_Media for the Study of the Chemical Composition of Bacteria._ ~Asparagin Medium (Uschinsky).~-- 1. Weigh out and mix Asparagin 3.4 grammes Ammonium lactate 10.0 grammes Sodium chloride 5.0 grammes Magnesium sulphate 0.2 gramme Calcium chloride 0.1 gramme Acid potassium phosphate (KH_{2}PO_{4}) 1.0 gramme 2. Dissolve the mixture in distilled water 1000 c.c. 3. Add glycerine, 40 c.c. 4. Tube, and sterilise as for nutrient bouillon. ~Asparagin Medium (Frankel and Voges).~-- 1. Weigh out and mix Asparagin 4 grammes Sodium phosphate, (Na_{2}HPO_{4}) 12OH 2 grammes Ammonium lactate 6 grammes Sodium chloride 5 grammes and dissolve in Distilled water 1000 c.c. 2. Tube, and sterilise as for nutrient bouillon. NOTE.--Either of the above asparagin media, after the addition of 10 per cent. gelatine or 1.5 per cent. agar, may be advantageously employed in the solid condition. ~Proteid Free Broth (Uschinsky).~-- 1. Weigh out and mix Calcium chloride 0.1 gramme Magnesium sulphate 0.2 gramme Acid potassium phosphate (KH_{2}PO_{4}) 2.0 grammes Potassium aspartate 3.0 grammes Sodium chloride 5.0 grammes Ammonium lactate 6.0 grammes 2. Dissolve the mixture in distilled water 1000 c.c. 3. Add glycerine 30 c.c. 4. Tube and sterilise as for nutrient broth. _Media for the Study of Biochemical Reaction._ ~Inosite-free Media--Bouillon (Durham).~-- 1. Prepare meat extract, 1000 c.c. (_vide_ page 148), from bullock's heart which has been "hung" for a couple of days. 2. Prepare nutrient bouillon (+10), 1000 c.c. (_vide_, page 161), from the meat extract, and store in 1-litre flask. 3. Inoculate the bouillon from a pure cultivation of the B. lactis aerogenes, and incubate at 37° C. for forty-eight hours. 4. Heat in the steamer at 100° C. for twenty minutes to destroy the bacilli and some of their products. 5. Estimate the reaction of the medium and if necessary restore to +10. 6. Inoculate the bouillon from a pure cultivation of the B. coli communis and incubate at 37° C. for forty-eight hours. 7. Heat in the steamer at 100° C. for twenty minutes.