62 Animal I. ntelligence 
placed at A and left to find its way out. The walls were 
made of books stuck up on end. 
Q was a similar pen arranged so that the real exit was 
harder to find. (See Fig. 16.) 
R was still another pen similarly constructed, with four 
possible avenues to be taken. (See Fig. 17.) 
S was a pen with walls 11 inches high. On the right side 
an inclined plane of wire screening led from the floor of the 
pen to the top of its front wall. Thence the chick could 
jump down to where its fellows and the food and drink 
were. S was 17X14 in size. 
T was a pen of the same size as S, with a block of wood 3 
inches by 3 and 2 inches high in the right back corner. 
From this an inclined plane led to the top of the front wall 
(on the right side of the box). But a partition was placed 
along the left edge of this plane, so that a chick could reach 
it only via the wooden block, not by a direct jump. 
U was a pen 16X14X10 inches. Along the back 
toward the right corner were placed a series of steps 14 
inches wide, the first 1, the second 2, and the third 3 inches 
high. In the corner was a platform 4X4, and 4 high, from 
which access to the top of the front wall of the pen could 
be gained by scrambling up inside a stovepipe 11 inches 
long, inclined upward at an angle of about 30°. From 
the edge of the wall the chick could, of course, jump down to 
food and society. The top of the pen was covered so that 
the chick could not from the platform jump onto the edge 
of the stovepipe or the top of the pen wall. The only 
means of exit was to go up the steps to the platform, up 
through the stovepipe to the front wall, and then jump 
down. 
The time-curves for chicks go, 91, 92, 93, 94 and 95, all 
2~8 days old when experimented on, follow on page 65. 
