DIPHTHERIA BACILLUS. 401 



through, nor does it injure the unbroken skin, it 

 produces necrosis of the mucous surfaces and un- 

 derlying tissue at the site of infection. Through 

 the wounded surface fibrin-forming elements es- 

 cape, as a consequence of which successive layers 

 of fibrin are deposited and the fibrin, together with 

 the necrotic surface, leucocytes and associated 

 micro-organisms constitute the membrane which 

 so often marks the disease clinically. The local 

 process is similar in diphtheria of cutaneous 

 wounds. The toxin becomes generalized by absorp- 

 tion through the lymphatic circulation. 



Characteristically the bacilli are confined to the Localization 

 site of infection. Although diphtheritic bacterie- of the Bacilli 

 mia rarely occurs, the bacilli have been found oc- 

 casionally in the blood and viscera of fatal cases. 



The clinical and anatomic conditions lead us to 

 believe that the parenchymatous organs, the lym- 

 phatic tissues and the cells of the nervous system 

 contain receptors with which the toxin unites, in- 

 asmuch as these tissues suffer demonstrable injury 

 during the disease. When the toxin is injected 

 subcutaneously into animals, localized edema and 

 necrosis occur; hence, the connective tissues may 

 also take up a portion of the toxin, diverting it, so 

 to say, from the more vital organs. 



Mixed infections render diphtheria a more dan- Mixed 

 gerous disease. According to Baumgarten, the Infectlons - 

 streptococcus is associated with the diphtheria ba- 

 cillus in most cases of diphtheria. The observa- 

 tion of Eoux and Yersin that the streptococcus in- 

 creases the virulence of the diphtheria bacillus 

 both in the test-tube and in animal experiments 

 may explain to some degree the severity of the dis- 

 ease when accompanied by streptococcus infection. 



