BEHAVIOR OF VERTEBRATES 431 



a maze and operate a puzzle box is retained better than ability 

 to choose between the forms and the brightness boxes." 



This paper is suggestive along many lines. The attempt to 

 approach in the experimental field the conditions of nature is 

 one too frequently neglected. One could wish, however, that 

 instead of covering so great a field some of the tests, especially 

 those on the sensory side, could have been carried farther and 

 under stricter control. 



Mclntyre (35), in a paper before the British Society for the 

 Advancement of Science treated the role of memory in animal 

 behavior. The chief questions considered were: the existence 

 of mental images or free ideas in animals, their origin, their 

 biological significance and the tests that indicate their presence. 



On the other side of the water the trained horses of Elberfeld 

 have occupied the focal point of attention in the field of animal 

 learning. Nothing seems too abstract, too great or too difficult 

 to attribute to them. The readers of this journal are familiar 

 with the work of Kluge Hans. It is known how his master, 

 von Osten, sincerely believed that the horse could read, spell, 

 etc., how the learned men who visited him were puzzled, and 

 how, finally, under controlled experimentation, it was proved 

 that the horse. failed in all questions where the answer was un- 

 known to those present and also when it was impossible for 

 him to see. 



Herr von Osten was broken hearted over the outcome but 

 continued his training with the aid of a friend, Herr Krall, who 

 had always remained convinced of the almost human intelli- 

 gence of the animal. To this friend Herr von Osten left the horse 

 at his death. Krall not only continued Hans's " education " but 

 has also acquired six horses of his own all of which are in train- 

 ing. Some of these far exceed Hans in their attainments. 



Krall is a man of intelligence and enthusiasm. He is said 

 to be a good man incapable of dishonesty and for years he has 

 made his home a laboratory for these animals. He is interested 

 in psychology and possesses a considerable psychological library. 



Many of the greatest savants in Europe have flocked to see 

 these horses and have made their reports to various societies 

 and in many articles. The account given here is a summary of 

 the facts and no attempt will be made to separate, in the review, 



