IQO SPECIAL MEDIA 



Media for the Study of Phosphorescent and Photogenic Bacteria. 



Fish Bouillon. ' 



1. Weigh out herring, mackerel, or cod, 500 grammes, and 

 place in a large porcelain beaker (or enamelled iron pot) . 



2. Weigh out sodium chloride, 26.5 grammes; potassium 

 chloride, 0.75 gramme; magnesium- chloride, 3.25 grammes; and 

 dissolve in 500 c.c. distilled water. Add the solution to the 

 fish in the beaker. 



3 . Place the beaker in a water-bath and proceed as in preparing 

 meat extract i. e., heat gently at 40 C. for twenty minutes, 

 then rapidly raise the temperature to, and maintain at, the 

 boiling-point for ten minutes. 



4. Strain the mixture through butter muslin into a clean flask. 



5. Weigh out peptone, 5 grammes, and emulsify with about 

 200 c.c. of the hot fish water; incorporate thoroughly with the 

 remainder of the fish water in the flask. 



6. Heat in the steamer at 100 C. for twenty minutes to 

 complete the solution of the peptone. 



7. Filter through Swedish filter paper. 



8. When the fish bouillon is cold, if it is to be used as fluid 

 medium, make up to 1000 c.c. by the addition of distilled water. 

 If, however, it is to be used as the basis for agar or gelatine media 

 store it in the "Double Strength" condition. 



9. Tube and sterilise as for nutrient bouillon. 



As an alternative method "Marvis" fish food (16 grammes) 

 may be substituted for the 500 grammes of fresh fish. 



Fish Gelatine. 



1. Measure out double strength fish bouillon, 500 c.c., into a 

 "tared" 2-litre flask. 



2. Add sheet gelatine, 100 grammes, cut into small pieces. 



3 . Bubble live steam through the mixture for fifteen minutes to 

 dissolve the gelatine. 



4. Weigh the flask and its contents; adjust the weight to the 

 calculated figure for one litre of medium (1135.5 grammes) by the 

 addition of distilled water at 100 C. (vide page 166). 



5. Cool to below 60 C., and clarify with egg. 



6. Filter through papier Chardin. 



7. Tube, and sterilise as for nutrient gelatine. 



Shake well after the final sterilisation, to aerate the medium. 



Fish Gelatine -Agar. 



1. Weigh out powdered agar, 5 grammes, and emulsify it with 

 200 c.c. double strength fish bouillon. 



2. Wash the emulsion into a "tared" 2-litre flask with 300 c.C. 

 fish bouillon. 



