INSTINCTS AND HABITS IN CHICKS 55 



and 2.5 cm. apart, two parallel bands.of black paper, each band 

 being rectangular in form and measuring 4.2 x .9 cm. On the 

 other set of cards two black bands of equal area and the same 

 material were fastened at right angles to each other and in 

 this wise (a). Chick no. 21 was tried first with this combination 

 of forms, but with negative results. No. 15 was tested at the 

 same time. It showed no improvement after 60 trials and 

 from that on the continuous training plan was used. On Mar. i 

 it was given 160 trials. The regular system of card exchanges 

 was disregarded and one setting of cards was allowed to remain 

 during several successive trials to see if the chick might thus 

 hit upon the habit of selecting the vertical bars. Sixty trials 

 were given in a similar way on Mar. 2 and as many more on 

 Mar. 3, with negative results. 



The plan of having forms at the tops of the display cards 

 was then abandoned and another scheme employed. This 

 time display cards were made of gray cardboard and the forms 

 were presented as openings in the cards through which the 

 chick had to pass on its way out of the apparatus. In one set 

 of cards a circular opening was cut the diameter of which was 

 8.47 +cm. In the other set of cards a rectangular opening was 

 cut: whose base was 6.35 cm. and altitude 8.89. The circle and 



