l62 CLINICAL BACTERIOLOGY AND HEMATOLOGY 



MALARIA 



The blood in a suspected case of malaria may be examined 

 fresh or in stained films. Of these methods the former is the 

 better, and should be used if possible. An examination of stained 

 specimens should also be made, and is convenient, as it can be 

 performed away from the patient and at leisure. 



Fresh films are made by touching a drop of blood on the 

 patient's finger with the centre of a perfectly clean cover-glass, so 

 as to remove an extremely small quantity of blood. This cover- 

 glass is then allowed to fall on to a clean slide, so that the droplet 

 of blood may be spread out by capillary attraction and by the 

 weight of the cover-glass, just as is the case in the method of 

 making blood-films, to be described subsequently. But the slide 

 is not separated from the cover-glass ; they are examined just as 



Fig. 30. — Malarial Parasites in the Blood. 

 The dark area shows the parasite as it appears when stained with thionin. 



they are, a ring of vaseline being painted round the edge of the 

 cover-glass to prevent evaporation. 



The specimen is examined with a |-inch objective, and a place 

 found in which the corpuscles are spread in a single layer ; this 

 part is then searched thoroughly with a j^-inch oil-immersion 

 lens. The parasites are seen as pale, irregularly shaped bodies 

 with indistinct margins, which occupy the interior of the red 

 corpuscles, and show amcehoid movements of greater or less rapidity. 

 When the parasites are older they occupy a larger space in the 

 corpuscles, and there are granules of dark pigment around their 

 periphery. These granules are often the first indications of the 

 presence of parasites in the examination of an unstained specimen. 

 At a still later stage the granules will be found in the centre of 

 the corpuscle (the haemoglobin of which is now almost entirely 

 removed), and the parasite will show segmentation into a larger 



