This paper is presented in the belief that infections about the head by anaerobic and microaerophilic streptococci are more important than is generally appreciated. Also, the behavior of these organisms may explain some of the doubtful factors in the pathogenesis of infection of cranial bones. If these anaerobes are responsible for such infections, it is likely that their control will be considerably helped by measures shown effective against such anaerobes elsewhere, particularly by the use of zinc peroxide. Conversely, the observation that zinc peroxide seems to be effective in the control of infection of the cranial bones in at least some cases should help strengthen the case against anaerobes.My earlier experience with frontal osteomyelitis seemed to fit into the conventional conception, with average success with radical surgical therapy. Four consecutive patients given such treatment in 1932 recovered and made the current ideas on pathology and management seem satisfactory.Then followed several clinical disasters in cases of infections of the sinuses and cranium due to anaerobic or microaerophilic streptococci which focused my attention on the work of Meleney and Johnson.1Later the excellent response to the treatment of other similar infections according with their methods made me feel that their ideas of such infections in soft tissues could be applied to infections involving the cranial bones.Meleney and Johnson saw some 40 patients with chronic under¬ mining ulcers in the soft tissues ; a wide variety of treatment had been tried without success. The causative organisms were anaerobic or microaerophilic streptococci, and nearly all of these previously resistant infections were cured by free dissection and contact with zinc peroxide. This agent gives up its oxygen slowly enough so that the wound may