224 INTELLIGENCE IN LOWER VERTEBRATES 



red color with the irritation caused by the tentacles so that 

 the red came to be a "warning color." Subsequently un- 

 colored Atherinas were given them which were for the most 

 part instantly taken. Red Atherinas were offered after 

 an interval of eight days when they were very sparingly 

 taken and then refused entirely, and again after an interval 

 of twenty days when they remained entirely untouched. 



There are a number of instances of fishes coming to be fed 

 when a bell was rung or some other sound made, but it is 

 probable as Kreidl has shown in one instance that the fish 

 associated the food with the appearance of the person 

 making the sound rather than with the sound itself. 



The memory of topographical relations seems to be well 

 developed in certain fishes as in certain insects. It is mani- 

 fested most clearly in those forms which have a more or 

 less fixed habitation or which build a nest for their eggs. 

 A good illustration of this faculty is afforded by a species 

 of Goby studied by Mile. Goldsmith. This species, Gobius 

 minutus, is commonly found in tide pools under a shell of 

 some bivalve mollusc where it may lie half buried in the 

 sand. That the fish recognizes its shell by sight is shown 

 by the fact that when Mile. Goldsmith drove a specimen 

 from under its shell and placed the aquarium where it was 

 kept in the dark the fish did not succeed in finding its shell 

 during twenty-four hours: when light was admitted it dis- 

 covered the shell at once. The experiment was repeated 

 many times with different individuals, with the same result. 



The ability of Gobius to learn a certain path to its shell 

 is shown in the following experiment : A goby was placed in 

 an aquarium divided in the middle by a glass plate which 

 left a narrow passage way at one end. The shell of the 

 goby was placed in one compartment C and the fish was 

 driven through the passage way into the adjoining part of 



