23O GARY N. CALKINS. 



Explanation of Plate XII. 



Fig. 8. Two primary nuclei showing broods of secondary nuclei (a). 



FlGS. 9 and 10. Development of the fertilized nuclei, two photographs of the 

 same section at slightly different foci. The upper nucleus at (a) shows the character- 

 istic vacuole which becomes the vacuole of the later stages ( cf. Figs. 13 and 14). 

 The karyosomes fragment into minute chromatin granules which can be seen in Fig. 9. 

 X 2,000. 



Fig. 11. Later stages in development of the fertilized nuclei; the chromatin 

 granules from the disintegrated karyosome now form accumulations about the periph- 

 ery, these, later, form the nuclei of the spores. X l>400. 



Fig. 12. Intermediate stages in development between that shown in Fig. 9 and 

 that of Fig. II. 



FlGS. 13 and 14. Sections of the amoeba nictured in Fig. 12 of my earlier paper 

 in the stage of encystment. In Fig. 13 (X 55°) the primary nucleus shown is the 

 residual nucleus comparable to the primary residual nucleus in the case of Poly- 

 stomella. Here it is surrounded by many sporoblasts, which, in Fig. 14, are shown 

 more highly magnified (X r^ 00 )- At (a) and (/>) the small but perfect peripheral 

 nuclei may be clearly seen. 



