36 INFECTION AND IMMUNITY. 



Tonsils. Streptococci, pneumococci and diphtheria read- 

 ily attack the tonsils, and it is probable that the 

 tubercle bacillus often enters through them, with 

 or without causing local infection. Similarly it is 

 believed by many that organisms causing septice- 

 mia (particularly the streptococcus), acute articu- 

 lar rheumatism, and osteomyelitis may enter 

 through the tonsils, and this may also be the case 

 in scarlet fever. 



Lungs. The bronchi become infected by the various or- 

 ganisms causing bronchitis (streptococcus, pneu- 

 mococcus, influenza bacillus, etc.), and, either 

 through surface or lymphatic extension, or by deep 

 inspiration, these and many other organisms, as 

 the tubercle and plague bacilli, and the actino- 

 myces, reach the deeper recesses. Some of the ex- 

 anthemata, as measles and smallpox, may find en- 

 trance through the pulmonary tissue. As explained 

 later, "dust infection" and "droplet infection" are 

 of great importance in pulmonary involvement, 

 particularly in relation to tuberculosis. "Pri- 

 mary" tuberculosis of the peribronchial lymph 

 glands indicates that some micro-organisms may 

 traverse the bronchi without involving them. 



stomach The stomach is comparatively free from infec- 

 tions. The intestines provide an atrium for ty- 

 phoid, cholera, dysentery (bacillary and amebic), 

 tuberculosis, plague,, anthrax, in children for the 

 streptococcus, Bacillus pyocyaneus and others; in 

 animals, for anthrax, plague, swine plague, mouse 

 typhus, chicken cholera, hemorrhagic septicemias, 

 intestinal diphtheria of rabbits, and others. 



The extent to which micro-organisms are carried 

 from the intestines into the body in a state of 

 health is greatly disputed, but frequent existence 



