The silver proteinate impregnating technique (Protargol) offers great results and many advantages among other silver-based impregnation techniques used for optical microscopy. Its results show in great detail morphological key features of ciliates, flagellates and opalinates.
Researches with protists of several environments have been increased using the protargol, which is an impregnation, not a coloration technique, whose impregnating agent is the silver proteinate. Several authors (Dieckerman, 1995; Foissner, 1991; Dragesco & Dragesco-Kernéis, 1986; Wilbert, 1975) have modified the primary technique of Bodian (1936, 1937) with the aim of obtaining satisfactory results, but these generally take a long time to develop.
The present work is a variation of the technique of protargol described by Tuffrau (1964, 1967) and was made with some modifications in the laboratory. The primordial objective was to get satisfactory results in a relatively short time and to process numerous slides with a reduced expense of silver proteinate.
The photomicrographs of the boards presented in this work were made using the technique described below. The boards show the improved structural details of the cortex and endoplasma of a flagellate, of an opalinate and of ciliates of different environments and which belong to several groups (Karyorelictea, Gymnostomatida, Prostomatida, Peniculina, Colpodida, Heterotrichida and Hypotrichida). For the identification of these organisms it is necessary to make the somatic and oral infraciliature evident, as well as the form of the macro and micronucleus. A brief comparison of the technique of protargol with other techniques that use silver salts as impregnating agent is made.