36 INFECTION 



tonsillitis, but the same organisms entering the skin cause erysipe- 

 las of phlegmons; or if the uterus is infected after the birth of a 

 child the disease is still different and more serious. If the tubercle 

 bacilli enter the skin they produce lupus; if swallowed they cause 

 ulceration of the bowels, and subsequently invade the peritoneum; 

 if inhaled, tuberculosis of the air passages, phthisis, or tuberculous 

 laryngitis may follow. If cholera spirilla be injected into a vein 

 of a guinea pig, it may develop choleraic septicaemia; if they are 

 injected into the peritoneal cavity, a choleraic inflammation of the 

 peritoneum is produced, and not a septicaemia. Pneumococci if 

 injected into a vein cause a rapid septicaemia, or they may give 

 rise to abscesses anywhere in the body. Like streptococci, they 

 may be the cause of inflammation in any tissue, particularly 

 serous membranes, and show different clinical entities, according 

 to the organs involved, and the morbid anatomy and physiology 

 produced. The fatality of a bacterial infection varies with the 

 avenue of inoculation: it is safer to have a skin infection than a 

 meningeal, or endocardial one, not only from the likelihood of 

 rapid toxin absorption, but from purely mechanical damage, as 

 pressure and interference with vital functions by inflammatory 

 products such as fibrin, tubercles, serum and pus. 



How Bacteria Are Brought to the Body. Air-borne infection 

 may occur by the direct transference of the bare organisms, a very 

 rare occurrence, or by dust or by droplets of fluid usually sputum. 

 Organisms settle on objects of our environment when leaving the 

 sick and can be stirred up with the dust. This is important for 

 diphtheria, the acute exanthemata and tuberculosis although 

 the 'most dangerous source for the last is the coughing con- 

 sumptive. The transmission of pertussis and pneumonia is almost 

 surely always a droplet convection. 



Water-borne infection, including typhoid, cholera and dysen- 

 tery occurs by the contamination of water courses with the dis- 

 charges of the respective diseases. 



Milk-borne diseases, tuberculosis, diphtheria, epidemic sore 



