46 LABORATORY MANUAL OF MICROBIOLOGY 



Medium 109 



Preserving Stock Cultures in Meat Infusion, Peptone, Gelatin 



Phosphate Agar^ 



Medium 110 

 Preservation of Stock Cultures in Vacuo^ 



111 



Preserving Plate Cultures 



Washed agar 20 . gm. 



Glycerol (C3H5(OH)3) 500.0 cc. 



Distilled water 500 . cc. 



Dissolve the agar in the water by heating in a steamer, add the 

 glycerol, and filter through glass wool. 



FAVORABLE CONDITIONS FOR THE DEVELOPMENT OF 

 ANAEROBIC BACTERIA 



Living Vegetable Tissue 



To an ordinary desiccator or a museum jar with tightly fitting 

 cover add finely chopped raw potato, carrots, lettuce or similar 

 vegetable tissue. If potato is used, about 50 grams per liter of 

 air will be found satisfactory. Now add the tubes or plate 

 cultures of bacteria and seal the jar. The respiring plant tissue 

 rapidly absorbs the free oxygen and gives off CO2 thus bringing 

 about favorable conditions for the growth of anaerobic bacteria. 



Sterile milk plus a small amount of methylene blue may be 

 used as an indicator for anaerobiosis. 



Pyrogallic Acid for Absorbing Oxygen 



For every 100 cubic centimeters of air space take 1 gram of 

 pyrogallic acid and 10 cubic centimeters of a 10 per cent solution 

 of sodium or potassium hydroxide. 



Note. — To prepare an anaerobic jar, cover the bottom of 

 the jar with 3^-inch layer of pyrogalUc acid. Fit the 

 cover tightly to the jar with vaseline and remove the air with a 

 suction pump, and when there is a good vacuum, run in 75 to 100 

 cubic centimeters alkali solution. 



1 Ayres, S. H.. and W. T. Johnson, J. BacL, 9: 112, 1924. 



2 Brown, J. H., Science, 64: 429, 1926. 



