1 . A case of parosteal osteoma with histologically low-grade sarcomatous areas is described.

2. Arteriography revealed abnormal arteries, the histological appearances of which are described.

3. Vascular shunts indicative of low-grade malignancy were also seen.

4. Reasons are given for accepting the view that this lesion is a tumour, originally benign, but liable to the development of low-grade malignancy.

1 . The repair of a simple crush injury was studied in rats, in both normally innervated and completely denervated muscle. In each case the histological findings at periods from two hours to thirty-two weeks are described.

2. The denervated muscle showed active and effective repair.

3. A comparison with the findings in normally innervated muscle establishes that the cellular processes of repair do not depend on connections with the central nervous system.