The tubercle bacilli are inhaled by persons in contact with consumptives, or by animals subjected to experiments with tuberculous dust, have been repeatedly shown. The lymphatic glands may act as filters preventing the tubercle bacilli from spreading to other parts of the body; just as glands in the armpit may prevent general blood poisoning from a whitlow. Rapid transport to more remote parts of the body can occur only when the bacilli have gained access to the blood vessels and are carried with the blood circulation. Tubercle bacilli are often present in the tonsils without any naked-eye evidence of disease. The larynx is only exceptionally the seat of primary tuberculosis, laryngeal implication being more often a symptom of advanced pulmonary tuberculosis. Infection of the substance of the lungs by direct inhalation is usually taught to be a frequent occurrence. The chapter finally considers the evidence for and against such direct inhalation.