132 THE ACUTE SELF-LIMITED INFECTIONS 



antisera or bacterins. When, however, there is a pro- 

 longed catarrh of sinuses, larynx, or bronchi, or when 

 it can be shown that a person is harboring the bacilli, 

 it is perfectly feasible to employ dead organisms as 

 a bacterin, using, wherever possible, a culture from the 

 patient. This is practically never in pure cultures and 

 mixed vaccination is the rule. For pneumonia, pleurisy, 

 and so forth we know nothing of the practical nature 

 of antiserum, but for meningitis it has been found 

 to have some curative effect. It is introduced into the 

 spinal canal after withdrawal of some fluid to make 

 room for it. It is made by injecting horses with 

 increasing numbers of the bacilli and separating the 

 serum as for diphtheria antitoxin. 



BACILLUS PESTIS. 



Bubonic plague or u the plague" or "pest," is an acute 

 infectious disease caused by the Bacillus pestis, and 

 characterized by high fever, suppuration, swelling of 

 the lymph glands, and a severe grade of bacteremia. 

 In the so-called pneumonic form, a pulmonary inflam- 

 mation dominates the clinical picture, but the infective 

 nature of the disease is the same. Occasionally, in 

 very severe attacks, subcutaneous hemorrhages occur; 

 this is called " black death." The commoner or lymph 

 gland form occurs where the bacteria gain entrance 

 by skin cracks or wounds, while the pneumonic type 

 follows inhalation of the germs. 



The bacteria enter chiefly through the skin by way 

 of minute wounds, or, as was shown in India, by the 

 bite of a rat flea. Rats and mice, indeed all rodents, 



