Osborn . — Spongospora subterranea , ( Wallroth ) Johnson. 341 
Fig. 3. Host cell which has recently divided, showing cell-plate formation with amoebae in 
each daughter cell. 
Fig. 4. Several large amoebae in a cell. Starch grains and host cytoplasm are still present ; the 
host nucleus is becoming enlarged. 
Fig. 5. Plasmodium formation. The host nucleus is here considerably enlarged and shows 
marked indentations. 
Fig. 6. Plasmodium showing the vegetative nuclei in process of degeneration. 
Fig. 7. The akaryote and chromidial stage. 
Fig. 8. Conclusion of akaryote condition, the new nuclei forming apart from the old nuclear 
sites. Cleavages in the protoplasm are shown in this plasmodium. 
Fig. 9. Nuclei approximating. The plasmodium still contains a number of densely staining 
particles. 
Fig. 10. Nuclei pairing. 
Fig. 11. Fusion of nuclei in pairs (Figs. 9 and 11 are from contiguous host cells). 
Fig. 12. Nuclei after pairing in synapsis state. The host nucleus is still visible, much lobed, 
and closely applied to the plasmodium. 
Fig. 13. First karyokinesis. 
Fig. 14. Second karyokinesis ; the cleavages are more apparent and the segmentation of the 
protoplasm is also marked. 
Fig. 15. Section through a mature spore ball, showing the rounded spores, and the cleavages 
between them which give the spongy appearance when seen in surface view. 
Fig. 16. Host cell with eight mature spore balls, and a starch grain. Under this power the 
spaces between the individual spores are not clearly visible, the cysts appearing polygonal, not 
rounded. (Reichert objective 7 a .) 
Fig. 17. Nucleus of a myxamoeba in a resting condition. 
Fig. 18. Division of nucleus in myxamoebae. a. Ring of chromatin around karyosome. 
b. Splitting of chromatin ring before the karyosome has elongated ; the nuclear membrane is becoming 
elliptical, c. Karyosome dumb-bell shaped, d. Later stage, e. Halves of karyosome and the 
chromatin of the plate nearing the poles, f Karyosome and plate chromatin blending to form the 
fresh karyosomes. g. Nuclear membrane disappearing between the two chromatin masses, h. Two 
daughter nuclei. The extra karyosome chromatin is appearing in the form of granules. 
Fig. 19. Degeneration of the vegetative nuclei, showing the diminished karyosome and the 
extrusion of chromatin granules. 
Fig. 20. Nuclei in process of reconstruction, showing the dense chromidia-containing protoplasm 
and the sites of the vegetative nuclei. 
Fig. 21. Dense mass of chromatin matter in reconstructed nuclei. 
Fig. 22. Chromatin network in pre-fusion nuclei, showing the absence of a karyosome. 
Fig. 23. Fusion of nuclei (Fig. 11 enlarged). 
Fig. 24. Late stage in fusion of the nuclei. 
Fig. 25. Post-fusion nuclei showing increased diameter. 
Fig. 26. Synapsis. 
Fig. 27. Spireme emerging from synapsis. 
Fig. 28. a. First division, metaphase showing nuclear area. b. First division, metaphase 
nuclear area not visible. 
Fig. 29. First division, anaphase. 
Fig. 30. First division, telophase. 
Fig. 31. Conclusion of first mitosis. 
Fig. 32. Second division, showing eight chromosomes in plates cut transversely to the long axis 
of the spindle. 
Fig* 33 * Second division, metaphase. 
Fig. 34. Second division, anaphase ; the proplasm at this stage shows marked segmentation. 
Fig. 35. Mature spores showing their rounded shape and single nucleus. 
A a 
