4 PROTOZOA. 



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 contents? 

 Do you know its supposed 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 Amoeba. 



Amoebse 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 Anmba verrucosa, Arcella, 

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

 understand how the shells of the last two genera are made, and 

 of what service they are? Wliy are not shells good for all forms? 



Drawings of these forms are desirable. 



FORAMINIFERA. 



With very few exceptions Foraminifera are marine and pro- 

 vided with shells. Empty shells from deep-sea dredgings or from 



