170 



Animal Intelligence 



sented by the lines in the figure, was shaded from the sun by 

 a cover, and all food was dropped in at this end. Along each 



side of the aquarium were 

 fastened simple pairs of 

 cleats, allowing the ex- 

 perimenter to put across 

 it partitions of wood, 

 glass or wire screening. 



B O 



FIG. 24. 



n_J 



One of these in position 

 is shown in the figure by 

 the dotted line. These partitions were made each with an 

 opening, as shown in Fig. 25. If now we cause the fish to 

 leave his shady corner and swim up to 

 the sunny end by putting a slide (with- 

 out any opening) in behind him at D ] 

 and moving it gently from D to A and 

 then place, say slide 7, across the 

 aquarium at i, we shall have a chance 

 to observe the animal's behavior to 

 good purpose. 



This fish dislikes the sunlight and 

 tries to get back to D. He reacts to 

 the situation in which he finds himself 

 by swimming against the screen, bumping against it here 

 and there along the bottom. He may stop and remain 

 still for a while. He will occasionally rise up toward the 

 top of the water, especially while swimming up and down 

 the length of the screen. When he happens to rise up to the 

 top at the right-hand end, he has a clear path in front of him 

 and swims to D and feels more comfortable. 



If, after he has enjoyed the shade fifteen minutes or more, 

 you again confine him in A , and keep on doing so six or eight 

 times a day for a day or so, you will find that he swims 



iLn 



