HATS AND PLAGUE 391 



agency of rats and mice in the spread of plague, which is as 

 follows : * 



" 1. Kitasato and Yersin, and many others after them, have found 

 the specific bacillus of plague in the dead bodies of rats and mice 

 collected in houses in which cases of the disease subsequently broke 

 out among the occupants, or in the streets of infected towns. They 

 have also placed beyond question the great susceptibility of these 

 rodents to the bacillus. 



" 2. In all the- towns of India manifest examples of contagion 

 from mice to men have been observed. At Bombay, in certain 

 establishments where the dead bodies of rats were found, it has been 

 noticed that the persons who collected them alone contracted plague, 

 although many other work-people were engaged at the same place. 



"3. The first cases of the disease have sometimes appeared in 

 warehouses where wheat, cotton seed, or other substances likely to 

 attract rats were stored. At Kurachee, where the warehouses are 

 situated in streets without dwelling-houses, the first sufferers were 

 the caretakers. 



" 4. Well-constructed and well-maintained houses, i.e. where rats 

 cannot find harbour, nearly always remain free from plague. This 

 same immunity was demonstrated by Eennie at Canton, in 1894, 

 among the occupants of boats anchored in the river. On the other 

 hand, is to be observed the permanence of infection in the houses of 

 poor natives, notwithstanding the removal of the residents and 

 furniture and the most rigorous disinfection, because of reinfection 

 by means of mice. 



"5. The epidemics at Bombay, Kurachee, and Karad were 

 chiefly localised in quarters where the disease had broken out 

 amongst rats. The spread of infection in other parts of these same 

 towns was regularly preceded by the immigration and death of rats, 

 and its diffusion always corresponded to the route of travel taken by 

 these rodents in their migrations. 



" 6. In healthy countries adjoining infected, the disease broke out 

 amongst the inhabitants without the importation of a single (human) 

 case, but was preceded by the immigration of rats from an infected 

 place. 



" 7. In many countries and towns the development of the 

 epidemic among the inhabitants followed a month after the importa- 

 tation of the first cases, or after the death of fugitives arriving from 

 infected localities. During the interval the plague had been propa- 

 gated by mice. 



" 8. Lastly, the mode of infection and propagation of plague on 

 certain ships proved that the rats on board had been the vehicles of 



* " The Prevention of Plague through Suppression of Rats," Revue d* Hygiene, 

 August 1899. 



