January, 1911. 



KNOWLEDGE. 



11 



and safety is dependent on factors which are in 

 themselves apparenth" sh'ght. For e.xample, it has 

 alread\- been said that plague is spread entirely by 

 plague fleas. This mav naturally lead to the inquir\- 



supposition be in conflict with the recorded facts 

 that whole families were stricken with the plague, 

 apparently taking it from one another ? That is 

 certainly true ; and the answer to these questions is 



The house (at Parel) with the plant pot in front, produced a 

 \ery large number of rats. 



whether the last Great Plague of London, which 

 proved so devastating, was spread by fleas ? If it 



Figure 4. 



An examination of plague infected rats at one of the Indian 

 Government Laboratories, 



to be sought in the fact that plague has more than 

 one development. It may develop into plague 



Takint 



Figure 5. 

 a systematic flea count. 



were so would not this argue that the habits and 

 dwellings of London in the late seventeenth century 

 \\ ere much more dirtv than we have any evidence to 

 show tliat they were ? Moreover, would not the 



Figure b. 

 Piclcing off fleas from live rats for experiments. 



pneumonia, which, of all forms of plague, is the most 

 dangerous and the most infectious. The mortality 

 in plague pneumonia approaches one hundred per 

 cent.; hardly anyone recovers from it. Moreover, 



