126 OTOLITH ORGANS AND SEMICIRCULAR CANALS 



one has once acquired the knack of this operation the results become 

 absolutely clear. The ampullae can be extracted one after another 

 with certainty and exactness. In sectioning the nerves one may 

 cut too much or too Httle; the fiber bundles are scattered, and certainty 

 is impossible. The attempted destruction of the ampullae in situ 

 cannot by any means have the exactness of their complete removal. 

 In many of my earher experiments I had the ampullae pasted on a 

 blank leaf of my note book when I wrote down on the same page 

 the results of their extirpation. Under these conditions there can 

 be no doubt as to the correctness of the results. In the summer of 

 1919, I repeated and extended these experiments at the Marine Bio- 

 logical Laboratory, and on account of the contradictions of previous 

 workers I took occasion to have the experiments witnessed by a 

 number of physiologists and zoologists. 



I had found* that removal of the ampullae of the four vertical 

 canals had Httle or no effect on the compensatory eye movements 

 resulting from the rotation around the longitudinal and transverse 

 axes. In order, however, that there could remain no possible function- 

 ing of the semicircular canals I have in a long series of animals removed 

 all six ampullae with uniform results. 



A dogfish from which all six ampullae have been removed shows 

 definitely the following reactions. (1) Compensatory movements of 

 the eyes and fins occur on rotation around a longitudinal axis; e.g., 

 on rotation to the right, the right eye goes up and the left eye goes 

 down. This position of the eyes is retained as long as the abnormal 

 body position is continued. (2) Compensatory movements of eyes 

 and fins occur on rotation around the transverse axis; e.g., when the 

 animal is tilted head downward the eyes make the characteristic 

 wheel-Hke backward rotation. (3) Compensation is absent on rota- 

 tion around the dorsoventral axis. (4) The animal swims in a man- 

 ner differing but Uttle from the normal. (5) The righting reaction 

 takes place promptly and vigorously; if the animal is placed belly 

 up in water it turns over at once. 



As a sample experiment I quote verbatim the following from my 

 notes. 



^Maxwell, S. S., Experiments on the functions of the internal ear, Univ. 

 California Pub. in Physiol., 1910-15, iv, 1. 



