128 SOIL BACTERIOLOGY 



(5) Meissner's Solution: 



Metallic iodin 7 gm. 



Potassium iodid 20 gm. 



Water.. . 100 c.c. 



(6) Aniline Oil Gentian-violet: 



Saturated alcoholic solution of gentian-violet 10 c.c. 



Aniline oil in water 30 c.c. 



Note. Prepare aniline water by shaking 2 c.c. of aniline oil with 100 c.c. 

 of water and filter until clear. 



Directions for the Use of Stains 



1. Take a clean cover-glass or a slide, flame, and add a 

 loopful of sterile water. 



2. With a platinum needle remove a small quantity of 

 the bacterial colony. Do not take too much growth on 

 the needle. Mix this thoroughly with the water and spread 

 over the cover-glass. If the cover-glass is not clean, the 

 water will collect in small drops. 



3. Allow to dry by passing back and forth high above the 

 flame, and finally pass rapidly two or three times through 

 the flame. This should fix the bacteria to the cover-glass 

 and precipitate albuminous substances. 



4. Flood the cover-glass with stain and let stand for 

 ten to thirty seconds. In order to secure a deeper stain, 

 warm gently. 



5. Wash in water until the mount is clear. 



6. For a temporary mount, invert the wet cover-glass 

 on a slide, blot with filter-paper, and examine under micro- 

 scope. For a permanent mount, dry the cover-glass above 

 the flame and mount in Canada balsam or euparal. 



