EXPLANATION OF PLATE. 



All drawings are of Scolopendra suhspinipes and were made by the author from 

 camera lucida outlines at a magnification of 1800 diameters. They were reduced 

 one third in reproduction, making a final magnification of 1200 diameters. 



Figure 1. Prophase of the last spermatogonial division, showing the plasmosome 

 with the accessory chromosome closely apposed to one side, and the other chromo- 

 somes lying free in the nucleus. 



Figures 2, 3. Early and late telophase of the last spermatogonial division. In 

 Figure 3 the accessory chromosome ean be readily distinguished from the other 

 chromosomes, which are granular filaments. 



Figures 4, 5. Early spermatocytes. The nuclear membrane is reappearing and 

 the chromatin segments of the reduced number are arranged irregularly throughout 

 the nuclear area. Evidences of the origin of the elements by an end to end union 

 of spermatogonial chromosomes is seen in the V-shaped character of most of them. 

 In Figure 5 the plasmosome is arising in close relation with the accessory chro- 

 mosome. 



Figure 6. A pair of spermatocytes during the growth period. The plasmosome 

 has increased in size and some of the chromosomes have become arranged upon its 

 periphery. Others are still free in the nucleus. 



Figure 7. Nucleus at a slightly later stage. 



Figure 8. Series of figures (a-f) showing the evolution of the plasmosome and 

 origin of the karyosphere. 



Figures 9-12. Various appearances presented by the karyosphere during the 

 " vesicle " stage. 



Figure 13. Large spermatocyte in the vesicle stage. 



Figure 14. Early prophase of a large spermatocyte. The chromatin has become 

 detached from the plasmosme in the form of several granular masses. 



Figures 15-18. Nuclei in the early prophase. 



Figure 19. Mid prophase of a large spermatocyte, showing the character of the 

 tetrads in Scolopendra subspinipes. The nucleolus is becoming more vacuolated. 



Figure 20. Later prophase. The tetrads have become condensed into homo- 

 geneous chromosomes, which are typically four lobed. 



Figure 21. Late prophase in a small spermatocyte. 



Figure 22. Prophase of secondary spermatocyte. 



Figure 23. Metaphase of a small second spermatocyte. 



Figurk 24. Spermatid of Scolopendra subspinipes. 



