H1STOLOGICAL STUDIES 41 



ually increases. Other tests may be made by running so- 

 lutions of various salts, etc., under the slide. 



D. Feeding Habits. Examine the contents of some of the 

 vacuoles and state your conclusions as to the form of food 

 taken in by the protoplasm. Note and describe the method 

 of ingulfing these food particles and the forming of the 

 vacuole. Compare several of these vacuoles as to the con- 

 dition of their contents. From these observations, what do 

 you conclude happens to food in the amoeba? 



(The process of taking in food is called ingestion. The 

 process of dissolving ingested food is called digestion. The 

 process of transforming digested food into protoplasm is 

 called assimilation. This last process is evidenced by the 

 decreasing size of the vacuole after the food is dissolved.) 



E. The Removal of Wastes. Study the action of the large 

 contractile vacuole. What does it appear to contain when 

 expanded? Where does this substance come from? Where 

 does it go when the vacuole is contracted? Does the 

 vacuole pulsate regularly? 



(The process of collecting the broken-down waste of the 

 body and its removal to the outside is called excretion. 

 The processes described in D, by means of which pro- 

 toplasm is made, are spoken of collectively as anabolism. 

 The processes by means of which old protoplasm is broken 

 down and removed are spoken of collectively as katabolism. 

 Metabolism is the simultaneous occurrence of these two ac- 

 tions in a living body of protoplasm.) 



F. Place several amoebae in a drop of water in a vial and 

 cork the vial tightly. The water used should be rich in 

 food bacteria. Also, for comparison, make a balance prep- 

 aration consisting of the same number of amoebae mounted 

 in the same amount of water in a watch glass, this prepara- 



