1. The lesions chiefly responsible for persistent pain and weakness after acromio-clavicular dislocations are tears of the trapezius and deltoid muscles.

2. These tears cannot be adequately treated except by open operation.

3. There are often physical barriers making closed manipulative reduction impossible.

4. Open reduction and repair of torn ligaments and muscle is advocated for manual workers.

1. A clinico-pathological study of a patient who suffered traumatic rupture of his right popliteal artery is outlined.

2. Collateral circulation from the genicular anastomosis developed within twenty hours.

3. Ischaemic necrosis of the belly of the tibialis anterior occurred, but voluntary power began to return about twenty-one weeks after injury.

4. Biopsy of the muscle nineteen, fifty-seven and seventy-six weeks after injury showed that the muscle belly was being reconstituted by new fibres and that the ischaemic tissue remained entombed in the deepest part of the muscle. The regenerating fibres arose from small numbers of subfascial fibres which either survived the ischaemic episode or had arisen by myoblastic differentiation of connective tissue cells. Sarcoplasmic outgrowths produced new contractile substance, and new fibres were formed by amitotic fission. Many of the fibres matured and the regenerative process was still active seventy-six weeks after injury.

5. Growth of new nerve bundles containing myelinated axons accompanied the development of new muscle fibres.