494 
OK THE MEDICAL TOPOGRAPHY OF SINGAPORE. 
brings them within the sphere of action of the malaria generated 
from the mud and decaying vegetables which continnually cover 
their banks” (Johnson on Tropical Climates p. 349). As instances 
of fever not being endemic where sulphuretted hydrogen exists in 
abundance, the town of Singapore may be quoted, various parts of 
Paris where poudrette is manufactured, and localities in Edinburgh 
where the city sewers are allowed to empty themselves. The indus¬ 
try of man can easily counteract the malarious evils of fresh water 
swamps by drainage, blit the malaria from saltwater swamps, or from 
localities where rivers join the ocean are far beyond his power ; to 
me it therefore appears as a dispensation of Providence, the formation 
of this gas, that under ordinary circumstances is so deleterious to 
man, but, existing in situations where malaria is generated, is his 
salvation by destroying the vital germs, the active principle of mala¬ 
ria. In conclusion I wonld venture to suggest that this is the solu¬ 
tion of the mystery for which Dr. McCulloch can offer no conjecture, 
that Singapore town, though possessing every imaginable circum¬ 
stance that ought to render it unhealthy, even one of the most pes¬ 
tiferous spots under the sun, yet is a land where fever is unknown, 
and that freedom is owing to these swamps which surround it, being 
under tidal influence and disengaging Sulphuretted Hydrogen, which, 
although one of the most poisonous gases, yet under these circum¬ 
stances is one of the most salutary, by destroying the animalcular 
germs, which are the vital principle of malaria, and X would have 
no hesitation in asserting that wherever mangrove swamps occur to 
any extent subject to tidal influence, and the disengagement of Sul¬ 
phuretted Hydrogen,* in the Malay Peninsula, Borneo and other 
islands in the Eastern Archipelago, that provided there are no other 
causes of fever, these swamps will not generate malaria, and fevers 
will not there be endemic. 
* Care must be taken not to suppose that every disagreeable odour is 
that of Sulphuretted Hydrogen, for in the majority of cases it is the ammo¬ 
nia odour of decomposing animal and vegetable matter. 
