vii] FLEAS AND PLAGUE 87 



French medical school went so far as to deny con- 

 tagion altogether. The modern view is that aerial 

 infection may be put aside as almost impossible 

 except in pneumonic cases ; but that plague may be 

 transmitted by any method which inoculates the blood 

 with Bdcillits pestis. 



Our modern knowledge dates from the year 1894 

 when the plague reached Hong Kong. Its existence 

 as a rat disease was recognised. In the autumn of 

 1896, when plague broke out in India, the men of 

 science, who made careful observations on the spot, 

 were struck by the fact that infection spread from 

 house to house in a fashion that seemed inexplicable, 

 unless the bacillus was carried by an animal. 



We pass now from rats to fleas. That fleas might 

 be connected with the spreading of plague was 

 suggested in the year 1897 when Ogata first found 

 bacilli in fleas. He obtained fleas from plague-sick 

 rats. These he crushed, and injected the liquid into 

 a couple of mice. One of these died of plague 

 in three days. The German Plague Commission 

 in Bombay found plague bacilli in fleas, but, for 

 various reasons, did not consider that the bite of 

 the flea was the means by which the disease was 

 transmitted. 



The real credit is due to Simond, a Frenchman, 

 who worked during the Indian epidemics. He took 

 fleas from infected animals and observed in their 



