30 GENERAL BACTERIOLOGY 



Anilin water is prepared by adding 2-3 cc. of anilin oil, drop by drop, to 

 50 ec. of water, thoroughly shaking and then filtering through moistened 

 paper until perfectly clear. 



This stain should stand 24 hours and then be filtered. It does not keep 

 well and must not be used when more than 14 days old. 



6. Gram's Iodine solution. 



Iodine 1 gm. 



Potassium iodide 2 gm. 



Distilled water 300 cc. 



7. Gabbett's Methylen blue solution. 



Methylen blue (dry) 2 gms. 



Sulphuric acid 25 cc. 



Distilled water 75 cc. 



8. Alcohol, 96%. 



REFERENCES. A. 163 ; H. 85 ; M. & R. 97 ; P. 200. 



SPECIAL DIRECTIONS. Prepare the 

 solutions of dyes from the saturated 

 alcoholic solutions (furnished) and 

 place them in 2 oz. bottles arranged 

 with pipettes and neatly labeled. The 

 bottles are conveniently kept in a 

 block. Fig. 10. 



EXERCISE 18. SIMPLE COVER-GLASS 



PREPARATION FIG. 10. Block for stain bottles. 



GENERAL DIRECTIONS. Bacteria may be studied under the micro- 

 scope in a living condition in a hanging drop preparation (21) ; 

 but on account of their hyaline character, which makes the exami- 

 nation difficult, the student should first learn to stain them and 

 later make the hanging drop preparation. With a few exceptions 

 all bacteria can be stained by the following process : A small drop 

 (about the size of a pinhead) of distilled water is placed on a clean 

 cover-glass by means of the platinum loop. With a sterile needle a 

 portion of the material to be examined is secured and while the 

 cover-glass is held in the fingers of the left hand the bacteria on the 

 needle are introduced into the water, thoroughly mixed and then 

 spread in a thin film over as much of the surface of the cover-glass 

 as possible. When the bacteria are taken from fluid media a drop 

 of water will not be necessary. In this case use a loop. The film 

 is now allowed to dry. If the drop is sufficiently small this will be 

 a short process. It may be hastened by holding the cover-glass high 



