648 A MANUAL OF BACTERIOLOGY 



as due to malarial infection plus quinine. It may be that under 

 particular conditions, of the nature of which we are at present 

 ignorant, hsemolysins may be set free and cause haemolysis, the 

 blood -pigment being eliminated by the kidneys. 



Clinical Examination 



The blood of malarial patients may be examined either in the 

 unstained or stained condition. 



Examination in the unstained condition. The finger or lobe of 

 the ear is pricked, and a droplet of blood taken up on a clean 

 cover-glass, which is then placed upon a slide, so that the droplet 

 of blood spreads out into a thin layer between the two glasses. 

 The cover-glass may then be ringed with oil or vaseline to prevent 

 evaporation. A little practice is required to judge the right 

 quantity of blood. The preparation should be examined with a 

 fsj-in. oil-immersion lens. 



Examination in the stained condition. To prepare stained films 

 of the malaria or other blood parasites, e.g. trypanosomes, the 

 finger or ear is pricked and a droplet of blood, the size of a pin's 

 head or so, is deposited towards one end of a perfectly clean slide. 

 The end of a second slide (the spreader) is then applied to the 

 drop of blood and, holding the spreader at an angle of 45, it is 

 pushed along the surface of the first slide so that a thin film of 

 the blood is left behind, and the process is repeated for as many 

 films as are required. A little practice is required to gauge the 

 right quantity of blood. Other methods of preparing blood - 

 films are to deposit a droplet of blood on a cover-glass ; another 

 cover-glass is applied, and the two are separated so that each is 

 smeared with a thin film of blood, or a droplet of blood on a slide 

 may be spread with a cigarette paper, or with the shaft of a 

 needle. Whatever method is adopted, the film is allowed to dry 

 in the air, and may then be fixed (not if Leishman's stain is used). 

 In order to fix, the smears should be immersed in a mixture of 

 equal parts of absolute alcohol and ether for not less than ten 

 minutes, preferably for half an hour ; this gives excellent results. 

 In hot countries a saturated solution of corrosive sublimate may 

 be used. The methods detailed at p. 113 may also be employed. 



Staining is usually carried out with Leishman's stain (No. 12, 

 p. 117). The blood films, unfixed, are flooded with a few drops 



