THE DEVELOPMENT OF AN INSTINCT 275 



amount of practice chicks would have had by this time when 

 growing naturally. In other words, mprovement does not 

 depend entirely upon practice. How much of the improvement 

 does depend upon practice, * * * So far as the facts are 

 concerned, the most one can say is that the development of 

 the pecking instinct proceeds somewhat without practice and 

 is hastened by it. Maturation and use run along in time together. 

 No means has yet been devised of measuring the amount either 

 factor apart from the other contributes to the development of 

 the pecking reaction." 2 



PROBLEM AND METHOD 



To devise and apply some method of separating these two 

 factors became the problem in the experimentation we are 

 reporting. The same variety of chicks was used as in the earlier 

 experiments. The same make and style of incubator and brooder 

 were also employed. As before, Cypher's Chick Food was used 

 in the tests. The method of recording reactions and measuring 

 accuracy was exactly the same as in the previous work. The 

 terms striking, seizing, and swallowing denote here as there 

 three distinguishable aspects of the chicks' feeding response, the 

 term missing denoting failure to hit the object. As they 

 appear in our records, the above terms have the following defi- 

 nite meanings: (i) Missing denotes all cases of the pecking 

 reaction in which the bill failed to hit the particular object 

 supplied by the experimenter; (2) striking, those cases in which 

 the bill hit the object without seizing it; (3) seizing, cases in 

 which the object was grasped momentarily in the bill and then 

 dropped (not rejected) ; and (4) swallowing denotes what may 

 be termed the perfect or complete reaction, the object being 

 struck, seized, and swallowed in an errorless series or chain of 

 movements. To facilitate the taking of records, the Arabic 

 numerals 1, 2, 3, and 4 were employed to represent missed, 

 struck, seized, and swallowed, respectively. Note was taken, 

 of course, of the reactions independently of the number of 

 food particles pecked at, for a single grain sometimes called 

 forth a half dozen or more reactions in succession. 



So much then for this study as it is related to certain pre- 

 vious work on the same instinct. Now a word in regard to 



2 Loc. cit., p. 40. 



