GROWTH STUDIES ON CILIATES

IV. THE INFLUENCE OF FOOD ON THE STRUCTURE AND GROWTH OF GLAUCOMA VORAX SP. NOV.

¹ From the Arnold Biological Laboratory, Brown University, Providence, Rhode Island

1. Glaucoma vorax sp. nov. was isolated from pond water in the vicinity of Providence, R. I.

2. It was sterilized and established in broth culture by a modification of the transfer washing method in which the containers were enclosed in cellophane bags before autoclaving.

3. Various form changes were correlated with types of food; bacteria-feeders are tailed, saprozoic organisms are spindle-shaped to ovoidal while carnivores and cannibals are irregularly ovoid with the greatest width at the posterior end.

4. When saprozoic forms are placed in a culture or washed suspension of other ciliates (Colpidium, Glaucoma, Colpoda) they change their form preparatory to becoming carnivorous. A large vacuole forms back of and continuous with the mouth to receive the prey.

5. The formation of the preparatory vacuole and the concomitant form changes seem to be evoked only in the presence of living ciliates, as killed ciliates (either autoclaved or freshly sand-shaken), living flagellates, bacteria or yeasts do not stimulate its formation.

6. A diagnosis of the species is given.