1. The late effects of lathyrism induced in rabbits by feeding beta-aminopro-prionitrile consisted of impairment of growth, emaciation, slipping of epiphyses, soft-tissue swellings, hyperostoses, exostoses, and osteoporosis.
2. In the shoulder and hip joints, the combination of factors often resulted in massive tissue overgrowth, while in a few animals there was only a severe bowing. The changes were commonly, although not invariably, symmetrically bilateral. Flat bones as well as long bones were affected.
3. The histological changes were both degenerative (involving, characteristically, the epiphyseal cartilage) and proliferative (involving fibroblasts of periosteum, adjacent fascia, and muscle sheaths).
4. The relation of these changes to muscle pull, tension, trauma, and hemorrhage, as well as to a fundamental disturbance of collagen fibril formation, is discussed.