INSTINCTS AND HABITS IN CHICKS 



65 



But the conclusion as to the general efficiency of the black- 

 blue training should not rest alone upon a comparison of the 

 rates of modification in the two groups of chicks. Having 

 learned in the course of the experimentation with the black- 

 blue habit, from data which will appear later, that this modifi- 

 cation persists for some time with relatively slight change, it 

 seemed of value to investigate the relation of the size training 

 to the color training by means of the so-called memory test. 



TABLE 22 



The Non-interference of Modifications 



Table 22 exhibits the results of this test. The table shows the 

 age of the chicks of Group I when the work on black-blue was 

 begun, 12 days; the number of trials necessary to complete the 

 training, exclusive of preference and final perfect series; the 

 number of errors made in the course of this training; and also 

 the corresponding age, trials and errors for the size training. 

 The interval, thirty days or more in each case, is the number of 

 days between the date when the black-blue modification was 

 pronounced perfect and the date upon which the memory test 

 was given. Of course sixteen days of this interval were occupied 

 with the development of the small-large habit. 



The reactions of the chicks to black-blue in the persistence 

 tests are detailed in the columns R and W. Chicks nos. 32 

 and 33 made perfect records, no. 39 made an error on its first 

 trial, being thereafter perfect, while the reactions of no. 38 

 seemed to show no trace of the original modification. The 

 results altogether weigh in favor of the view that the modifi- 

 cations with which we have dealt proceed quite independently 



