812 



CULTURE MEDIA FOE CULTIVATION OF MICROORGANISMS 



(7) Prepare small paper molds about 

 3.0 cm. high and 8 or 9 cm. in diam- 

 eter. Place these molds on glass 

 and pour (6) into them. When they 

 have solidified level off the upper 

 surface and remove the paper from 

 the discs. 



(8) Place the small discs in Petri dishes 

 and add (4) to the Petri dish until 

 the discs are nearly 2/3 immersed. 

 Place the smooth side up and inocu- 

 lations are made upon it. 



(9) For the preparation of tubes mix 

 only 40.0 g. of gypsum with the 

 MgCOa and MgNH4P04 instead of 

 300.0 g. as in (5). 



(10) Continue as above only pour the 

 mixture on glass and when it has 

 nearly solidified cut into strips. 



(11) Place the strips in test tubes, add 

 the solution as above. 



Sterilization; Sterilize for 30 minutes at 

 120°C. 



Use: Cultivation of nitrite formers. The 

 author reported that nitrite formers 

 showed increased growth in presence of 

 small amount of leaf or soil infusion. 



Reference: Makrinoff (1909 p. 419). 



2484. Makrinoff's Soil Infusion Gypsum 

 Block 



Same as medium 2483 but treat 16.0 to 

 25.0% dry soil rich in humus in the same 

 manner as the leaves, and use instead of 

 the leaves. 



2485. Omelianski and Makrinoff's Soil 

 Infusion Gypsum Block (Ldhnis) 

 Constituents : 



J- J^^,*" 1000.0 cc. 



?-?°^^ 250.0g. 



3. Gypsum gQQ q 



^■MgCOs 3.0g 



5. MgNH.PO, 30^" 



6-FeSO. o:4g" 



^•K.HPO. 0.5^ 



8-MgSO. o.3g 



9-NaCl 05 J; 



Preparation : 



(1) Mix 300.0 g. gypsum, 3.0 g. MgCOj 

 and 3.0 g. MgNH4P04 carefully. 



(2) Prepare a soil infusion from 250.0 g. 

 of soil rich in humus and a liter of 

 tap water. Do not filter. 



(3) Moisten (1) with (2) and stir the 

 whole into a pasty mass. 



(4) Spread (3) on a glass plate in a layer 

 about 0.5 to 0.75 cm. thick. 



(5) Cut suitable slices to go into Petri 

 dishes, using a glass dish, or into 

 strips to be placed in tubes using a 

 knife. 



(6) Dissolve 6, 7, 8 and 9 in a liter of dis- 

 tilled water. 



(7) Moisten the sterile discs or strips of 

 (5) from the bottom with sterile (6). 



Sterilization: Sterilize (5) in the hot air 



oven. Sterilize (6) method not given. 

 Use: Cultivation of nitrate bacteria. 

 Reference: Lohnis (1913 p. 110). 



