, MORTALITY IN THE PAST 119 



commercial centre created, it is certain to cause tlie 

 explosion of the latent malignity of the poison in 

 the air." 



No wonder, then, that around such a disease, magic 

 and mystery were freely invoked to account for it. 

 Yes, and little wonder that to-day may still be found 

 surviving some old practitioners of medicine who 

 cannot shake the juju off and will take you to see 

 a " yellow fever house " — a house haunted with the 

 yellow fever pestilential miasm of former generations, 

 and in which, if you reside, you will surely get yellow 

 fever ! 



Just as in the case of malaria, so in this disease : 

 miasms — the chemical reactions arising from the union of 

 salt water with fresh — were considered an ideal explana- 

 tion, for it fitted in with appearances. Our tropical 

 seaports were attacked by yellow fever, and in these 

 tropical seaports it invariably happened that the in- 

 coming salt-water tides met with the outflowing fresh 

 water of the tropical river or the water of the lagoon ; 

 and it was to that natural phenomenon that wise men 

 attributed a chemical reaction and the engendering of 

 a " fibrilifying influence." The " fibrilifying influence " 

 was described as a terrestrial poison which a high atmo- 

 spheric heat generates amongst the newly arrived. 

 The frequent outbreak of yellow fever on board ships 

 led to a host of theories which are amongst the most 

 absurd of the modern period of the history of medicine, 

 only finding their parallel away back in the days of 

 alchemy and witchcraft. The outbreaks on board ship 



