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 
