granular mass, the endoplasm, containing food vacuoles, etc. (d) 

 A contractile vacuole is present just below the disk. Note its shape, 

 (e) The nucleus, an elongated cylindrical body. Is it in the ecto- 

 plasm or endoplasm? (f ) The oesophagus or gullet, a ciliated tube 

 leading down from the vestibule, (g) Anus, an opening into the 

 side of the vestibule, to be seen only at the moment of egestion of 

 food remnants. 



B. PHYSIOLOGY. 



I. MOVEMENT. 



a. General movements. Study the manner in which the stalk 

 contracts? What part of the stalk causes the contraction? What 

 change takes place in the body during contraction ? Note the rapid- 

 ity of the movements. How does the animal assume the expanded 

 condition? What causes it? What part is the first to assume the 

 expanded state? Compare the rate of contraction with that of 

 expansion. Note that the body sometimes separates from the stalk. 

 How does the body move after separation? 



b. Ciliary movements. Add powdered Chinese ink to the water 

 and observe the direction of the currents produced and the method 

 of feeding. What is the significance of the animal's scientific name? 

 How many kinds of cilia does Yorticella have? To how many 

 uses are they put? How does it differ from Paramecium in this 

 respect ? 



II. REPRODUCTION. 



i. Fission. Look for animals undergoing fission. Where does 

 the division begin? By the aid of stains study the nuclear phenom- 

 ena of division. 2. Conjugation. Individuals may sometimes be 

 seen undergoing conjugation. Study the process and compare with 

 the conjugation of Paramecium. 



Make drawings of all you have observed. 



III. STYLONYCHIA MYTILUS. 



(A Ciliate Protozoon). 



In the same sort of material in which Paramecium is found look 

 for a broad, flattened infusorian, which moves swiftly about. This 

 is Stylonychia. Compare its size with that of Paramecium. 



Notice two sorts of motion : a rapid swimming as in Paramecium, 

 and a crawling by means of the large ventral cilia. 



STRUCTURE. Note the ectosarc and endosarc, the former contain- 



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