375 



moving inside the capillaries. These cells are of doubtful 

 nature but resemble the macrophages seen in the organs in 

 malaria. In some cases these cells contain melanin. The 

 parasites in these cells have the characteristic structure. They 

 appear to lie in vacuoles, but these are undoubtedly the body 

 of the parasites (Fig. 24). 



Spleen. — The parasites occur in similar cells. They are 

 very conspicuous in sections. Large mononuclear cells con- 

 taining parasites are more abundant than in the liver. Neither 

 do the red cells contain parasites, nor do free forms occur. 



In contrast to what is seen in blood films made 

 by spleen or liver puncture where most of the para- 

 sites are either free or contained in a matrix, in 

 sections no such relation exists ; the parasites lie 

 in cells. These cells are of various types. 



(a) But slightly modified endothelial cells. These have 

 an oval nucleus and extensi\e protoplasm showing vacuolization 

 (Fig. 20). The protoplasm may show buds or protrusions. 

 These cells contain six to twelve parasites, Identical cells are 

 seen in the capillaries of the testis and of granulation tissue. 



(6) Large round cells with a large nucleus. The protoplasm 

 has a ground glass appearance and is vacuolated. In the testis 

 and in granulation tissue these cells are attached at one point 

 to the capillary wall, the rest of the cell projecting freely. 

 They also occur in the blood taken post-mortem from the large 

 veins. They contain twenty or more parasites (Fig. 21). 



(c) Very large cells with one or two vesicular nuclei, They 

 occur in the liver and spleen in immense numbers. They occur 

 either extended along the capillary wall or in a retracted form. 

 In the spleen their processes extend among the smaller cells of 

 the pulp. They contain numerous parasites, 



^ (d) Large cells staining more intensely than the last and 

 sometimes showing signs of necrosis. The nucleus is pushed to 

 the side The centre of the cell is occupied by a large vacuo- 

 lated space, around which are arranged numerous parasites. 

 The cells, in fact, contain so many parasites that they appear 

 to be on the point of rupture, and such cells are rarely seen 

 whole in films unless fixed extremely carefully with osmic acid 

 vapour. They contain as many as two hundred and fifty bodies 

 (Figs. 22, 23). 



