Amoebidae 75 



A culture of Amoebae is then set up in bowls containing 600 cc. of 

 pond water. The bottom of each bowl is sprinkled with exceedingly 

 fine sand which has been carefully washed and sifted through bolting 

 cloth. The individual grains of sand should be scarcely larger, and for 

 the most part smaller, than a single Amoeba. To each bowl is added 6 

 grains of boiled wheat. (The development of the culture may be 

 hastened by using boiled brown rice in place of the wheat, although the 

 latter culture does not last so long.) Some ooze from the fish bowls is 

 now introduced and the culture kept at about 73 ° F. 



In order that the Amoebae may thrive, fungus must grow on the grains 

 of wheat. If this fails to appear, it may be obtained by adding a bit of 

 dead worm or dead fly from some other culture. 



Within twelve days there should be an abundance of the Amoebae. 

 Large numbers may be present as early as six or seven days, and usually 

 so in eight days. A culture lasts about a month, but new ones should 

 be started while the Amoebae are still active and healthy. Old cultures 

 should be made over completely. 



The fine sand in the culture is most helpful in picking the Amoebae 

 out of the bowl for microscopic study, since a little sand taken into a 

 pipette will have the organisms attached to it. The sand also forms an 

 excellent support for the coverslip, allowing the Amoebae to move about 

 freely. As part of the habitat of the culture the grains of sand afford a 

 cover under which the organisms can hide. In an undisturbed culture 

 the Amoebae will be found contracted and resting either under the grains 

 or close beside them. If disturbed by jarring or by a beam of light the 

 Amoebae glide or "walk" away from this protecting cover. 



References 

 For the culture of Amoeba see also pp. 62, 134, 136, and 177. 



STOCK CULTURES OF AMOEBA PROTEUS* 



IN the course of experiments it has been necessary to maintain cultures 

 of Amoeba proteus in stock. The writer endeavored to find a medium 

 that made requisite a minimum amount of attention. The effort in this 

 direction met with considerable success. In view of the wide use of 

 Amoeba of the proteus type in biological research and elementary in- 

 struction in biology, a culture medium that is simple, reproducible, and 

 extremely reliable will be of general interest. The medium used is as 

 follows: 



NaCl 0.1 gr. 



KC1 0.004 gr. 



CaClo °-°o6 gr. 



H2O 1000 cc. (glass distilled) 



♦Reprinted with slight changes from an article in Science 71:442, 1930, by H. W. 

 Chalkley, U. S. Public Health Service. 



