OF NORTHU.MBF.RLAND AND DURHAM 1 83 



b. LlTKRATURl'.. 



Now things are changed. Mr. Rothschild has pubHshed a 

 "Synopsis of the British Siphonaptera" in the " luitomologist's 

 Monthly Magazine" (19 15, pp. 49-112) with very useful tables 

 and 8 plates; Mr, Harold Russell has published in the 

 "Cambridge Manuals of Science and Literature" series 

 a volume entitled "The Flea" (1913), and Mr. James 

 Waterston is responsible for a brochure published by the 

 British Museum (1916) on "Fleas as a Menace to Man 

 and Domestic Animals, their life-history, habits and control." 

 For a student of the plague flea the researches of Bacot and 

 Martin (which one feels will be regarded as classic) will be 

 found in the Journal of Hygiene. 



c. Bubonic Plague. 

 Waterston's brochure epitomises these researches, and 

 though the literature above cited is accessible to all, I make no 

 excuse in quoting him as follows : — 



" The greatest danger of the flea's attack, however, is that 

 through it plague may be contracted. Bubonic plague is a 

 kind of blood poisoning, characterised, among other features, 

 by an enlargement of the glands (buboes). This disease, 

 caused by the presence of a specific organism {Bacillus 

 pestls) in the victim's blood, is more or less always to be 

 found in certain parts of the world. From these regions, 

 underconditions as yet imperfectly understood, plague becomes 

 virulent and spreads over the world {e.g., 1894-1900). Rats 

 and fleas are the chief factors in the propagation of the 

 disease, the insects conveying plague from rat to rat, and 

 from rat to man. While it is impossible to give here the 

 detailed evidence on which these statements rest, one may 

 state shortly the ways in which the plague bacillus is con- 

 veyed by the flea. The problem has proved to be by no 

 means a simple one. 



(i) Arguing from the analogy of malaria, etc., the earliest 

 efforts were made to find plague bacilli in the salivary glands 



