54 MEDIA AND THEIR PREPARATION 
no change. If this is then kept covered with a layer of petrolatum, it 
may be kept for three weeks at room temperature. 
Endo’s Medium (After Levine, 1918). Levine states the method 
of preparation as follows: 
Distilled water............... pee ee cee eee 1000 c.e. 
Peptone (Difco)........0. 0.0.0. ce ee eee ee 10 gms. 
Dipotassium phosphate................2005 2-5 gms. 
FN 15-30 gms. 
These ingredients should be boiled until dissolved and the loss by 
evaporation made up with distilled water. No adjustment of the 
reaction is necessary; neither is filtration necessary if the medium 
is to be used for streaked cultures. Store in quantities of 100 ¢c.c. in 
Erlenmeyer flasks and when used add the following materials: 
20 per cent lactose solution......... 1 gm. or 5.0 c.c. 
10 per cent alcoholic solution of basic fuchsin. 0.5 c.c. 
Freshly prepared sodium sulphite solution.... 2.5 c.c. 
Eosin Brilliant-Green Agar (Teague and Clurman, 1916). This 
medium was devised for the rapid isolation of B. typhi from stools 
and was prepared by these workers after the following method: 500 
gms. of chopped beef are placed in 1 liter of distilled water and kept in 
the icebox over night. The infusion is squeezed through cheese cloth, 
heated in the Arnold sterilizer and passed through filter paper. Witte’s 
peptone (1 per cent), chemically pure sodium chloride (0.5 per cent) 
and agar (1.5 per cent) are added to the warm infusion, the peptone 
being rubbed into a paste in a little warm water. Then heat the 
flask of medium in the autoclave for thirty minutes at 120° C. Adjust 
the reaction to 1+ by adding 2N sodium hydroxide, cool to 55° C., 
clear and filter through cotton. Put into flasks in 100 c.c. quantities 
and sterilize at 120° C. for twenty minutes. 
When ready to use, melt the agar and add 1 per cent each of 
sucrose and lactose. To every 50 c.c. of agar add 1 c.c. of a 3 per cent 
solution of yellowish eosin. From the stock solution of brilliant green 
in 50 per cent alcohol, a % per cent solution is prepared in distilled water 
and 1 ¢.c. of this is added to each 50 c.c. of the agar. After the dyes 
are well distributed, pour into plates. 
Eosin~Methylene Blue Agar (Levine, 1918). This is a modification 
of Harris and Teague’s medium and was found by Levine to allow 
