288 THE PROTOZOA 



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time of the commencement of the sweating stage of the paroxysm. Two chromatin 

 dots in the line of the ring are rare as is also true of more than one ring in a red cell. 



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 Schiiffner'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. 



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 cen- 

 trally 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 pig- 

 ment of the female gamete is dark brown while that of the male is yellowish brown. 



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. 



The distinctions between the male and female gametes are similar to those of the 

 benign tertian gametes. In Romanowsky stained smears it is difficult to distinguish 

 the young quartan schizont from the benign tertian one but, after twenty-four 

 hours, the tendency of the quartan schizont to assume equatorial band forms across 

 a red cell of normal size and staining characteristics and without Schiiffner's dots 

 makes the differentiation easy. In the fully developed sporulating parasite or 

 merocyte the eight merozoites assume a regular distribution giving it a daisy 

 appearance. 



The gametes show practically the characteristics of the benign tertian ones but 

 are smaller. 



Plasmodium Falciparum. The young schizont of malignant tertian is extremely 

 difficult to detect in fresh preparations, there being noted early in the rather long 

 continued, hot stage, only small crater-like dots, about one-sixth of the diameter of 

 a red cell which, however, show an active amoeboid movement. 



Later on in the hot stage these ring-like dots enlarge to become about one-third 

 of the diameter of a red cell, most often occupying the periphery of the infected 

 red cell. About this time, or at the very commencement of the pigmentation, the 



