PEEPABATION OF MEDIA. tt 



XX. "Hugar-ash" Solution For Radicicola. 



1. To 1 liter (1,000 cc.) of distilled water, add 15 gms. 

 of wood-ashes (beech, elm, maple). 



2. Heat in steam, boil one minute and filter through 

 moistened filter paper. 



3. To the filtrate add 10 gms. Maltose and stir until dis- 

 solved. 



4. Sterilize in the autoclave at 10 lbs. pressure for 20 

 minutes. 



XXI. "Sugar-ash" Agar. 



1. Make a paste of 20 gms. of powdered agar in cold 

 water and add to 1,000 cc. of "sugar-ash" solution. 



2. Boil until dissolved. 



3. Filter through absorbent cotton. 



i. Sterilize in the autoclave at 10 lbs. pressure for 20 

 minutes. 



XXII. Omelianshi's Magnesia Gypsum Blocks For Culti- 

 vating the Nitrifying Organisms. 



1. One per cent, carbonate of magnesia is uniformly 

 mixed with gypsum and water is added with constant stir- 

 ring until the mass assumes the consistency of sour cream. 



2. Pour out on plate glass and spread out. 



3. As soon as the mass becomes of a doughy consistency, 

 and is ready to harden, circular pieces for Petri dishes, or 

 strips for test tubes, are cut out. 



4. When the gypsum plate has become hard, it is pried 

 loose from the glass and placed bottom up in the Petri 

 dishes. 



