1. The ability of Artemia to select particles from mixed suspensions has been studied.
2. The animal shows no appreciable ability to discriminate between plant cells presented in mixtures containing two or three different types.
3. The animal shows no appreciable ability to discriminate between nutritious and non-nutritious particles.
4. When presented with mixed suspensions of Phaeodactylum and sand particles the animal ingests much greater volumes of sand, over a wide range of concentration of sand particles. Low concentrations of inorganic particles appear to promote increased ingestion of plant cells.