This study was undertaken to determine the effects of beryllium nitrate on regeneration in the tail of Rana Pipiens larvae. The tails were amputated approximately 3 rom from the tips. Some were then treated with different concentrations of beryllium nitrate (0.5 N, 0.7 N, and 1.0 N). Normal regeneration of untreated amputated tails was fulfilled in an orderly manner. In the animals treated with beryllium nitrate, general tissue regeneration was inhibited. Considerable degeneration was observed in all tissues of the tail stumps. Holfever, the elastic lamella of the notochordal sheath was stimulated to stretch, oftentimes breaking the continuity of the fibrous lamella. The elastic layer appeared highly ravelled within the degenerated tissues of the tail, and, in some cases, extended for 3 to 4 inches from the tail stump due to a break in the covering epithelium.