526 Tuberculosis. 



young cattle and produced exclusive infection of the broncho- 

 mediastinal lymph glands. Klebs, in 1884, supported this view- 

 when he referred to the meat and milk of tuberculous cattle 

 as the commonest source of infection for human beings. Orth 

 (1887) emphasized the importance of intestinal infection as a 

 source of pulmonary tuberculosis. This question came into 

 particular prominence through Koch's well known address at 

 the London Tuberculosis Congress (1901) and more so through 

 the position assumed by v. Behring (1903), according to which 

 the principal cause of tuberculosis was intestinal infection of 

 nurslings, while inhalation tuberculosis was of wholly secondary 

 importance, and which asserted that when this form appeared 

 to exist the infection usually resulted through the lymphatic 

 vessels of the naso-pharyngeal or intestinal mucous membranes, 

 thus being after all an intestinal infection. Following this a 

 great number of experiments were conducted by Weleminsky, 

 Ravenel, Kovacs, Calmette & Guerin, Vallee, Weichselbaum and 

 others which threw more light upon this mode of infection and 

 led many to regard it as the most frequent. 



Formerly a primary intestinal infection was not admitted 

 unless the peripharyngeal lymph glands or the intestine and 

 the mesenteric glands were the exclusive or at least the principal 

 seat of disease. In direct contrast to this view experimental 

 feeding of tuberculous material showed that tubercle bacilli, 

 especially when introduced in small quantities per os, would 

 pass through the intact mucous membrane of the intestine and, 

 without necessarily lodging in the lymph glands along their 

 path, would pass, in part at least, to the glands in distant regions 

 of the body or even directly into the blood vessels and be 

 finally carried to the lungs where they produced a primary 

 pulmonary infection with all the appearances of an inhalation 

 tuberculosis. The usual course taken by the bacilli is then, 

 on the one hand, from the pharyngeal region through the cervical 

 lymph vessels to the broncho-mediastinal lymph glands and on 

 the other hand from the small intestine, especially the posterior 

 portion of the ileum by way of the lymphatics to the mesenteric 

 glands, through the latter to the thoracic glands or, through the 

 thoracic duct directly into the pulmonary circulation. 



Behring produced characteristic inhalation tuberculosis in guinea 

 pigs by injecting cultures into the tissue of the tongue. The submental 

 glands became affected first, following these, the cervical and then the 

 mediastinal glands. Later, the virus reached the bronchial glands 

 through the blood vessels; The subpleural ramifications of the pul- 

 monary artery then carried the virus to the lung tissue where miliary 

 tubercles developed. 



"Weleminsky and Kovacs fed young guinea pigs repeatedly with 0.1 

 mg. of culture per 100 g. body weight and after a few days found the 

 bacilli on the one hand in the submental, submaxillary and cervical 

 glands and, on the other hand, in the ileo-caecal, mesenteric and portal 

 glands. These results agree with those obtained by Behring. Calmette 

 & Guerin introduced tubercle bacilli (0.1-1.0 g.) partly through a tube, 



