76 FREDERICK S. BREED 



The chicks, left to develop naturally in the vicinity of food 

 and water, usually found the water by fortuitous pecking or 

 by performing the drinking movement in imitation of other 

 chicks. By imitation here I mean that the performance of 

 drinking by one chick in the presence of another sometimes 

 stimulated that other itself to perform the drinking act. I 

 reach this conclusion on the basis of incidental observations in 

 the course of the study of other problems. I have no doubt 

 that a special study of this point will bear out the above 

 conclusion. Chicks kept without drink until the third day 

 did not perform 'the drinking reaction by accident or imita- 

 tion only. The reaction was elicited by a variety of objects 

 before drink of any kind had touched the bill of the chicks, 

 showing that, when the need of the organism became sufficiently 

 imperative, the drinking reaction appeared in response to many 

 of the same kind of stimuli as the unpracticed pecking reaction. 

 The drinking instinct does not " have to be supplemented by 

 imitation, accident, intelligence, instruction, etc., in order to 

 act." And it is not improbable that the " sight of still water " 

 will be found to evoke this reaction. 



The few tests that were made to determine the effect on the 

 pecking reaction of disuse during the first two days of the life 

 of the chick seemed to show (i) that the development of the 

 instinct was retarded by disuse, and (2) that the retardation was 

 quickly overcome with use. 



The stimulus for the pecking reaction did not have to be 

 some object of a size convenient for eating. The bill of the 

 chick was used as a testing organ. 



Pecking situations were found in which the reaction to one 

 stimulus exerted an inhibitory effect on the reaction to another. 



The assumption that chicks do not peck at or eat food when 

 they cannot see it is not supported by the experimental data 

 submitted in this paper. The chicks did peck at and eat food 

 when the light was excluded. 



The pecking instinct was investigated primarily to discover 

 the meaning that should attach to such terms as perfection, 

 accuracy, or congenital definiteness, when applied to this re- 

 sponse. Pecking is a co-ordination of three reactions, — striking, 

 seizing, and swallowing. The amount of improvement from day 

 to day of the complete co-ordination, not only, but of the com- 



