PREPARATION OP MEDIA. 79 



XXV. Winogradshi's Silicate Jelly. 



1. To 100 ce. HCl (sp. gr. 1.10° Beame's) is added drop 

 by drop 100 cc. sodium silicate (sp. gr. 1.09) stirring con- 

 stantly with a glass rod. 



2. Place in collodion sacks and dialyze for 12 hours in 

 running water. 



3. The dialyzed silicate jelly is then poured out of the 

 collodion sacks into a beaker and boiled for a few miautes to 

 drive off the absorbed air. 



4. Cool down to 50° C. and the following boiled and 

 cooled solution is added: 



0.4 gm. (NHJjSOj. 

 0.05 gm. MgSO.. 

 0.1 gm. K2HPO.. 

 0.6 gm. Na^COa. 

 Trace CaClj. 

 These substances are dissolved in as little water as possible and 

 added to : 



100 gm. silicate jelly. 



5. Sterilize in the autoclave at 110° C. for 15 minutes. 



XXVI. "Modified Radicicola Solution." 

 1. To 1 liter (1,000 ec.) distilled water add the following: 



5 gms. saccharose. 

 2 gms. K^HPOj. 

 0.1 gm. MgSOi. 

 0.5 gm. NaCl. 



3. Boil until dissolved. 

 3. Sterilize in the autoclave as usual. 



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