324 Tuberculosis 



losis. It does not seem necessary that tuberculous ulcers 

 shall be present in the udders ; indeed, the bacilli have been 

 demonstrated in considerable numbers in milk from udders 

 without tubercular 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 forma- 

 tion of ulcers; but usually to invade the more distant 

 mesenteric lymphatic glands. Nicolas and Descos* and 

 Ravenelf found that when fasting dogs were fed upon soup 

 containing large quantities of tubercle bacilli, they were able 

 to discover 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. 



Koch 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 

 usually from the male to the female, primary tuberculosis 



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

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



