Observations on the Food Reactions of Actinophrys Sol

1. Actinophrys sol is essentially omnivorous. 2. Certain inanimate objects are ingested more often than others. Some inanimate objects apparently are not ingested at all. 3. Motionless animate objects are accepted, but not in appreciably greater numbers than inanimate objects. 4. Many free-swimming ciliates and flagellates are readily eaten, but certain ciliates apparently are not taken. 5. A degree of selection or discrimination was exercised between different food objects in every class of materials used. 6. Large objects of prey may be taken in by temporary colonies of Actinophrys sol which are formed for the purpose of taking in such objects. 7. As a rule, motionless animate objects and inanimate objects are closely embraced by the ingesting pseudopod; objects which struggle while being ingested are subtly embraced.