THE SPERMATOGENESIS OF THE MYRIAPODS. 



211 



in Scolopendra undergoes processes analogous to those reported in 

 insects by a number of investigators. It is found in one of the 

 cells resulting from the first mitosis and does not occur in the 

 other (Fig. 17) showing that it takes no part in this division 

 but goes over to one cell undivided. 



With the reconstruction of the daughter nuclei, all of the 

 chromosomes except the accessory become granular (Fig. 18) 

 and present the appearance of rather short rods of diffuse chro- 

 matin, the center of each of which is slightly constricted, thus 



FIG. 1 8. X 96 dia. Prophase of a second spermatocyte containing the accessory 

 chromosome. The ordinary chromosomes are diffuse and of a dumb-bell form, while 

 the accessory is homogeneous and spherical. Centrosome and persisting archoplasm 

 visible. 



FIG. 19. X96odia. Late prophaSe of second spermatocyte. Chromosomes are less 

 diffuse. Accessory chromosome seen to be constricted longitudinally, while the others 

 show indications of a transverse division. 



^ 



producing a dumb-bell-shaped body. In the succeeding stages 

 these become more dense (Fig. 19) and finally go to the equa- 

 torial plate as small homogeneous bodies of a distinctly lobate 

 structure. When arranged in the equatorial region (as in the 

 first division, there is no true equatorial plate) the lobes of these 

 bodies are directed toward the poles of the spindle, thus giving 

 further basis for the conclusion that we have here a cross division 

 of the chromosome. 



