Cellulase was detected in the medium when red clover (Trifolium pratense) seedlings were grown aseptically in flasks. The amount of cellulase found depended on the ionic composition and pH of the medium. Cellulase was found when plants were grown in distilled water. With added salts the amount of cellulase detected was negligible at pH 5.5 or less, but increased with increasing pH; less was released when seedlings were grown throughout in the presence of CaCl2. The enzyme may be extracytoplasmic, located on the root surface, and released by changes in the salt content and pH of the medium.