Explanation of Plate X. 



Fig. 40. Anaphase of first spermatocyte. Accessory chromosome x at one 

 pole. The form of chromosome in the anaphase well shown. The lagging chro- 

 mosome c seen in two cells. X 1300. 



Fig. 41. Anaphase of the first spermatocyte, showing the longitudinally di- 

 vided condition of the accessory chromosome x in the cell near the center. Com- 

 pare with the accessory chromosome in the metaphase of second spermatocyte, 

 figure 43. X 1300. 



Fig. 42. Second spermatocyte in metaphase. In most of the cells the focus 

 is upon the ends of the chromosomes, but in one a side view is obtainable. Com- 

 pare with the chromosome of the upper cell in figure 40. No accessory chromo- 

 some in most of the cells in focus. X 1300. 



Fig. 43. Second spermatocyte metaphase and spermatids. Note the relative 

 sizes of the accessory chromosome and the other chromosomes. In the sperma- 

 tids the accessory chromosome has taken its place on the periphery of the 

 nucleus in the same way that it does in the prophase of the first spermatocyte. 

 X 1300. 



Fig. 44. Anaphase of the second spermatocyte, showing the accessory chro- 

 mosome .r separated. Other cells in metaphase. X1300. 



Fig. 45. Telophase of the second spermatocyte. Two daughter-cells with 

 persisting spindle between, showing the accessory chromosome x in each. Other 

 nuclei in focus show no accessory chromosomes. X 1300. 



