vi PREFACE 



The naturalists now living who have devoted 

 any time to the special study of fleas may almost 

 be counted on one's fingers. In England there 

 are Mr Charles Rothschild and Dr Jordan ; in 

 the Shetland Islands, the Rev. James Waterston ; in 

 Germany, Taschenberg of Halle and Dampf of 

 Konigsberg ; in Russia, Wagner of Kieff ; in Holland, 

 Oudemans of Arnhem ; in Italy, Tiraboschi of Rome ; 

 in the United States, Carl Baker and a few others. 

 I have not mentioned medical men who have investi- 

 gated fleas in connection with plague. 



There are small collections of fleas in the Natural 

 History Museums at South Kensington (London), 

 Paris, Berlin, Konigsberg, Vienna, Budapest, S. 

 Petersburg and Washington. Of private collections 

 Mr Charles Rothschild's at Tring is by far the best 

 in the world. It contains something like a hundred 

 thousand specimens and is most admirably kept. 

 I must express profound and sincere gratitude to 

 Mr Rothschild for having helped me in numberless 

 ways and advised me in many difficulties. 



It is well known that the mere mention of fleas 

 is not only considered a subject for merriment, but 

 in some people produces, by subjective suggestion, 

 violent irritation of the skin. The scientific study of 

 fleas has, however, received a great impetus since it 

 has been ascertained that they are the active agents 



