29 



2. Large I ntr a- corpuscular Forms (Fig. 6). 

 They appear as more or less extensive areas of blue 

 protoplasm, with one or more distinct red areas. Pig- 

 ment may be seen scattered over the parasite. These 

 large forms are generally simple tertian or quartan 

 parasites. 



3. Crescents and Spherical Bodies. These are 

 most definite bodies, and readily recognized by 

 the coarse pigment granules centrally situated. The 

 presence of this pigment should absolutely preclude 

 the possibility of mistaking distorted red cells, cres- 

 centic in shape, or a crescentic mass of platelets, for 

 parasites. In neither of these is there a definite 

 central pigment mass, nor should a foreign body be 

 mistaken for a crescent. Moreover, crescents again 

 have quite definite outlines, and shew a red-stained 

 central portion and blue extremities. 



Fig. 7. Pigmented Large Mononuclear Leucocytes 



The same criteria apply to the spherical form of 

 the crescent. 



4. Pigmented Leucocytes (Fig. 7). Large leuco- 

 cytes with a large nucleus. Pigment (melanin) may 

 occur scattered about the periphery of the cell or in 

 little clumps, or even in very fine powdery grains. 

 The pigment is brownish-black in colour. Skin pig- 

 ment may be seen in epithelium scales or free in the 

 specimen, but the definite position of the pigment in 

 the protoplasm of the leucocyte characterizes melanin. 



