1888-89.] Dr R. W. Felkin on Tropical Diseases. 275 
Class III. The East Coast of Africa ; Egypt ; the coast-line of 
Arabia ; Mexico ; China Proper ; the Brazils and Peru. 
Second Category. 
Class I. Tripoli ; Algeria ; Morocco ; the Cape de Verde Islands ; 
and the Oases of the Sahara. 
Class II. Turkey, in Europe ; Greece ; the Islands of the Archi- 
pelago ; Sardinia ; Malta ; Sicily, and parts of Italy. 
Class III. Roumania ; Hungary ; Italy ; Corsica ; Spain ; Portu- 
gal; Southern Russia, and a large part of the United States. 
Third Category. 
Southern Sweden ; Denmark; Belgium and Holland; Germany; 
France ; La Plata ; Chili, and the Islands of Madeira ; Bourbon and 
at Helena. 
Fourth Category. No Malaria or Insignificant. 
The British Islands ; Norway ; the southern parts of Sweden ; 
Finland and Russia; all North America above the 50th parallel of 
N. latitude ; Uruguay ; the Argentine Republic and Patagonia ; 
Northern China ; almost all Siberia and the greater part of Japan ; 
New Zealand and the southern part of Australia. 
Remarks . — Of the malarial fevers, the intermittent is the most 
widely distributed type, and it will be noticed that the remittent 
and pernicious fevers are only met with in comparatively small 
areas, and that they are, as a rule, confined to tropical or sub-tropical 
countries. A glance at the map will show, without further specifica- 
tion, their distribution. It may be noted, however, that the quo- 
tidian and quartan types of intermittent fever are those which are 
most frequently met with in the tropics, and that the Tertian type 
is that form which is most widely distributed in the more temperate 
zones. In fact, the type of fever stands in a definite relation to the 
intensity of the malarial process ; thus we find that the Tertian type 
prevails in those regions within the tropics where the milder 
malarial fevers are indigenous. Again, the frequency of the occur- 
rence of the quotidian type of fever in endemics or in epidemics is in 
direct proportion to the severity of the disease. When an epidemic 
