72 THE BRAIN OF THE TIGER SALAMANDER 



plex forms an integrated equilibrated system. This is the apparatus 

 of the stable heritable components of the action system — the reflexes 

 and instincts. A second integrating apparatus is found in the all- 

 pervasive neuropil, and a third in specialized derivatives of the latter, 

 the associational tissues locally differentiated in the brain stem and 

 reaching maximal development in the cerebral cortex. 



The total behavior of neuromuscular type emerged within a pre- 

 existing bodily organization, which maintained the unity of the indi- 

 vidual by nonnervous apparatus. The nervous system is from its first 

 appearance a totalizing apparatus. Local differentiations of tissue 

 for the analysis of sensory experience and of motor responses arise 

 within this integrated structure, and local reflexes similarly emerged 

 within a total neuromuscular pattern of action adapted to maintain 

 the unity of the organization. As development advanced, the mecha- 

 nisms of the local reflexes acquired increasing autonomy, but they 

 are never completely emancipated from some control in the interest 

 of the behavior of the body as a whole. The organic unity of the 

 whole is preserved while local specificity is in process of development, 

 and this unitary control is never lost during the normal life of the 

 individual. 



THE STIMULUS-EESPONSE FORMULA 



The stimulus-response formula has wide application and great 

 usefulness as a basic concept in physiology and psychology, but its 

 apparent simplicity is illusory and has tended to divert attention 

 from essential features of even the simplest patterns of behavior. 

 This I have illustrated ('44a) by an examination of the simplest reflex 

 connection known in Amblystoma — from retina to ocular muscles by 

 way of the basal optic tract. 



The late G. E. Coghill, during a productive period of foi'ty years, 

 studied the development of the action system of Amblystoma and 

 the correlated processes of bodily growth. These researches have 

 demonstrated beyond question that in this animal the neuromuscular 

 system is so organized in prefunctional stages that, when first acti- 

 vated from the sensory zone, the resulting movement is a total re- 

 sponse of all the musculature that is mature enough to respond to 

 nervous excitation. These "total patterns" of activity are not dis- 

 orderly, and they become progressively more complicated while the 

 apparatus of local reflexes ("partial patterns") is slowly differenti- 

 ated within the larger frame of the total pattern. The development 

 of both the total pattern and the partial patterns is initiated cen- 



