16 ELEMENTARY BACTERIOLOGY LABORATORY EXERCISES 
EXERCISE 24 
FLAGELLA STAIN: CASARES-GIL’S METHOD 
A number of methods have been described for staining flagella. While none 
of these methods has been entirely satisfactory, the method of Casares-Gil as 
modified by Mrs. Barber is probably as reliable as any. 
(1) Mordant: 
Tannic acid 10 grams 
Aluminum chloride (hydrated) : 18 grams 
Zinc chloride 10 grams 
Rosanilin hydrochloride 1.5 grams 
Alcohol (60%) 40 c.c. 
The solids are dissolved in the alcohol by trituration in a mortar, adding 
10 c.c. of the alcohol first, and then the rest slowly. This alcoholic solution may 
be kept several years. For use, dilute with two parts of water, filter off precipi- 
tate and collect filtrate on the slide allowing it to act for 60 seconds. 
(2) Stain: Carbol-fuchsin. 
