Fig. 31. Earliest prophase of 1° maturation division. 



P'iGS. 32-34. Prophases of 1° maturation division showing the two 

 main types of chromosomes, the rings and the much elongated, longi- 

 tudinally split, rods. 



Figs. 35-37. Longitudinal section of 1° maturation spindles in 

 metaphase showing the predominance of rods. 



Fig. 38. Cross-section of the same. 



Figs. 39-40. Longitudinal and cross-section respectively of late 

 rnetaphase. 



Figs. 41-42. Early anaphase of 1° maturation division showing 

 separation of the dyads. 



Figs. 43-44. Later anaphases showing in some instances the true 

 nature of the dyads. 



Figs. 45-46. Early and late telophase of 1° maturation division. 



Figs. 47-48. Longitudinal and cross-section of metaphase of 2° 

 maturation division. 



Fig. 49. Early anaphase of same showing strand of chromosomal 

 substance connecting the monads. 



Figs. 50-52. Middle and late anaphase of 2° maturation spindles. 



Figs. 53-54. Early and late telophase of the same. 



Fig. 55. Young spermatid after breaking down of the dense 

 chromatin mass of the preceding telophase. 



Fig. 56. Early differentiation of the sperm head and concentra- 

 tion of the chromatin before and behind. 



Figs. 57-60. Elongation of head; filling up of open spaces with 

 chromatin substance and formation of middle piece and tail. 



Fig. 61. Mature spermatozoon. 



(60) 



