!34 Phylum Protozoa 



Miscellaneous Classes and Microbiology 



A NOVEL METHOD OF OBTAINING PROTOZOA 



W. H. Davis, Massachusetts State College 



FOR years, when I taught zoology, I placed small, green grass culms 

 (in April) in covered jars with wet cotton in the bottom. These 

 remained in an upright position against the glass surface. When Amoeba, 

 Arcella, Stentor, Paramecium, Vorticella, etc., were desired, I scraped 

 dead plant tissue from the surface of the stems or mashed the rotten 

 leaves and incubated 24 hours in a 1% aqueous solution of citric acid. 



For the region where this method was developed it did not fail for five 

 consecutive years to produce the desired results. 



PERMANENT CULTURES* 



Very frequently instructors are required to keep protozoan cultures 

 over long periods of time. The following method has been used with 

 great success for such cultures as Paramecia, the smaller forms of 

 Amoeba, and certain forms of flagellates. 



A large number of hay infusions are started in ordinary drinking- 

 water tumblers, using pond water from different localities. They are 

 then placed in various positions about the room and examined from time 

 to time until the proper culture has been found. When a desired culture 

 is found it should be fed five or six scrapings of dried whole wheat bread. 

 These scrapings are made by taking a scalpel and scraping a crust of 

 bread, care being taken to feed only what the culture will utilize. The 

 glasses are then covered and the process repeated every two weeks or 

 so. Whole wheat bread is far superior to ordinary wheat bread. 



Using the above method I have kept ordinary classroom cultures alive 

 for a period of a year. It is also excellent for maintaining such cultures 

 as rotifers and small crustaceans. 



FOOD ORGANISMS FOR MARINE AND HALOBIONT 



ANIMALS 



R. M. Bond, Santa Barbara School, Carpinteria, California 



Dunaliella salina is a large green, yellow, or orange flagellate of world- 

 wide distribution in natural and artificial brines of various compositions. 

 It is most easily obtained from salt-works recovering salt from seawater 

 by solar evaporation. It may sometimes be raised from crude sea-salt, 

 and I once recovered it from seawater from Monterey Bay. 



Pure cultures, free of all other organisms, may be grown in any of the 



* Reprinted from Science 64:362, 1926, by Frederick Bauer, Rhode Island State 

 College. 



