These long-continued and varied tests with Nos. 151 and 152 revealed three facts: that the mice depend chiefly upon brightness differences in visual discrimination; that they probably have something which corresponds to our red-green vision, although their color experience may be totally unlike ours; and that the red end of the spectrum seems much darker to them than to us, or, in other words, that the least refrangible rays are of lower stimulating value for them than for us. TABLE 25 GREEN-RED TESTS June 1, 1906 No. 151 BRIGHTNESS VALUE IN CANDLE RIGHT WRONG TEST POSITION METERS (GREEN) (RED) 1 Green on left Green 4, Red 448 Right -- 2 Green on right Green 448, Red 4 Right -- 3 Green on right Green 4, Red 448 Right -- 4 Green on left Green 448, Red 4 Right -- 5 Green on left Green 3, Red 1800 -- Wrong 6 Green on right Green 1800, Red 3 -- Wrong 7 Green on right Green 3, Red 1800 -- Wrong 8 Green on left Green 1800, Red 3 Right -- 9 Green on right Green 5, Red 34 Right -- 10 Green on left Green 34, Red 5 Right -- 11 Green on right Green 6, Red 74 Right -- 12 Green on left Green 74, Red 6 Right -- 13 Green on left Green 4, Red 448 -- Wrong 14 Green on right Green 448, Red 4 Right -- 15 Green on right Green 4, Red 448 -- Wrong 16 Green on left Green 448, Red 4 Right -- 17 Green on right Green 3, Red 1800 -- Wrong 18 Green on left Green 1800, Red 3 -- Wrong 19 Green on right Green 1800, Red 3 -- Wrong 20 Green on left Green 3, Red 1800 Right -- Totals 12 8 So many of the results of my color experiments have indicated the all- important role of brightness vision that I have hesitated to interpret any of them as indicative of true color discrimination. But after I had made all the variations in brightness by which it seemed reasonable to suppose that the mouse would be influenced under ordinary conditions, and after I had introduced all the check tests which seemed worth while, there still remained so large a proportion of correct choices that I was forced to admit the influence of the quality as well as of the intensity of the visual stimulus.