Reighard. — Senses and Learning in Fishes 165 



member what they have learned for as long as eighteen 

 days. Fish may also learn and remember in what direc- 

 tion to go to pass through an opening in a partition in 

 order to reach the nest (Goldsmith, 1914). They may 

 also learn and remember the shortest way through par- 

 titions with openings at different places. Churchill 

 (1916), placed two such partitions across an aquarium 

 so that it was divided into three compartments. Food 

 was placed in the compartment at one end and gold fish 

 in the compartment at the opposite end. The gold fish 

 at the first attempt sometimes required nearly two hours 

 to get through the openings in the two partitions and the 

 intervening compartment and reach the food. But as 

 they repeated the attempt to get through they succeeded 

 in shorter time until finally they learned to go from end 

 to end of the aquarium in three or four minutes. 



IV. SUMMARY. 



We see then that fish possess all the senses that men 

 have and one besides. The sense of touch they have of 

 course. The sense of smell, as in man, makes them aware 

 of some things good or bad in their neighborhood. If bad 

 they flee from it. If good they seek it and are directed 

 in the search by the sense of smell. When they come 

 into contact with the food, they may taste it with the 

 organs on the surface of the body. Then with the help 

 of touch they locate and seize it. 



Mass movements of the water — slow vibrations and 

 currents, they sense by means of their lateral-line organs 

 — structures not possessed by land vertebrates. Thus 

 probably they are aided in detecting approaching danger 

 or possibly in securing food. These same organs may 

 help them to detect currents in the water and to regulate 

 their movements with reference to them. They may also 

 aid the fish to detect unseen solid bodies before they swim 

 against them. 



More rapid vibrations of the water they sense with 

 their ears, as sounds. Owing to the great energy of 



