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VETERINARY PHYSIOLOGY 



direction of the ampullae in which the pressure is 

 increased. The mode of action may be analysed by a 

 study of the sensations which accompany acceleration or 

 retardation of movements. Acceleration produces a sensa- 

 tion ; when the motion is uniform there is no sensation, 

 but when it is suddenly stopped a sensation of rota- 

 tion in the opposite direction is produced. The fact that 

 only fairly rapid acceleration or retardation of movements 



Fir;. 57. — Diagram of the Arrangement of Fibres and Cells in the Cortex of 

 the Cerebellum. G.L., molecular layer; N.L., nuclear laver ; 

 P., Purkinje's cells sending out axons to the deeper ganglia. (After 

 Ramon y Cajal. ) 



produces an effect explains why it is that the action of 

 the canals may fail to make an aviator when flying in 

 cloud aware of his position in space, so that he may actually 

 be upside down without knowing it. 



The information conveyed from the labyrinth must 

 concord with that derived from other channels, e.g. from 

 vision. When they do not accord, a sensation of giddiness 

 and an inability to maintain the balance are induced. If 

 one sets a poker point down upon the ground, then places 

 the forehead on the top and rapidly circles the poker three 

 times, when one stands up one experiences a sense of 



