Distribution of Tropical Diseases in Africa. 457 
38° F., the rainfall 23:12 inches. At Port Elizabeth the 
rainfall is only 19°71 inches, and at King William’s Town, 
16°48 inches. At Graham’s Town the air is bright and ex- 
hilarating; the mean annual temperature is 60° F., mean 
annual range 15° F., rainfall 22 inches, and, occurring as it 
does chiefly in summer, it keeps down the temperature and 
secures remarkable equilibrity. In this region malaria may 
be said to be absent. Again here, typhoid fever, dysentery, 
and diarrhcea are the most frequent and fatal diseases, and 
rheumatism, also, is very prevalent. Syphilis, leprosy, and 
scrofula are widely prevalent, but respiratory diseases are 
unimportant. Pneumonia, however, is more frequently seen 
in Cape Colony than it is farther north. Phthisis, owing to 
the number of imported cases, is more prevalent than one 
would expect, but apart from this, it is probable that the 
disease does exist in the Colony more than in other parts 
of the district we have just had under review. Scarlet fever, 
diphtheria, small-pox, and measles occur in epidemics, but 
infrequently. Heart disease appears to be specially pre- 
valent. Cholera has never visited the Cape, and hydrophobia 
is unknown. Diseases of a parasitic nature are rare, and 
hydatids are infrequent. 
VIII. Arrican ISLANDs. 
Madagascar, the largest African island, is situated in the 
Indian Ocean, between 12° and 25°S, latitude. It can be: 
divided into a low coast-line, and extensive highlands having 
an altitude of from 3000 to 4000 feet. The mean annual 
temperature of the coastal region is between 74° and 80° F.; 
the mean annual temperature of the highlands is 64° to 70° F., 
the mean variation between 5° and 10° F. The annual rain- 
fall on the western half of Madagascar varies from 25 to 50 
inches; on the eastern half it varies from 50 to 100 inches. 
At Nossi Bé, to the north-west of the island, it is over 100 
inches. Malaria is most prevalent during the first three 
months of the year, and it prevails over practically the whole 
of the island. It is especially prevalent on the coast, and 
least so in the central provinces. Typhoid fever is also 
