Two Cases of Trichromie Vision. 195 

Match. Difference. Match. Difference. 
fl. 13°40 + 0°67 * .@, EE G5 — 0°98 
M2: 1 12'0 —0°73 eA TS —0:98 
Foy k2 KO + 0°02 * S, 13°50 +0°77 
*4. 1270 —0°73 T 9. 12°90 + 0°17 
T5. 13°50 +0°77 7105 18:75 +1:02 
Average, 12°73. Average difference, 0°684. 
I find that my colour vision agees with that of the large majority of 
persons and may, therefore, be regarded as normal. I made the following 
10 observations for comparison with those given above :— 
Match. © Difference. Match. Difference. 
*1h11-0 + 0°629 S63 10°0 —0°371 
#29) 1h0°25 —O 121 Pim 1050 +0129 
*3. 9°80 —0°571 82 L050 +0°129 
74. 10°33 —0°041 9. 0560 + 0°229 
Hoe “10:33 —0°041 *10. 10°40 + 0-029 
Average, 10°371. Average difference, 0°229. 
* Red shown first in the mixed colour. + Green shown first. 
My match appeared to him bright red and bright green, the yellow 
appearing as green. The match appeared more correct through a pin hole. 
The mixed colour of his match always appeared green to me. It will be 
noticed that his average difference is very nearly three times the amount 
of mine. On comparing the differences, according to the colour which was 
shown first, it will be found that these were all positive when the green 
was shown first, and four out of the five were negative when he commenced 
with the red. 
Green first + 0°67 Red first —0°73 
+ 0:02 —0°73 
O47 —0°98 
+0°77 AES) 
+017 +1:02 
Average, 0°48 
Below I give my differences for comparison. 
Green first —0-121 Red first +0°629 
Average, 0°888 

— 0041 
— 0041 
+0°129 
+ 0°229 
Average, 0°1122 
—0°571 
—0°371 
+ 0°129 
+ 0:029 
Average 0°3458 
