FORMS OF THE MALARIAL PARASITE 587 



annul) u he ; the cycle is thus completed. The parasites are most 

 numerous in the blood during the development of the pyivxia, 

 and, further, they are also much more abundant in the internal 

 organs than in .the peripheral blood; in the malignant type, for 

 example, the process of schizogony is practically confined to the 

 former, 



In addition to these forms which are part of the ordinary 

 asexual cycle, there are derived from the anuebuhe other forms, 

 \\hich arc called i/n/m-fnri/fes, or sexual cells. These remain 

 unaltered during successive attacks of pyrexia, and undergo no 

 further change until the blood is removed from the human body. 

 Fn the simple tertian and quartan fevers (vide infra) the gameto- 

 cvtes resemble somewhat in appearance the fully developed 

 aiiKL'huUe before sporulation, whereas in the malignant type they 

 have a characteristic crescent-like or sausage-shaped form ; hence 

 they are often spoken of as "crescentic bodies" (Plate V., Fig. 



--.'.<; .-/). 



The various forms of the parasite seen in the human blood 

 may now be described more in detail. 



I . '/'//< Merozoites (Enhcemospores, Lankester) are the youngest 

 and smallest forms resulting from the segmentation of the 

 adult amoebula or schizont. They are of round or oval 

 shape and of small size, usually not exceeding 2 //, in 

 dia meter; the size, however, varies somewhat in the different 

 t \pi-s of fever. A nucleus and peripheral protoplasm can be 

 distinguished (Fig. 162). The former appears as a small 

 rounded body which usually remains unstained, but contains a 

 minute mass of chromatin which stains a deep red with the 

 I (omanowsky method, the peripheral protoplasm being coloured 

 fairly deeply with methylene-blue. The merozoites show little or 

 no anneltoid movement; at first free in the plasma, they soon 

 attack the red corpuscles, where they become the intra-corpuscular 

 an in -Iniho. If the blood, say in a mild tertian case, be examined 

 in the early stages of pyrexia, one often finds at the same time 

 schi/onts, free merozoites, and the young amcebuhe within the 

 the red corpuscles. 



_' . / / / / / " --,, , -f , uscular A mcebula' or Trophozoites. These include 

 the parasites which have attacked the red corpuscles ; they are at 

 first situated on the surface of the latter but afterwards penetrate 

 their substance. They usually occur singly in the red corpuscles, 

 but sometimes two or more may be present together. As seen 

 in fresh blood, the youn^-st "i smallest forms are minute colour- 

 It -ss specks, of about the same si/e as the spores; they exhibit 

 more or less active amoeboid movement, showing marked 



