134 The Story of the Bacteria 



where for a long time there have been scatter- 

 ing cases. 



The plague bacillus is short and plump and 

 grows very easily in cultures and in such 

 characteristic ways that it is readily recognized. 

 It is easily killed by drying, sunlight, and 

 disinfectants. 



<. In one form of the disease pneumonia is a 

 prominent feature, and then the germ may be 

 transmitted from the sick to the well by the 

 discharges from mouth and nose. 



But in severe epidemics of plague the num- 

 ber of persons affected is so large that some 

 other mode of transmission of the bacillus 

 than by personal contact has to be assumed. 

 And here we come upon a keen reminder that 

 some of the lower animals which we cordially 

 despise, as is the case with the house-fly, are 

 significant factors in the discomfort which 

 man derives from inheriting the earth. 



It has been found that in plague epidemics 

 rats share with man in the predilections of 

 the plague bacillus, having an enormous 

 mortality of their own. The evidence indeed 

 is strong that man derives his plague bacilli 



