792 



THE SENSE OF EQUILIBRIUM 



continued for a brief period of time, a point will be reached when the 

 walls and the water move with practically the same velocity. Im- 



E 



FIG. 402. DIAGRAMMATIC REPRESENTATION OF A MODEL ILLUSTRATING THE DEVIATION 



OF THE HAIR PROCESSES OF THE AMPULLA. 



D, disc rotated by hand; T, circular glass tube filled with water; B, bulbular enlarge- 

 ment containing a long camel's hair brush, vertically placed. 



mediately upon ceasing the rotation, the walls are brought to a stand- 

 still, while the water continues to move in this direction until it is 



finally stopped by the friction. These 

 phenomena may be illustrated in a more 

 striking manner with the help of a cir- 

 cular glass tube filled with water and 

 enlarged at one point for the reception 

 of a bundle of soft hairs placed trans- 

 versely into its lumen (Fig. 402). When 

 rotated, this primary and secondary 

 dissociation between the movements of 

 the walls of the tube and the water are 

 now made more evident by the devia- 

 tion of the hairs, first against and then 

 in the direction of the rotation. 



If this hydrodynamical principle 

 is applied to the semicircular canals, 



FIG. 403. DIAGRAM ILLUSTRAT- & must be concluded that the move- 



THE POSITION OF THE HAIR PRO- ment of the head gives rise to a move- 



ment of the canals situated in this 

 A, the canal being moved in the particular plane. To begin with, the 



direction of the black arrow, the en- endolymph lags behind the Walls of 



doiymph at first lags behind. The fa e ca nals, but soon attains the same 



hairs processes are deviated against , , , T , . 



the rotation from a to b. On stop- speed as the latter. Lastly, it con- 

 ping the rotation of the canal, the tinues in this direction even after the 



endolymph is carried onward in the canalg haye ceaged t moye ^ tu j t 

 direction of the red arrow deviating . . . 



the hair processes from a to c. motion has again been arrested. This 



implies that the hair processes are first 

 turned against the rotation, then vertically into the fluid, and lastly 



