1892 - 93 .] Dr William Pole on Colour-Blindness. 109 
complementary colour to red, green-blue. But this is con- 
tradicted by experiment, for the fact is that the colour-blind eye 
sees white as white, or precisely the same as the normal eye 
The warm colour of the red-blind is not green, but yellow with a 
slight green tinge. 
Blue and yellow shadows were correctly described with the right 
eye just as with the left; what to the left eye were red and green 
appeared to the right eye as colourless or grey. Other tests 
were applied in which, though the left eye saw them as normal, the 
right eye saw the usual dichromic appearances, giving a positive 
confirmation to the ordinary ideas as to the two main colours being 
yellow and blue. 
I. 
Remarks hy Professor Hering on a One-Eyed Case of Dichromic 
Vision., 1890. 
(1) All the colours used appeared to the affected eye less 
saturated, ^.e., much whiter or greyer than to the healthy eye. 
(2) Yellow and blue appeared yellow and blue ; and suffered no 
remarkable change of their hue {Hires Tones')., but were seen much 
less saturated. 
(3) Green and red, which were near the primitive red and green 
{Uvrotli und Urgriln), and which were not highly saturated, 
appeared colourless to the affected eye. 
(4) The intermediate colours, viz., spectral red, orange, 
yellow-green, and violet not too much saturated, lost for the 
affected eye their red or green, and therefore appeared yellow 
or blue, but very pale and greyish. 
(5) White, grey, and black were seen by the affected eye as by 
the healthy one, i.e., perfectly colourless. 
These results lead to the conclusion that the power of the 
affected eye to see yellow and blue in comparison with the power of 
the colourless sensation, is materially lessened, but the power 
of seeing red and green has very nearly disappeared. Thus the 
affected eye is nearly red-green blind, and has a much weakened 
sensitiveness to yellow and blue. 
It is superfluous to show specially that the facts described cannot 
be reconciled with the Young-Helmholtz theory, for it follows 
