PROBLEM 112 133 



a. Reaction to Stimuli 



Observations. — Do the moving structures appear to have any 

 definite shapes? Do they move with any definite end forward ? 

 Do they collect in any locality ? If so, what influences them to do 

 this ? Heat a needle and introduce at one side of the cover glass. 

 Any movement on the part of the paramcecia ? Notice some of 

 the animals grouped around masses of food. Why do you suppose 

 the paramcecia are there? Notice other paramcecia with refer- 

 ence to the position of air bubbles or to threads of spirogyra. How 

 do they lie with reference to the air bubble? What might the 

 animal get from the air bubble if it is to do work? How would 

 a cell covered with a membrane take anything from an air bubble ? 

 What might it give in exchange? 



NOTE. — All things that influence a plant or animal to react are called stimuli. 



Conclusion. — 1. Write a paragraph explaining how a para- 

 mcecium reacts to the stimuli in its environment. 

 2. Make drawings to illustrate your conclusions. 



b. Movement 



Observations. — Look at the chart or at the prepared material 

 for tiny projections from the body walls of the paramcecium. 

 These structures, which are flexible threads of Uving matter, are 

 called cilia. 



Conclusion. — ■ How might locomotion be accomplished by 

 means of cilia? Explain with the aid of a diagram. 



c. Internal Structure 



Observations. — To study the internal structure of paramcecia 

 use living animals which have been fed on green microscopic 

 plants or on carmine grains. Examine with high power and also 

 use charts. The small round spaces filled with green plant mate- 

 rial or with red carmine grains are food vacuoles. Look for a groove 

 on one side of the cell ; this leads into a funnel-like opening, the 

 gullet (g). (See page 134.) Explain how food might be taken in 

 by a paramcecium. How might it circulate within the body? 



