1. A strain of pure epithelial cells was obtained from the part of the iris which adheres to the extirpated lens.
2. The optimum condition under which epithelial cells grow in vitro is on the free surface of the plasma clot under a film of embryonic tissue juice.
3. The epithelial cells did not dedifferentiate. Although the strain is 3 months old, they grow as a pavement membrane and have kept their epithelial characteristics.