114 THE BIOLOGY OF THE ANIMAL 



G. Nervous Projperties. 



a. Touch. — Does the starfish seem to feel objects 

 with which it comes in contact as it moves 

 about? Touch one of the feet with a pencil 

 point or a bristle. Is the foot sensitive ? In like 

 manner touch one of the aboral tentacles. "What 

 happens? "With a hand-lens find a large pedi- 

 cellaria and touch the end of it with a fine 

 bristle. What does the pedicellaria do ? Do you 

 find any organs which appear to be specialized 

 as organs of touch? If so, where are they and 

 from what have they been modified? 



5. Sight. — Put a number of vigorous starfishes into 

 a tank of sea-water and allow them to disperse 

 at will. ISTote their positions, then cover the 

 tank with thick cloth to exclude the light, leav- 

 ing only a small aperture, two or three inches 

 in diameter, at one end for a small amount of 

 light to enter. After a time, fifteen minutes to 

 several hours, look into the tank to see if the 

 animals have changed their positions ? Are they 

 attracted b^^- the light ? How do you tell ? From 

 several starfishes carefully remove the eyes, no- 

 ticing particularly the behavior of the surround- 

 ing spines, and put the animals into a tank pre- 

 pared as above. Do they now pay any attention 

 to the light ? Have you any reasons for thinking 

 that these animals can perceive small objects ? 



c. Hearing, taste, and smell. — Do any of your ob- 

 servations lead you to suppose that the starfish 

 possesses these powers ? 



d. Co-ordination.— Exsimine a moving starfish and 



