Pathogenesis 729 



considerable numbers in milk from udders without tuber- 

 culous lesions discoverable to the naked eye. 



The meat from tuberculous animals is less dangerous than 

 the milk, because it is nearly always cooked before being 

 eaten, while the milk is generally consumed in the raw state. 



The ingested bacilli may enter the tonsils and be carried 

 to the cervical lymph-glands, but seem more commonly 

 to reach the intestine, from which they enter the lymphatics, 

 sometimes to produce lesions immediately beneath the 

 mucous membrane, and lead to the later formation of 

 ulcers; but usually to invade the more distant mesenteric 

 lymphatic glands. Nicolas and Descos* and Ravenel f found 

 that when fasting dogs were fed upon soup containing 

 large quantities of tubercle bacilli, they were able to dis- 

 cover the bacilli a few hours afterward in the contents 

 of the thoracic duct. The thoracic duct is sometimes 

 affected, and from such a lesion it is easy to understand 

 the development of general miliary tuberculosis through 

 systemic distribution of bacilli thrown into the circulation. 

 The occasional absorption of tubercle bacilli by the lacteals, 

 and their immediate entrance into the systemic circulation 

 and subsequent deposition in the brain, bones, joints, etc., 

 are supposed to explain primary lesions of these tissues. 



Kochf believes that human beings are infected only by 

 bacilli from other human beings, and his paper upon this 

 subject has stimulated extensive experimentation on the 

 problem. Most authorities believe both human and bo- 

 vine bacilli to be equally infectious for man. Behring 

 believes that nearly all children become infected by ingest- 

 ing tubercle bacilli in milk, though a certain predisposition 

 is necessary before the disease can develop. Baumgarten 

 believes that all children harbor bacilli taken in the food, 

 but that the disease does not develop until a certain sus- 

 ceptibility occurs. 



Infection also occasionally takes place through the sexual 

 apparatus. In sexual intercourse tubercle bacilli from 

 tuberculous testicles can enter the female organs, with 

 resulting bacillary implantation. Sexual infections are 



' "Jour, de Phys. et Path, gen.," 1902, iv, 910. 

 t "Jour. Med. Research," x, p. 460, 1904. 



t " International Congress on Tuberculosis," London, 1901, and 

 Washington, 1908. 



"Deutsche med. Wochenschrift," 1903, No. 39. 



