APPENDIX 



HOW TO PREPARE CULTURES OF PROTOZOA 



Mixed cultures. Ordinary clear pond water may be used. Water 

 taken from an aquarium, in which plants have been growing, fre- 

 quently contain Protozoa. If tap water is to be used, let it stand in 

 open vessels for at least a week in order to let the chlorine or other 

 antiseptic gases escape. 



Cultivation of Paramecia. Prepare a hay infusion by cutting 

 timothy hay stems into short lengths. Fill a six-inch by eight-inch 

 sterilized battery jar one half to two thirds full of water and add a 

 small handful of the cut hay stems. Set the jar on a table in medium 

 light and do not cover. After a few days a scum will form on the 

 surface of the water. First bacteria and then Protozoa including 

 Paramecia, will appear. The Protozoa will feed on the bacteria. A 

 succession of forms will appear within a space of three to four weeks. 



Pure culture of Paramecia. Cut timothy hay stems into short 

 lengths. Boil these with plenty of distilled water until the water turns 

 brown. Three different concentrations of culture media should be 

 prepared. Sterilize all glassware by boiling. 



Solution 1 — Put two heaping tablespoonfuls of boiled hay in a 



large beaker containing two thirds of the undiluted hay water. 

 Solution 2 — Put one tablespoonful of boiled hay in a large beaker 



containing diluted hay water (half hay water, half boiled water, 



plain). 

 Solution 3 — Put a heaping teaspoonful of boiled hay in a large 



beaker containing two thirds of diluted hay water. 



Let the solutions ripen, exposed to the air for about a week. Then 

 inoculate with a pure culture of Paramecia.^ Check your solutions 

 carefully so that you will know which one gives the best results. 



Cultivation of amoeba. Water weed method. — Boil some fresh 

 water plants, Elodea or Ceratophyllum. Place a very few of these 



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