ABSTRACT
The sort of development that means a mere substitution of stimulus or response is different from that type of growth which involves the creation or emergence of a new type of behavior; new, that is, in so far as the particular individual is concerned. The analysis of growth in behavior-patterns is quite in line with observations which have frequently been made upon organic development. The secret of a full understanding of the meaning and process of development lies hidden in the factors which determine the rhythms and fluctuations of growth. In the development of a behavior-pattern the outstanding fluctuations or spurts appear to occur in connection with conspicuous changes in the growth cycle. The maturational level of each behavior-pattern should be calculated in terms of its phylogenetic history and of the neurostructural level at which ontogeny is controlled. In fact and in principle the underlying processes which obtain in the development of behavior also apply to the modification of behavior.
