Mechano- and Equilihrium-Reception 



519 



c 

 o 



a, 



a, 

 S 



seconds 



Fig. 188. Relationship between the frequency of the spike potential discharge and 

 ipsilateral angular acceleration. The horizontal line indicates the frequency level of 

 spontaneous discharge. From Lowenstein and Sand."^ 



seconds 



Fig. 189. Relationship between the frequency of spike potential discharge and 

 contralateral angular acceleration. From Lowenstein and Sand.°" 



cupula is the adequate stimulus for changing the frequency of nerve im- 

 pulses in the afferent nerve fibers. Thev show further that a given canal 

 will respond to rotation in two directions. The earlier notion,^"* that in 

 fishes, amphibia, and reptiles the movement of fluid in the semicircular 

 canals stimulates only in one direction, is not quite correct. What is im- 

 plied here, probably, is that the functional organization of the nervous 

 systems in these animals does not take cognizance of a reduction in nerve 

 impulse frequency. 



