REFLEX ACTION. 269 



localized. We also know that the cortex receives impressions 

 through the channels of the different sense organs, and we can 

 respond through various channels, speech, writing, facial 

 expression, etc. We would therefore expect, theoretically, 

 that the various parts of the cortex of the brain are connected. 

 As a matter of fact, we find anatomically that this is the case. 

 Not only are the cells of the gray matter connected with the 



Nerve Cells Connected by Interlacing Nerve Network 



Afferent Nerve Fiber 41 YY Efferent Netve Fiber 



Sensory 

 Epithelium 



Fig. 84. Diagram of Reflex Action. 



various parts of the body, but cells of different parts of the 

 cortex are in communication with each other by what are 

 called "association fibers." Thus a sensation roused in one 

 part of the brain gives rise to the sending out of an impulse 

 from another part of the brain to produce the response. 



The Nature of Sensation. Of the real nature of sensa- 

 tion we know but little. Like consciousness, we call it a con- 

 dition of the gray matter of the cerebral convolutions. Perhaps 



