38 LABORATORY DIRECTIONS 



3. STRUCTURES AND FUNCTIONS. The body layers. Study 

 under high power. The outer clear layer is the ectoplasm. Struc- 

 ture? What part does it play in the movements of the animal? 

 The inner granular mass is the endoplasm. Structure? Move- 

 ment? Within the endoplasm distinguish food vacuoles, which 

 are usually dark in color and may be of any shape or size, and 

 the small 'water vacuoles which appear grey or colorless and are 

 always perfectly spherical in form. 



The blunt processes which are thrust out from time to time 

 and retracted are pseudopodia (false feet). How are they 

 formed? Do any of them branch? About how many can you 

 count at any given time? Are they confined to any particular 

 part of the body? Mention two functions which they perform. 

 Describe in detail the method of locomotion in the Amoeba, tell- 

 ing what part the ectoplasm and the endoplasm each plays. Is 

 there any coordination in movements ? Notes required. 



Make six outline sketches of your specimen at intervals of 

 approximately twenty seconds to show the changes of form. In- 

 dicate with arrows in each drawing the direction of movement 

 of the granules in each pseudopodium. Each drawing should be 

 at least 40 mm. in diameter. 



Note differences in number and in arrangement of pseudo- 

 podia in an Amoeba that is floating free in the water and in one 

 that is creeping upon the surface of the slide or coverglass. 



Watch an Amoeba feeding and describe the process of tak- 

 ing food. Watch and describe any changes in particles of food 

 which have been engulfed. Where does digestion take place? 

 What becomes of the food particles? Notes required. 



CONTRACTILE VACUOLES. Find one or more. They are cir- 

 cular in outline and disappear from time to time. Note and de- 

 scribe carefully the method of disappearance and reappearance. 

 Has the contractile vacuole any color? Any definite position in 

 the body? In which body layer? Source of its contents? Nature 

 of its contents? What becomes of the contents when a vacuole 

 disappears? Notes required. 



