CHAPTER IV 
A Note ON THE PsycHoLocy or FisueEs! 
NumeErovs facts witness in a vague way to the ability of 
fishes to profit by experience and fit their behavior to situa- 
tions unprovided for by their innate nervous equipment. 
All the phenomena shown by fishes as a result of taming are, 
of course, of this sort. But such facts have not been exact 
enough to make clear the mental or nervous processes in- 
volved in such behavior, or simple enough to be available as 
demonstrations of such processes. It seemed desirable to 
obtain evidence which should demonstrate both the fact and 
the process of learning or intelligent activity in the case of 
fishes and demonstrate them so readily that any student 
could possess the evidence first hand. 
Through the kindness of the officials of the United States 
Fish Commission at Woods Holl, especially of the director, 
Dr. Bumpus, I was able to test the efficiency of some simple 
experiments directed toward this end. The common Fun- 
dulus was chosen as a convenient subject, and also because 
of the neurological interest attaching to the formation of 
intelligent habits by a vertebrate whose forebrain lacks a 
cortex. 
. The fishes studied were kept in an aquarium (about 4 feet 
long by 2 feet wide, with a water depth of about 9 inches) 
represented by Fig. 24. The space at one end, as repre- 
1 This chapter appeared originally in the American Naturalist, Vol. XX XIII, 
No. 396. 
169 
