When there are two generations of tertian parasites, each maturing on successive days, we have a paroxysm every day—a quotidian fever. Such a tertian infection is called a double tertian. In quartan infections, with the seventy-two-hour cycle of development, if we have two generations of parasites sporulating on succeeding days, but with an apyretic day intervening, we have a double quartan. If three generations of quartan parasites sporulate on three successive days we have a triple quartan infection. When two species of parasites are present in the same case we have a mixed infection. Mixed infections of malignant tertian and benign tertian are the most common, next, those of quartan and malignant tertian and very rarely those showing quartan and benign tertian. All three species have been found in a single individual. CLINICAL TYPES _A Typical Benign Tertian or Quartan Paroxysm._—(Other than for the difference in periodicity the paroxysms of these two malarial infections are alike.) The ague attack generally commences with malaise and slight headache, frequently accompanied by yawning and stretching. Chilly sensations radiating from the spinal column to the extremities and the jaws give way to actual chill with shaking body and chattering teeth, face pinched and bluish and cutis anserina. The pulse is frequent, small and of rather high tension, there is increased frequency of urination and nausea and vomiting may be present. Notwithstanding the fact that the rectal temperature is steadily rising five or six degrees during this cold stage there is a desire on the part of the patient to cover himself with all the wraps obtainable. The cold stage, which usually lasts from twenty to sixty minutes, is succeeded by the hot stage. At first there is a feeling of slight relief from the misery of the chill but this is soon lost sight of in the increasing headache and feeling of intense heat. The previously welcome blankets are cast aside. The face now becomes flushed, the eyes shining, and the pulse more full. Epigastric discomfort, nausea and vomiting are apt to become more prominent in this stage. The patient often complains of a throbbing headache. It is at this time that he may become slightly delirious. A sense of tension or even pain may be experienced in the region of the spleen, which organ will be found tender even if not already palpable. Herpes about the nose and lips is almost as common as in lobar pneumonia. An attending bronchitis is not uncommon. The fever remains high, from 105° to 106°F., and continues so elevated for from four to six hours to be succeeded by the sweating stage. In this the dry skin becomes moist and perspiration breaks out first on the forehead to be followed by a more or less marked profuse sweating of the entire body. The pulse becomes slower, the temperature falls rapidly and the patient falls asleep to awake slightly exhausted but feeling well.