INTELLIGENCE IN LOWER VERTEBRATES 225 
the aquarium. In its endeavors to reach its nest the goby 
swam against the glass partition ten times and then found 
the passage. It was then driven from its shell into the 
adjoining compartment again. It now rammed its head 
against the partition six times, then found the passage and 
entered its shell. In the next trial the fish made only three 
or four attempts to go through the glass plate, and after 
this it found the passage way at once. In a short time the 
fish had learned the way to its nest and thereafter followed 
it with little hesitation. 
After this set of trials the goby, now left to itself, began 
to explore the aquarium of its own initiative, by making 
excursions farther and farther from the nest, keeping close 
to the outer wall and returning each time by the same route 
by which it set out. When it arrived at the partition it 
bumped against it, but after two or three trials it stopped 
a little short of the barrier and continued to do so in its 
subsequent excursions. 
After the habit of avoiding the glass plate had become 
well established the plate was removed. The goby never- 
theless continued to follow the old path in its journeys to 
and from the nest. Even when the fish had happened two 
or three times to cross the place where the partition had 
been, it still persisted in taking the old round-about course 
from one part of the aquarium to the other. Finally after 
the fish had crossed directly several times the old habit 
became gradually broken up and the fish paid no attention 
to the place where the partition had been located. In one 
interesting experiment Mlle. Goldsmith filled the shell of a 
goby with mastic and placed it in its old position. The 
goby came to its shell and endeavored to get under it, trying 
first its accustomed point of entrance, and then making 
attempts to dig under it in various other places. It dug 
15 
