ELEMENTARY BACTERIOLOGY LABORATORY EXERCISES 9 
EXERCISE 9 
GENTIAN VIOLET STAIN 
Using a solution of gentian violet make stained preparations from the same 
materials as used in Exericsé 8. Make drawings. 
Procedure 
Use the same procedure as in Exercise 8, except step (4). In step (4) allow 
the stain to act about ten seconds. 
Formula 
Gentian violet, saturated alcoholic solution 10 cc. 
Ammonium oxalate, 1.0% aqueous solution 40 c.c. 
EXERCISE 10 
CARBOL-FUCHSIN STAIN 
Make stained preparations from the same materials as used in Exercises 
8 and 9, using a solution of carbol-fuchsin. Make drawings. 
Procedure 
Use the same method as followed in Exercises 8 and 9, except steps (3) 
and (4). 
In step (3) moisten the film with water, then apply an equal amount of the 
staining solution. 
In step (4) allow the stain to act five to fifteen seconds. 
As carbol-fuchsin is even a more powerful stain than gentian violet diff- 
culty may be experienced from overstaining, especially in preparations which 
contain large amounts of organic matter and foreign debris. 
Formula 
Basic fuchsin, saturated alcoholic solution 3 cc. 
Phenol, 5.0% aqueous solution ; 19 ce. 
EXERCISE 11 
PREPARATION OF PERMANENT SLIDES 
_ Make stained preparations and mount in Canada balsam on a slide, as 
demonstrated. 
