31S A Manual of Veterinary Physiology. 



in the pressure it exercises transmits movement to the fluid 

 of the internal ear, and excites the terminal organs of the 

 auditory nerve which are lying free in the endolymph. 



In the cochlea the nerve endings of the eighth pair are 

 distributed over a large surface, which is one explanation of 

 the peculiar shape of the part, and in connection with the 

 nerve endings are the peculiar rods of Corti ; these are so 

 arranged that they are supposed to each be capable of 

 vibrating to its own particular tone, and thus really striking 

 its own note. 



The excessively hard bone in which the internal ear is 

 lodged, with its central fluid medium, are both of the 

 highest acoustic value. 



The semicircular canals, though they undoubtedly take 

 some part in hearing, are particularly connected with 

 maintaining the equilibrium of the body, and of keeping 

 the mind acquainted with its position. This remarkable 

 function is probably carried out by alterations in the position 

 and pressure of the fluid contained within them, which 

 results from every movement of the head (see p. 2S1). 

 Division of these canals causes the most remarkable irregu- 

 larity in the movements, and a side-to-side or upward 

 movement of the head. 



In certain parts of the vestibule are found small particles 

 of calcareous matter termed otoliths. They are brought 

 closely in connection with the nerves in the labyrinth, 

 and produce upon them more intense impressions than 

 would be produced by fluid alone. 



Touch. 



The sense of touch in the lower animals is developed to a 

 considerable degree in those parts of the body used for con- 

 tact purposes, such as the muzzle and the feet (where pro- 

 bably special nerve endings exist), and generally through- 

 out the skin, especially in the horse, in which a wry acute 

 sense of touch exists, though no special touch organs have 

 been found in connection with the nerves of the skin. 



The sense of touch is for the purpose of rendering the 



