8 Laboratory Guide in Zoology 



XIII. — Draw a Paramecium, sho'ving the structure as 

 you have observed it. Make the sketch at least two 

 inches long. 



THE VORTICELLA, OR BELL ANIMALCULE 



The Vorticella is usually attached by one end to some 

 stationary object. Its movements thus being confined to 

 a narrow range, it is comparatively easy to study under 

 high powers of the microscope. 



I. — Notice the two principal divisions — body and stalk. 



Compare the animal with a bell, and see at what part 

 of the bell the stalk is attached : this part is called the 

 proximal end. Tap the cover glass gently, and notice 

 the sudden contraction of the stalk into a spiral and 

 the change in the shape of the body. Watch the 

 creature as the stalk straightens out and the body 

 resumes its previous shape. 



II. — Focus carefully on the stalk to determine its structure. 

 Can you see a slender band — the axial fibre — ^on the 

 inside of the cylindrical outer portion } 



III. — Study the outer or distal end of- the body. Watch 

 the ring of cilia immedia^tely within the enlarged edge 

 of the bell — called the peristome — within and partly 

 attached to which is a ilattened disk. Between the 

 edge of the disk and the peristome on one side, is the 

 mouth, which leads into the gullet. The latter is lined 

 with cilia, and leads directly to the inner protoplasm 

 of the body. Add a little powdered carmine to the 

 slide, and see if you can observe the taking in of the 

 food. 



IV. — A contractile vacuole may be seen in the body near 

 the gullet. Watch its action. Distinguish also, if you 



