I first secured the partial formation of the habit of coming down when I took a bit of food in my hand. I then used the apparatus for exposing cards, YES in front being the ‘yes’ signal and a circle at the back being the ‘no’ signal. I gave No. 2 25 trials with the ‘yes’ signal and then began a regular experiment similar to those described. After about 90 trials (November 9-12, 1900) there was no progress toward differentiation of response, and it was evident from No. 2’s behavior that he was reacting solely to the movements of my hand. So I abandoned the exposing apparatus and used (November 11-13, 1900) as the ‘yes’ signal the act of taking the food with my left hand from a pile on the front of the box and for the ‘no’ signal the act of taking food with my right hand from a pile 4 inches behind that just mentioned. No. 2 did come to differentiate these two signals. The record of his progress is given in Fig. 31 by _A_ and _A₁_. I then made a second attempt with the exposing apparatus, using cards 2 and 102 (November 6, 14-21). No. 2 did react to my movements in pulling the string but in over 100 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) (November 26, 27, 1900). No. 2 did come to differentiate these signals. His progress is given in the diagram in Fig. 31 entitled ‘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 diagram entitled ‘low front’ (_C_ and _C₁_). 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 0.5, 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_).