MALARIAL FEVER. 



521 



site loses its amoeboid movement more or less completely, has a some- 

 what rounded form, and contains a considerable amount of pigment. 

 In the malignant form it only occupies a fraction of the red corpuscle. 

 The adult parasites may then undergo sporulation, but not all of them 

 do so ; some become degenerated and ultimately break down. 



3. Sporocytes or Sporulation Forms. In the largest amoebulse 

 before sporulation the nuclear chromatin becomes scattered throughout 

 the parasite. During sporulation the pigment becomes collected as a 

 more or less central mass, and the protoplasm segments into a number 

 of spores, each of which contains a small mass of chromatin (Fig. 161). 

 The spores are of rounded or oval shape, as above described, and are 

 set free by the rupture of the envelope of the red corpuscle. The pig- 

 ment also becomes free and may be taken up by leucocytes. The num- 

 ber and arrangement of the spores within the sporocyte varies 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 appear- 

 ance ; in the tertian they number 15-20, and have a somewhat rosette- 

 like arrangement (Fig. 161) \ in the malignant there are usually 6-12 

 spores of small size and somewhat irregularly arranged. 



Gametes. As stated above, these are sexual cells which are formed 

 from certain of the amoebulse, and which undergo no further develop- 

 ment in the human subject. In the mild tertian and quartan fevers they 

 resemble somewhat the largest amoebulse, the female cells being rather 

 more granular in appearance than the male. In the malignant fevers 

 the gametes have the special crescentic form mentioned above. They 

 measure 8-9 ^ in length, arid occasionally a fine curved line is seen join- 

 ing 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. It is stated that the 

 male crescents can be distinguished from the female by their appearance. 

 In the former the pigment is less dark and more scattered than in the 

 latter, 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. Accord- 

 ing to the Italian observers the early forms of the crescents are some- 

 what 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. 



The Cycle in the Mosquito. As already explained, this starts from 

 the gametes. After the blood is shed, or after it is swallowed by the mos- 



