358 MANUAL or BACTERIOLOGY. 



The small tubercles first formed are called gray or miliary 

 tubercles. As they become larger they also frequently become 

 confluent. The larger, confluent, caseous tubercles are often 

 called yellow tubercles. Swollen tuberculous lymph nodes of 

 the neck are among the manifestations of the condition 

 formerly known as scrofula. 



Masses of caseous tubercles sometimes undergo softening. 

 In the lungs the discharge of the softened material results in 

 the formation of a cavity. This formation of a cavity in the 

 lungs is frequently, if not usually, accompanied by secondary 

 infection with pyogenic micrococci. Caseous tuberculous 

 masses may become partly calcified. Very often they may be 

 encapsulated by new formed fibrous or scar tissue. It is 

 possible for tuberculosis to become cured for all practical 

 purposes by means of this process. Autopsies on human 

 subjects have shown that such cures not rarely take place, 

 especially in tuberculosis of the lungs occurring over a localized 

 area. The statistics of autopsies vary widely as to the number 

 of persons that at some time of life suffer from tuberculosis, 

 from 25 or 30 per cent, up to much higher figures. When a 

 tuberculous area has become caseous and encapsulated and 

 apparently quiescent, it is possible for it to be excited to 

 renewed activity under suitable conditions, and, owing to the 

 softening and the discharge of infected material into one of the 

 vessels or cavities of the body, a wide-spreading and rapidly 

 fatal tuberculosis may follow. 



Tuberculosis may become disseminated throughout the 

 body from a small focus as a starting-point. The tubercle 

 bacilli may travel through the lymph-spaces and affect 

 adjacent tissues, some of them reaching the nearest group of 

 lymph-nodes. In tuberculosis of the lungs it is usual also to 

 find tubercles in the bronchial lymph-nodes, and in tuber- 

 culosis of the intestines there is also tuberculosis of the mesen- 

 teric lymph-nodes. The disease may travel along the serous 



