48 PRELIMINARY STUDIES. 



and Paramcecia. With a pipette transfer to a microscope 

 slide repeated portions of the sediment from the vessel 

 until good specimens of Amoeba are found, using the high 

 power, or with a camel's hair brush remove the Amoebae 

 from the surface of some of the larger pieces of de'bris 

 taken from the vessel. A little care must be exercised at 

 first in searching for them, or they will be overlooked. 

 They are so colorless and transparent, like little masses 

 of clear jelly, that only careful watching will enable the 

 beginner to make them out at first. After they have once 

 been recognized, there will be no trouble. 



FIG. 24. Amoebae. The clear spot in each is a contractile vacuole. Each 

 contains particles of food in process of digestion ; a is in the act of surround- 

 ing a food mass. 



1. Observe a difference between the central portion of 

 the organism and the portion around the edges. The 

 latter is very clear and transparent ; it is known as the 

 ectosarc. The central portion has a granular appearance ; 

 it is called the endosarc. 



2. Watch the motions of different specimens. Observe 

 that projections of the ectosarc, pseudopods, are thrown 

 out ; after a time portions of the endosarc flow into these, 

 and a movement of the whole organism is caused. 



3. Search for food particles in the endosarc. These 

 are easily distinguished from the protoplasm of the endo- 

 sarc. Watch Arncebse that are in active motion until 



