66 FREDERICK S. BREED 



of each other. By consulting table 26 it will be seen that the 

 persistence of the black-blue habit in these chicks after 30 days 

 measures fully up to the average made by other chicks that had 

 not had intervening training. If it be objected at this point 

 that one should expect the small-large training to exert an 

 influence in the direction of strengthening the black-blue modifi- 

 cation, I agree, in so far as brightness is concerned, but the 

 inference is that something more than brightness was involved 

 in each habit. That color and not brightness was the effective 

 element in these tests of persistence I have not shown. The 

 results are offered in their present stage for their possible value 

 as a suggestion for method. It is not too much to expect relative 

 permanency of the black-blue habit even if the brightness rela- 

 tions of the first training were reversed in the second. Though 

 both forms of training are habits of response to optical stimuli, 

 they are probably quite separate from each other in their develop- 

 ment. Physiologically, this likely means the formation of 

 separate neural bases. For our explanations we look to the central 

 nervous system. Judd' observes that " Discrimination is not a 

 process of impression." " The raw materials for adaptation, the 

 impressions, are there very early, waiting for the individual 

 gradually to adjust himself to them." Discrimination depends 

 upon the ability of the individual to react specifically. Capacity 

 to discriminate is linked with the capacity to react. If this 

 be true, the animal's scope of reaction will determine the limits 

 of its modifiability. According to this view, the grouping of 

 elements to form a single object of reference in reaction derives 

 its unity from the co-ordination in a single active brain process. 

 This does not ignore the fact that the structure of the end organs 

 will also define in advance the range of objects that may be dis- 

 criminated. Impressions to be distinct must be accompanied by 

 distinctive neurological dispositions. " In short," says Judd 

 again, " so far as this raw material for development which 

 presents itself in the form of impressions is concerned, it must 

 all be worked over and connected with individual reactions 

 before it can be regarded as really assimilated by the develop- 

 ing individual." 



But let us return from theory to facts. 



'Judd, C. H.: Genetic psychology for teachers. New York, 1903, p. 153 ff. 



