Since there cannot be a function without a structure nor a structure without a function, development implies concomitant changes in structure.1
One of the important problems in medicine and psychology today is that of genesis of human behavior. Within recent years heightened interest has given considerable impetus to the study of the subject, and with the elaboration of more adequate methods of approach a better understanding of the fundamental nature of behavior is gradually evolving. Activity has been particularly great in the field of child psychology, much progress having been made between the pioneer efforts of Comenius (1592-1670)2 and the present day organized applications of the principles of experimental science3 to investigations on the behavior of infants and young children.
It is not within the scope of this paper to review historically the extensive literature on the subject. Reference may be had to the critical survey by
ABRAMSON H. GRADED SEQUENCE IN POSTURAL AND IN LOCOMOTOR DEVELOPMENTITS RELATIONSHIP TO THE MATURATION OF THE CENTRAL NERVOUS SYSTEM. Am J Dis Child. 1937;53(5):1282–1302. doi:10.1001/archpedi.1937.04140120106010