The individual may be infected through the mouth, nasopharynx, or oesophagus. The next possibility of infection is through the stomach. The effect of the gastric juice on swallowed tubercle bacilli. The lesions produced by ingested tubercle bacilli. Most of these follow on the passage of the bacilli through the intestinal mucous membrane. The local effect on the mucous membrane varies with the dose and the virulence of the bacilli, and possibly with the age of the patient. The age of tuberculous lesions is judged by the presence or absence of caseation or calcification; these signs being taken to indicate an older lesion than tuberculous disease in which these degenerative changes have not occurred. The author assumes that the evidence of death-returns and still more of post-mortem examinations, gives some indication of the relative frequency of intestinal and of more direct pulmonary infection.