Before beginning training in the labyrinth, preliminary observations were made to discover whether the animals had any tendencies to go either to the right or to the left.  When the colored cardboards were removed it was found that there was usually no preference for right or left.  In Table I. the results of a few preliminary trials with No. 2 are presented.  For these the colors were used, but a tendency to the right shows clearly.  Trials 1 to 10 show choice of either the right or the red throughout; that it was partly both is shown by trials 11 to 30, for which the colors were reversed.  This individual has therefore, to begin with, a tendency to the right at the entrance.  At the exit it went to the right the first time and continued so to do for several trials, but later it learned by failure that there was a blocked passage as well as an open one.  In the tables the records refer to choices.  It was useless to record time or to lay much stress upon the course taken, as it was sometimes very complicated; all that is given, therefore, is the action in reference to the passages. Right in every case refers to the choice of the open way, and wrong to the choice of the blocked passage.  The paths taken improved steadily in that they became straighter.  A few representative courses are given in this report.  Usually if the animal was not disturbed a few jumps served to get it out of the labyrinth.

TABLE I.

PRELIMINARY TRIALS WITH FROG NO. 2.

Trials.  Red on Right.  White on Left.
1 to 10 10 times to red 0

Red on Left.     White on Right.
11 to 20 4 times to red        6

Red on Left.     White on Right.
21 to 30 3 times to red        7

To Red.  To White.  To Right.  To Left. 
Totals. 17 13 23 7

This table indicates in trials 1 to 10 a strong tendency to the red cardboard.  Trials 21 to 30 prove that there was also a tendency to the right.

Training was begun with the labyrinth arranged as shown in Fig. 1, that is, with the left entrance passage and the right exit passage open, and with red cardboard on the right (red was always on the side to be avoided) and white on the left.  Table II. contains the results of 110 trials with No. 2, arranged according to right and wrong choice at the entrance and exit.  Examination of this table shows a gradual and fairly regular increase in the number of right choices from the first series to the last; after 100 experiences there were practically no mistakes.

With another subject, No. 6a, the results of Table III. were obtained.  In this instance the habit formed more slowly and to all appearances less perfectly.  Toward the end of the second week of work 6a showed signs of sickness, and it died within a few weeks, so I do not feel that the experiments with it are entirely trustworthy.  During the experiments it looked as if the animal would get a perfectly formed habit very quickly, but when it came to the summing up of results it was obvious that there had been little improvement.