MORPHOLOGY 775 



2. The rosette or marguerite form. The rosette, marguerite or segmenting 

 forms represent the schizogonous mode of reproduction of the Hsematozoon 

 of malaria. They are only met with in very small numbers in chronic con- 

 ditions and are best looked for during the early stages of an attack of fever : 

 sometimes they are not to be found in the peripheral blood but only in the 

 liver and spleen. 



In some of the amoeboid bodies the margins will be seen to be slightly 

 indented and the pigment grains collected in the centre of the parasite this 

 is the first stage of schizogony. The periphery soon becomes more deeply 

 indented and gives the parasite a marguerite appearance : each segment then 

 separates from its neighbours, in such a way that a number of little spherules 

 (merozdites] are formed, none of which contain pigment pigment being only 

 found in the adult forms of the parasite. 



The number of segments into which the marguerite form breaks up is very 

 variable (six to twenty). According to Golgi, those breaking up into eight 

 segments are found in quartan fever, those giving rise to sixteen or twenty 

 spherules in tertian fever (p. 180). 



I, 



FIG. 372. The hsematozoon of malaria. FIG. 373. The haematozoon of malaria, 



x 1000. a, the crescent form of macrogamete ; x 1000. a, macrogamete ; b, microgametes 



b, the crescent form of microgametocyte (Plas- separating from the microgametocyte (fla- 



modium -prcecox). (Diagrammatic.) gellated body). (Diagrammatic.) 



3. The crescent form. Crescents are seen in the blood of persons who have 

 been infected for a long time and are suffering from malarial cachexia. 



The crescent-shaped parasites measure 8-9/x long by about 2//, broad : 

 their protoplasm is transparent and colourless except for a collection of black 

 pigment grains in the centre. On their concave side a very fine line is often 

 seen connecting the two horns of the crescent. Crescents are either found 

 free in the serum or attached to red cells. 



Laveran was the first to show that these crescents later change their shape, 

 becoming first oval then spherical. Crescents represent a stage in the sexual 

 life-history (sporogony) of the Hsematozoon (vide post). 



4. Flagellated bodies. At the periphery of certain medium-sized spherical 

 parasites motile filaments (flageUa) are sometimes seen which are endowed 

 with considerable powers of movement and displace the red cells in their 

 neighbourhood. The flagella are three or four times the diameter of a red 

 cell, but so transparent and delicate that when at rest it is almost impossible 

 to see them. One to four flagella may originate from a single spherical body 

 and these may be arranged symmetrically around the parasite or grouped 

 together at the same point. The flagella move independently of each other, 

 and their displacement often imparts some slight movement to the spherical 



