372 



In contrast to what is seen in blood films made 

 by spleen or liver puncture where most of the parasites 

 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 extensive 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. 



() 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 some- 

 times showing signs of necrosis. The nucleus is pushed to the side. 

 The centre of the cell is occupied by a large vacuolated 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). 



Bone marrow. In films the parasites occur in macrophages in 

 immense quantity. To some extent also in large mononuclear cells, 

 and a few in polynuclear cells, and in myelocytes. 



Large intestine. Parasites occur in large numbers in the granu- 

 lations, and in the mucous membrane in the early stages of infiltration. 

 They occur in similar cells to those found in other situations. 



Granulation tissue. Sections of papules or ulcers of the skin 

 show a few parasites in what are apparently endothelial cells of the 

 fine capillaries. In larger capillaries cells may contain three or four 

 parasites, while in small vessels large cells similar to those in the liver 

 and spleen are found crowded with parasites. These cells are attached 

 at one point to the capillary wall. 



