326 G. H. PARKER 



In all the tests I carried out, as already stated, the turtles were 

 uniformly positively geotropic. 



Having determined that young turtles are positively geotropic, 

 I next turned my attention to their responses to water. That 

 they are not directed in their movements by water vapor in the 

 air, by the smell of water, or of materials associated with it, or 

 by the sound of waves, etc., has been abundantly shown by 

 Hooker ('11), and on these points I can confirm practically all 

 his statements. If next a course over which young turtles are 

 making their way toward the sea a shallow vessel of water is 

 placed so that they might enter it, they pass it by without showing 

 even a deflection in their line of march. Had the water in itself 

 possessed a quality attractive to the turtles, some change in their 

 course would certainly have been evident. That water does not 

 thus attract them is also evident from the fact that turtles liber- 

 ated in the pen on the laboratory wharf in the darkness of night 

 did not move toward the water as they did in the daylight, but 

 crept about indiscriminately. 



If water in itself does not influence the direction of movement 

 of the young turtles and if sources of light, such as the sun, are 

 equally ineffective in this respect, what is the factor that deter- 

 mines the course that they take on a horizontal surface? When 

 turtles were liberated at the center of the horizontal pen already 

 described as set out on the laboratory wharf and their courses 

 toward the w^ater were closely observed, it was found that these 

 courses were not directly toward the water, which was almost 

 exactly west, but they were a little to the north of west. When 

 the surroundings were inspected to ascertain what might be 

 present to cause this peculiarity, it was seen that the main mass 

 of the aquarium building loomed up a little to the south of east 

 from the pen and that if a straight line was drawn from this mass 

 through the center of the pen westward it would point to a very 

 open unobstructed horizon. Such a line included the course 

 taken by the turtles. It therefore seemed possible that the young 

 turtles took a course which led away from the most considerable 

 mass upon the horizon and toward the most unobstructed and 

 open parts of that line. To test this view I tried an experiment 



