TRYPANOSOMIASIS EXPEDITION TO SENEGAMBIA 
23 
The granules occurred on an average in thirty to fifty per cent, ot the large 
mononuclear. 
,, „ ,, „ two to seven per cent, of the small 
lymphocytes. 
,, ,, ,, eight to twelve per cent, of the large 
lymphocytes. 
In specimens stained by Ehrlich's or Romanowsky's methods and fixed by 
any of the three previously mentioned methods, circular, refractile, non-staining, 
and sharply circumscribed areas were not infrequently seen in both the cytoplasm 
and nucleus of the leucocytes. 
Their most usual situation was, however, in the cytoplasm close to the 
nucleus. They varied in diameter greatly, being usually about 0*5 to pom in 
width. They occurred in about two per cent, of all leucocytes, but were, however, 
more numerous in the mononuclear elements. 
The slight virulence ot this trypanosome and the consequent lack of symptoms 
has frequently suggested to us the possibility that the natives in this disease may bear 
the same relation to the European as does the wild game of Central Africa to 
domestic animals in the tsetse fly disease. 
We have had no opportunity of investigating the course of the disease — if 
we can call it a disease — in the native, but the ages of those infected indicate that 
there can be no absolute acquired immunity. It would be rather curious if the 
woman at Lammin or the man at Kuntur had only recently become infected for the 
first time after having been exposed to infection from childhood. We think that the 
varying ages of the various cases is another point in favour of our belief that the 
parasite frequently occurs in the natives, but appears in a periodic manner in their 
peripheral circulation. 
