LOCOMOTION 47 



I. Take a drop of the infusion, place it on a slide and cover with a cover 

 glass. The microorganisms called Paramecia should be present. 



A. Describe the cellular structure of a Paramecium. 



B. How does its movement differ from that of the amoeba ? 



C. What proof have you that the Paramecium is cylindrical and not flat ? 



D. Describe the shape of a Paramecium. The end that goes forward 

 most of the time is called the anterior end. The opposite end is the pos- 

 terior end. Describe the shape of the anterior and posterior ends. 



II. Put a few threads of cotton or some finely shredded lens paper on a 

 glass slide. Place on this a drop of the Paramecium culture and focus under 

 the low power. 



A . Describe the appearance of the threads of cotton under the microscope. 

 What effect do the threads of cotton seem to have on the movement of 

 the Paramecium ? 



B. Note the furrow in one side of the animal. This is called the groove. 

 At the base of the groove is a mouth, and the cylindrical structure below 

 is the gullet. 



C. Look closely at the plasma membrane. The structures that you 

 should observe there, are projections of protoplasm and are called cilia. 

 Describe any movements of the cilia. Suggest a function of the cilia. 



D. The groove and gullet are also lined with cilia. Suggest a function 

 for these cilia. 



E. At either end of the Paramecium you will see a small clear bubble. 

 Watch each bubble form, grow larger, and burst. These are the contractile 

 vacuoles. 



III. Stain the Paramecium with dilute iodine and mount under the low and 

 high power. What evidence of ectoplasm and endoplasm can be seen? De- 

 scribe a difference between these two kinds of protoplasm. 



IV. Take a new culture and add a small amount of blue fountain pen ink 

 to it, and again put a few threads of cotton on it. 



A. Focus under the high power. Observe the long hairlike structures 

 that are thrown out. These are protective structures of offense and defense 

 called trichocysts. 



B. Observe the two nuclei. The larger nucleus is called the macro- 

 nucleus (makros large) and the smaller, the micronucleus (mikros 

 small). It may be necessary to stain the specimen with iodine to see these. 



C. Draw a Paramecium three inches long and label all the structures 

 observed. 



D. Write a brief description of the Paramecium. 



