Note 3 — Chapter II

Much stress has been laid on the apparent insalubrity of marshes of this sort; and it has been maintained that in many parts they are the chief, if not the sole, cause of the most fatal of intertropical diseases, remittent fever. Humboldt, in his Essay on New Spain, lays great stress on the effect produced by the growth of Rhizophora Mangle, Pothos, Arum, and of the other plants which flourish in a marshy soil charged with saline particles, in the production of yellow fever. Without calling into question the insalubrity of marshy situations in general, there appears great reason to believe that we are still ignorant of the actual causes of this frightful disease. The settlement of Singapore is possessed in an eminent degree of the circumstances which are thought to be most conducive in producing the disease. Yet here it is as yet unknown. An intertropical climate on the margin of the sea, a continually high temperature, rapid and intense evaporation, a humid and extensive series of saline and fresh water marshes exposed to a burning sun, the vegetative impulse in a degree of activity unequalled perhaps in any other part of the globe, the occasional suspension of herbaceous vegetation by long-continued heat, accompanied by drought, profusion of vegetable matter, as leaves, felled wood, fruits, &c., intermixed with animal matter, forming fomites in every stage of the putrefactive process, are amongst the more conspicuous of the causes to which the occurrence of this disease is usually attributed; and here all the causes enumerated operate with tenfold force.