626 MALARIAL FEVER 



pleted. The parasites are most numerous in the blood during 

 the development of the pyrexia, 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 amcebulse other forms, 

 which are called gametocytes, 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. 

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

 cytes are rounded in form, resembling somewhat in appearance 

 the fully developed amcebulse before schizogony, 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. 22, /, g). 



The various forms of the parasite seen in the human blood 

 may now be described more in detail. 



1. The Merozoites (Unhcemospores, Lankester) are the young- 

 est and smallest forms resulting from the segmentation of 

 the adult amcebula or schizont. They are of round or 

 oval shape and of small size, usually^ not exceeding 2 /*. in 

 diameter ; the size, however, varies somewhat in the different 

 types of fever. A nucleus and peripheral protoplasm can be 

 distinguished (Fig. 180). 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 

 Romanowsky method, the peripheral protoplasm being coloured 

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

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

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

 amcebulae. If the blood, say in a mild tertia-n case, be examined 

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

 schizonts, free merozoites, and the young amcebula? within the 

 red corpuscles. 



2. Intra-corpnsoiilar Amcebulce 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 youngest or smallest forms are minute colour- 

 less specks, of about the same size as the merozoites; they; 

 exhibit more or less active amoeboid movement, showing marked 

 variations in shape. The amount and character of the amoeboid 



