452 Ben^. C. Gnit'iihrrg 



4 EXPERIMENTAL OBJECTIONS TO THE HYPOTHESIS 



On removing the semicircular canals entirely, or on cutting the 

 acoustic nerve, Girard ('92) and Schrader ('87, p. 87) report com- 

 plete loss of compensatory motions; while Tomaszewitz ('77), 

 Breuer ('75, p. 99), Baginsky ('81), Cyon ('88), Kreidl ('92, 2), 

 Ewald ('92),Strehl('95, p. 216), Bechterew ('96), and others, found 

 all the phenomena in response to rotation continued as in the 

 normal animal; and Steiner ('85, '89) concludes that there is not 

 complete loss of compensatory movements. Breuer ('91), Ewald 

 and Delage-Aubert ('88) observe, however, that the compensa- 

 tory movements disappear after the operation if care is taken to 

 exclude the use of the eyes also, and therefore they do not abandon 

 the theory; but Cyon ('97) speaks sarcastically of the logic of this 

 argument. 



When single canals only were operated upon, Hensen ('79) 

 found the movements disturbed in the plane of the canal in ques- 

 tion; whereas Ewald ('90, Experiment 66) cauterized the mem- 

 branous canals in pigeons without in any way affecting the move- 

 ments of the animals. 



According to Girard and Ewald, the destruction or removal of 

 the labyrinth on one side of the head caused the frog to take on an 

 unsymmetrical attitude, the head and body being inclined toward 

 the operated side; Ewald found that this new attitude was main- 

 tained in one case for a year after the operation. According to 

 Loeb ('91, 2) cutting the acoustic nerve brings about a perma- 

 nent tendency in the shark to turn toward the injured side. On 

 the other hand, Cyon, Steiner ('89), Baginsky ('85) and Bech- 

 terew ('96) found on cutting the acoustic nerve that "all the phe- 

 nomena that served to support the assumption of the sensory 

 function [of the semicircular canals] continued to appear" (Cyon, 

 '97), while Mach found that under these conditions the eye- and 

 head-nystagmus appeared as in normal animals. 



Breuer ('89) found that mechanical, thermal and electrical 

 (galvanic) stimulations of separate canals set up head-turnings in 

 the corresponding planes; the movements are in response to the 

 streamingof the lymph, and are in the same direction as the stream- 



