OPTIC AND VISUAL-MOTOR SYSTEMS 229 



differentiated visual apparatus, with similar results. After the cutting 

 of the optic nerve and its regeneration in the adult animal, the same 

 results were obtained. Vision was normal in those animals whose 

 retinas had been kept in normal position, but it was reversed about 

 the optic axis in animals whose retinas had been rotated through 

 180° prior to nerve section (Sperry, '44, '45). In frogs, destruction of 

 quadrants of the tectum of both normal and operated animals re- 

 sulted in scotomas of local quadrants of the visual field in a pattern 

 which is in agreement with the anatomical observations of Stroer 

 ('39rt); and, in cases in which the eyeball was rotated, the scotomas 

 were in arrangement reversed from that found when the eyes were 

 in the normal position. 



These experiments increase the probability that, in Amblystoma, 

 retinal loci are in some way projected locally upon the tectum; but 

 the mechanism employed in localization of visual functions can be 

 clarified only by further experimentation. Sperry 's experiments dem- 

 onstrate "the high degree to which the complex and precisely pat- 

 terned neural mechanisms subserving adaptive visuomotor coordina- 

 tion are dependent upon inherently predetermined rather than upon 

 functionally acquired neural adjustments." 



