PROBLEM OF COLOR VISION—DANE. 625 
to be gathered by separate nerve cells of the retina, and the optic 
nerve consequently contains certain fibers transmitting only red, green, 
and blue sensations respectively. The mixing of the sensations, giving 
rise to the perception of shades and tints, is therefore accomplished in 
the brain and not in the cones. In an attempt to test this supposition, 
attention has been called to the perception of the colors of stars. The 
image of the star is so minute that it would cover but a single cone, 
but the conclusion that one cone perceives its color is invalidated 
by the fact that the retina is not sufficiently stationary; the image of 
the star falls in rapid succession upon several cones which may unite in 
giving the color perception. Those who believe in the specific energy 
of the rod and cone fibers dismiss at once several of the theories of 
color vision. It must be remembered, however, that the separation 
of the cones into forms responding to red, blue, and green light, with 
three corresponding sets of nerve cells and fibers to convey these 
separate stimuli to the brain, does not rest upon anatomical evidence. 
