284 J. F. SHEPARD AND F. S. BREED 



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In the course of our observations chicks were taken from the 

 dark-room and brought to the experiment table at the beginning 

 of the fourth, fifth, and sixth days, as previously detailed. The 

 pecking tests were conducted directly before a window, the 

 animals working .at a distance of about two feet from the glass. 

 True these chicks had not been hooded. But in no case was 

 an animal observed to run at the approach of the experimenter 

 or show more excessive signs of fear. Generalization on the 

 basis of these facts reported by Spalding seems highly premature. 



SUMMARY AND CONCLUSIONS 



In a previous study of the pecking instinct of barred Plymouth 

 Rock chicks data were gathered from which a curve of develop- 

 ment of the instinct was plotted. This curve represents the 

 improvement in accuracy of the pecking coordination from the 

 second to the twenty-fifth day. With this curve as a standard 

 an attempt was made to determine the relative amounts con- 

 tributed by maturation and use to this improvement. Two 

 lots of chicks, divided into five groups, in all twenty-three in 

 number, were tested. By confinement in a dark-room prior to 

 the first tests practice was prevented for a definite time in each 

 group — three, four, or five days from date of hatching. Mean- 

 while the animals were fed and watered artificially. The most 

 interesting features of the results are (i) the uniformly poor 

 initial records, and (2) the rapidity with which normal accuracy 

 was attained. Regardless of the duration of the period of con- 

 finement, within the limits specified, the chicks began below an 

 efficiency of 18% and with from one to two days' practice 

 reached normal efficiency. In the first two days of the curves 

 the necessary practice component, it seems, is represented, and 

 in the remainder a record mainly of maturation. 



The improvement ensuing upon the first practice was both 

 rapid and regular. The rapidity was not due to excessive prac- 

 tice following the enforced delay of the instinct. If, as sug- 

 gested, the curve after the first two days is mainly a record 

 of maturation, there would seem to be some explanation for 

 the negative results in previous tests of the effect of social 

 influence on the development of this instinct. 



Although chicks with previous practice have been found to 



