Preparations of Protozoa and Algæ

Abstract

WISHING to get some permanent preparations of the Protozoa of West African forest pools, I have adopted a simple little technique which if not known is worth publication. Two clean cover glasses are tied together back to back with thread, one end being left long. They are suspended in the water with the lower edge just touching the bottom and sloping somewhat. They are left for several days and then lifted out and immersed at once in alcoholic Bouin's fixative. Afterwards I stain with Erlich's acid hæmatoxylin, 1 in 20 or 30 per cent alcohol, 3 hours, differentiate in 1 per cent acetic acid in 70 per cent alcohol, 1–3 hours, no counterstain being needed. The cover slips may be kept tied together if desired up to the stage of dehydration. Most, if not all, of the species of Protozoa and Algæ which may be seen in the fresh sample can be found excellently fixed and stained in the mounted specimen.