148 EXPERIMENTAL PHYSIOLOGY. 



side world situated along the line which joins that part with the 



nodal point of the eye. That this is actually the case may be seen 



from the following experiment. 



Experiment 55. Close the right eye and direct the eyes as far as 

 possible to the left. With the tip of the finger press lightly on 

 the right eye at different points near the margin of the orbit 

 and note the positions in the visual field of the resulting "phos- 

 phenes". 

 In this experiment although we press the right side of the retina 



all the light spots which we see appear to be on our left, in the upper 



field if we press below and in the lower if we press on the upper part 



of the eyeball. 



