202 Animal Intelligence 
No. 2 did come to differentiate these two signals. The record 
of his progress is given in Fig. 31 by A and A. 
I then made a second attempt with the exposing appara- 
tus, using cards 2 and 102 (November 6, 14-21). No. 2 
did react to my movements in pulling the string but in over 
too trials made no progress in the direction of a differential 
reaction to the ‘no’ signal. I then tried feeding him at each 
signal, feeding him at the bottom of the cage as usual when 
I gave the ‘ yes’ signal and at the top when I gave the ‘no’ 
signal. After a hundred trials with the ‘no’ signal there 
was no progress. 
I then abandoned again the exposing apparatus and used 
as signals the ordinary act of taking food with my left hand 
(yes) and the act of moving my left arm from my right side 
round diagonally (swinging it on my elbow as a center) and 
holding the hand, after taking the food, palm up (no) (No- 
vember 26, 27,1900). No. 2 did come to differentiate these 
signals. His progress is given in the diagram in Fig. 31 en- 
titled ‘Palm up’ (B). 
I next used (November 27, 1900) as the ‘yes’ signal the 
same act as before and for the ‘no’ signal the act of holding 
the food just in front of the box about four inches below 
the edge. No. 2’s progress is shown in Fig. 31 in the dia- 
gram entitled ‘low front’ (C and C)). 
I next used (November 27-30) the same movement for 
both ‘yes’ and ‘no’ signals save that as the ‘ yes’ signal I took 
the food from a brown pasteboard box 3 by 3 by o.5, and as 
the ‘no’ signal I took it from a white crockery cover two 
inches in diameter and three eighths of an inch high which 
was beside the box but three inches nearer me. No. 2’s 
progress is shown in Fig. 31 in the diagram entitled ‘Box 
near’ (D). ’ 
I next used for the ‘yes’ signal the familiar act and for the 
