1. The intervertebral disc is an organic viscous elastic structure capable of maintaining very great loads without disintegration.

2. Recovery of the disc after deformation depends upon: a) the imbibition of tissue fluid by the disc, b) the removal of the deforming force. Complete recovery is modified by the duration of the force.

3. Factors that interfere with the elasticity of the disc are: extreme youth (immaturity of the disc), chronic wasting diseases (general nutritional disturbance), and local pathological changes in the bodies of the vertebrae which interrupt or damage its blood supply. The intervertebral disc reaches its greatest state of efficiency in adult life—that is, when the nucleus pulposus has disappeared as an entity. The function of the disc appears not to depend upon the presence of the nucleus : rather does the presence of the nucleus indicate immaturity of the disc.

4. The highly resilient elastic nature of the vertebral column is provided by the intervertebral discs, which constitute one-third of the whole length of the column.

5. The imbibition of fluid requires further investigation. It appears that from lacunae in the adjacent bodies finger-like pockets dip into the discs and that fluid passes through the lining membrane of these pockets.