2406 Journal of Applied Microscopy 



Methods of Cultivating Amoeba and Other Protozoa for 



Class Use. 



One of the periodical problems with which every teacher of zoology is met is 

 that of having on hand at the proper time an abundant supply of Amaba for 

 class use. Certain methods by which various teachers have solved this and 

 similar problems have been published in this journal, and have been very wel- 

 come. A method differing from any of those yet given has been used with much 

 success by the writer for furnishing classes of eighty or more students at any 

 desired time with a plentiful supply of Amoeba, as well as of almost any other of 

 the common Protozoa. The method is as follows : Two weeks or so before the 

 specimens are desired, bring from a river or pond a large quantity of some of 

 the aquatic plants which grow everywhere. If possible, obtain Ceratophyllum, 

 though Elodea and various other plants will do (Potamogetons are not satisfac- 

 tory). Put this material into dishes, not too deep (circular "crystalizing dishes " 

 or " bacteria dishes," three inches deep and eight or nine inches in diameter, are 

 convenient). The dishes are to be crowded full of the plant material, which is 

 then covered with water and left to decay. The dishes may be covered by a glass 

 plate. To be certain of a large supply of Amcebas, a dozen or twenty such cul- 

 tures should be set in operation. After a certain stage in decay has been 

 reached, the layers of the plant at the surface of the water become covered with 

 a brown slime or scum. In this brown slime will be found, in some of the 

 dishes, many Amcebas. Not all the dishes contain the animals, but if a dozen 

 or more dishes have been provided, after two weeks or thereabouts, some of the 

 vessels will be found to contain unlimited numbers of Amoebas. For the last 

 three years the writer has supplied a class of eighty to a hundred in this way, 

 and has never known it to fail. Dozens of Amcebas will sometimes be found in 

 the field of view when a bit of this brown slime is examined. It is well to 

 remove a bit of the plant and scrape the slime from this ; in the slime on the 

 surface of the water fewer Amcebas will be found. The points to which special 

 attention should be paid, if certain results are to be obtained, are : (1) be certain 

 to provide a sufficient number of cultures ; (2) begin at least two weeks before- 

 hand; (3) it is well to add a few dishes of new material every four or five days 

 after the first was obtained, so that there will always be cultures in the proper 

 stage. In a given culture frequently the Amcebas last in quantity only two or 

 three days. 



The above method is, of course, rather a rough and ready one than an ele- 

 gant one, but this is its recommendation. It relieves one, at the cost merely of 

 a little industry, of all anxiety as to whether there will or will not be material on 

 hand when it is required. 



Arcella, Dififlugia, Chilomonas, Chlamydomonas, Euglena, Stentor, Parame- 

 cium, and many other rhizopods, flagellates and ciliates may be obtained in quan- 

 tity from the same cultures, so that the latter form a general source of supply, 

 €ven for very large classes, for most or all of the protozoan material needed in 

 any ordinary laboratory course. H. S. Jennings. 



University of Michigan. 



