Amoebidae 81 



pidium [see pp. 63 and 108] and Chilomonas [see pp. 59 and 63] to 

 the medium. Allow this to stand for two or three days before using. 

 The Amoebae multiply rapidly on this medium so that the bottom of 

 the culture dish is soon covered with them. 



These cultures should be examined weekly. Amoeba proteus and A. 

 dubia have been observed to injest 50 to 100 Chilomonas within 24 

 hours. This results in the rapid disappearance of the food organisms 

 from the culture. If the food organisms become few in number pipette 

 off half of the culture medium and add an equal amount of fresh pro- 

 tozoan hay infusion. At the same time add 2 grains of uncooked rice, 

 boiled wheat, or 4 one-inch lengths of boiled timothy hay stalks per 

 50 cc. of culture medium. 



The Amoebae in such cultures divide rapidly up to 13 divisions per ten 

 day period as judged from organisms kept in isolation. The cultures 

 may be run successfully for as long as six months. They may be kept 

 at room temperature even during the summer months though it is best 

 to use refrigeration if the temperature reaches oo° F. or higher. 



Subcultures are made by pipetting half of the material on the bottom 

 of the old culture into a new dish and adding an equal amount of pro- 

 tozoan hay infusion and food material. 



This culture method may be varied somewhat, but the following facts 

 should be kept well in mind. Large numbers of bacteria in a culture 

 tend to cause the death of the Amoebae ; therefore other Protozoa should 

 be present in the medium. The use of large amounts of organic ma- 

 terial such as boiled rice, wheat, or cracked wheat should be avoided. 

 These ferment very readily, causing the death of most of the Amoebae. 

 The depression period observed by many investigators is due to this 

 cause. If the protozoan hay infusion with a small amount of food is 

 used about 90% of the cultures will be successful. This compares with 

 only 50% of bacterial cultures in the author's experience. In the former 

 case there is no depression period, in the latter a depression period of a 

 month is not unusual. 



CULTIVATION OF MAYORELLA (AMOEBA) BIGEMMA 

 ON EUGLENA GRACILIS 



John C. Lotze, Ohio State University 



THE food of Mayorella bi gemma is listed by Schaeffer (1918) in his 

 original description as "flagellates, ciliates, diatoms, rhizopods, 

 nematodes, vegetal tissue, etc." Botsford (1922) reported the culturing 

 of Mayorella bigemma in solutions of beef extract. Taylor (1929) 

 stated that Mayorella bigemma may easily be cultivated under the same 

 conditions as Amoeba proteus. 



