CARRIAGE OF DISEASE 171 



pox the children who were attacked all lived in the 

 southwest of the village, the northern part of the vil- 

 lage remaining free from the disease. This distribu- 

 tion was thought to be due to the direction of the pre- 

 vailing winds, and observations were made to the effect 

 that flies and mosquitoes were distributed with the 

 wind. Laforgue himself believed that flies played an 

 important part in the spread of the virus of small-pox. 



PLAGUE 



So much is now known concerning the specific origin 

 of bubonic plague and concerning its carriage by the 

 several species of fleas which occur upon rats, which 

 are also subject to the same disease, that house flies 

 cannot be claimed to be of importance in this connec- 

 tion ; but old writers have noted the occurrence of flies 

 in large numbers in plague years, and one of them at 

 least considered that house flies carried the disease, 

 simply from the fact that they visited food after they 

 had abandoned plague patients. 



Nuttall and Jepson call attention to the fact that 

 Yersin, in writing upon bubonic plague at Hong-Kong 

 in 1894, stated that he saw many dead flies lying 

 around in his laboratory when he was conducting au- 

 topsies on animals killed by the plague. He demon- 

 strated by inoculation into animals that a dead fly con- 

 tained virulent plague bacilli. 



Nuttall himself had in 1897 already experimented 

 with the house fly, feeding it upon organs of animals 

 dead by the plague. He found that the flies might 



