[Illustration: FIG. 18.—Typical fever charts of the 3 types of malaria.] This feeling of well-being continues during the fever-free day which is often referred to by a patient as “my good day.” The sweating stage lasts usually about four hours so that the entire paroxysm of cold, hot and sweating stages occupies approximately eight to twelve hours. While most cases of the benign infections show the typical stages yet we meet cases where the cold and sweating ones are absent or but slightly marked. Blood examination will show the parasites of the benign infections to be in the peripheral circulation during the entire apyrexial period. During the paroxysm we have a moderate leucocytosis and during the afebrile period a leucopenia with an increased percentage of large mononuclears. Billet thinks that quartan paroxysms can be distinguished from benign tertian ones by their showing a less abrupt fever rise and a more rapid fall of temperature with a shorter duration of the paroxysm, four or five hours as against eight to twelve hours for benign tertian. _A Typical Malignant Tertian Paroxysm._—The characteristic features of the paroxysm are slight chilliness instead of a frank chill, prolonged and intensified hot stage, lack of marked terminal sweating and a tendency to exhibit a continuous or at least remittent fever curve instead of the distinct intermittence, with an apyrexial period, of the benign infections. During the period of the remittence the patient fails to experience a sense of well-being. He is sick and does not have a “well day.” The temperature of a malignant tertian paroxysm may fall to normal during the first attack but succeeding attacks only show the tertian periodicity by an exacerbation of the more or less continuous fever. In these cases the temperature rise is gradual rather than abrupt and the fall rather by lysis than crisis. The paroxysm lasts from twenty to thirty-six hours instead of ten hours. To explain the continuous type of fever it is often stated that anticipation and retardation are characteristic of malignant tertian infections. This simply means that the new paroxysm tends to come on before the tertian periodicity of forty-eight hours has expired and, having appeared, tends to delay its termination. At any rate there is an extreme irregularity in the course of the paroxysm. These attacks are often termed “dumb chills” and are greatly dreaded. The onset is insidious, occurring as a rule in the forenoon or early afternoon, with rarely a chill but only chilly sensations. The headache and backache are severe, the face is flushed, the pulse quickened and the thirst urgent.