290 Proceedings of Royal Society of Edinburgh. [sess. 
characters of the soil, nor has altitude anything to do with its 
production. With regard to water, however, it may he that we 
should consider it as a cause, for there are instances on record 
where a change of the source of the water supply has exerted a 
marked influence upon the number of cases seen. When, however, 
we come to inquire as to what substance in the water produces or 
might produce the disease, we are met by various statements which 
are contradictory, or at any rate give no certain clue on which to 
base a definite opinion. For instance, the gypsum found in the 
water at Aleppo is given as a cause : the abundance of nitrates in 
the water of the Punjaub, or the presence of sulphurated hydrogen 
due to putrefying matters, is blamed. Hard water is suspected by 
others, and in Algiers the excessive amount of choride of sodium is 
considered suspicious ; lastly, the amount of earthy salts contained 
in some waters is said to cause the sore. But there are many other 
observations which cause grave doubts as to the correctness of any 
of these views. 
Meteorological conditions must, we believe, exert a not incon- 
siderable power in the production* of Oriental sores. It will be 
noticed that the distribution of the disease is over arid regions, but 
in these regions it is strictly localised to various foci. In the sub- 
tropical regions the disease makes its appearance in the late autumn, 
and it is met with in the winter in the tropical zone. Where it is 
found at all seasons of the year, the climate is characterised by hot, 
dry air during the day, sometimes heavy dew at night, and rapid 
fluctuations of the thermometer. It must, however, be remembered, 
that in some places the Oriental sore attacks its victims in the 
season of the year when vital powers are lowest. It is important 
not to mistake phagedsenic tropical ulcers for the Oriental sore, 
as the former are due to constitutional debility, induced either by 
anaemia, malaria, scurvy, fatigue or want, in persons residing or 
travelling in swampy regions, where the atmosphere is hot and 
moist. 
YI. Endemic Hematuria. 
(See Plate IY. C.) 
Synon . — Distoma Haematobium ; Bilharzia Haematobia. 
Definition . — Endemic haematuria is caused by the entrance into 
