140 YELLOW FEVER. 
ing, or yellow fever) makes its appearance. These 
persons, we may add, are not affected by it during 
the passage ; it manifests itself only on the spot. 
Has the constitution of the atmosphere been changed? 
asks Humboldt; or, has a new form of disease de- 
veloped itself in individuals whose excitability is 
raised to a high pitch? 
The malady forthwith attacks other Europeans 
born in warmer countries. Immediate contact does 
not increase the danger, nor does seclusion diminish 
it. When the sick are removed to the interior, and 
especially 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, al- 
though no ship may have entered the harbour for 
several months. 
The yellow fever disappears periodically at Ha- 
vannah and at Vera Cruz, when the north winds 
carry the cold air of Canada towards the Mexican 
Gulf; but as Porto Cabello, La Guayra, New Bar- 
celona, and Cumana, possess an extreme equality of 
temperature, it is probable that it will become per- 
manent there. Happily, the mortality has dimi- 
nished since the treatment has been varied accord- 
ing to the modifications which the disease assumes. | 
In well-managed hospitals, the number of deaths is 
often reduced to eighteen or fifteen in a hundred ; 
but when the sick are crowded together, the loss 
increases to one-half or even more. 
To the west of La Guayra there are several in- 
dentations of the land which furnish excellent an- 
chorage. The coast is granitic, and a great portion i 
