182 MANTON COPELAND 
the following tests were made: A wooden box open at the top, 
nearly one hundred and seventy centimeters long and about 
twelve centimeters wide, was lined with glass, and placed in a 
horizontal position on a table. A rubber tube for conducting 
sea water was inserted in one end of the box near the bottom. 
The water flowed the length of the box and out an opening at 
the opposite end. The current was moderately strong, and care 
was taken to keep it as uniform as possible throughout the 
experiment. 
A snail whose reactions were to be studied was placed in a 
position near the middle of the box, and all its movements with 
or against the current recorded until it passed a line seventy-five 
centimeters, either down or upstream, from the starting point. 
Each animal was first tested four times in the current without 
food. Two, which moved against the current to the seventy- 
five centimeter line in all their trials, were discarded, as the 
experiment necessitated the selection of individuals which 
showed at least some tendency to move in the direction of the 
current. Five animals were finally selected which answered the 
requirements. After determining their responses to the current 
alone, they were tested again with two fish (Fundulus) placed 
near the head of the stream above the seventy-five centimeter 
line. The fish were constantly bathed by the water after it 
left the tube, but were so situated on the right and left margins 
of the stream as not to interfere with the force of the current. 
They were cut open, and were turned over or moved from time 
to time during the tests in order to disperse the Juices more 
freely. In trial one, throughout the experiment, the snail 
was placed heading across the current, so that its initial impact 
was on the animal’s left side. It was started in the opposite 
direction in trial two; in trial three it was headed down stream 
and in trial four, upstream. ‘The position of the snail at the 
beginning of the test, however, seemed in no way to affect its 
later activity and the final result. A single snail was given but 
one trial a day, and all were kept in good physiological condition 
by occasional feeding. 
Table 1 shows the result of the experiment. 
