1. A time study is presented in which alterations in the concentration of water and hexosamine were observed in connective-tissue structures about immobilized knee joints of dogs.
2. The reaction to immobility was not uniform in the different connective tissues studied. Differences in rate and direction of change are described.
3. After four to twelve weeks of immobilization, the water concentration was reduced in tendon, synovial membrane and capsule, skin, and fascia by 2 to 3 per cent.
4. Hexosamine was reduced about 10 per cent in synovial membrane and capsule and in tendon over the four-to-twelve week period.
5. Correlation between experimental findings and present concepts of connective-tissue metabolism has led to a hypothesis concerning the mechanism of development of joint contractures.