mid-anaphase, with the giant chromosome still undivided. 



Fig. 21. Later anaphase, in which the accessory chromosome is seen at the 

 lower pole. This figure shows, also, the character and extent of the intercellular 

 material. 



Fig. 22. Later anaphase. The accessory chromosome at the upper pole. An 

 undivided chromosome lying between the groups of daughter chromosomes. 



Fig. 23. About the stage of figure 22, but the lagging chromosome has divided. 



Fig. 24. Very late anaphase. Here, again, the lagging chromosome is divided. 



Fig. 25. Pole view of first spermatocyte telophase, showing the accessory 

 chromosome at one side of the daughter chromosomes. 



Fig. 26. Pole view of a cell in the same stage as that represented in figure 25. 

 Here, however, the accessory chromosome is not present. 



Fig. 27. Lateral view of telophase, with the accessory chromosome in the 

 lower daughter-cell. 



Fig. 28. Fragment of second spermatocyte, showing the chromosomes in 

 metaphase. The relative sizes of the accessory chromosome and the remaining 

 chromosomes is well shown. 



Fig. 29. Metaphase of a second spermatocyte, in which the accessory chro- 

 mosome is not present. 



Fig. 30. Anaphase of second spermatocyte, in which there is no accessory 

 chromosome. 



Fig. 31. Anaphase of second spermatocyte, where the accessory chromosome 

 is present — a -1 and z 2 . 



Fig. 32. Telophase of the same class of second spermatocytes. The acces- 

 sory chromosome extends out from the mass of chromosomes at each pole — x 1 

 and x-. 



Fig. 33. Telophase of the class of second spermatocytes from which the ac- 

 cessory chromosome is absent. 



