When the parasite is about twenty-four hours old we note that it contains much pigment and has an amoeboid or multiple figure-of-eight contour, is about three-fourths the size of a red cell and that the infected red cell is about one and one-half times as large as in the beginning and presents a washed-out appearance. It is an anaemic-looking cell. We also note, as characteristic of a benign tertian infection, reddish-yellow dots in the pale red cell, which are known as Schüffner’s dots. These, practically, are characteristic for benign tertian. A few hours before the completion of its forty-eight-hour cycle the contained pigment begins to clump, the chromatin to divide and, finally, we have a sporulating parasite, in which the 16 to 20 small, round, bluish bodies, with chromatin dots, are irregularly distributed over the area of the merocyte. [Illustration: FIG. 3.—_Plasmodium vivax._ (Benign tertian) Development of schizonts of nonsexual cycle in peripheral blood of man. Red cell swollen and stains feebly. Note Schüffner’s dots. X 2200. (MacNeal after Doflein.)] The gametes, or sexual parasites, show a thicker blue ring and have the chromatin dot in the center of the ring. The pigmentation of the half-grown gametes is more marked than that of schizonts of equal size. The shape of the gametes is not amoeboid, as is that of the twenty-four to thirty-six-hour-old schizont, but round or oval. _The full-grown gametes have the pigment distributed and the chromatin in a single aggregation—just the opposite of nonsexual parasites._ The male gamete stains a light grayish blue and has a very large amount of chromatin, usually centrally placed. The female gamete stains a pure blue, has only about one-tenth as much chromatin as plasma, with the chromatin often placed at one side. The pigment of the female gamete is dark brown while that of the male is yellowish brown. [Illustration: FIG. 4.—_Plasmodium vivax_. (Benign tertian.) Double infection of a red blood cell which is enlarged and shows Schüffner’s dots. X 2200. (MacNeal after Doflein.)] =Plasmodium Malariae.=—In fresh preparations the young quartan schizont has only slight amoeboid movement and, as development proceeds, the rather dark brown, coarse pigment tends to arrange itself peripherally about the band-shaped or oval parasite. The infected red cell shows but little change. At the end of seventy-two hours the rather regular daisy form of the merocyte is more distinct than that of the benign tertian merocyte.