84 WALTER E. CARREY. 



we fix the eyes on any near object which is then moved, the 

 whole visual field has an apparent motion in the opposite sense. 

 Seated in a moving car our eyes follow the near objects as they 

 are passed, but the distant landscape appears to revolve in a direc- 

 tion with the moving train. As a tentative hypothesis it may be 

 assumed that in our experiments the moving stimulating object 

 fixes the attention of the fish, the apparent motion of the visual 

 field as a whole is then in a direction opposite to that of the 

 moving object. This apparent motion may be the determining 

 factor in causing the orientation and movement which is the 

 essence of this peculiar reflex shown by sticklebacks. 



PHYSIOLOGICAL LABORATORY, COOPER MEDICAL 

 COLLEGE, SAN FRANCISCO. 



