FOIJMS OF THE MALARIAL PARASITE 591 



The number and arrangement of the merozoites within the 

 srhi/ont 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 ].") _'<) or more, and have a somewhat rosette-like 

 arrangement (Fig. 161); in the malignant there are usually 

 6-20 merozoites of small size and somewhat irregularly arranged. 



Gametocytes. As stated above, these are sexual cells which 

 are formed from certain of the amoebulce, 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, macroyametocytes, are 

 of large size, measuring up to 1 6 /x in diameter ; they contain 

 coarse grains of pigment, and the protoplasm stains somewhat 

 deeply witli methylene-blue. The male cells, microffometocytes, 

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

 umerally 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 /x 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. 164). They are colourless and transparent, and 

 are enclosed by a distinct membrane ; in the central part there 

 is a collection of pigment and granules of chromatin. The male 

 crescents can be distinguished from the female by their appear- 

 ance ; in the former the pigment is less dark and more scattered 

 through the cell, and there are several granules of chromatin ; 

 in the latter the pigment is dark and concentrated, often in a 

 small ring, and there are one or two masses of chromatin in the 

 centre of the crescent (Plate V., Fig. 22 /, g). 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. 



It is well known that after a patient has apparently recovered 

 from malarial fever a relapse may take place without fresh 

 infection occurring, sometimes several years afterward, and 

 Schaudiim has published interesting observations bearing on 

 this point. He has found, and his observations on this point 

 have been confirmed, that the macrogametocyte of tertian fever 

 may by a process of parthenogenesis give rise to merozoites, 



