106 GEOGRAPHIC DISTRIBCTJOy OF llffiOXIC FLAG IE 



evidence or b}^ what is known of other specific infectious diseases. 

 Whatever may have been the original home of the disease or the cir- 

 cumstances to whicli it owes its birth, there is no reason to believe 

 that during the period covered by our historical data it has occurred 

 in any other way than by the introduction of infected individuals 

 or animals or articles of clothing and merchandise from infected 

 localities. 



I must now refer briefly to the history of plague during the past 

 decade. The disease seemed to be almost a thing of the past and no 

 longer gave any uneasiness in the countries of Europe which had 

 formerly suffered from its ravages, when, in February, 1894, it made 

 its appearance in the city of Canton, China, and three months later 

 in Hongkong. The disease is known to have been epidemic in the 

 province of Yunnan, which is about 900 miles distant from Canton, 

 since the year 1873, but it attracted little attention until the lives of 

 Europeans living in the city of Hongkong were threatened by the 

 outbreak of an epidemic among the Chinese residents of that place- 

 Many thousands of deaths occurred in Canton during the three months 

 which elapsed after its introduction into that city before it effected a 

 lodgment in Hongkong. 



Fortunatel}' this outbreak gave the opportunity for comjjetent bacte- 

 riologists to make scientific investigations relating to the specific cause 

 of this scourge of the human race and to the demonstration that it is 

 due to a minute bacillus. This discovery was fir.st made by the Japa- 

 nese bacteriologist, Kitasato, who had received his training in the 

 laboratory of the famous Professor Robert Koch, of Berlin. This dis- 

 covery was made in the month of .June, 1894, in one of the hospitals 

 established by the P]nglish officials in Hongkong. About the same 

 time the discovery was made, independently, b}'^ the French Vjacte- 

 riologist. Yersin. From this time the study of plague has been estab- 

 lished U])on a scientific Vjasis, and ver\' material additions have been 

 made to our knowledge with reference to the prevention and treat- 

 ment of the disease. We have learned that certain of the lower ani- 

 mals, including rats and mice, are very susceptible to infection, and 

 that they ]day an important part in the i)ropagation of the disease; 

 also that the germs are found not only in the blood and in pus from 

 suppurating buboes, but also in the discharges from the bowels of in- 

 fected individuals. This being the case it can readily be seen how 

 im])ortant a strict sanitar}'- police is in arresting the spread of an epi- 

 demic. As in other filth diseases in which the germ is present in the 



