Malaria, in its various manifestations, has ever constituted the principal obstacle to the civilization of all tropical and semi-tropical countries, and as a consequence vast tracts of the richest and fairest portions of the world have remained uncultivated and unredeemed from their primitive savage state. Recent investigations have shown that this disease can be easily prevented if the matter is taken up intelligently. Malaria is a disease produced by a parasite belonging to the very lowest order of animal life--the _Plasmodium malaria_, which is conveyed from man to man by that genus of mosquitoes called the Anopheles. The parasite attacks and destroys the red cells of the blood, and produces a poison that causes the symptoms characteristic of malaria. _Course of the Disease._--The most common and well-recognized symptoms of malaria are those that occur in that variety of the disease which is known as malarial or intermittent fever. In this type the patient--who may or may not have at intervals for some days noticed chilly sensations, a feeling of fullness in the head, and general bodily depression--is suddenly seized with a chill followed by a high fever and subsequent profuse perspiration; after these symptoms subdue, which generally requires several hours, the patient returns to a practically normal condition and feels, on the whole, well until the next attack occurs. These chills-and-fever paroxysms occur at various intervals depending upon the character of the parasite inducing them, the most common form being that which produces a chill every day. In some instances the malady comes on more insidiously, there being no marked chills but only periodical elevations of temperature. In the more chronic forms of the disease the unfortunate victim is frequently subjected for years to attacks of fever coming on at irregular intervals, the patient being more or less of an invalid throughout the course of the disease. In other instances the brain becomes affected, producing very alarming symptoms; and in quite a proportion of cases the malady ultimately terminates in chronic Bright's disease. _Treatment of the Disease._--Most fortunately, we have in quinine, when properly administered, a medicine that in practically all instances acts as a specific in this affection; but it should be used only on the advice and under the directions of a physician. In the more chronic forms of the disease, combinations of arsenic, with such tonics as nux vomica, iron, and small doses of some of the preparations of mercury, produce permanent cures where quinine has failed. It is of the utmost importance that attention be given to the treatment, as, so long as the patient remains with the parasites in his blood, so long is he a menace to his friends and neighbors.