The Relationship between the Flagellate Protozoon Hexamita and the Oyster Crassostrea virginica

Abstract

. . . L'Hexamita inflata se reproduit donc normalement dans l'estomac de l'Huitre ce qui vient a l'appui du commensalisme que je lui attribue. Mackin, Korringa, and Hopkins (1952) were the first to describe Hexamita as a parasite of Ostrea edulis and Crassostrea virginica, although they had neither a knowledge of its complete life cycle nor experimental evidence of its pathological effects. The intracellular stages observed by Mackin et al. are not conclusively implicated as part of the life cycle of Hexamita because, as the authors explain (p. 272), an effort ... to piece the various intracellular elements of the intestinal epithelium and the leucocytes into a cohesive life cycle [was] without success. Because of the uncertainty regarding the identity of the intracellular stages described and owing to the frequently observed accompaniment of heavy bacterial infection (p. 275), the evidence presented by Mackin et al. relating the pathological conditions of the oysters which they examined with the presence of the flagellate Hexamita must be regarded as inadequate. Stein, Denison, and Mackin (1961) have attempted experimental infection of the Olympic oyster, Ostrea lurida, with Hexamita. At a temperature of 6 C they found that normal oysters exposed to diseased oyster tissue showed significantly higher mortality than control oysters which were not exposed. How-