IRON PEPTONE SOLUTION 185 



3. Filter through papier Chardin. 



4. Tube, and sterilise as for nutrient gelatine. 



Sugar Agar. 



1. Prepare nutrient agar (vide page 167, sections i to 8). 

 Measure out 1000 c.c. 



2. Weigh out glucose, 20 grammes ( = 2 per cent.), and dissolve 

 in the clear agar. 



3. Tube, and sterilise as for nutrient agar. 



NOTE. Other "sugar" media are prepared by substituting a 

 corresponding percentage of lactose, maltose (or any other of the 

 substances referred to under "Sugar Media," page 177) for the 

 glucose. 



Iron Bouillon. 



1. Measure out nutrient bouillon, 1000 c.c. (vide page 141, 

 sections i to 6). 



2. Weigh out ferric tartrate, i gramme ( = 0.1 per cent.), and 

 dissolve it in the bouillon. 



3. Tube, and sterilise as for bouillon. 



NOTE. The lactate of iron may be substituted for the tartrate. 



Lead Bouillon. 



1. Measure out nutrient bouillon, 1000 c.c. (vide page 163, 

 sections i to 6). 



2. Weigh out lead acetate, i gramme ( = 0.1 per cent.), and 

 dissolve it in the bouillon. 



3. Tube, and sterilise as for bouillon. 



Nitrate Bouillon. 



1. Measure out nutrient bouillon, 1000 c.c. (vide page 163, 

 sections i to 6). 



2. Weigh out potassium nitrate, 5 grammes ( = 0.5 per cent.), 

 and dissolve it in the bouillon. 



3. Tube, and sterilise as for bouillon. 



NOTE. The nitrate of sodium or ammonium may be sub- 

 stituted for that of potassium, or the salt may be added in the 

 proportion of from o . i to i per cent, to meet special requirements. 



Iron Peptone Solution (Pakes). 



1. Weigh out peptone, 30 grammes, and emulsify it with 200 

 c.c. tap water, previously heated to about 60 C. 



2. Wash the emulsion into a litre flask with 800 c.c. tap water. 



3. Weigh out salt, 5 grammes, and sodium phosphate, 3 

 grammes, and dissolve in the mixture in the flask. 



4. Heat the mixture in the steamer at 100 C. for thirty minutes, 



