Silver Impregnation of Ciliated Protozoa by the Chatton-Lwoff Technic

Abstract

The ciliates are manipulated at all stages by means of micropipettes and fine needles, proceeding by the following steps: Fix the material in a small receptacle with Champy's fluid 1–3 minutes following with Da Fano's solution for several hours. Transfer the specimens to a slide, withdraw excess fluid and embed them in warm (35°–45°C.) gelatin containing 0.05% sodium chloride. Refrigerate in a moist chamber until the gelatin has set, and then immerse 10–20 minutes in 3% silver nitrate (aqueous) at 5–10°C. Wash with cold distilled water, submerge the preparation in cold water to a depth of several centimeters and expose to a strong light for 10–30 minutes. Silver is deposited on various pellicular structures which then appear black in the dehydrated and mounted specimens. Neatly revealed are the many longitudinal and transverse fibrils of the “silverline system”, basal granules of the cilia, bases of buccal ciliary organelles, contractile vacuole pores and the cytoproct. None of these structures, which today are considered to be of inestimable value in comparative morphological and taxonomical studies of ciliates in general, is so precisely made evident by any other technic known to the author.