... Nowadays, however, there are few authorities who do not admit that tubercle bacilli which have gained lodgment in the nasopharynx or in the oral cavity may cause _primary lesions in the lung_ in an entirely different way [different from direct infection by inhalation], namely, through _lymphogenous_ or _hæmatogenous channels_ after an _intestinal infection_ (the intestine reckoned from the pharynx down through the stomach to the rectum). Whether this inhalation of tubercle bacilli from the air into the nasopharynx is followed by a pulmonary tuberculosis, and whether, if it be demonstrated that this actually occurs, the disease is to be ascribed to _intestinal_ or _pulmonary_ infection, is the thema probandum.... How little I deny the possibility of an inhalation of tubercle bacilli and the consequent danger of infection to many persons can be seen from two quotations, one from my Vienna lecture, March 12, 1903, and the other from the lecture held at Cassel, Sept. 27, 1903. “In my plans for the suppression of tuberculosis I give the central place to the feeding of infants with milk both harmless and capable of healing. But as already stated in my previous communications, it is absolutely important to keep coughing consumptives away from the nursing infant. The tubercular virus scattered throughout the dwelling of the consumptive surely finds its way in one way or another into the mouth of the nursling, and then, just like the tubercle bacilli in the milk, it reaches the lymph-vessels and the circulation. It will, of course, also get into the infant’s milk, and when, therefore, in my lecture in Cassel, I stated that ‘the milk fed to infants is the chief cause of consumption,’ I presumed that my auditors and readers were familiar with the following paragraph of my Vienna lecture: ‘If I may apply the experiences gained in studying the conditions under which tubercular and other cattle are housed, etc., I must say that model hygienic housing can do little to prevent the spread of tuberculosis, if at the same time the scattering of tubercle bacilli by the cattle with open tuberculosis is not prevented or at least lessened. It is absolutely impossible to determine all the numerous ways in which tubercle bacilli coughed up, or otherwise scattered about by the tuberculous animals, will finally reach the organism of the other cattle in the stable; and I regard it as almost impossible, by means of mechanical or other measures, to prevent the spread of virus from a case of open tuberculosis to the other inmates of the same room. For adults who, in healthy circumstances, possess a strong protection against the action of the tubercle bacilli, in the form of the epidermis, the epithelial covering of the mucous membranes, and the anti-bacterial ferments, I regard the danger of infection as not particularly great, provided, of course, the dose introduced is not as large as in our laboratory experiments. On the other hand, the