454 ELERY RONALD BECKER. 



EXPLANATION OF PLATE. 



X 1420. 



FIG. i. Free form of Endamceba citelli with typical nucleus fixed with two 

 pseudopods extended. Two food vacuoles in cytoplasm contain respectively a 

 bacterium and a partially digested yeast. 



FIG. 2. Amoeba infected with young uninucleate and binucleate Sphcerita. 



FIG. 3. Amoeba with same stages plus one younger individual with nucleus in 

 process of formation and an individual with four nuclei. 



FIG. 4. Large amoeba with one parasite having four nuclei. 



FIG. 5. Sphczrita has eight nuclei, each dumb-bell-shaped preparatory to 

 division. 



FIG. 6. Multinucleate Sphcrrita in cytoplasm of amoeba. 



FIG. 7. Large sporangium with nuclei developing into spores. 



FIG. 8. Amoeba with large food vacuole containing infective bacterium-like 

 stages developing into typical uninucleate cytozoic forms. 



FIG. 9. The eight-nucleate cyst of E. citelli. 



FIGS. 10-11. Free bacterium-like stages of Sphcerita endamcebce. 



FIGS. 12-14. Bacterium-like stages in food vacuoles of the amoeba. 



FIGS. 15-22. Developmental cycle of Sphcerita in cytoplasm of amoeba. Fig. 

 16 does not represent a division of the organism in Fig. 15, but rather the same 

 stage of development, the next stage after Fig. 14. The two members of the pair 

 later separate. 



