This study was undertaken to clear up several obscure points in the process of healing of fractures, but chiefly to ascertain the exact rôle assumed by the periosteum. Three sets of experiments were performed on cats, and in all the humerus was fractured.
In the first series, the humerus was fractured by direct external violence, applied laterally. I used my thumb as a fulcrum, and, in case the bone was too tough to be broken thus, I broke it over the edge of the table. In the second series, I made a lateral incision, dissected the tissues down to the periosteum, divided the periosteum circularly, fractured the bone with a Gigli saw or Liston bone forceps, and sutured the wound. The third series was similar to the second, except that the periosteum was simply slit longitudinally to give access to the bone.
Complete narcosis under ether was employed, and in