164 INFECTION AND IMMUNITY 



meningitis or tubercular peritonitis is usually doomed 

 to death, but many children recover from the other 

 forms of tuberculosis just mentioned and may grow 

 up to be useful citizens, although the results of the 

 disease from which they suffered are manifest in the 

 stiff knee, immovable hip joint, or deformed spinal 

 column. 



Susceptibility to pulmonary tuberculosis is much 

 greater in young adults than in children. This sus- 

 ceptibility depends upon several factors which consti- 

 tute the predisposing causes. First we may mention 

 an inherited weakness of constitution, or conforma- 

 tion of body narrow chest, insufficient lung capacity, 

 feeble circulation, imperfect digestion. Second come 

 the conditions relating to an unfavourable environ- 

 ment living in ill-ventilated or overheated rooms, 

 absence of sunlight and dampness in apartments 

 occupied, insanitary surroundings, overcrowding of 

 living- and sleeping-rooms. Next we must place 

 lowered vitality as a result of other acute or chronic 

 diseases or of vicious habits, and the catarrhal inflam- 

 mation of the bronchial mucous membrane which is a 

 prominent feature of certain other infectious diseases 

 especially measles, whooping-cough, and influenza 

 or which may result from " taking cold." Finally, 

 occupation has much to do with establishing a predis- 

 position to the disease. 



