Fig. 75. Diagram representing the two retinae and the cortical centres connected with 

 them. The upper four circles represent the cortical levels of the red, green, blue, 

 and white systems connected with the left retina, the lower four those connected with 

 the right retina. The broken line bisecting all the circles represents the purely 

 anatomical separation of each centre into two halves lying in opposite cerebral hemi- 

 spheres. The continuous lines on the left side represent the sympathetic relation 

 between corresponding points of the two systems of similar function connected with 

 the right and left retinae respectively. The dotted lines represent the antagonism 

 between any point of any one colour- system of the one eye and the corresponding 

 points of the other two colour-systems of the other eye. The broken lines represent 

 the feebler antagonism between any point of any one colour-system of one eye and the 

 corresponding points of the other two colour-systems of the same eye. The arrows 

 radiating from the centre of eacli circle represent the antagonism between any point of 

 the cortical level of any one of the systems and every other point of the same. 

 (McDougall.) 



