THE EFFECTS OF DISLOCATION OF THE EYE UPON 



THE ORIENTATION AND EQUILIBRIUM OF 



THE GOLDFISH (CARASSIUS AURATUS). 



J. FRANK PEARCY AND THEODORE KOPPANYI. 

 (From the Hull Physiological Laboratory of the University of Chicago). 



It has long been known that the eyeballs of various fishes show 

 different movements during locomotion. It is also established 

 that the body movements have an influence on the movements of 

 the eyes. 



Lyon 1 has shown that the dogfish compensates rotation about 

 a dorso ventral axis by moving its eyes in the opposite direction. 

 "The eyes," states Lyon, "sometimes show the same motions 

 when the animal moves voluntarily and normally." "A dogfish, 

 for example, when swimming on its side may keep the upper eye 

 to the ventral, the lower one to the dorsal side of the orbit. 

 Compensatory motions are not, therefore, confined to passive 

 rotation by external means." 



Lyon found that these compensatory motions of the eyeballs 

 in fish are practically independent of the sense of light, for they 

 cannot be abolished by blinding (transection of the optic nerves). 

 He also found a causal relationship between the semicircular 

 canals and these eye motions. 



The opposite question, whether the eye or visual impressions 

 can influence the body orientation and movements in fish has also 

 been investigated but only in reference to the positive and nega- 

 tive heliotropism. Parker 2 has shown that in an unilluminated 

 field dogfish will swim toward a single light, i.e., they are posi- 

 tively phototropic. Thus the light has a stimulating effect on the 

 progressive movements of the fish and Parker concludes that the 

 retinal image is an important factor in guiding the locomotion of 

 these fishes. 



Admitting the fact of positive phototaxis in fishes, there still 

 remains the possibility that in diffused light visual impulses or the 

 fields of vision as a whole may influence the orientation, despite 



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