Acton . — Observations on the Cytology of the Chroococcaceae. 453 
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EXPLANATION OF PLATES XXXIII AND XXXIV. 
Illustrating Miss Acton’s paper on Chroococcaceae . 
All figures x 2,500 approximately, unless otherwise stated. 
PLATE XXXIII. 
Fig. 1. Chrcococcus turgidus : A, actual appearance of cell; B, semi-diagrammatic optical 
section showing protoplasmic reticulum, p.m . = plasmatic microsomes, m. = metachromatic 
granules. Stained with Loeffler’s methylene blue after fixing with absolute alcohol. 
Fig. 2. Portion of reticulum, showing accumulations of metachromatin at nodal points. 
Stained with Delafeld’s haematoxylin after fixing with Flemming’s solution. 
Fig. 3. Ckroococcus [? Ckr. minutus (Kiitz.), Nag.] stained with brilliant blue after fixing with 
absolute alcohol, c , cyanophycin granules. 
Fig. 4. Ckroococcus turgidus. Cells which contain few metachromatin granules, showing 
differential staining in the ground substance ; A, actual appearance ; B, semi- diagrammatic optical 
section. Stained with Loefiler’s methylene blue after fixing with absolute alcohol. 
Fig. 5. As Fig. 4. Stained with iodine-green-fuchsin after fixing with absolute alcohol. The 
unstained portions of the ground substance correspond to the deeply stained portions in Fig. 4. 
Fig. 6. Section showing that reticulum extends throughout the cell. The darker granules are 
metachromatic granules, stained with iodine-green-fuchsin after fixing with formalin. 
Fig. 7. Cell showing slight elongation of network in central region which sometimes occurs in 
dividing cells. Stained with iodine-green-fuchsin after fixing with absolute alcohol. 
Fig. 8. Merismopedia elegans. x 1,500; a colony showing the position of the ‘nucleus’ in 
dividing cells ; 11 = nucleus. Stained with Delafield’s haematoxylin after formalin. 
Fig. 9. A, Cells which are enlarging and separating after division ; the ‘ nucleus ’ is beginning 
to disappear, b, Cells about to divide ; in one cell the ‘ nucleus ’ has actually divided, though the 
cell is only just beginning to constrict. The reticulum is very indistinct and plasmatic microsomes 
are small, c, Cell in which no ‘nucleus’ could be seen. The network and plasmatic microsomes 
are very distinct. 
Fig. 10. Merismopedia glaaca, x 1,500; dividing cells — no ‘ nucleus ’ can be distinguished. 
