In a discussion of the changes in the head of the femur following a complete intracapsular fracture of the neck, a preliminary consideration of its blood supply is necessary for a proper comprehension of the secondary changes which may take place in it. It is generally accepted that the main blood supply of the femoral head comes from: 1. The ligamentum teres. Hyrtl,1 Senn2 and Langer3 considered the vessels running through this ligament of little importance and thought that they became obliterated in old people; but recently Schmorl4 showed in a study of serial sections that the vessels of the round ligament are active even in old age. He cited a case in which, in spite of fracture of the neck of the femur and complete destruction of the capsule, the whole head was adequately nourished through the vessels of the ligamentum teres. This was also