Plate I.
Termopsis angusticollis.
Figs. 1-3. Resting nuclei of spermatogonia, showing division of nucleolus.
4. Equatorial plate of spermatogonial mitosis, 52 chromosomes.
5-6. Young spermatocytes, showing division of nucleolus.
7. First maturation spindle, and two nuclei (6 and 8) in same cyst.
8-10. Skein-stage—so-called synapsis-stage.
11-14. Bouquet-stage, showing two nucleoli, centrosome (c) in fig. 11, and loops made up of fine, then coarser granules.
15-17. Stage following preceding; loops straightened out and extending in various directions through nucleus.
18. a, Chromosomes much shortened and longitudinally split; b, chromosomes contracted to form diamond-shaped figures.
19. Stage between 18a and 18b.
20. Stage between 19 and 18b.
21. Stage similar to 18a, one chromosome in double diamond form.
22. First maturation spindle in metaphase, chromosomes in single and double diamond shapes.
23. Chromosome in single diamond or tetrad form, as they usually come into the spindle.
24. Double diamond-form assumed before metakinesis.
25. The 26 chromosomes of an early metaphase.
26. First maturation spindle in metakinesis.
27. Equatorial plate of first maturation spindle in metakinesis.
28. Another spindle, showing three granules which are probably remains of nucleoli.
29. Anaphase of first maturation mitosis, one centrosome divided.
30. Late anaphase.
31-32. Telophase, exceptional cases of division of the cell.
33-36. Partial rest stage between first and second maturation divisions, two nucleoli present. Chromosomes in fig. 36 in form of double diamonds ready for metakinesis.
37-38. Second maturation spindle in metaphase.
39. Equatorial plate of second maturation spindle, 26 chromosomes.
40. Same in anaphase.
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.
