OF THE RETIHA TO LIGHT AND COLOUR. 
181 
Two other positions Avere chosen in the yellow-green at (X 5614), and in the blue 
(X 4603), corresponding to the scale numbers of the spectrum 46‘3 and 22*8. The 
relative luminosities of the rays transmitted to the eye were 96'5 and 21‘5 respec¬ 
tively. 
The colour field for each of these four colours was taken with the left eye, and the 
following table shows the results (fig. 11) :— 
Table XIV. 
Angle of field 
Extent of fields in degree.s. 
in degi’ees. 
Red. 
Green. 
Yellow-o’ieen. 
Bine. 
0 
30 
35 
39 
36 
3oq 
28 
34 
i 37 
35 
60 
31 
37 
’ 42 
38 
90 
>N 
33 
40 
44 
41 
120 
32 
36 
42 
37 
L50J 
28 
34 
38 
34 
180 
29 
35 
39 
.36 
1.50"] 
34 
43 
50 
44 
120 
40 
50 
57 
50 
90 
h T 
43 
55 
62 
55 
60 
41 
51 
56 
50 
30. 
1 
33 
38 
43 
39 
Here we have two fields, the green and the blue, which are practically identical, 
showing that the limits of the boundaries are not affected by the hue, though, of course, 
the illumination is very different in the two cases. Attention must here be drawn to 
the fact that, though, according to Hering’s theory, the fields of the dissimilation 
colours ought to be both external, or else both internal, to the fields of the assimilation 
colours, they differ in each pair, and the frequency of similar want of accordance 
has been very generally met with. 
14. Fields of Iminire or Mixed Colours. 
When considering the question of the fields of mixed colours, such as those 
produced by pigments, it became apparent that a crucial test as to their efficiency 
might be made by mixing colours of the spectrum together to imitate some single 
spectrum colour, and, after making the mixture of the same luminosity, to compare 
the fields. With this in view, a red and green, near E, were mixed together to 
match the D light in hue and in intensity. The fields for each colour, including D, 
were taken, as also was that of the mixed colours. 
