76 Phylum Protozoa 



Two hundred to 250 cc. of this solution is put into a finger bowl or 

 glass crystallizing dish 8 or 10 cm. in diameter and to each of such dishes 

 is added 4 or 5 grains of polished rice (any brand carried at the corner 

 grocery is suitable) . The cultures thus prepared are immediately seeded 

 with 50 to 100 Amoebae, covered with glass plates to prevent evaporation 

 and entry of dust, and then left, preferably in a dark cool place, to 

 develop. Such cultures will produce a fine crop in from 2 to 4 weeks and 

 so far in some 30 to 40 cultures the writer has had only one or two 

 failures. Out of five cultures that were set up as a test, three cultures 

 one year old had ample numbers of Amoebae; the other two died out in 

 eleven months. 



These five cultures during their existence were deliberately neglected. 

 No detritus was removed. Rice was added only when it was discovered 

 that none was apparent in the culture. Water too was added to compen- 

 sate for evaporation with no attempt at regularity, say, on the average of 

 once a month. The temperature variation was from 19° to 2 8° C. 



In other words, the cultures were subjected to as careless handling as 

 if in the hands of a somewhat below par student assistant, but they sur- 

 vived. 



M. E. D. 

 References 

 For the culture of Amoeba proteus see also p. 59. 



THE CULTURE OF 

 AMOEBA PROTEUS LEIDY PARTIM SCHAEFFER 



D. L. Hopkins, Duke University and D. M. Pace, Johns Hopkins University 



THE Amoebae used in the development of the following culture 

 methods correspond to those designated by Schaeffer as Amoeba 

 proteus Pallas (Leidy) in 1916 and as Chaos diffluens Mueller in 1926. 

 We shall follow Mast and Johnson (1931) and retain the generic name, 

 Amoeba, but shall follow Schaeffer (19 16) in separating Amoeba proteus 

 (Leidy) into two species, Amoeba proteus Leidy partim Schaeffer and 

 Amoeba dubia Schaeffer. While our experience has been limited to 

 Amoeba proteus, it is probable that the culture methods described would 

 also be satisfactory for Amoeba dubia. 



Collection and culture. Amoeba proteus is not found in nature as 

 frequently as are smaller Amoebae. When found it will usually be in 

 ponds or pools where there is neither too great nor too little organic 

 material, where there are no excessively swift currents, and in water that? 

 is not too alkaline. If, with a spoon or dipper, surface water containing 

 a considerable amount of organic material is collected, taken to the 

 laboratory, poured into tall slender jars and allowed to settle it will be 



