6 PROTOZOA. 



SARCODINA. 



AMCEBA PROTEUS. 



Amcebse 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 con- 

 tain amoebae, and determine the following points: 



1. With the high power observe the peculiar method of loco- 

 motion, 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 endo- 

 plasm. Observe in detail the formation of a pseudopodium. 

 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 inter- 

 vals; this is the contractile vacuole. Determine the length of 

 time between successive contractions. Are the intervals regu- 

 lar? When the vacuole contracts what becomes of the con- 

 tents? What is its function? 



4. Note the oval or rounded nucleus moving with the flowing 

 endoplasm. What is its structure? 



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

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

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

 ner in which food is ingested and the manner in which the undi- 

 gested matter is egested. 



Make a careful drawing of an Amceha. 



Amoebae of various kinds represent in many respects the 

 simplest type of protozoan, and are therefore placed in the first 

 class of these animals, the Sarcodina. The individuals of this 

 class all possess pseudopodia, but many are quite unlike those 

 of Amoeba. Look over the figures of various Rhizopoda. 



If time and material permit, study Amoeba verrucosa, Arcellaj 

 and Difflugia, and compare them with Amoeba proteus. Do you 



