No. 383.] BASIS FOR A THEORY OF COLOR VISION. 849 
A 
should be accom- 
panied by an in- 
creased range of vi- 
sion at the red end of 
the spectrum. Ifthe 
base of the cone were 
absent, red blindness 
should follow; but if 
the base of the cone 
should become cylin- 
drical, with a diame- 
ter approaching that 
at V or G, then red 
blindness would fol- 
low, but accompanied 
by increased sensi- 
tivenessto thevarious 
shades of yellowish- 
green, because short- 
ening the red fibrils 
would add so many 
more to the yellow- 
ish-green set. 
We may also ac- 
count for the gradual 
diminution in sensi- 
tiveness to red light 
toward the periphery 
of the retina by the 
fact that the cones, 
the bases of which 
alone contain the 
long red fibrils, di- 
minish in number in 
that direction. Onthe 
other hand, on the 
outermost margin of 
Fic. 9. 
ier 
I 
{ 
I 
See’ 
{ 
7 
SS E 
“iS: E 
po 
(E Gr 
— 
= 
a ae 
- 
Smm 
— — Black 
of thie haman cones = the way in which various gers 
waves affect the fibril 
the retina, all sense of color is lost and the sensation of black 
