PATHOGENIC BACTERIA AND DISEASES 47 



disease for months after recovery. The usual site of 

 infection is the mucous membrane of the throat and naso- 

 pharynx, though wounds in any location may be infected. 



The germ gains entrance through some alteration 

 of the mucous membrane and proceeds to produce its 

 characteristic lesion, namely, a fibrinous membrane, 

 which rapidly spreads over the contiguous mucous 

 membrane. The germs do not enter the body, but re- 

 main localized at the site of infection. Their toxins, 

 however, are absorbed, causing temperature, exhaustion, 

 and occasionally paralysis of certain muscles, as those 

 of the palate, vocal cords, and heart. 



Bacteriologic Diagnosis. Boards of health furnish an 

 outfit containing two test-tubes. In one is a sterile 

 swab and in the other blood-serum. A piece of the 

 membrane or some of the secretion from the throat is 

 obtained on the swab and smeared over the blood-serum 

 in the tube, which is stoppered and sent to the laboratory 

 where it is placed in the incubator for twelve hours, 

 when, if the case be diphtheria, the germ may be recog- 

 nized by examination of the culture with the micro- 

 scope. 



It is difficult to differentiate a diphtheritic infection 

 from a simple tonsillitis or other angina at an early 

 stage except by this means. As the success of antitoxin, 

 which is the only treatment relied upon at this time, 

 depends upon its early administration, this means of 

 diagnosis is important. When the infection is located 



