142 BACTERIOLOGY FOR NURSES 



often if not always accompanied by great mortality 

 among rats, and investigation proved that the plague 

 of rats and the plague of man were both due to B. 

 pesiis, some writers believing that plague is prima- 

 rily a disease of rats and contracted from them by 

 men. This theory led to much study of the methods 

 whereby the infection is transferred to man. As the 

 infection does not take place through the alimentary 

 tract, it could not be carried by food or utensils 

 which had been contaminated by rats, neither was it 

 possible for every infected person to have come into 

 direct contact with rats; but it was discovered that 

 fleas taken from the bodies of plague-infected rats, 

 or from rats in an infected house, and transferred to 

 the bodies of healthy rats, would transmit plague to 

 the latter. 



The Advisory Committee of the Indian Plague 

 Commission, in 1905, by a series of experiments, 

 proved conclusively that rat fleas carried plague to 

 healthy animals and to man. 



The following are some of the experiments which were 

 conducted. A series of six huts were built which only 

 differed in the structure of their roofs. In two the roofs 

 were made of ordinary native tiles, in which rats freely 

 lodge; in two others flat tiles were used, in which rats 

 live, but in which they have not such facilities for move- 



