CULTURE MEDIA FOR CULTIVATION OF MICROORGANISMS 



phate solution so that the am- 

 monium sulphate is present in 

 1.0%. Then add the sterile soda 

 solution in 2 to 4.0% strength. 



(11) Mix well, may be inoculated if 

 desired, and pour into sterile 

 Petri dishes. 



(12) Place over night in the incubator 

 to solidify. 



(b) Fremlin prepared a medium as 

 follows: 



(1) Add an equal amount of HCl, 

 solution, sp. gr. 1.1 to a pure 

 silicate of soda of a strength be- 

 tween 3.3 to 4.0%. (Add the acid 

 to the silicate.) 



(2) Dialyze 4 days in running tap 

 water. 



(3) Continue to dialyze all the chlo- 

 rides from the mixture by dialyz- 

 ing in distilled water. 



(4) Pour the dialyzed mixture into a 

 narrow necked flask and evaporate 

 to about I its volume. 



(5) Dissolve 0.4 g. (NH4)2S04, 0.05 g. 

 MgS04, 0.1 g. Potassium phos- 

 phate, trace of CaCU and 0.0 to 

 0.9 g. NaaCOa in 100.0 cc. dis- 

 tilled water. 



(7) Add to each dish about ^ the 

 quantity of (5) as there is silicate 

 solution. 



(8) Evaporate the whole slowly over 

 hot water until silicate coagulates. 



(9) Sterilization not specified. 



(c) Smith gave the following method of 

 preparation : 



(1) Dissolve 4.0 g. (NH4)2S04, 0.5 g. 

 MgS04, 1.0 g. potassium phos- 

 phate, 6.0 to 9.0 g. NaoCOg and 

 a trace of CaCh in the least 

 possible amount of water. 



(2) Add (1) to the dialyzed silicate 

 jelly. 



(d) Johnson prepared the medium as 

 follows: 



(1) Dissolve 0.4 g. (NH4)2S04, 0.5 g. 

 MgS04, 0.1 g. K2HPO4, trace of 

 CaCl2 and 0.75 g. Na2C03 in 

 100.0 cc. water. 



(2) Sterilize (method not given). 



(3) Pour a solution of commercial 

 "waterglass" in dilute HCl. 



(4) Dialize in a sausage parchment 

 tube to get rid of the HCl. 



(5) Sterilize the pure silicic acid solu- 

 tion (method not given). 



(6) Evaporate (5) until a jelly is 

 formed on mixing with (2). 



(Amount of (2) not given.) 

 (e) Abbott gave the following method 

 of preparation: 



(1) Prepare a 3.0 to 4.0% solution of 

 silicic acid in distilled water 

 (method not given.) 



(2) Dissolve 0.4 g. (NH4)2S04, 0.05 g. 

 MgS04, trace of CaClo in 50.0 cc. 

 of distilled water. 



(3) Sterilize (2) method not given. 



(4) Dissolve 0.1 g. potassium phos- 

 phate and 0.6 to 0.9 g. Na2C03 in 

 50.0 cc. distilled water. 



(5) Sterilize (4) method not given. 



(6) Mix (3) and (5) when cool. 



(7) Add (6) to (1), little by little, until 

 the proper degree of consistency is 

 obtained. This is best accom- 

 plished in a culture dish. If one 

 desires to have isolated colonies, it 

 is necessary to add the inoculum 

 to the silicic acid before the addi- 

 tion of the salts. 



(f) Winogradsky (Harvey) prepared the 

 medium in the following manner: 



(1) Prepare No. 1 solution: Ammo- 

 nium sulphate 0.4; magnesium 

 sulphate 0.05; calcium chloride 

 0.01; distilled water 50. 



(2) Prepare No. 2 solution: Potassium 

 phosphate 0.1; sodium carbonate 

 0.6; distilled water 50. 



(3) Prepare No. 3 solution: Silicic 

 acid 3.4; distilled water 100. 



(4) Mix No. 1 and No. 2 solutions in 

 equal quantities. 



Note: The sterile nutrient mix- 

 ture of Nos. 1 and 2 solutions may 

 first be inoculated and then added 

 with sterile precautions to sterile 

 silicic acid (No. 3 solution) in a 

 Petri dish. Rotate to mix and 

 solidify. 



(5) Add by degrees this mixture to 

 No. 3 solution with constant stir- 

 ring until solidification occurs. 



(6) Distribute the solidified medium 

 in plates. 



