THE FIGHT AGAINST YELLOW B'EVER. 341 



eral character have offered the scientific public a collective view of 

 the ideas gained. Among- these works special mention should be made 

 of Dr. Kaphael Blanchard's elaborate volume upon the natural his- 

 lory of mosquitoes and their relation to medicine, and of the excel- 

 lent little book of jNIessrs. Chantemesse and Borel upon the j^ellow- 

 fever misquito. 



Through these documents, traced to their different sources, I shall 

 explain, not so much the practical methods employed in the strug- 

 gle against yellow fever as the scientific theories upon which the 

 defense is based. 



I. 



The history of yellow-fever epidemics in various epochs shows a 

 remarkable tendency for the disease to extend its ravages. Origi- 

 nating in the islands and on the coast of the Gulf of Mexico, it re- 

 mained for a long time bound to its birthplace. At Vera Cruz the 

 Spanish conquerors waged war against it from their first attempts 

 to conquer Mexico at the beginning of the sixteenth century. It was 

 as formidable an enemy to them as the Aztecs, Historians of the 

 conquest record that the band under Diego cle Nunes, numbering 780 

 men when in 1509 it had just taken possession of the lowlands of 

 Vera Cruz, lost 400 men in a short jDeriod, and fifteen months later 

 their number was reduced to 60 men. This first disaster was signifi- 

 cant. It announced to invaders the frightful consumption of lives of 

 Europeans which this minotaur of the Tropics, known as the yellow 

 typhus, black vomit, or yellow fever, was to make during four cen- 

 turies. 



All along the coast of the Gulf of Mexico, at the mouths and on 

 the banks of rivers, the disease lived in an endemic state, showing at 

 long intervals periods of epidemic outbreak more or less violent. 

 From this permanent center, called the " Mexican source," there ex- 

 tended numerous epidemic radiations. Several, mounting toward the 

 north, attacked the Bermuda Islands and the Atlantic coast of the 

 Hnited States; others, summering in the south, infected the Guianas 

 and Brazil ; then encircling the South American Continent, set upon 

 the Pacific ports. Sugar-laden vessels from Cuba carried the con- 

 tagion to the maritime cities of Europe. In the eighteenth century 

 slave ships returning from the Antilles infected the western coast of 

 Africa. 



Most of these epidemics, emanating from their original Mexican 

 center, Avere extinguished on the spot only after disastrous ravages. 

 But at other times the yellow fever, encountering in the new coun- 

 tries conditions favorable for its developuient. establishcMl itself per- 

 manently in an endemic state. This is what hai)pened in Brazil and 

 on the coast of Africa. 



