THE THRESHOLD OF VISION FOR DIFFERENT COLOURED LIGHTS. 127 
contained in Table VII. With the light adapted eye it was found that the ratio was 
independent of the intensity so only the mean values are entered in the table. As the 
intensity of the illumination is increased from a very low value, the ratio of the central 
to the parafoveal illumination for equal brightness at first decreases rapidly, but as the 
intensity increases the change becomes slower and slower. Finally, for the higher 
illuminations, the ratio becomes practically constant and approximates to the value 
obtained with the light adapted eye. 
Table VII. 
Colour. 
Intensity of peripteral illu- 
Ratio of central to peripheral 
mi nation in terms of— 
illumination for equal brightness. 
SSN. 
/*/*■ 
Luminosity (lux). 
Dark adapted. 
Light adapted. 
53-3 
609 
0-027 
1-93 
- 
o-io 
1-67 
0-20 
1-70 
0-40 
1-42 
>1-07 
0-79 
1-47 
1-85 
1-17 
2-28 
1-09 
- 
48-6 
576 
0-037 
2-98 
0-14 
2-20 
- 
0-26 
1-83 
0-54 
1-42 
U-99 
1-07 
1-38 
2-51 
0-96 
3-08 
1-02 
42-8 
541 
0-11 
2-64 
0-21 
2-00 
0-42 
1-58 
0-85 
1-41 
L 1*04 
1-98 
1-24 
2-44 
1-29 
4-94 
1-21 
37-6 
514 
0-049 
4-05 
1 
o-io 
2-82 
0-20 
2-28 
0-38 
1-74 
0-78 
1-44 
f 1 • 13 
0-90 
1-52 
1-11 
1-39 
1-81 
1-22 
2-24 
1-33 
- 
I 
I 1 
