Plate II. 

 Talorchestia longicornis. 



T, 10. Speriiiatocytic prophase. 18 chromosomes. 



T, 11. Spermatocytic prophase. Origin of kinoplasm within the nucleus. 



T, 12. Spermatocytic prophase. Centrosomes within the nucleus. 



T, 13. Formation of equatorial plate. Pole view. 18 chromosomes. 



T, 14. Metaphase. 



T, 15. Young spermatid. 



T, 16-18. Gradual diffex'entiation of head, middle-piece and tail. 



Idotea irrorata. 



I, 10. Post-syuapsis. Peculiar appearance of the nucleolus. 



I, 11. Resting spermatocyte or very early prophase. 



I, 12. Spermatocytic prophase. Origin of kinoplasm within the nucleus, 



I, 13-15. Spermatocytic prophases. The chromosomes are joined either 



end to end (a) or side by side (b). c, cross-shaped chromosomes. 



14-15, surface views. 

 I, IG. Later prophase. One of the chromosomes is abnormally late in 



condensing. Centrosomes visible within the kinoplasm. 

 I, 17. Equatorial plate. Pole view. 28 chromosomes. 

 I, 18. Equatorial plate. Side view. Two types of chromosomes. 

 I, 19-25. Development of the spermatid. 



Oniscus asellus Linn. 



O, 3. Spermatocytic prophase. Origin of centrosomes without the nucleus. 



Compare Figs. I, 12, 13 and 10. 

 O, 4-5. Young spermatids. 



Hippa talpoides. 



Hi, 15-16. Spermatocytic prophases. Longitudinal splitting of the chro- 

 matin. Increase of cytoplasm. 



Hi, 17. Later prophase. Origin of kinoplasm within the nucleus. 



Hi, 18. Later prophase. Chromosomes mostly U or V-shaped. ISIitochon- 

 dria in the cytoplasm. 



Hi, 19. Late prophase of the first spermatocyte. Kinoplasm within the 

 nucleus. 



Hi, 20. Metaphase. Pole view. GO chromosomes. 



Hi 21. Metaphase. Side view. 



Astacus fluviatilis. 



A, 4. Prophase of the lirst spermatocyte. Polarity of chromatic loops. 



Mitochondria in the cytoplasm. 

 A, 5. Spermatocytic metaphase. 



