The existence of an epidemic of influenza at Camp Pike was recognized on September 23, when 214 cases of influenza were admitted to the base hospital. Preceding this date and beginning September 1 there had been a gradual increase of the number of patients admitted with the diagnosis of acute bronchitis. It is noteworthy that the demonstration of B. influenzæ had been regarded as essential for a diagnosis of influenza and since this microorganism had not been found, instances of acute inflammation of the respiratory passages with the symptoms of influenza were classified under a variety of names. After September 23 influenza was recognized by its symptoms. The number of cases increased with great rapidity and on September 27 reached over 1,000 per day; this number was approximately maintained during one week and after October 3 the epidemic gradually subsided. Among 52,551 men in the camp, including those who arrived during October, 12,393 were attacked by influenza; of these 1,499 suffered with pneumonia and 466 died. The height of the outbreak of pneumonia followed approximately one week after that of influenza. The statistics from September 20 to October 14 collected by Major Freeman show that pneumonia following influenza, like the pneumonia at Camp Funston during the interepidemic period, has a conspicuous tendency to select men who have been in the camp less than one month, designated in Table I as new recruits: TABLE I ════════════════════════════════╤══════════╤═════════════╤═════════════ │POPULATION│ INFLUENZA │ PNEUMONIA ────────────────────────────────┼──────────┼──────┬──────┼──────┬────── „ │ „ │ No. │ Per │ No. │ Per │ │ │cent. │ │cent. ────────────────────────────────┼──────────┼──────┼──────┼──────┼────── Men in camp more than one month │ 27,782│ 4,462│ 15.6│ 493│ 1.7 New recruits │ 23,769│ 7,263│ 30.6│ 1006│ 4.2 ────────────────────────────────┼──────────┼──────┼──────┼──────┼────── Total │ 51,551│11,725│ 22.7│ 1499│ 2.9 ────────────────────────────────┴──────────┴──────┴──────┴──────┴────── New recruits were nearly two and a half times as susceptible to pneumonia as men who had been in camp more than one month. This statement does not take into consideration differences in the environment and mode of living of the new men.