324 G. H. PARKER 
middle of the pen thus constructed turtles were liberated one at a 
time and with their heads pointed in sequence north, east, south, 
and west. The water and the late afternoon sun were both to 
the west and the turtles almost' Without an exception took that 
course. 
To ascertain whether the sun or the water was the effective 
element in the situation, I carried the paper-board and about a 
dozen turtles across the narrow key on which the town of Miami 
Beach is situated to the opposite shore. Here the water was to 
the east while the sun of course remained in the west. On re- 
setting the pen on the beach and liberating the turtles as before 
at its center, they were found to go as regularly to the east, i.e., 
toward the water, as they had previously gone to the west. It 
was therefore plain that the sun had no significant influence over 
their movements, but that these were related to the body of 
water. 
On my return from the ocean on the east side of the key to the 
bay on the west side I stopped in a field about midway between 
the two bodies of water, and having set up the pen here with its 
floor horizontal, I proceeded to a third set of tests. I was greatly 
interested to see that under these circumstances the turtles were 
not disposed to move much from the center of the board and that 
when they did move they were as likely to go in one direction as 
in another. During these tests the sun was still high in the 
western sky and the results showed again that this source of light 
was not a significant factor in determining the direction of motion. 
Not only did these observations demonstrate that the sun was 
ineffective, but they showed also that the water, at least at the 
distance of about a quarter of a mile, was also ineffective, for the 
turtles went as often to the north or the south as they did to the 
east or the west. Had they been under the influence of the water, 
they should have turned even in this intermediate position to the 
east or the west, but not to the north or the south. Apparently 
the middle of the key was a region in which the turtles were as in- 
different to the influence of the water as they were in all places 
to that of the sun. So far as the sun is concerned, my observa- 
tions agree entirely with those of Hooker, who declared both in 
