CHAPTER XT. 



REFLEX ACTION AND UNCONSCIOUS COGNITION. 



THE nature of a Reflex Action has been already indicated, 

 and the tissue elements usually concerned in such an 

 elementary nervous operation have been described. They 

 consist of ingoing fibres continuous in a Nerve Centre with 

 so-called ' sensory' nerve cells, which m their turn are 

 in communication with some group or groups of ' motor ' 

 nerve cells, whence issue outgoing fibres for the trans- 

 mission of stimuli to muscles. 



Such groups of tissue elements variously connected 

 together are continually increasing in definiteness and num- 

 ber during the course of structural development, as well as 

 during the whole time in which the ' education ' of animal 

 organisms progresses. The cellular elements are aggre- 

 gated into Ganglia of different sizes, and, by reason of 

 their close approximation in these bodies, the establish- 

 ment of structural connections between those cells which 

 are functionally related, either on the side of 'impreb- 

 sion ' or on that of ' reaction,' is doubtless facilitated. 



Thus it seems to result from the very nature of nerve 

 tissues and their mode of development, that variations 

 in the kind and combination of impressions acting upon 

 any particular organism, as part of its life phenomena, 

 become by slow degrees organically linked to different 

 and severally appropriate motor results. The organism 



