41. Four spermatid nuclei in one cell, each nucleus containing one nucleolus.
42. A later stage, showing elongation of nuclei, centrosome and sphere at posterior end.
43-45. Later stages in the development of the spermatozoa, nucleolus grows gradually smaller.
Plate II.
Stenopelmatus.
Figs. 46-47. Nuclei of spermatogonia, showing 2 and 3 nucleoli (n).
48-49. Prophase of spermatogonial mitosis, showing two exceptionally large chromosomes of equal length.
50. Equatorial plate of spermatogonial mitosis, 46 chromosomes.