PHENOMENA OF INFECTION. 97 



life as to have given rise to specialists. The specialty 

 is called pcBdiatrics. 



Besides the general infectious diseases, children are 

 more predisposed to infections of the lymphatic glands 

 and bones than adults. The glands most frequently 

 affected are those of the neck (cervical) ; and the infec- 

 tious agents are either the tubercle bacillus, or the 

 common pus cocci. Inflammation of bone, osteomy- 

 elitis, is also a frequent affliction of childhood. The 

 thigh and lower leg are the most likely sites for infec- 

 tious foci. In this affection the tubercle bacillus, and 

 the pyogenic cocci, are again the common cause. The 

 unsightly deformity of hunchback (Pott's disease), 

 and the lesser evil, hip- joint disease, are also examples 

 of the localization of the tubercle bacillus in bone. 



Young adults still exhibit some suscepti- 

 bility to the diseases of childhood, but in a 



CENCE. -^ 



much lessened degree. However, at this 

 period susceptibility is principally shown towards two 

 wide-spread diseases, pulmonary tuberculosis and 

 typhoid fever. Predisposition to the former is almost 

 entirely the result of heredity and environment; to 

 the latter it appears that age is the most important 

 contributing factor. 



Pneumonia is the commonest infectious 

 Old Age. disease of the declining years of life, and 



the principal cause of death. In men, 

 prostatic enlargement frequently interferes with the 



