Finally, I would here note a rather interesting observation for which I am indebted to Mr. Schillings and the Count zu Castell. They had noticed, independently of each other, that the horse would often fail to react when for any length of time he was given problems dealing with abstract numbers, even though they were of the simplest kind; but that he would immediately improve whenever the questions had to do with concrete objects. They believed that Hans found applied mathematics more interesting, and that abstract problems, or those which were altogether too elementary, bored him. The Count zu Castell furthermore noticed that the responses tended to be more correct as soon as he had the horse count objects which he, himself, (Castell) could see during the test. Quite in accord with this is the statement to be found in the report of the September-Commission, in which we find this note in a discussion of the arithmetical problems (not involving visible objects), which the gentlemen already mentioned had given the horse. "The horse responded with less and less attentiveness and appeared to play with the questioner." Here again, that was looked for in the animal which should have been sought in the man. Mr. Schillings was capable of intense, but not continued concentration and it was he who was bored, and not the horse. And it was the Count zu Castell and not the horse that found it necessary to invoke the aid of perceptual objects to bring his attention to the proper height of concentration. The reader will see that thus far I have supposed the horse to be a never-failing mechanism and that I have placed all errors to the account of the questioner. The horse never failed to note the signal for stopping and therefore never was the immediate cause of an error. It is not to be denied that now and then he would cease tapping spontaneously and in this way would become the cause of an error. We have no data on this point, but undoubtedly the horse's share in the total number of errors was very slight. (_b._) Another source of error was faulty computation on the part of the questioner. The questioner made the signal for stopping when the expected number of taps had been reached. The horse faithfully mirrored the miscalculation of the questioner. I have knowledge of only one such case. The journals report that once Mr. von Osten, when someone called to his attention that Hans had indicated the wrong day of the week, replied: "Yes, you are right, it was not Thursday, but Friday," whereupon Hans being asked again, promptly responded correctly. This appeared to the reporter in question as proof of the subjective influence of Mr. von Osten upon the horse.