22 PROTOZOA 



SARCODINA 



AMOEBA PROTEUS 



Amoebae are usually just discernible under the low power 

 of the microscope as irregular, semi-transparent, granular 

 bodies. Find a specimen in the material provided, which is 

 known to contain amoebae, and determine the following 

 points : 



1. With the high power observe the peculiar method of 

 locomotion, the constant but slow change in the shape of the 

 body by means of projections, pseudopodia, or "false feet." 



Make sketches at intervals of one or two minutes to show 

 the changes in the form of the body. 



2. Observe the peripheral zone of hyaline protoplasm, the 

 ectoplasm, and compare this with the inner protoplasm, the 

 endoplasm. Observe in detail the formation of a pseudo- 

 podium. Does the endoplasm extend into the pseudopodium? 

 Can you explain how the movement is caused? 



3. Find a clear space which appears and disappears at in- 

 tervals; this is the contractile vacuole. Determine the length 

 of time between successive contractions. Are the intervals 

 regular? When the vacuole contracts what becomes of the 

 contents? What is its function? 



4. Note the nucleus. In order to determine the actual 

 shape of this structure observe it carefully as it is moved 

 through the endoplasm. The nucleus of Amoeba proteus may 

 appear at one time with a circular outline and in another 

 view may seem much flattened or even somewhat biconcave. 



5. Food materials in process of digestion are readily seen. 

 Of what do they consist? They are contained in food vacu- 

 oles. By careful watching, it is often possible to observe the 

 manner in which food is ingested and the manner in which 

 the undigested matter is egested. 



6. Observe the crystals within the endoplasm. What is 

 their shape? Is more than one type present? 



7. Determine whether the surface of the amoeba shows 

 ectoplasmic ridges. 



