APPETITES AND AVERSIONS. 99 



though she happened to be very near the nest. This was the 

 more remarkable as she had a well-formed habit of going to the 

 nest on all occasions. At length she did go to the nest with her 

 straw, and made well-ordered movements to build it in. 



4. The male and the female dove take regular turns in sitting 

 on the eggs. The male is seized by the appetite for brooding 

 about 8 or 9 A. M., and the female about 5 P. M., the state 

 evidently being brought on in each case by physiological causes 

 which are part of the daily physiological rhythm. When either 

 one, e. g., the female, comes to the side of the nest prepared to 

 enter and sit, she already has somewhat the attitude of the sitting 

 bird, the body sunk down on the legs and the feathers fluffed 

 out (incipient consummatory action). If her sitting appetite 

 be thwarted, as by her mate refusing to budge from his position, 

 she shows restlessness and makes intelligent efforts to obtain pos- 

 session of the nest. When at last her mate yields his place, she 

 steps exultingly into the center of the nest and settles herself on 

 the eggs with many movements indicative of satisfying emotion 

 (complete consummatory reaction). 



A broody hen of course illustrates the same principle. 



5. It is an interesting fact, exhibited in a variety of instincts, 

 that a young bird may make feints of performing actions which 

 it has never yet performed. Thus the young dove makes feints 

 of flying before it has ever flown. This was illustrated in a 

 peculiarly instructive manner by one of my young doves, no. 46, 

 which developed cripple wings and was unable to fly. When 

 placed in a box with sides 3^ inches high it was just able to 

 jump on the edge. Nevertheless, when its roosting instinct 

 developed, it endeavored strenuously every evening to fly to the 

 perch which was some inches above its head. It looked at the 

 perch and aimed at it with perfect definiteness, opening its wingfe 

 and making feints of flying. In the evolution of birds, there can 

 be no doubt, flying developed gradually from jumping. The 

 new movements of flying were gradually intercalated into the 

 interval between the initial action, leaping from the ground, and 

 the final action, landing again upon the feet. The young dove 

 to this day shows first the incipient end action, aiming at the 

 perch to be alighted on, and only after it has launched itself 



