A CYTOTOXIN FROM BLEPHARISMA ARTHUR C. GIESE * Department of Biological Sciences, Stanford University, Stanford, California When a few paramecia were added to a concentrated suspension of Blepharisma undulans in a Cartesian diver, they \vere injured, began to rotate, and after swelling, died, although the Blepharisma remained normal and active (Giese and Zeuthen, 1949). A few individuals from a Blepharisma culture were placed with a lot of paramecia with no ill effect. An attempt was made to determine what caused the injury to Paramecium placed in a concentrated culture of Blepharisma. The re-sults are described below. EXPERIMENTAL Cultures of Blepharisma were grown as previously described (Giese, 1938b). Practically all the other organisms were grown in lettuce infusions of the same type (0.05 per cent lettuce, buffered at pH 7.0 or 8.0), or obtained from wild cultures. Paramecium multimicronucleatuin for division studies was grown as previously described (Giese, 1945). In the first experiment the culture of Blepharisma was handled with great care and the animals were gently centrifuged down into the cone of a centrifuge tube. The supernatant was carefully withdrawn and after a dense suspension was avail-able, some paramecia were added. They were in no way adversely affected. It was therefore apparent that when Blepharisma individuals are handled with care they do not liberate any substance injurious to Paramecium. The inference may be drawn that in the pipetting of the suspension of Blepharisma into the diver some individuals may have been injured. To test this possibility individuals in a dense culture of Blepharisma were fragmented by sucking the animals up into a pipette partially blocked by cotton fibers, making a "brei." In this process the animals were torn open and the fluid became pinkish. Paramecia added to the brei reacted violently by reversed ciliary action and then quickly began moving and died. In a freshly prepared brei, the time from immer-sion to killing was only a few minutes. A Paramecium-brei similarly prepared was not toxic to Blepharisma nor was a Didinium-brei toxic to Paramecium. There-fore Blepharisma presents a special case worthy of further study. Questions arise as to the nature and properties of the material liberated by Blepharisma (hereafter called the toxin without any implications other than that it is a poison of organismal origin). It is desirable to know whether the toxin is * I am indebted to Dr. L. Garnjobst of Stanford University for a culture of Actinosphaerium, to Dr. W. H. Johnson of Wabash College for a culture of Woodruffia, and to Dr. Frederick Evans of the University of Utah for a culture of Podophrya. I am also pleased to acknowledge the skillful assistance of Mrs. Helene Leighton in the experiments on the rate of growth of Paramecium in the presence of Blepharisma and to Miss Eugenia Brandt for repetition of a number of experiments on the effects of the toxin upon a number of protozoons. 145
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