Subject: Why are certain animal's nicitating membranes colored?

I have read that dogs are color blind,but I am not sure.I suppose wolves are
too,since dogs and wolves are pretty much the same.I have read that wolves have
nicitating membranes in their eyes that reflect yellowish light.I know that this
light is reflected from the back of the animal's eye for the animal to see with.
The light wolves' eyes reflect is probably a blend of wavelengths, but shouldn't
an eye that relected yellowish light have to be able to detect at least       
one of the colors it reflected for the reflected light to be of use? Shouldn't
color blind animals have eyes that reflect only white light? Please tell me why
certain color blind animals have nicitating membranes that are colored.Thank
you.     

Re: Why are certain animal's nicitating membranes colored?