Parameciidae 121 



The basic part of the medium is the usual hay infusion of 10 grams of 

 chopped timothy hay boiled for 15 minutes in a liter of well water. This 

 infusion is filtered and sterilized in the Arnold sterilizer at ioo° C. one 

 hour a day for 3 days. It is diluted with 9 volumes of sterile well water 

 just before using. Two portions of this infusion are placed in sterile 

 liter flasks with sterile cotton stoppers. One liter is inoculated with 

 Bacillus subtilus and the second with B. coli communis. A third portion 

 of the medium is made up as follows: Approximately 30 grains of wheat 

 are boiled in a small amount of water for 10 minutes. The wheat grains 

 only are then placed in a third liter flask of sterile well water. The three 

 portions are incubated at 37 C. for 24 hours, and then combined in 

 one large sterile flask. The medium is now ready for use. The culture 

 may be used in almost any size of container, but that used has been the 

 300 cc. Erlenmeyer flask. These flasks are fitted with cotton stoppers 

 and sterilized. Each flask is filled about % full of the medium, and 

 different species are transferred to the cultures with sterile pipettes. 



The original basic infusion may be made up, sterilized, and stored in a 

 refrigerator until ready for use. Likewise, the medium, made of the three 

 portions, may be stored in a refrigerator for later use. 



Sterile precautions are maintained throughout the procedure, but after 

 Paramecium has been transplanted, such strict precautions are no longer 

 necessary. The essential part of the process is to provide a medium 

 rich with a suitable food in which Paramecium will continue to grow 

 normally. With these sterile precautions, other ciliates and flagellates 

 are eliminated. A single organism placed in such a medium will produce 

 a flourishing culture in 7 to 10 days. One should transplant every 2 to 

 3 weeks. Paramecium multimicronucleatum, P. bursaria, and P. aurelia 

 have thrived in this medium. 



M. E. D. 



Reference 



For the culture of Paramecium see also pp. 62, 63, 72, 134, 136, and 177. 



CULTIVATION OF PARAMECIUM AURELIA AND 

 P. MULTIMICRONUCLEATUM 



T. M. Sonneborn, Johns Hopkins University 



OF THE many media tried, the most successful is an infusion of 

 1.5 gms. of desiccated (but not burned), powdered lettuce boiled 

 for 3 minutes in a liter of double distilled water. This infusion is filtered 

 while hot, dispensed into pyrex test tubes or flasks, containing an excess 

 of pure CaC03 (which adjusts the pH to about 7.2 ), plugged with cotton, 

 and autoclaved. When ready for use, it is filtered to eliminate the 

 CaCOs and is inoculated with the bacterium, Flavobactcrium brunneum, 



