484 MALARIAL FEVER. 



birds and reptiles, parasites of somewhat similar character 

 to those in malaria, though of distinct species, occur in the 

 blood of these animals. 



Methods of Examination. The parasites may be 

 studied by examining the blood in the fresh condition, or 

 by permanent preparations. In the former case, a slide 

 and cover-glass having been thoroughly cleaned, a small 

 drop of blood from the finger or lobe of the ear is caught 

 by the cover-glass, and allowed to spread out between it 

 and the slide. It ought to be of such a size that only a 

 thin layer is formed. A ring of vaseline is placed round 

 the edge of the cover-glass to prevent evaporation. For 

 satisfactory examination an immersion lens is to be pre- 

 ferred. The amoeboid movements are visible at the 

 ordinary room temperature, though they are more active on 

 a warm stage. With an Abbe condenser a small aperture 

 of the diaphragm should be used. 



Permanent preparations are best made by means of 

 dried films. A small drop of blood is allowed to spread 

 itself out between two cover -glasses, which are separated 

 by sliding the one on the other. The films are then 

 allowed to dry. A very good method is that of Manson, 

 who catches the drop of blood on a piece of gutta-percha 

 tissue, and then makes a film on a clean slide by drawing 

 the blood over the surface. The dried films are then 

 fixed by heating for half an hour at 115 to 120 C., or by 

 placing them in a mixture of equal parts of alcohol and 

 ether for the same time, or by placing them in a saturated 

 solution of corrosive sublimate for five minutes. In the 

 last method they should be washed well in water before 

 staining. They may be stained by a saturated watery 

 solution of methylene-blue for five minutes, or by Ehrlich- 

 Biondi fluid for half an hour. A double stain may be 

 obtained by staining first with a i per cent watery solution 

 of eosin for five minutes, then washing well in water, and 

 thereafter staining for two to three minutes with a saturated 

 watery solution of methylene-blue ; the red corpuscles are 

 red, the parasites and nuclei of leucocytes are coloured 



