No. I.] THE VERTEBRATE EAR. 253 



than the eyes. If the canals were specially charged with the 

 equilibrative control of the body, why do they not overcome 

 the abnormal but powerful and for the time being controlling 

 sensations induced by rotating the body with the eyes open } 



It seems to me that there can be no question that all the 

 theories and the supporting experiments have, not only not 

 proved that the semicircular canals have any function whatso- 

 ever, but that they have, on the contrary, proved conclusively 

 that providing they have a function, it is not either statically 

 or dynamically equilibrative nor in any way connected with the 

 spatial relations of the canals. The favorite and certainly one 

 of the very best arguments to be brought forward as proof of 

 the function of an organ is that the morphological relations not 

 only favor or are entirely in harmony with the assumed physio- 

 logical action of the organ, but are such as render the function 

 ascribed the only available or the most highly probable function. 



This argument from structure to function has been applied 

 to the ear canals from the time when the theory, according them 

 the function of determining the directions in space, was put 

 forward by Scarpa, and the justice of the application no one 

 has questioned, and the argument has retained its ascendency 

 in the minds of physiologists above and beyond all negative 

 testimony heretofore adduced.^ 



Although at present there are no more important facts to 

 be brought out, an examination of the views of a few more 

 anatomists will prove instructive. In the last edition of his 

 Text-book on Physiology, Foster says (p. 1013) : ". . . that afferent 



1 Since Scarpa's time the physiology of the ear has been furnished with the " direc- 

 tion" theory of the semicircular canals. Autenrieth, and later Kerner (1808), ac- 

 cepted and again propounded the same views, which had been generally accepted by 

 English, French, and Italian anatomists since Scarpa's time. Johannes Miiller raised 

 objections to this view, and since his time the evidence has grown so steadily that 

 to-day there is no longer any adequate foundation for the explanation. It has been 

 generally discarded for many years, although several years ago Ogston again at- 

 tempted to prove Scarpa's position to be the correct one. Hasse accepted no theory 

 as apphcable throughout the vertebrate series, but thought the ear might be con- 

 nected indirectly with the orientation of the body. Hensen concluded that among 

 the Mammalia, especially man, there was little probability that such a function was 

 exercised by the canals. He attributed the perception of direction of sound to the 

 differential action of the ears of the two sides of the head, and to the work of sensa- 

 tions other than the auditory. Meyer accepts this view as concerns the Sauropsida 

 and Mammalia at least. According to Manilin (190, 1866) the semicircular canals 

 serve to annihilate the sonorous vibrations. 



