72 



FREDERICK S. BREED 



chirped, or attempted to make flapping movements with the 

 wings. For the tests of persistence, excitement of this kind 

 was avoided as much as possible. 



In estimating the value of the results printed in table 25, 

 it must be remembered that chicks nos. 32, 33, 38, and 39 had 

 16 days' size training in the interval. Also, nos. 43 and 44 had 

 orange-white training to perfection between the first and the 

 second persistence tests. 



TABLE 25 

 The Persistence op Habit 



Of eight mice which Yerkes trained in black-white or white- 

 black, only two showed perfect persistence of the habit after an 

 interval of four weeks. Of nine chicks trained in black-blue and 

 tested in a similar way after 30 days, five obtained perfect records. 



The behavior of no. 34 in the reaction box equipped with the 

 size cards 71 days after the completion of the original training 

 furnished a nice commentary on the ' ' intelligence ' ' of the 

 animal. This chick, standing naturally, was 19 cm. high, meas- 

 ured to the highest point of its back. So large that the larger 

 of the two openings would permit its passing out with difficulty, 

 it crouched at the smaller opening and attempted to go through 

 it at every trial but the last. Each time, as soon as it got its 

 head through the small opening and was just beginning to 



