62 Phylum Protozoa 



70 F. Place the culture near a window; diffused light is quite satis- 

 factory. From three to six weeks are needed for the development of the 

 culture. This time will depend on the density of the population desired. 

 Ordinary half-pint milk bottles make satisfactory containers, and ab- 

 sorbent cotton stoppers, which will admit air, may be used to keep out 

 dust and spores of other forms of life. Good results have been obtained 

 in culturing other species of Euglena in the same manner. 

 . A pure culture of Euglena may be obtained by selecting under the 

 microscope with a fine pipette [see p. 43] individual specimens of the 

 desired species. A clean culture is very valuable and, once it is obtained, 

 it may be perpetuated indefinitely if care is taken to prevent contamina- 

 tion. Obviously, only sterilized pipettes should be used in removing 

 specimens from the culture for class use. 



References 



For the culture of Euglena spp. see pp. 53, 63, and 71. 



For the culture of Euglena deses see p. 53- 



For the culture of Euglena anabaena see p. 53. 



A CULTURE MEDIUM FOR FREE-LIVING FLAGELLATES* 



THE following culture method, which has been tried out for two years, 

 may be of use to other laboratories. Whole wheat is weighed into 

 5 gm. lots, which are then put into large test tubes and 25 cc. of tap 

 water added. These are then plugged with cotton, capped with lead 

 foil, and autoclaved at 15 pounds' pressure for 2 hours, which very 

 thoroughly macerates the wheat. Tap water is again added up to 50 cc, 

 and desired percentages of this fluid are used after shaking. After open- 

 ing a tube it is necessary to sterilize again in an Arnold sterilizer, as 

 bacterial growth is vigorous in the mixture. However, a tube may be used 

 day after day, if sterilized daily. 



Various percentages of this mixture afford a very good medium for 

 many Protozoa. Bacterial feeders such as Chilodon, Paramecium, 

 Oicomonas, and others thrive on it. Ochromonas, Chilomonas, and several 

 of the smaller Euglenas (E. gracilis [see also pp. 53 and 82], E. quar- 

 tana, and E. mutabilis) have been grown in abundance in various dilu- 

 tions. There are several species of Amoeba which likewise occur or are 

 capable of being cultured in large numbers. It has proved best, how- 

 ever, for Entosiphon and Peranema. Both of these forms are easily 

 grown in quantities sufficient for classroom use; isolation cultures of the 

 former have been carried over a year on this medium. In general 

 it seems much better than cracked boiled wheat, which is often used. 



♦Reprinted from Science 65: 261, 1927, by James B. Lackey, U. S. Public Health 

 Service. 



