Chapter IV. 



The influence exerted upon motility by the N. octavus 



in rabbits and in pigeons with regard to the 



central distribution of this nerve. 



After the minute description of the anatomical details of the 

 octavus-systems , given in the proceeding chapters, an endeavour 

 may now be made to bring the central distribution of this nerve 

 in connexion with the physiological facts found after its section. 

 Especially the motor disturbances following its section on one side 

 may now be proved to have a relative simple genesis. 



The intact eighth nerve provides, as is generally admitted, the 

 integrity of two functions. 



The first of these, a true sensory function, is the function of 

 hearing. 



The other one, more difficult to define, has been called by a 

 happy conception of EWALD, the tonic function of this nerve. 



As regards hearing, there are strong arguments to postulate, 

 that fibres of the octavus-systems, conducting centralward the im- 

 pulses received by the irritation of ciliated cells in CORTI'S organ, 

 after having been interrupted many times f. i. in the ganglion of 

 the corpus quadrigeminum posticum and of the corpus geniculatum 

 mediale reach the temporal part of the cortex cereboi. 



In that area of the cortex the perception of sound should be 

 localisated. 



In regard of the tonic function of the N. octavus, it has been 

 the purpose of this monography to study the fibres of the octavus- 

 systems in their central course to the motor nuclei in the mesen- 

 cephalon, the medulla oblongata and the spinal cord. 



