Fig. 56.—Illustrates the genus Spirochæta
.
Fig. 57.—Illustrates the genus Chlamydothrix. Fine threads with a delicate sheath.
Fig. 58.—Illustrates the genus Crenothrix. The thickness of the cell walls is due to deposits of iron hydroxide. (After Lafar.)
Fig. 59.—Illustrates the genus Beggiatoa. The filament A is so full of sulphur granules that the individual cells are not visible. B has fewer sulphur granules. In C the granules are nearly absent and the separate cells of the filament are seen. (After Winogradsky, from Lafar.)
ORDER I. Eubacteria.
Cells without nuclei, free from sulphur granules and from bacteriopurpurin ([p. 112]); colorless, or slightly colored.