Since there appears to be a slight preference on the part of most dancers' for the black box in comparison with the white box, white-black training tests were given to fifty mice, and black-white to only four. The tests with each individual were continued until it had chosen correctly in all of the tests of three successive series (thirty tests). As the reproduction of all the record sheets of these experiments would fill hundreds of pages and would provide most readers with little more information than is obtainable from a simple statement of the number of right and wrong choices, only the brightness discrimination records of Tables 6 and 7 are given in full. As a basis for the comparison of the results of the white-black tests with those of the black-white tests, two representative sets of data for each of these conditions of brightness discrimination are presented (Tables 9 and 10). In these tables only the number of right and wrong choices for each series of ten tests appears. Tables 9 and 10 indicate--if we grant that the precautionary tests to be described later exclude the possibility of other forms of discrimination-- that the dancer is able to tell white from black; that it is somewhat easier, as the preference tests might lead us to expect, for it to learn to go to the black than to the white, and that the male forms the habit of choosing on the basis of brightness discrimination more quickly than the female. TABLE 9 WHITE-BLACK TESTS No. 210 No. 215 AGE, 28 DAYS AGE, 28 DAYS SERIES DATE RIGHT WRONG RIGHT WRONG (WHITE) (BLACK) (WHITE) (BLACK) A June 22 4 6 2 8 B 23 4 6 2 8 1 24 4 6 3 7 2 25 6 4 5 5 3 26 7 3 7 3 4 27 5 5 8 2 5 28 7 3 9 1 6 29 8 2 8 2 7 30 9 1 9 1 8 July 1 10 0 10 0 9 2 10 0 9 1 10 3 10 0 10 0 11 4 -- -- 10 0 12 5 -- -- 10 0 TABLE 10 WHITE-BLACK TESTS