1. Normal guinea pigs exposed to tuberculous cage mates infected intraperitoneally and with no cutaneous ulceration readily contract spontaneous tuberculosis.
2. The incidence of spontaneous tuberculosis increases with the intensity and with the duration of exposure.
3. Spontaneous tuberculosis acquired from infected cage mates has with few exceptions the characters of an infection which has entered by way of the digestive tract, disease of mesenteric and cervical lymph nodes being conspicuous.
4. Guinea pigs exposed to tuberculous animals in the same room but not in the same cage may acquire tuberculosis which has the characters of a bronchiogenic infection associated with lesions of the lungs and tracheobronchial lymph nodes.