Smith. — Cytological Studies in the Protococcales. II. 479 
EXPLANATION OF FIGURES ON PLATE XII. 
Illustrating Mr. G. Morgan Smith’s paper on Cell Structure and Zoospore Formation in 
Pediastni 77 i Borya 7 iW 7 i. 
All the figures were drawn with the aid of the Abbe camera lucida, the drawings being made 
at the level of the base of the microscope, and with the Leitz oil-immersion objective ^ and 
ocular 4. The magnification is about 2,100 diameters. 
Fig. 1. A young cell showing position and nature of nucleus. 
Fig. 2. Metaphase in the first nuclear division. 
Fig. 3. Young binucleate cells. 
Fig. 4. The second nuclear division. The vacuolate appearance of the cytoplasm is due to 
unstained ‘ stroma * starch plates. 
Fig. 5. Metaphases in the third series of nuclear divisions. 
Fig. 6. Eight-nucleate cells. 
Fig. 7. A cell showing 1 stroma ’ starch plates scattered throughout the cytoplasm. 
Fig. 8. The appearance of the wall when deeply stained. 
Fig. 9. A sixteen-nucleate cell. 
Fig. 10. Pyrenoids of different forms and their surrounding starch plates. 
Fig. 11. Showing the disappearance of the pyrenoid and the aggregation of the nuclei in fours. 
Fig. 12. Showing the beginning of cleavage before the disappearance of the pyrenoid. 
Figs. 13-15. Multinucleate protoplasts formed by first cleavage furrows. 
Figs. 16-17. The completion of the cleavage into uninucleate protoplasts. 
Figs. 18-19. Showing the disappearance of the cleavage lines and an apparent return to the 
pre-cleavage condition. 
Figs. 20-23. The reappearance of the cleavage lines. 
Fig. 24. Colony formed by the germination of the zoospores without liberation from mother- 
cell wall. 
Figs. 25, 26. Ripe zoospores or very young stages in germination of zoospores within mother- 
cell wall. 
