BACILLUS PESTIS 371 



modern methods of investigation have shed upon the etiology, 

 of bubonic plague, an epidemic disease characterized by 

 suppuration of the lymphatic glands, and accompanied by 

 a very high rate of mortality, especially when the infection 

 involves the lungs, as is sometimes the case. 



This pestilence, probably endemic in certain sections of 

 the Orient, is one of the most conspicuous epidemic diseases 

 of history. Since early in the Christian era epidemics and 

 pandemics of plague have made their appearance in Europe 

 at different times. During and for a time after the Middle 

 Ages it was more or less frequent in India, China, Arabia, 

 Northern Africa, Italy, France, Germany, and Great Britian. 

 In history it is variously known as the "Justinian Plague" 

 of the sixth century, the "Black Death" of the fourteenth 

 century, and the "Great Plague of London" of the seven- 

 teenth century, though it is difficult to say to what extent 

 these outbreaks were uncomplicated manifestations of 

 genuine bubonic plague. During the existence of the Jus- 

 tinian Plague 10,000 people are said to have died in Con- 

 stantinople in a single day, and Hecker estimates that during 

 the pandemic of the Black Death 25,000,000 people (a 

 quarter of the entire population of Europe) succumbed to 

 the disease. During the Great Plague of London (1664-65) 

 the total mortality for one year was 68,596, out of an esti- 

 mated population of 460,000 souls. 



It is not surprising to learn that it was to guard against 

 the plague that quarantine regulations were first estab- 

 lished. 



The first and certainly the most exact information con- 

 cerning the exciting cause and the pathology of the plague 

 was furnished by investigations of Yersin, of Kitasato, and 

 of Aoyama, conducted during the epidemic of 1894 in Hong 



