260 ARTHUR C. WALTON 



blem, unless the experimenter was entirely concealed. This 

 disposition was not conducive to the giving of good attention, 

 and, as her seemingly dainty appetite caused the ' hunger 

 stimulus ' to lose its potency, her attention was so poor that 

 results from only the simplest associations could be obtained. 

 The male was affectionate, but never fawning and, as the "hun- 

 ger stimulus" was very strong in his case, his attention was very 

 good in the more complex problems as well as in the simpler 

 ones. For these reasons the results set forth in this paper 

 are based almost entirely on the records obtained from the male. 



The native disposition of the dogs was to shrink from the 

 electric light bulbs employed in the experiments, and only long 

 training would lead them to overcome this aversion to any 

 place thus indicated. The artificiality of the light stimulus is 

 unquestioned, and to react to it, the native fear of the dog must 

 be overcome. For this reason reaction to light stimuli cannot, 

 as some experimenters have claimed, be taken as indicating 

 the true native capacity of the dog. It seems more logical to 

 conclude that only the reactions to stimuli that are naturally 

 attractive to the dog can be taken as true indices of its native 

 capacity. 



The health of the dogs during the whole period of the exper- 

 iments was good. Occasionally slight indispositions were shown. 

 The dogs were kept out of doors, and were allowed to run with 

 other dogs and play with the children of their owner. This 

 life prevented the acquisition of any characteristics peculiar to 

 housed animals. 



DESCRIPTION OF APPARATUS AND METHODS OF • 

 THE EXPERIMENTS 



The experiments were given in a room that was kept partially 

 darkened in order to have the light stimuli in a strong contrast 

 to the general lighting of the room. 



The apparatus is illustrated in Fig. 1. 



The release box (" B ") was thirty inches wide and forty 

 inches high with a glass top measuring fourteen by fourteen 

 inches. The door, made of wire screening, occupied the whole 

 of one side, hinged at the top and provided with a counter- 

 poise which enabled it to swing easily. The box could be rotated 

 very easily on its " domes of silence." This release box stood 



