No. I.] THE VERTEBRATE EAR. 255 



among those questions that have been definitely decided in the 

 affirmative either by morphologists or physiologists. As to the 

 third thesis, our author is undoubtedly correct, but if I do him 

 no injustice, unintentionally so ; for his reasons, according to 

 which the semicircular canals form a part of vertebrate anat- 

 omy, are not those which appear to find expression in the phylo- 

 genesis of these beautiful structures. 



After stating that vertigo can only be produced by pressure 

 on or disturbance of the ampullar nerves (an assumption which 

 is well known to be incorrect), he says that if the canals were 

 for equilibration only, they would probably have been put by 

 themselves instead of being connected with the auditory appa- 

 ratus, and the semicircular canals would not have been so un- 

 necessarily exposed were this their only function, since they 

 would thus present a striking contrast to all other physiological 

 arrangements. " On the other hand, if they be so placed, as I 

 believe, for some useful purpose, the most probable explanation 

 is that while some sonorous vibrations are conveyed by the 

 cochlear nerve to the true auditory centre, an afferent impulse 

 is at the same time sent to the various motor centres through 

 the ampullar nerves." 



Of a truth both cochlear and ampullar nerves, as representa- 

 tive of the two roots of the auditory, do connect through the 

 auditory nuclei with the motor centres, but there is no reason 

 at present for holding that the ampullae are specially connected 

 with the motor apparatus. 



Finally, to come to the main point for which this historical 

 introduction is intended to serve as a preliminary and a pre- 

 paratory, for the conclusion which I wish to draw, that the 

 semicircular canals are so innocent of all the functions which 

 have been heaped upon them that now that I have shown, by 

 giving the results of the physiological experiments of other 

 investigators, to what conclusion they have been forced to come 

 by depriving themselves by experiment, one after another, of 

 all the assumed facts concerning the assumed functions of the 

 semicircular canals, it only remains for me to bring forward the 

 architectural reasons for the semicircular canals to prove be- 

 yond doubt that they as canals have no participation in the 

 physical processes leading up to auditory or other afferent 

 sensory stimulations, and hence are in nowise auditory or 



