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80 appears to depend on an exaggeration of the symptom usually hailed as bringing relief and, for the time, freedom from danger. Thus the sweating of the stage of defervescence may be excessive and cause collapse, which, if the patient rise up suddenly or make an undue effort, may lead to fatal syncope. Weak and cachectic patients, therefore, should be warned of this possibility.

The pathology of these various forms of algidity is in all likelihood of a very mixed character. In the gastric, choleraic, hæmorrhagic, and dysenteric types there is probably an accumulation of parasites in the vessels of the intestinal mucosa; such accumulations of parasites have been described. In those attacks in which profuse sweating is the dangerous element, the diaphoresis may be regarded, at all events in part, as symptomatic of excessive blood destruction—— of what is, in reality, equivalent to a sudden and extensive hæmorrhage; or it may be that it is only an excessive reaction to the malarial toxin. The dangerous syncope attending all types of algidity is secondary, and merely an expression of collapse.

A phenomenon occasionally observed in pernicious attacks, especially in those of an algide type, is the flooding of the peripheral blood with vast numbers of parasites, it may be at all stages of development——gametes as well as schizonts. The prognosis in such cases is bad.

A practical experience of these suddenly developed pernicious fevers of the tropics teaches that we should never make light of any malarial attack; particularly if it be of a mild irregular character and imperfectly controlled by quinine, and if small parasites, or the crescent form, be present. The practitioner should be on the alert for any danger signal mental aberration, restlessness, tremor, peculiarity in behaviour, alteration in knee reflexes, and other indications of grave implication of the nervous system. It further teaches that the subjects of such fevers should be particularly careful to guard against chills, fatigue, insufficient and unwholesome food, etc.