VOL. xm.] THE OYSTERCATCHER. 213 



discrimination with innate modes of response. Response is 

 thus made more appropriate and more precise, while inhibi- 

 tion of response becomes more certain and more prolonged 

 whenever the stimulus reacted to comes not from the parent 

 but from the environment. 



The life of the chick is a monotonous one and rarely involves 

 situations to which an appropriate and adequate response 

 is not forthcoming. When there arises or is provided a 

 situation novel and urgent, yet capable of solution in a few 

 seconds or less by a simple inference and an original piece of 

 behaviour, the chick responds with and repeats the various 

 actions that constitute its motor repertory, while the parent 

 aroused by the appeal to its senses and emotions liberates 

 several or all of its stereotyped reactions to " chick in danger " 

 or " chick in difficulties," until sooner or later, or not at all, 

 one or the other organism obtains relief from the unpleasant 

 situation. Routine is also apparent in the daily round which 

 is made up of an alternation of short spells of activity and of 

 surprisingly long periods of inactivity during which the mental 

 state of the chick appears to be an absolute blank. A similar 

 physical and mental condition is observed in the young of 

 other waders. It may favour growth and development. 



