BUBONIC PLAGUE 141 



plague patient, the discharges from buboes, and the 

 excreta are the sources of infective materials, which 

 must find entrance to the body through breaks in 

 the skin or mucous membranes to produce a plague 

 infection. 



The usual mode of infection is through an abrasion 

 of the skin, the buboes developing in the neighbor- 

 hood of the point of infection. Infection through 

 the tonsils and air-passages may occur, but pneu- 

 monic plague is usually secondary to the infection of 

 other tissues through abrasions. 



Infection by swallowing is not supposed to occur. 

 Aoyama points out that during the Hong Kong 

 epidemic doctors and nurses who were in attendance 

 upon plague-infected patients were rarely infected; 

 neither were three hundred English soldiers who vol- 

 unteered to clean and disinfect the plague pesthouses, 

 which is strong evidence that the disease is not con- 

 tracted through the alimentary tract and rarely 

 through the air-passages. 



It was long observed in many epidemics that 

 transmission and infection did not always occur, 

 even when healthy persons, such as doctors and 

 nurses, were brought into close contact with plague- 

 infected patients. 



It was also noted that epidemics of plague were 



