Some relationships betweenChlorohydra, its symbionts and some other chlorophyllous forms

Abstract Two species of Chlorohydra , two free‐living algae and a green flagellate were used to investigate the following: (1) Removal of algal symbionts, (2) reinfection of albinized hydra, (3) autonomy of the partners once separated, (4) infection of albino hydras by algal symbionts from another species of Hydra and by free‐living algae and a green flagellate. C. viridissima could not be albinized by the usual methods, while C. hadleyi was easily albinized. The albino form could be reinfected easily by injection and grafting methods but it could not readily be infected with symbionts from C. viridissima . One free‐living alga ( Oocystis ) gave limited infection after injection of the algal cells into albino hydras. Survival of green and albino forms of C. hadleyi under starvation conditions was the same but budding rate of the albino form was higher than that of the green form. Attempts to maintain continuous cultures of the green symbionts in vitro were unsuccessful, but with a specially devised method it was shown that the algae survived at least 14 days in an artificial medium.