MODE OF INFECTION
J. O. Cobb1 is of the opinion that tuberculous infection in man and animals is generally brought about by the ingestion method. He believes that even where the bacillus is planted on the respiratory mucous membrane by means of dried sputum or by dried feces, as often happens with cattle, the anatomic method is still through the intestinal tract, because the number of bacilli that would be swallowed is out of proportion to the very doubtful number that might possibly reach the air vesicles by inhalation. Cobb agrees with Aufrecht that tubercle bacilli gain entrance into the circulation, however introduced, and then traverse the blood vessels as foreign bodies, until arrested in some organ, most commonly in the pulmonary terminal arteries. Here the bacillus passes through the thin vessel wall barrier, to be picked up by lymphocytes and promptly carried to the nearest lymph gland. Moreover,