Quarterly Journal of Microscopical Science, Vol s2-79, 43-56, Copyright © 1936 by Company of Biologists

Memoirs: Observation on Protozoa: I. The Impermanence of the Contractile Vacuole in Amoeba Vespertilio. II. Structure and Mode of Food Ingestion of Peranema

¹ Laboratory of Experimental Biology, American Museum of Natural History, New York

1. In A. vespertilio Pènard (1902) there is a continuous de novo formation of water vacuoles, each of which in turn increases to maximum size, acquires a stiffened wall, lags into the rear end of the amoeba, and discharges apparently through pressure from the gelating ectoplasm. No continuity exists between successive vacuoles.

2. The observations indicate that the contractile vacuole system serves to discharge water necessarily taken in in hypotonic medium. The more fluid the ectoplasm and the thinner the surface membrane, the less permanent is the vacuolar system of a protozoan.

3. In P. trichophorum Ehrb. the gullet opens and the flagellum passes inward at the anterior tip of the animal, not at the heads of the two pharyngeal rods. No evidence was found for the existence of a mouth at the rod-heads as maintained by Brown (1930), and the gullet entrance is believed to be the mouth.

4. In feeding on large objects Peranema applies the greatly expanded gullet lips to the object and sucks in the contents; smaller objects are swallowed whole. The pharyngeal rods are not used to pierce the food object, but serve as trichites to assist the upper or more protruding lip in grasping objects and to stiffen the food-ingesting parts. Food is swallowed by peristaltic contortions.