301 
1888 - 89 .] Dr R. W. Felkin on Tropical Diseases. 
both contagious and hereditary, and that it is caused by the bacillus 
leprae, but for the present we must confess ignorance as to its 
origin. It should be stated, however, that the production of leprosy 
has been ascribed to extremes and frequent and rapid transi- 
tions of temperature, associated with high degrees of atmospheric 
moisture, but a glance at the chart will disprove this idea. Again, 
it has been said that leprosy must bear a special relation to the sea 
coast; but although in isolated cases it does occur chiefly near the 
sea, its area of distribution completely disproves this theory. 
Various articles of diet have been blamed as its cause — fish diet, 
salt or rotten fish, immoderate use of pork, and the use of decom- 
posed rice or maize. It is, however, impossible, after studying the 
subject, to arrive at the conclusion that any of these causes is the 
true one. The mere fact of the very definite isolation of the areas 
of endemic leprosy goes against these theories. 
XI. Yaws. 
(See Plate VIII. A.) 
Synon. — Framboesia; Button Scurvy; Verruga-Peruviana; Peru- 
viana Wart; Buba or Boba, and Patta (West Indies); Framosi 
(Calabar); Tetia (Congo); Tonga or Coco (Fiji); Lupani and Tono 
(Samoa); Fr. and Ger. Pian. 
Definition . — Yaws consists of an eruption of yellowish or reddish- 
yellow tubercles, which gradually develop into a moist exuding 
fungus without constitutional symptoms, or with such only as result 
from ulceration and prolonged discharge, namely, debility and 
prostration. It is epidemic, and contagious by actual contact. 
The period of incubation of the poison varies from three to ten 
weeks, and as a rule it only occurs once in a life-time. 
Geographical Distribution . — In Africa, yaws is to be met with on 
the west coast, from Senegambia in the north, as far south as 
Angola, together with the westerly Soudan, where it is especially 
frequent in Timbuctoo and Bornu. It is occasionally seen in the 
Xiie Valley, as well as on the northern and north-eastern African 
coast -line. It is very frequently met with in Madagascar, 
Mozambique, and the Comoros. In the East Indies it is chiefly 
seen in the Moluccas, Java, Sumatra, and Macassar; it is also 
