458 STELLA B. VINCENT 



evoke them and then examines the proof of the same in the 

 Elberfeld horses. Pi6ron (25) whose ideas on the subject are 

 a little more sane than those of some other investigators gives 

 an excellent review of the situation with a very complete 

 bibliography. 



A careful report by Haenel (7) shows that the horses seem 

 to have lost ground during the year. Krall attributes this to 

 the almost unbroken succession of visitors and their many 

 questions. Krall admitted that the vocabulary of Zarif had 

 decidedly suffered and that many of the arithmetical operations 

 which Muhammed formerly performed were now beyond him. 

 Barto, the blind horse, which had previously acquired the 

 foundations of arithmetic in a few days, had, in the summer, 

 after five weeks vacation, forgotten it all, and learned it the 

 second time with much greater difficulty than at first and had 

 not yet acquired his former facility. All of the first horses 

 which Krall undertook to train were teachable — had under- 

 standing as he thought. But during 1914 he had three horses 

 from the stud of the King of Wurtemberg and after three or 

 four weeks endeavor he was forced to confess that he. could teach 

 them nothing and had to send them back as unlearned as they 

 came. He has similarly failed with a young female elephant. 

 Those who were inclined, with Krall, to rate the intelligence 

 of the horse very high wonder now if these horses have reached 

 the limit of their ability. Others ask, is it not possible that 

 the criticism which has been made upon these claims has influ- 

 enced Krall so that clues which the horses could use in their train- 

 ing, possibly unconscious to Krall himself, are being excluded. 



One of the best articles on the subject is a critical paper by 

 Schroeder (28) which not only inquires into the proof of the 

 facts but also into the philosophical and scientific implications 

 of the theories which have arisen in their explanation. 



GENERAL PAPERS 



Besides these articles reported above there are others of a 

 more general nature which do not properly belong under any 

 of the above headings. Hubbert .(11) discusses the value of 

 units of time versus units of distance in learning. In the way 

 of apparatus four graphic methods of recording maze reactions 

 are described by Yerkes and Kellogg (40) which they designate 



