82 Phylum Protozoa 



In 1929, the author found a few amoebas of this species in an old hay 

 infusion culture of mixed Protozoa. A clone culture was successfully 

 established and maintained with good results by using Euglena gracilis 

 as the source of food. The amoebas have been cultured by this method 

 for a period of over four years. 



Distilled water, well water, and a synthetic well water were used in the 

 preparation of culture media. Natural well water proved to be the 

 most satisfactory. The source of this water was a well on the campus of 

 Ohio State University. The synthetic well water was more satisfactory 

 than distilled water ; however, fair results were obtained with the latter. 



Solutions of aminoids* were used in the cultivation of Euglena gracilis. 

 A solution of 0.04% aminoids was very satisfactory and had no ap- 

 preciable effect upon the amoebas introduced into such cultures. 



Pyrex Erlenmeyer flasks were used exclusively. The best results were 

 obtained by using 125 cc. flasks with 75 cc. of culture medium. The 

 medium was first made up in a liter flask ; then the proper amount was 

 poured into each of the smaller flasks. The flasks were then loosely 

 stoppered with sterile cotton and placed on a hot plate. When the con- 

 tents just came to a boil, the flasks were removed and allowed to cool. 

 Immediately thereafter, the medium was inoculated with Euglena. This 

 procedure was very effective in eliminating contamination of the cultures 

 by other Protozoa. 



Although it was found that the amoebas could be introduced into the 

 cultures with the euglenas, the number of amoebas produced in such 

 cultures was never as great as it was when the euglenas were given a good 

 start beforehand. Satisfactory results were also obtained when amoebas 

 were introduced into Euglena cultures in which the euglenas were passive 

 and many were enveloped in gelatinous sheaths. 



A few cultures were maintained for a long period of time by the 

 addition of euglenas previously concentrated with a centrifuge. Food 

 was added only when that of a culture had become scarce. These addi- 

 tions compensated for the loss of water from a culture due to evaporation. 

 One culture has been maintained by this method since the spring of 1929. 



Another satisfactory method consisted of adding aminoids to an 

 amoeba culture when the euglenas contained in it had become scarce. 

 An amount of aminoids sufficient to make a 0.04% solution was roughly 

 estimated and added to the culture. An addition of a very large amount 

 of aminoids was always followed by a rapid increase in the number of 

 bacteria in the culture, and finally, the death of the amoebas. 



No attempt was made to control the hydrogen-ion concentration in 



* Either beef or milk aminoids, commercial products of the Arlington Chemical Co 

 Yonkers, N. Y. 



