172 M. P. WASHBURN AND EDWINA ABBOTT 



the pair ? The white paper used was white letter-paper with a 

 dull finish as nearly like that of the grey paper as we could find. 

 The rabbit chose the grey door in each of the ten tests. 



Series 36. Red and Hering grey number 15. Red opens. 

 This series was given to re-establish the habit of choosing red 

 rather than grey. If the rabbit were capaple of forming a 

 steady habit of choosing the darker of the two papers presented, 

 irrespective of their absolute brightness, the red -grey discrimina- 

 tion would not need to be re-established after the grey-white 

 series, since in both sets of experiments the darker paper was 

 the one to be chosen. As a matter of fact the red-grey dis- 

 crimination was not so good after the grey-white series had been 

 made as it had been immediately before. Ten experiments a 

 day for three days, November 10, ir, and 12, were made, the 

 percentages of choices of the red being 80, 70, and 80. 



Series 37. Tests with red and grey number 15, the red open, 

 intermingled with tests with grey number 15 and white, the 

 grey opening. Tnis series followed a new plan. Twelve experi- 

 ments were usually given on a day. Six of them were red and 

 grey 15 tests, the other six were grey 1$ and white tests. 

 Two of a kind were usually given in succession, the open door 

 being on opposite sides in the two. The grey door was closed 

 if shown with red, open if shown with white. The open door, 

 though on opposite sides in the two succeeding tests of the same 

 land, was sometimes in the next following test on the same 

 side as in the one immediately preceding, and sometimes on 

 the opposite side: that is, the alternation of the sides on which 

 the open door was to be found was not continued through the 

 whole series. 



The total number of red and grey experiments was 77; in 

 73 per cent, of these the red was chosen. The total number of grey 

 and white experiments was 70; in 72.8 per cent, of these the grey 

 was chosen. The percentages calculated every three days, that 

 is, for (usually) every 18 tests of each kind, were as follows: 

 choices of the red in red-grey tests, 74, 73, 68, 76; choices of the 

 grey in grey-white tests , 73, 78, 86, 52. On one day, November 

 20, a perfect record was obtained in the whole twelve experiments. 



It does not seem possible to explain the high percentages of 

 choices of the grey in the grey-white tests, the very same grey 

 which the rabbit had learned to avoid in the red-grey tests, 



