THE FIELD OF VISION 



37 



Though the anatomical evidence as to the course taken 

 by the macular fibers in the chiasma is very uncertain, it 

 seems highly probable, on physiological and clinical grounds, 

 that semi-decussation of them takes place. It would be 



FIG. 7. Diagram to show hypothetical semi-decussation of macular nerve 



fibers at the chiasma. 



difficult to understand how stereoscopic vision for detail 

 could be brought about, unless the images coming from 

 objects focussed on each macula were superimposed in the 

 visual cortex. It seems most probable that in man and 

 monkeys, not only are the visual impressions received from 



