THE subject of enteric or typhoid fever is of considerable importance in India, particularly to the British troops stationed there, and the Indian Government has therefore been well advised to institute an inquiry into the factors influencing the occurrence of the disease.1 The work has been carried out under the direction of Lieut.-Colonel Semple, I.M.S., and Captain Grieg, I.M.S., at the Central Research Institute, Kasauli. The problems to be solved were:—(i) What is the nature and duration of the saprophytic life of the Bacillus typhosus? (2) What is the duration of the life of the Bacillus typhosus within the human host? (3) How are epidemics produced? As a result of a large series of experiments and observations, evidence is brought forward to show that (1) the Bacillus typhosus continues to be excreted for long periods in the urine and fæces of a certain percentage of patients convalescent from enteric fever, the number in the urine being very large, and the excretion being markedly intermittent; (2) the “chronic bacilli carrier” exists in different units in India, and can cause epidemics and cases of enteric fever; (3) enteric fever orderlies may become “chronic bacilli carriers”; (4) in India the saprophytic existence of the Bacillus typhosus outside the human host is short. Thus in fæces and in urine kept at 80° F. in the dark, the typhoid bacillus had died out in ninety-six hours and seventy-two hours respectively, and an exposure to the sun of thin cotton and of blanket soaked with urine containing typhoid bacilli for two hours and six hours respectively proved fatal to the organism.