1. Direct injection of contrast material into bone indicates its extreme vascularity, particularly near an epiphysis, and emphasises the extraordinary capacity of the minute periosteal vessels. The nutrient artery of a long bone appears to play little part in its nourishment and may be regarded as a vestigeal structure.

2. The vascular pattern of bone tumours may be investigated by injection of the appropriate artery, and sometimes, if a haemangioma is suspected, by direct injection into the lesion.

3. The examination is easily and quickly carried out by direct arterial puncture under local anaesthesia and injection of 35 per cent diodone. A tourniquet applied distally at the appropriate level is often helpful.

4. A study of the vascular pattern of suspected bone tumours has provided useful information in a positive and negative way, assisting both the diagnosis and the planning of treatment. The pathological diagnosis of some tumours, notably osteosarcomas and haemangiomas, may be made with such assurance that possible dissemination of the tumour by biopsy may be avoided.

1. As a result of degenerative changes in the intervertebral disc, nuclear tissue often herniates through its confining structures. These lesions are common, even in children, and often lead to difficulty in diagnosis.

2. The radiological manifestations of nuclear herniations into the spongiosa of the vertebral body, through the anterior part of the annulus fibrosus, beneath the epiphysial ring, and through the posterior part of the annulus are described and illustrated. The clinical significance of these radiological appearances and their pathological basis is indicated.

3. An understanding of the significance of the radiological findings in herniation of the nucleus pulposus and a careful correlation with the clinical features of the case are necessary for accurate diagnosis.