The Behaviour of Balantidium coli Malm. in Cultures

Abstract

Balantidium coli (from the domestic pig) can be readily cultivated in the medium devised by Dobell and Laidlaw (1926) for the cultivation of entozoic amoebae (inspissated horse-serum and Ringer-eggwhite, with solid rice-starch). If the hydrogen-ion concentration does not exceed the limits p H = 5·4–8·0, rich cultures can be obtained in this medium, at 37° C.; and strains of the ciliate can be readily propagated for any desired period if subcultures are made every 3–5 days.In such cultures conjugation occurs periodically; but encystation has never been observed, and all attempts to induce it under cultural conditions have hitherto failed.The conjugation of Balantidium, as seen in cultures, is peculiar, but it has been impossible as yet to elucidate all details of the process. Conjugants are always much smaller than non-conjugants, and frequently unequal in size. Apparently but one conjugant is fertilised, and survives as an exconjugant—the partner dying after separation.Encystation has never been seen to follow conjugation, as described by Brumpt (1909).