1. There is a fundamental difference in the reaction to immobilization of the tibialis anterior and the gastroenemius its the rabbit.
2. There is an increased blood flow in both atrophy and hypertrophy of skeletal muscle in this animal.
3. Atrophy and hypertrophy appear to represent a change in intracellular cotsstituents without change in the water content of the muscles studied.
4. Tension appears to protect against atrophy, in so far as the tibialis anterior is concerned in the rabbit.
5. Both atrophy and hypertrophy of skeletal muscle in the rabbit appear to represent a metabolic change.
Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh