186 AIDS TO BACTERIOLOGY 



Examination of Fresh Blood. A droplet of blood (p. 46) 

 is touched with the centre of a cover-glass, which is im- 

 mediately placed on a flip. If cover-glass and slide are 

 clean the blood runs out in a delicate film. The slide is 

 examined with T Vinch immersion lens, in a not too bright 

 light, and the interior of every corpuscle is searched for 

 specks of black pigment, surrounded by a pale, hyaline, 

 slightly or markedly amoeboid, substance; also for smaller, 

 pale, unpigmented, hyaline, and more actively amoeboid 

 bodies in the same situation. 



Stained Blood Preparations. A film is made (p. 46), 

 allowed to dry spontaneously, fixed by immersion in a 

 mixture of equal parts of absolute alcohol and ether, and 

 stained with Lomer's methylene blue. 



Leishmaris stain (0-15 per cent, in the purest methyl 

 alcohol) is used for staining the malarial parasite. Blood- 

 films, unfixed, are flooded with a few drops of the stain, 

 which is spread by tilting, no attempt being made to 

 check evaporation. After half a minute about double 

 the quantity of distilled water is added, allowed to mix 

 with the stain on the film, and staining is continued for five, 

 or in some cases for ten, minutes. The film is then washed 

 in distilled water, some of the water allowed to remain on 

 the film for one minute, and it is then dried and mounted. 



Jenner's blood-stain may be used. After the film has 

 dried spontaneously, without fixing it is placed in a pot 

 of the stain for five minutes. The film is washed in dis- 

 tilled water (already coloured with a drop or two of stain) 

 till pink. 



Haematoxylin and eosin is also a good stain, and very 

 permanent. 



The Coccidia. 



The coccidia are sporozoa possessing thick cuticles. 

 While some species produce fatal disease in sheep, game 

 birds, and poultry, human infections are rare. The liver 

 and intestines are sites for their activity, and the parasite 

 occurs in large numbers in the droppings. 



Coccidium oviforme infects the epithelium of the 

 intestines and bile-ducts in young rabbits with fatal 

 results. In the liver it occurs as a large (30 fj, to 40 JLL) 

 oval, encapsuled organism in yellowish nodules, consisting 

 of an adenornatous proliferation of the biliary epithelium. 



