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52, and quartan intermittents or agues, and remittents. But since it has been found that what was designated remittent fever is produced by either quartan, tertian, subtertian, or by quotidian parasites—the fact of intermittency or remittency being more or less a matter of accident—it has been considered advisable to expunge the term remittent fever as indicative of a distinct species of malarial disease. Any one of the five kinds of parasites enumerated may cause what was known as remittent fever. The intermittency or the remittency of any given fever depends, in great measure, on the simultaneousness or the reverse of the maturation of the swarm of parasites giving rise to it. If all the parasites present are of nearly the same age, they mature approximately simultaneously and we have an intermittent; if they are of different ages, they mature at different times scattered over the twenty-four hours and we have what was known as a remittent. Further, two generations of tertian parasites maturing on successive days will produce a quotidian fever, Tertiana duplex; two generations of quartan parasites maturing on successive days will produce fever fits on two successive days followed by one day of freedom, Quartana duplex; three generations of quartan parasites will produce what clinically appears to be a quotidian fever, but in reality is a Quartana triplex.

Present classification not final.—The classification adopted is merely provisional. In practice it may be hard, often impossible, to bring the cases met with into exact line with such an arrangement. Moreover, as this classification is based in great measure on observations made in very limited districts, principally in Italy, and principally on Roman fevers, it may not apply to the entire malarial world. That it lies on a substratum of fact there can be no doubt; nor can there be much doubt that it has in many particulars a general application to malarial disease as found all over the world. Still, judging from clinical facts, there seems ground for believing that there are other species or