Basic light and scanning electron microscopic methods for taxonomic studies of ciliated protozoa.

The following methods for taxonomic studies of ciliated protozoa are described in detail: live observation, supravital staining with methyl green-pyronin, dry silver nitrate impregnation, wet silver nitrate impregnation, silver carbonate impregnation, protargol impregnation (three procedures), and scanning electron microscopy. Familiarity with these methods (or modifications) is an absolute prerequisite for successful taxonomic work. No staining method is equally appropriate to all kinds of ciliates. A table is provided which indicates those procedures which work best for certain groups of ciliates. A second table relates to the structures revealed by the procedures. Good descriptions usually demand at least live observation, silver nitrate and protargol or silver carbonate impregnation. Some instructions are provided for distinguishing mono- and dikinetids as well as ciliated and non-ciliated basal bodies in silvered ciliates. The brilliancy of the silver preparations has unfortunately recently tempted some taxonomists to neglect live observation. However, many important species characters cannot be seen or are changed in silvered specimens. I thus consider all species descriptions based exclusively on silver slides as incomplete and of doubtful value for both α-taxonomists and ecologists. Especially the latter are usually not trained to correlate the silvered structures with the live appearance of the cell.