286 Proceedings of Royal Society of Edinburgh. [sess. 
elevated temperature. The second is characterised by depression 
of the nervous and muscular powers, and of the circulation, with 
slow and often intermittent pulse; jaundice; suppression of urine, 
albuminuria, and desquamation of the renal epithelium; diminution 
of the fibrin of the blood, capillary congestion, passive haemorrhages 
from the mucous surfaces and black vomit ; fatty degeneration of the 
heart and liver ; and convulsions, delirium and coma. As a general 
rule, it occurs but once during life. 
Geographical Distribution . — Although yellow fever extends over 
the areas mentioned below, it must be noticed that there are only 
three districts where it is really endemic, i.e ., (a) in the West 
Indies, especially in the Greater Antilles ; ( b ) on the Mexican part 
of the Gulf Coast ; and (c) on the Guinea coast at Sierra Leone, 
The area of distribution of yellow fever is at present limited in 
Africa to the west coast from 19° N. to a point on the mainland 
opposite Fernando Po. In the Western Hemisphere it occurs along 
the eastern shores of the United States from lat. 38° JSL, and, 
skirting the coast round the Gulf of Mexico and Central America, 
it passes along the northern coast of South America and the eastern 
coast as far as 32° S. On the western shores of South America 
yellow fever has appeared in epidemics from 5° S. to 42° S. It is 
also prevalent throughout the whole of the West Indies. Although 
in the United States and South America yellow fever chiefly 
infests the coast regions, exception must be made to the great 
rivers, such as the Mississippi, the Amazon, and the Rio de la Plata, 
for it extends up these rivers to varying distances. In the western 
hemisphere the yellow fever area is bounded on the north by 
44° 39' K (Halifax), and on the south by 34° 54' (Monte Video); 
in the eastern hemisphere by 43° 34' N. (Leghorn), and 8° 48' S. 
(Ascension); these are its extreme limits. 
Remarks . — There are some curious facts with regard to yellow 
fever and its relation to climate which it is necessary to remember. 
Firstly, Negroes are congenitally exempt from it, unless they 
leave the tropics for any length of time and then return; if 
they do this their immunity seems to be lost. It appears, too, 
that Mongolians escape yellow fever. All other races, however, 
suffer from it, and it is noteworthy that the further north from its 
area a person was born the more likely is he to suffer from it, 
