9i 
of the Genus Hillhousia . 
Fig. 3. Rhombic crystals of calcite obtained by allowing the organisms to dry and then re-irrigating 
with distilled water, x 850, The apparent triangular face on the side of the crystal away from the 
observer is an illusion due to refraction. 
Figs. 4 and 5. Two specimens stained with safranin after fixation by drying (the usual dry- 
staining method for Bacteria), x 850. The central concentration of the protoplast is in each case 
an artifact. 
Fig. 6. An individual stained with safranin by the wet-staining method after fixation in absolute 
alcohol and acetic acid, x 850. 
Fig. 7. Two sulphur crystals obtained from solution in dilute acetic acid, x 1,200. 
Figs. 8-15. Hillhousia palustris. x 850. 11-14, different examples showing stages of 
division; 15, cell immediately after division. The protoplasmic reticulum is only shown in Figs. 
8-10 and 15, and both the calcium carbonate and sulphur have been removed. 
Fig. 16. Achromatium oxaliferum. x 2,200. This figure is copied from one given by 
Schewiakoff (t. ii, f. 3 in his work) and shows the nature of the protoplasmic reticulum. 
