CHAPTER X 



THE PROBLEM OF NEURON PATTERN 



It has been shown in preceding chapters that a 

 definite relation exists, as regards localization differ- 

 entiation, and the course and degree of centralization 

 and cephalization, between the nervous system as a 

 whole and the physiological pattern of the organism. 

 Moreover, it has been pointed out that the problem 

 - of the nature of this relation is first of all a problem of 

 developmental physiology and that it must be solved 

 in terms of the physiology of organismic pattern. And 

 finally, an attempt has been made on the basis of a 

 physiological conception of organismic pattern to throw 

 some light on this problem. 



THE NEURON 



The current conception of the cellular constitution 

 of the nervous system is that, except in its most primi- 

 tive forms, it is made up of distinct cells, the neurons, 

 which usually give rise to outgrowths of two sorts, the 

 axons or neurites and the dendrites (Figs. 45-53). In 

 such a nervous system functional continuity from cell 

 to cell is established during the course of development. 

 It has been demonstrated in many cases and is believed 

 by many to hold for all that this continuity consists in a 

 contact relation between axon and dendrite, axon and 

 cell body or dendrite and cell body of different cells 

 with persistence of the cell membrane between the parts 

 in contact. This region of contact between two cells is 



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