42 
pheral blood. Apart from the actual presence of the 
parasites, one may still derive evidence of malarial 
infection from— 
1. The presence of pigmented leucocytes. 
2. An alteration in the proportion of the leuco¬ 
cytes. 
Pigmented Leucocytes .—Pigmented leucocytes, 
even in severe malaria are often very few, and often 
require for their detection prolonged search in large 
films. In other cases, however, they are abundant. 
The presence of very few is quite compatible with a 
severe malarial infection. For instance, in two cases 
seen by us, only very few were found in the peripheral 
blood, but in the spleen, post-mortem, enormous 
numbers occurred. To detect them it is necessary to 
make large and good films by the method already 
described. By following the margins and termination 
of the film, the majority of leucocytes in the film will 
■have passed beneath the eye, and pigment, if present, 
is readily seen. 
In the vast majority of cases the pigment will be 
found in the large mononuclear forms, and only very 
rarely indeed in the polymorphonuclear forms. As a 
rule, a pigmented large mononuclear (Fig. 7) is 
crowded with granules of pigment, the presence of 
only a few grains, or a single granular clump, is excep¬ 
tional. The appearance of the clearly defined 
yellowish-brown ' or black pigment granules in the 
clear protoplasm is so characteristic that no doubt 
ought to exist. It should be remembered, however, 
that in dirty films specks of dirt may be over a leuco¬ 
cyte, and so resemble pigment. In this case similar 
specks will be found lying free. The occurrence of 
malarial pigment free in the blood has never been 
seen by us. 
