Between the first and second series of tests the following experiments were interpolated. The names of six members of the commission were written upon six slates respectively, which were then suspended from a string. Mr. von Osten pointed to one of the men and asked: "On which of the slates is this gentleman's name to be found?" The correct number was tapped in every case. The command to approach the slate in question was also obeyed as a rule, although this was not as uniformly successful as tapping. In the conference which followed, Mr. Busch declared that the feats appeared inconceivable to him; and again none of the men had noted anything in the way of signs. Now followed the second series of tests mentioned above. In order to be sure to get the correct responses, Mr. Schillings, who up to this point had not been present at any of the experiments, was asked to put the questions to the horse. Mr. von Osten went into the house, accompanied by a member of the commission. And again, Mr. Schillings would go out before the second part of the test, without having met Mr. von Osten. Five tests were made in this way. They were not attended by such amazing success as were the preceding ones, but nevertheless the results were surprising. The horse nearly always repeated the number itself, instead of performing the operation required. Since, however, Mr. Schillings, owing to a misunderstanding, had, in the first two cases, said to the horse: "You are to repeat this number for Mr. von Osten", the errors might appear to be a result of this request. At the final discussion, the result of which was the unanimous declaration which was given for publication, not only the data obtained during these two sessions, but also the earlier experiences of some of the members of the commission were taken into consideration. None of the tests witnessed could be referred to chance or to the use of tricks. Count zu Castell pointed out that in the course of eight days he had elicited forty correct responses from the horse, among them some in regard to which he himself had been momentarily in error. Other members recalled the many instances in previous exhibitions, during which both Mr. Schillings and Mr. von Osten were absent, when questions were put to the horse by others. The commission also had access to a detailed account written by Professor Stumpf on Mr. von Osten's method of instruction, based on the explanations and demonstrations which Mr. von Osten had himself given. As a result of these considerations the commission felt under obligations to give public expression to its conviction. In the report it limited itself, however, to the purely negative side--principally in denying the use of tricks,--and expressed no opinion with regard to the actual genesis of the horse's accomplishments, since it believed that there was great possibility that other factors were involved which ought to be carefully investigated. SUPPLEMENT IV