1892-93.] Dr William Pole on Colour-Blindness. 105 
The confusions of colour which our patient makes at the level of 
his scotome are, in fact, the same confusions as are made by persons 
born colour-blind ; but while with the latter there has often been 
uncertainty, our patient was absolutely positive in his answers ; not 
showing the least hesitation or the least contradiction. 
The prevailing opinion, dictated by Helmholtz, is that the colour- 
blind, who persist in designating yellow by the name of yellow, and 
blue by the name of blue, see in reality green and violet instead of 
these two colours. The authority of Helmholtz in this matter is so 
great that there has been an almost general reception of his view, 
which has been imagined in order to satisfy the Young-Helmholtz 
theory of the three specific energies of the retina. 
Well ! here is a patient presenting us with a retina which, in a 
part of the area, is Daltonian, while, in the other part, it acts 
normally. He has at every moment a point of comparison at hand, 
and the names which he gives to the colour sensations ought to 
correspond with those used by the normal eyed. 
The result is that the colour-blind see really yellow and hlue, and 
not green and violet as the theory would require us to believe. 
C. 
Von Kries's Account of Dicliromatism hy Disease^ 1882. 
During the progress of the disease the distinction of green becomes 
difficult, and at last impossible ; green then becomes yellow or grey. 
The next stage is that red cannot be distinguished from yellow ; 
only blue can be rightly so distinguished, all else is yelloAv or grey. 
Violet becomes dark blue, and red is usually denoted as black. At 
last even blue becomes invisible, and total colour-blindness sets in. 
Whenever red fails, green fails also. 
D. 
Uhtlioff 071 Dicliromatism hy Disease, 1887. 
He found four cases in each of which there was a total loss of 
the red and green sensations over the whole field of the eyesight, 
the vision becoming perfectly dichromic. One of these cases was 
carefully examined by Dr Konig with spectral colours, in the same 
way as the colour-blind (whom Konig was then elaborately examin- 
