16 THE BIOLOGY OF THE CELL 



How does it take place? How often is sucii 

 a vacuole formed when the animal is feeding 

 quietly ? "What changes take place in a food- 

 vacuole during its passage around the body? 

 How is the refuse matter passed out of the 

 body? "What causes the changes noticed in 

 the particles of food in the body ? The slipper 

 animalcule may be fed with particles of indigo 

 or of carmine in the same manner as described 

 for Amceha. 



0. Nervous Properties. 



1. Automaticity. — "What determines the motions 



which the animal makes, the food which it se- 

 lects, the times for resting or moving, etc., etc. ? 

 Does it appear to perform actions " of its own 

 accord"? Is it possible to predict what the 

 animal's behavior is to be at any given mo- 

 ment? In what part of the body does this 

 property seem to reside ? 



2. Irritability. — Does the animal appear to feel ob- 



jects with which it comes in contact ? Does it 

 respond in any way, as by movements of va- 

 rious kinds, to external stimuli ? 



3. Co-ordination. — Do the cilia move rhythmically, 



or does each move independently of aU the 

 others? "What regulates their motions? Do 

 their motions seem to be made for &nj piirjMse ? 



4. Special Senses. — Do any of your observations 



lead you to think that the slipper animal has 

 the sense of touch ? Does it exercise selection 

 in the choice of its food — i. e., has it the sense 

 of taste ? Place a shallow dish — e. g., a saucer 

 — painted black inside and then coated with 



