THINKING ANIMALS 165 



some way through it. The difficulty naturally con- 

 sists in deciding precisely how this happens. But it 

 does not seem to me altogether impossible to arrive at 

 a proper hypothesis. 



I have already said that we must discard, because 

 of its inability to explain a great part of the facts, the 

 most easy and simple hypothesis that of some 

 mechanical signal (e.g. by means of a supposed pressure 

 of the hand under the cardboard, or by the hand itself 

 which is held out to the animal, in the case of the 

 dogs which have so far been experimented with). 

 Here we also have to remember the proposition laid 

 down by Miss Kindermann herself that " She did 

 not wish to let herself be carried away by sentiment," 

 and that she would seek all possible proofs which were 

 good logically. Having excluded the hypothesis of 

 deceit, it is a further proof of the sheer impotency of 

 the theory of signals, when regard is had to the available 

 amount of the material observed and recorded in the 

 authoress, if we ask how is it possible to imagine that 

 she (knowing very well, as she says, the suspicion 

 resting on the method) in a year or more of work with 

 Lola should not herself have perceived that she herself 

 had been producing by mechanical means the rapped 

 answers of her pupil ? 



In my opinion the answer is that the authoress was 

 not only not aware of, but could not in the least have 

 been aware of, the action that may have passed from 

 herself to the dog so as to bring about the rapping of 

 the answers ; and that on the other hand it is not a 

 question at all of thinking of a simple mechanical 

 operation of the kind mentioned above, because in 

 the presumed action of the authoress on the dog there 

 is no need to have recourse to such a crude hypothesis 

 (as surely there was no similar action of Krall's on 



