2 HANDBOOK OF INVERTEBRATE ZOOLOGY. 



sun; fill them with fresh water, and allow them to stand 

 undisturbed for two or three days, in order to allow the 

 amoebae to creep out of the ooze and accumulate at its 

 surface. 



If a permanent supply of amcebre is desired, each dish 

 may be converted into a small aquarium by the addition 

 of a few floating water-plants, such as "duck-weed," and 

 v, hen covered with a pane of glass, to exclude dust and 

 prevent excessive evaporation, may be kept in good order 

 for several months by simply replacing with fresh water 

 the loss by evaporation. 



In a day or two a thin brownish-yellow film will usually 

 be visible over the whole or parts of the surface of the 

 ooze ; and portions of this film, almost entirely made up 

 of microscopic organisms which have crept to the sur- 

 face, may now be examined for amu-ba 1 , in the following 

 manner : 



Compress between the fingers the upper bulb of a 

 medicine-dropper, a glass tube drawn out to a point at 

 one end, and furnished with a rubber air-chamber at the 

 other, and then pass the pointed end of the tube into 

 the water close to the surface of the yellow film, and re- 

 lax the pressure on the bulb. The water will rush into 

 the tube and carry a little of the film with it. 



Take the tube out of the water ; hold the tip over the 

 centre of a clean glass slide, and, gently compressing the 

 bulb, force a drop or two of the water out of the tube on 

 to the slide. 



Cut a strip of writing-paper about a quarter of an inch 

 wide, and, moistening one end of it with water, cut off 

 about a quarter of an inch from the moistened end and 

 lay it upon the slide close to, but not so as to touch, 

 the drop. 



