A CYTOTOXIN FROM BLEPHARISMA

¹ Department of Biological Sciences, Stanford University, Stanford, California

1. A brei of fragmented Blepharisma contains some substance which is quite toxic to Paramecium and a variety of other protozoans and to sea urchin larvae, but it is not toxic to Blepharisma itself.

2. Paramecia suspended in a dense culture of Blepharisma are unaffected by the mere presence of Blepharisma.

3. Blepharisma is eaten by Actinosphaerium; therefore the toxin does not protect it from attack and use as food, but it is not eaten by Woodruffia, Podophrya or Didinium.

4. In the presence of Blepharisma, paramecia grow at the same rate as they do alone, indicating that no toxin is secreted during growth.

5. Brei of Blepharisma bleached by light is not toxic to paramecia.

6. The pigment of Blepharisma extracted in alcohol and after drying re-extracted in alcohol and, after another drying, re-extracted in water is highly toxic to paramecia.

7. The tentative conclusion is drawn that the toxin is the pigment or something very closely associated with it.