PREFACE vii 



in spreading plague. Rat-fleas are of various kinds, 

 and not all fleas will bite man. A knowledge of the 

 different species has suddenly become useful. The 

 humble, but ridiculous, systematist with his glass 

 tubes of alcohol for collecting fleas, his microscopic 

 distinctions, and Latin nomenclature has become a 

 benefactor of humanity. Some people seem to be 

 practically immune to the bites of fleas, but even to 

 such persons their visits are unwelcome. A famous 

 Frenchwoman once declared : " Quant a moi ce n'est 

 pas la morsure, c'est la promenade." 



H. R. 



LONDON, 



September, 1913. 



