122 YELLOW FEVER. 



CHAP. XL lias proved fatal not onl}^ to troops newly arrived from 

 I'ataTeffects. Sp^i"? ''^t also to those raised far from the coast, in the 

 Llanos, between Calabozo and Uritucu, a region nearly 

 as hot as La Guayra itself. It scarcely ever passes 

 beyond the ridge of mountains that separates this pro- 

 vince from the valley of Caraccas, which has long been 

 exempted from it. The following are the principal 

 pathological facts having reference to this fi'ightful pes- 

 tilence : — 

 Pathological When a great number of persons, bom in a cold 

 facts. climate, arrive at a port in the torrid zone, the insalu- 



brity of which has not been particularly dreaded by 

 navigators, the American typhus (black vomiting, or 

 yellow fever) makes its appearance. These persons, we 

 may add, are not affected by it dui-ing the passage ; it 

 manifests itself only on the spot. Has the constitution 

 of the atmosphere been changed 2 asks Humboldt; or, 

 has a new form of disease developed itself in individuals 

 whose excitability is raised to a high pitch I 

 . , The malady forthwith attacks other Europeans born 



:iie disease, in warmer countries. Immediate contact does not 

 increase the danger, nor does seclusion diminish it. 

 When the sick are removed to the interior, and espe- 

 cially to cooler and more elevated places, they do not 

 communicate the typhus to the inhabitants. Whenever 

 a considerable diminution of temperature occurs, the 

 distemper usually ceases ; but it again begins at the 

 commencement of the hot season, although no ship may 

 have entered the harbour for several months. 

 Vt Havan- '^^^^ yellow fever disappears periodically at Ilavannah 



uh aiui and at Vera Cruz, when the north winds carry the cold 

 .'eia Cruz. ^^jj. ^f Canada towards the Mexican Gulf ; but as Porto 

 Cabello, La Guayra, New Barcelona, and Cumana, 

 possess an extreme equality of temperature, it is prob- 

 able that it will become jiermanent there. Happily, the 

 mortality has diminished since the treatment has been 

 varied accordijig to the modifications which the disease 

 assumes. In well managed hospitals, the number of 

 deaths is often reduced to eighteen or fifteen in a hun- 



