No. 480] 



THE PROBLEM OF COLOR VISION 



371 



tions. In the cones the gray molecules have undergone a devel- 

 opment such that a certain portion only of the molecule becomes 

 disassociated by the action of light of a given color. 



Tlie ditt'erentiation of the primitive gray molecule is supposed 

 to have taken place in three stages (Fig. 2). The first stage is 



" " ' other the sensation of red. 



If the rcil and u'rccii liToupini^s are disassociated together the 



