384 Major W. B. Fry and Captain H. S. Ranken. [Dec. 23, 



cannot be seen in any individual preparation. We have endeavoured, so far 

 as possible, to correlate the various appearances met with ; at the same time 

 we cannot be sure that we set them out in exact chronological order. 



In the first place granules, like many other free bodies in the blood 

 plasma, are liable to undergo phagocytosis, and have been seen in all 

 conditions within polynuclear leucocytes. 



Granules somewhat older have also been seen in hyaline mononuclear 

 and in endothelial cells, but in cells of this type, on the other hand, the 

 contained granules are quite unchanged, and we are unable to say that they 

 are being destroyed. It is possible that they may be entering on an intra- 

 cellular phase of existence. They have been very well seen by one of 

 us (W. B. F.) in a large mononuclear leucocyte during examination of the 

 blood of a cat infected with T. nanum. They have also been seen in 

 endothelial cells in liver puncture preparations from cases of sleeping 

 sickness. 



The first change seen in the free granule is a slight enlargement and 

 elongation, rendering it more definitely pear-shaped. Then one begins to 

 note a slight differentiation of structure into a central area staining a dark- 

 blue or purple, and a peripheral zone which is only faintly tinted blue. 

 The enlargement is progressive, and the body becomes more uniformly blue, 

 while a small dark blue or purple spot is visible, varying in position from 

 the centre of the body to the apex. This may be assumed to be the earliest 

 differentiation of cytoplasm from nuclear material. At this stage there is 

 sometimes a definite flagellum-like projection which is usually short and 

 rather thick, and more like a pseudopodium (Plate 11, fig. 2). 



The same early forms have been studied in dark-ground preparations 

 from bone-marrow in animals infected with T. nanum and are illustrated in 

 Plate 9, fig. 2, A to I. 



From this point the body enlarges, and the flagellum-like body becomes 

 relatively, if not actually, reduced in size, so that forms are seen as in Plate 11, 

 figs. 3 and 4. Later on the mass of chromatic material divides, and two 

 are seen — one much smaller than the other. The body then becomes more 

 rounded. Some are regularly spherical, while others show projections from 

 various points, and have on surface view a roughly triangular appearance. 



At this time of their development they resemble very closely the Leishman- 

 Donovan bodies in Kala-azar ; they are found sometimes in enormous numbers 

 in lungs, bone-marrow and spleen. Death in acute trypanosomiasis is caused 

 by plugging of the cerebral capillaries with these forms. This cause of death 

 is very similar to that in pernicious malaria. 



From this stage — the binucleate body — there appear to be two directions 



