376 



Bone marrow. — In filiils 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 

 granulations, 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 con- 

 tain 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. 



Lymphatic glands. — In those draining the area of a skin 

 lesion parasites are found. They occur in large cells in the 

 lymph sinuses and in cells of the reticulum. 



We have thus in an infection caused by these 

 parasites two processes — (i) 'Tropical ulcer,' a 

 local invasion of the nature of a granuloma ; (2) a 

 systemic infection of the nature of a septicaemia, 

 involving" chiefly the visceral endothelia. The 

 endothelial cells increase in size, and become so 

 distended with parasites as eventually to undergo 

 necrosis. Such cells would appear eventually to 

 rupture, and the parasites set free to be again taken 

 up by other cells. 



Development of the parasites. — Rogers states that he has 

 observed further development of these bodies in vitro To 

 splenic blood from a case of Kala-azar he added some citrate 

 of soda to prevent coagulation, and then incubated the solution 

 at about 20° C. He then observed : — 



(i) Multiplication of the parasites so that they became far 

 more numerous, 



(2) In a few days flagellates made their appearance , These 

 closely resembled trypanosomes except that thev had no undu- 

 lating membrane, 



One of us, S.R.C., confirmed the observation 

 that flagellates are formed, but these flagellates 

 are certainly not trypanosomes. 



