MICROSCOPIC STUDY AND STAINING 119 



LOEFFLER'S METHOD. 12 The preparation is dried in the air and fixed by 

 heat. It is then treated with the following' mordant solution: 



Twenty per cent aqueous tannic acid 10 parts. 



Ferrous sulphate aq. sol. saturated at room temperature. . . 5 parts. 

 Saturated alcoholic fuchsin solution 1 part. 



This solution which should be freshly filtered before using, is poured over 

 the cover-glass and allowed to remain there for one-half to one minute, 

 during which time it should be gently heated, but not allowed to boil. 



Wash thoroughly in water. 



Stain with five per cent anilin water fuchsin or anilin water gentian-violet 

 made slightly alkaline by the addition of one-tenth per cent sodium hydrate. 



The stain should be filtered directly upon the cover-slip. Warm gently 

 and leave on for one to two minutes. Wash in water. Mount in balsam. 



VAN ERMENGEM'S METHOD. IS This method requires the preparation of 

 three solutions. 



(1) Twenty per cent tannic acid solution 60 c.c. 



Two per cent osmic acid solution 30 c.c. 



Glacial acetic acid 4-5 drops 



The cover-slip carrying the fixed preparation is placed in this solution 

 for one hour at room temperature, or for five minutes at 100 C. (boiling). 

 Wash in water. 

 Wash in absolute alcohol. 

 Immerse the cover-slip for one to three seconds in 



(2) Silver nitrate, 0.25-0.5 per cent solution. 

 Without washing, transfer to 



(3) Gallic acid 5 gin. 



Tannic acid 3 " 



Fused potassium acetate 10 lt 



Distilled water 350 c.c. 



Immerse in this for a few minutes, moving the cover-slip about. 



Return to the silver nitrate solution until the preparation turns black. 



Wash thoroughly in water. 



Blot and mount. 



SMITH'S MODIFICATION OF PITFIELD'S METHOD. 14 A saturated solution 

 of bichlorid of mercury is boiled and is poured while still hot into a bottle 

 in which crystals of ammonia alum have been placed in quantity more than 



12 Loeffler, Cent, f . Bakt., I, vi, 1889. 



18 Van Ermengem, Cent. f. Bakt., I, xv, 1894. 



14 Smith, Brit. Med. Jour., I, 1901 r p. 205. 



