40 



only very rarely indeed in the polymorphonuclear 

 forms. As a rule, a pigmented large mononuclear 

 (Fig. 3) is crowded with granules of pigment, 

 the presence- of only a few grains, or a single 

 granular clump, is exceptional. The appearance 

 of the clearly defined yellowish-brown or black 

 pigment granules in the clear protoplasin 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 leucocyte, 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. 



Leucocytic Variation. — Often in cases where 

 pigmented leucocytes are difficult to find, there is 

 a very obvious increase in the percentage of the 

 large mononuclear leucocytes. This change, which 

 is usually very pronounced in the apyretic periods 

 of an attack of malaria, is, however, most fre- 

 quently absent during pyretic periods. If, during 

 a period of low temperature, this change is not 

 found, there is a strong presumption that the case 

 is not malarial. If the blood be taken at the 

 height of the fever, a negative result does not ex- 

 clude malaria, and a further examination should 

 be undertaken, if possible, during an apyretic 

 period. In some cases, the change can be detected 

 even during the pyretic periods, but in these it is 

 always more marked in the apyretic. In some 

 cases, during the course of the fever, no such 

 change occurs, but appears immediately the tem- 

 perature subsides, and diminishes as convalescence 

 proceeds. Perhaps the cases where this test is of 

 the greatest value, are those where the patient has 



