PHYSIOLOGICAL INTERPRETATIONS 73 



trally, and throughout Hfe all of them are under some measure of uni- 

 fied central control so that the body acts as an integrated whole with 

 diverse specialization of its parts (Coghill, '29; Herrick, '29). Cog- 

 hill's contributions of factual observations and the principles derived 

 from them have been critically reviewed by the writer in a book 

 ('48), to which the reader is referred. 



The patterning of these orderly movements is determined by the 

 intrinsic structure of the nervous system. This structural pattern is 

 not built up during early development under the influence of sensory 

 excitations, for in the embryo the motor and sensory systems attain 

 functional capacity independently of each other; and when central 

 connection between the sensory zone and the motor zone is made, the 

 first motor responses to excitation exhibit an orderly sequence, the 

 pattern of which is predetermined by the inherited organization then 

 matured (Coghill '29, p. 87; '30, Paper IX, p. 345; '31, Paper X, 

 pp. 158, 166). This early structural differentiation goes on inde- 

 pendently of any stimulus-response type of activity, though the 

 latter may modify the pattern of subsequent development. This is a 

 principle of wide import, applicable not only in lower vertebrates but 

 in higher forms as well (Coghill, '40), including man (Hooker, '44). 

 The stimulus-response mechanism is not a primary factor in embry- 

 ogenesis; it is a secondary acquisition. 



REFLEX AND INHIBITION 



It has been pointed out that the functions of the sensory and 

 motor zones are fundamentally analytic — analysis of environmental 

 influences and analysis of performance in adjustment to those influ- 

 ences. How the units of the analytic apparatus are actually related so 

 as to insure the appropriate correlated action of the separate parts is 

 the key problem, which must be resolved before animal (and human) 

 behavior can be approached scientifically in other than a descriptive 

 way. Good progress has been registered. The sensory and motor 

 analytic apparatus has been exhaustively studied and well described; 

 and this was the appropriate place to begin, for these organs are most 

 accessible to observation and experiment. Because these systems of 

 peripheral end-organs and the related pathways of conduction and 

 centers of control are, in the human nervous system, obviously inter- 

 connected in stable and definitely localized patterns, it was natural 

 to use this structural framework as the point of departure in the 

 elaboration of the hypothetical superstructure of current doctrines of 



