The Human Malarial Parasites 



479 



face, corresponding to the divisions into which it is to segment, the 

 pigment gathers at the center, and the substance undergoes cleavage 

 resulting in the formation of from six to fourteen, but usually eight, 

 spores. It is to be noticed that it is not until a few hours before 

 segmentation that the parasite becomes as large as the corpuscle, 

 and that the corpuscle is never enlarged nor bleached by the presence 

 of the parasite. The meroblasts form regular rosettes, or "daisy- 

 heads," within the corpuscles. 



In single infections the parasites are all of the same age and all 

 mature at the same time, so that in any examination of the blood 

 they will all appear uniform. It is, however, sometimes true that 

 the patient may have been infected one day by one mosquito bite, 

 and again infected the next day or the third day by a second mos- 

 quito bite, so that his blood contains two crops of the microparasites, 

 arriving at maturity at different times. This perplexes the clinician 



Fig. i8i. — Parasite of quartan malarial fever : a, J,. c, i, enlarging intracellular 

 parasites; e, f, g, h, segmentating parasites forming a distinct rosette from which 

 the spores separate; i, macrogametocyte; j, microgametocyte; k, sporozoit. 



through the variety of parasitic forms in the blood and the abnormal 

 frequency of the paroxysms. 



The gametocytes of the parasite remain for some time in the red 

 corpuscles without division, but, finally, become free spherical bodies. 

 Two sizes can be made out, the larger, the macrogametocyte or 

 female, the other, the microgametocyte or male. Each has proto- 

 plasm, with a tendency to take a blue-gray color and appear uni- 

 formly granular, except that at some part of the periphery of each 

 there is a circular or semicircular area that is free from granules. 

 This area is larger in the microgametocyte. 



II. Plasmodium Vivax (Grassi and Feletti,* 1890).— This is the 



Synonyms. — Oscillaria malarias pro parte, Laveran, 1881. Plasmodium var. ' 

 tertiana, Golgi, 1889. Haemamoeba vivax, Grassi et Feletti, 1890. Hsemamceba 

 laverani var. tertiana, Labb6, 1894. Plasmodium malarias tertianum, Labb6, 

 1899. Haemamoeba malariae var. magna, Laveran, 1900. Haemamoeba malariae 

 var. tertianse, Laveran, 1904. Plasmodium tertianae pro parte, Billet, 1904. 



most common of the malarial parasites of man, and occasions the 

 benign " tertian fever. It is a large parasite, the full-grown schizont 

 * "Centralbl. f. Bakt. u. Parasitenk.," 1890, vii, 396; 1891, x, 449, 481, 517. 



