1 April 26 18 c.m. on left 1800 c.m. on right 11 9 7 13 2 27 Same 16 4 16 4 3 28 Same 20 0 17 3 4 29 Same 19 1 19 1 5 30 Green 18 c.m. Red 18 c.m. 9 1 10 0 6 30 Green 64 c.m. Red 18 c.m. 9 1 8 2 7 May 1 Green 6 c.m. Red 1500 c.m. 7 3 9 1 8 1 Green 4 c.m. Red 1500 c.m. 8 2 7 3 9 2 Both varied from 4 to 1500 c.m. 18 2 18 2 10 3 Green 2 c.m. Red 1800 c.m. 6 4 7 3 11 3 Same 10 0 10 0 12 4 Same 7 3 8 2 13 4 Same 8 2 6 4 14 5 Green 1 c.m. Red 1800 c.m. 19 1 19 1 Filters were now removed. An illumination of 15 c.m. was established on one side and an illumination of 0 on the other side, in order to ascertain whether the mice would choose the brighter box. This was done to test the assumption that the green in the previous tests had always appeared brighter to the mice than did the red, and that in consequence they had chosen the brighter box instead of the green box. TABLE 24--CONTINUED No. 151 No. 152 SERIES DATE CONDITIONS RIGHT WRONG RIGHT WRONG (GREEN) (RED) (GREEN) (RED) 15 May 5 Brighter 15 c.m. 8[1] 2[2] 10[1] 0[2] Darker 0 c.m. 16 5 1 c.m. on left 1800 c.m. on right 10 0 10 0 17 5 1 c.m. on left 0 c.m. on right 9 1 4 6 18 5 Green 18 c.m. Red 18 c.m. 19 1 17 3 19 9 Same 9 1 9 1 20 9 Same 10 0 10 0 21 10 Same 10 0 10 0 22 11 Same 10 0 10 0 23 June 1 Both varied from 1 to 1800 c.m. 12 8 10 10 24 2 Same 18 2 14 6 25 June 3 Both varied from 2 to 1800 c.m. 19 1 17 3 26 4 Same 17 3 17 3 27 5 Same 18 2 18 2 [Footnote 1: Brighter.] [Footnote 2: Darker.]