24 FREDERICK S. BREED 



in succession between the two grains, and one record in which 

 there were four such successive pecks. There are two other 

 observations that help to explain this reaction. On Dec. 23, 

 no. 70 and on Dec. 29, no. 87, were working rapidly in their 

 regular pecking tests. The pecking activity was interrupted 

 momentarily while the bill poised in air above and about mid- 

 way between two grains approximately i cm. apart. On Dec. 

 24, no. 76 was on the experiment table going through its 

 pecking test. In the presence of two grains lying as those in 

 the preceding dases, its pecking reaction started in the direction 

 of one of the grains and was completed by a perfect reaction 

 upon the other. I concluded, therefore, that case two was not 

 an ordinary instance of missing, but that the reaction in response 

 to one of the stimuli exerted an inhibitory effect on a reaction- 

 in response to the other. The poising of the bill in air, the zig- 

 zagging first toward one grain and then toward the other during 

 a continuous forward movement of the bill, and the striking of 

 the cardboard fairly between the grains, have at bottom, I 

 believe, the above common principle of explanation. 



In view of the recent important work of Hess and that of 

 Katz and R^v&z, I feel impelled to report some activities of 

 the chicks in the dark-room. The assumption that hungry 

 chicks do eat when they can see the food is ordinarily true, but 

 the second assumption, that chicks do not eat when they cannot 

 see it, surely is not borne out by observations of the behavior 

 of chicks in the dark-room. During some studies of individually 

 acquired reactions, the chicks were placed in a dark-basket in 

 the dark-room for ten minutes prior to the regular daily tests. 

 The basket which was used for this adaptation work was a 

 willow waste-paper basket lined with black cloth and covered 

 with the same material. Food was placed in the bottom of the 

 basket before the basket and chicks were taken into the dark- 

 room. The animals were thus allowed to eat in the basket 

 a short time before the period of darkness adaptation began. 

 Again and again, after the basket was taken into the dark-room, 

 the door closed, all Hghts turned off, and the basket covered, the 

 animals continued to eat the chick food in the bottom of the 

 basket. I have also gone out of the dark-room and returned at 

 the end of the ten minute period to find the chicks eating. The 

 darkness was so nearly absolute in the room that I could not 



