476 ORGANIC SENSATIONS 



organs of the cochlea. Conclusive proofs for this apportionment of the 

 acoustic stimuli to two kinds of terminal auditory apparatus, however, were 

 not forthcoming. Instead, it has been shown by numerous experiments that 

 the semicircular canals and the sacs play a very important part in the media- 

 tion of our sensations of position, orientation, and the like. 



B. EXPERIMENTAL SUPPRESSION OF THE SEMICIRCULAR CANALS 



In 1828 Flourens published a- paper on the phenomena which follow de- 

 struction of the semicircular canals of the pigeon. After transection of a 

 canal he observed peculiar pendulumlike movements of the head in the plane 

 of the canal transected. Thus, if the horizontal canal were the one operated 

 on, the head was rotated incessantly to and fro in the horizontal plane. These 

 movements ceased after a time; but if the corresponding canal of the other 

 side were sectioned, the movements began again with still greater intensity. 

 They came on suddenly, if the animal was disturbed in any way. The 

 pigeons could no longer fly and could only take food with difficulty. The more 

 extensive the destruction of the canals, the more intense were the disturbances 

 produced, and the animals continued to exhibit such disturbances for years. 



Goltz performed a great service for this line of investigation when he 

 observed that the result of the operation can be described primarily as a 

 disturbance in the ability of the animal to keep its body in equilibrium. He 



FIG. 187. FIG. 188. 



FIG. 187. Pigeon with both membranous labyrinths removed, after J. R. Ewald. 



FIG. 188. Pigeon five days after removal of the right membranous labyrinth, after J. R. 

 Ewald. The head is inclined toward the operated side. 



also laid stress on the idea that since this disturbance persists for several 

 years after the operation, it must be regarded not as a symptom of irritation, 

 but as a symptom of some deficiency caused by elimination of the semi- 

 circular canals. This, moreover, is confirmed by painting the canals with 

 cocaine, exactly the same phenomena being produced as by section (Ch. 

 Koenig, Gaglio). Goltz concluded that the semicircular canals constitute a 

 peripheral sense organ, which supplements the visual and motor senses in 



