While the question of the relation that Pfeiffer's bacillus bears to influenza or "grip" may be considered an open one, the pathogenicity of this organism is strikingly demonstrated by its occasional occurrence in pure growth in the meningeal exudate in cases of meningitis. Such a case, illustrating the fact that this organism at times may be highly pathogenic and presenting certain other interesting features, is here described. REPORT OF CASE The clinical history, furnished by Dr. F. Churchill and Dr. C. B. Reed, is as follows: Patient. —Male child, one of twin brothers, each weighing 7 pounds, born Oct. 3, 1908. The mother had borne nine children and was in perfect health before the present delivery, which was normal and at full term. Other members of the family were also well. The baby was put to the breast eleven hours after birth, fed every three hours and did well until