Life and Instinct 



199 



sound, or vibrations of any kind, it rises upon its pliant stomach 

 as upon a pillar, and with neck up-stretched, trembling like a 

 tuning-fork, it opens wide its mouth, thus exposing its sensitive 

 throat like a pink, yellow-rimmed target to the eye of the parent. 

 The whole body is taxed in the performance of this act, which is 

 done to perfection for the first time and without a teacher. It 

 seems to be a typical reflex response, as automatic as an electric 

 bell. Press the button, that is, 

 jar the limb, or make any kind of 

 sound, and up goes the head 

 again and again, until fatigue 

 comes to its aid. That the act 

 is adaptive or purposeful the se- 

 quel presently shows. When the 

 parent is at hand with food in its 

 gullet, it immediately tosses back 

 its head; visible waves of con- 

 tracting muscles are seen passing 

 upward from the invisible stom- 

 ach, when it regurgitates a crushed 

 berry or insect ; then bending low 

 it aims for the center, placing a 

 few drops or pieces well down in 

 the throat. Here another 

 "spring " is suddenly touched, and 

 note the result. The swallowing 

 reflex is started, and the nestling enjoys its first meal. By a 

 reversal of the process already witnessed in the adult, the food 

 is carried downward to the stomach, where a complicated series 

 of changes awaits it. The comparison of such instinctive acts in 

 the nestling, to a " chain" of reflexes would seem to be justified. 

 In this case the actions of the parent bird imply a long 

 series of nicely related and orderly movements : the search after 

 prey and its capture, the varied and often strange treatment 

 which this sometimes receives, its transportation to the nest and 

 disposition among the young, the general trend or form of 

 which may remain the same from generation to generation, 



Fig. 121. Cedar-bird about thirty-six 



teristic response to any sound or vi- 

 bration. Notice that the bird rests on 

 its pot-belly, and uses both wings and 

 legs for support. Enlarged to life. 



