Staining Flagellate Protozoa by Various Silver-Protein Compounds

Seven samples of silver protein (Protargol type) were tested on flagellate protozoa from the alimentary tract of frogs, golden hamsters, and termites. The samples consisted of one of Protargol (Winthrop's prewar German), one of Protargol S (Winthrop-Stearns, Inc., present manufacture, Commission Certified), and five of the experimental batches (4Z, 20, 20B, 22, and 36) by H. A. Davenport and collaborators (1952). The pre-war Protargol is rated best and batch 22 second best for staining of all flagellates. Protargol S gave uniform, but only fair results, with all organisms, while batch 20B, better than Protargol S in several instances, was poorer in a few. Thus Protargol S and batch 20B are rated third, as about equal. Batch 4Z is rated fourth; and batch 20, which stained some species, fifth. Batch 36 stained no protozoa. The tests show that while the present Protargol S is usable for protozoa, it is still inferior to the old German variety. Since some of the experimental batches, none of which was made by exactly the same process, gave promising results, further study of the relation between manufacturing process and subsequent staining reaction should be fruitful.