1. The exanmination of forty lumbosacral intervertebral discs removed from cadavera of different age groups revealed certain changes in the cartilage plate, time annulus fibrosus, and the nucleus pulposus which must be considered physiological, — either the result of repeated minute traumatic episodes or of aging.

2. In comparing the findings in the cadavera with those in 182 intervertebral discs partially removed at operation, it was apparent that the difference was in number rather than kind. The principal changes encountered consisted of extensions of the tissue of the nucleus pulposus into the cartilaginous plate; vascularization of this defect; scarring with vascularization of the annulus fibrosus and nucleus pulposus; and granular degeneration, considered the result of desiccation, in the nucleus pulposus.

3. At the time of operation the disc was described as herniated, bulging, or softened. No significant microscopic differences were found in the three groups.

4. Follow-up studies on the surgical cases show good results in 86.7 per cent. The best results were achieved in those cases in which the disc was described at operation as herniated. No relation appears to exist between microscopic findings and end results.