3. The leather blindfold was now applied. There is not the slightest doubt in my mind as to the entire adequacy of Captain’s blindfold for purposes of excluding visual stimuli. At my request Mr. Sigsbee stood facing me and called for 2, 9, 3, 1, and 7 separately and in the order given. The horse stood where I had previously decided to have him stand, and I made sure that no directive stimuli were reaching him either from the stage or from the rear and sides. He stamped twice for “2,” nine for “9,” etc., until this test was completed. The only mistake occurred when, in response to the command to “give us three” he stamped three times and struck his toe on returning his foot to the standing position. His master accused him of this mistake and Captain gave us three clean-cut taps. 4. I gave the command, “Give me your right foot,” “Give me your left foot,” “Put your head down and bite your right knee,” and “Scratch your head.” He responded appropriately, although it was necessary for me to repeat these commands to satisfy the inquiry contained in Captain’s wiggling ears. Mr. Sigsbee stood by my side, a wholly negligible factor for the moment. I am thoroughly satisfied that Captain’s activities were solely directed by my commands. 5. Captain, still blindfolded, was given the following problems by his master, from whom I had concealed my program. It seemed to be difficult for the horse to follow my unfamiliar voice, and since Mr. Sigsbee was invisible to the horse and wholly under my control I decided to employ him as interlocutor: “Divide ten equally between your two feet, the first half with your right foot, the second half with your left foot.” Captain stamped five times with his right foot, then pawed tentatively, apparently in doubt as to the correctness of his answer, and awaiting a cue. He received no cue, and soon withdrew his right foot to the standing position and tapped five times with the left foot. His master accused him of inaccuracy, telling him that he “got one too many” with his right foot. Captain corrected his mistake by giving us a clean-cut and accurate response. “Divide twelve equally between your two feet, the first half with the right foot, the second half with your left foot.” This command elicited a perfect response. “How much is three times three?” A perfect response was again obtained. Captain gave nine taps with his right forefoot. “How much is two times two?” I gave this command.