354 DYNAMIC FUNCTIONS OF LABYRINTH 



This movement was very much more readily produced and lasted 

 much longer than that in the canal. 



It has not been a part of the problem I have set myself to find expla- 

 nations for the existence of structures in the labyrinth, but, on the 

 contrary, to find out where and how definite functions are performed. 

 Nevertheless nearly every person to whom I have communicated 

 these results has asked, "What then are the functions of the semicir- 

 cular canals?" It may be suggested that possibly a movement of 

 liquid does take place through the canals, not as a stimulus to the 

 nerve endings in the cristse, but as a means of equalization of pressure. 

 Indeed if the ampullae were merely diverticula from the vestibule it is 

 conceivable that pressure conditions could arise in them which might 

 seriously affect their functioning. It is not unreasonable to suppose 

 that the canals provide a means for the equalization of liquid pressure 

 quite analogous to the use of the Eustachian tubes in equalizing air 

 pressure. 



The fact that in man and many mammals a nystagmus may be 

 caused by irrigating the auditory canal with hot or cold water and 

 that the character of this nystagmus differs for different positions of 

 the head can be explained perfectly without assuming an unbelievable 

 flow of liquid in the semicircular canals. If the temperature differ- 

 ence can cause convection currents in the inner ear at all under the 

 conditions existing in such an experiment, it is certainly more reason- 

 able to suppose that such movements of convection would arise in 

 the mass of liquid contained in the vestibule than in the much smaller 

 space of the canals where the friction would more readily overcome 

 the tendency to movement. These considerations would not in the 

 least invalidate the diagnostic use which Barany has made of the 

 phenomenon, but they do supply a rational explanation of its causa- 

 tion. 



The Dynamic Functions of the Otolith Organ. 



Breuer and others had suggested that the otoliths are concerned 

 only with the static functions of the ear. Importance was attached 

 to the space relations of the different otolith masses. But Parker^ 



"^ Parker, G. H., Influence of the eyes, ears, and other allied sense organs on the 

 movements of the dogfish, Mustelis canis (Mitchill), Bull. Bureau oj Fisheries, 

 1909, xxix, 43. 



