630 MALARIAL FEVER 



schizont vary in the different types. In the quartan there are 

 6-12, and the segmentation is in a radiate manner, giving rise 

 to the characteristic daisy-head appearance ; in the tertian they 

 number 15-20 or more, and have a somewhat rosette- like 

 arrangement (Fig. 179); in the malignant there are usually 

 6-20 or more merozoites of small size and somewhat irregularly 

 arranged. 



Gametocytes. — As stated above, these are sexual cells which 

 are formed from certain of the amcebuloe, and which undergo no 

 further development in the human subject. In the mild tertian 

 and quartan fevers they are rounded and resemble somewhat 

 the largest amoebulae. The female cells, macrogametocytes, are 

 rounded and of large size, measuring up to 16 /t in diameter; 

 they contain coarse grains of pigment, and the protoplasm stains 

 somewhat deeply with methylene-blue. The male cells, micro- 

 gametocytes, are smaller, and the protoplasm stains faintly ; the 

 nucleus, generally in the centre, is rich in chromatin. In the 

 malignant fevers the gametocytes have the special crescentic or 

 sausage- shaped form mentioned above. They measure 8 to 9 fi 

 in length, and occasionally a fine curved line is seen joining the 

 extremities on the concave aspect, which represents the envelope 

 of the red corpuscle (Fig. 182). They are colourless and trans- 

 parent, and are enclosed by a distinct membrane ; in the central 

 part there is a collection of pigment and granules of chromatin. 

 The male crescents (Plate V., Fig. 22 /) can be distinguished 

 from the female (ibid., g.) by their appearance ; the former are 

 somewhat sausage-shaped, the pigment is less dark and more 

 scattered through the cell, and there are several granules of 

 chromatin ; the latter have more pointed ends and their 

 substance stains more deeply with the blue, the pigment is 

 dark and concentrated, often in a small ring, arid there are 

 one or two masses of chromatin in the centre of the crescent. 

 According to the Italian observers, the early forms of the 

 crescents are somewhat fusiform in shape and are produced 

 in the bone-marrow. The fully developed crescents do not 

 appear in the blood till several days after the onset of the 

 fever, and they may be found a considerable time after 

 the disappearance of the pyrexial attacks. They are also 

 little, if at all, influenced by the administration of quinine. 

 Ross and Thomson have enumerated directly (p. 640) the 

 malarial parasites in the blood at different stages of the disease, 

 and have found that a certain relationship exists between the 

 asexual and the sexual forms, a rise in the number of the former 

 bejng followed eight to ten days later by a rise in the number of 



