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 thisend. 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. 
I One of these in position 
ee 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- L 
out any opening) in behind him at D | 
and moving it gently from D to A and 
then place, say slide J, across the 
aquarium at 1, 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 See al 
the situation in which he finds himself aaa 
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 
> 
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a 
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