No. I.] THE VERTEBRATE EAR. 47 



have already shown that they did not primitively have such a 

 function ; and consequently, if they now have a function in the 

 ear, it must be an acquired one. 



We have no evidence that there is any special restraint placed 

 upon the cells involuted with the sensory structures, — we will 

 say in the Shark's ear, — and they certainly have not specialized 

 in any direction, so far as we can see. All that they do is to 

 serve as a lining of the auditory canal chambers, and the most 

 that we are entitled to say, in the present state of our knowl- 

 edge, is that they may have the function of secreting calcareous 

 salts, held somewhat in abeyance, owing to the lack of external 

 stimuli to encourage it. 



While we are considering the question of stimulation, this 

 fact should not be lost sight of; viz. during the time when 

 the auditory sense organs were superficial in position the sur- 

 face cells about them had this ^^ calcareous'' function in greater 

 or less degree. It was controlled centrally, and carried out by 

 alterations of blood supply. This control by inhibition or ex- 

 citation was effected by a central co-ordinating mechanism com- 

 posed of association fibres which brought into direct or indirect 

 relation all the centres of the brain. Since these organs were 

 superficial, their immediate surroundings must have been thus 

 controlled ; and since this control could only have been exercised 

 through the fibres of the nerves supplying this region, it follows 

 that the so-called auditory nerve must contain within it those 

 fibres which controlled calcareous production on the surface ; 

 and since we are not at liberty to assume an entire annihilation 

 of the co-ordinations of earlier days, it follows that there must 

 be some sort of control of this function exerted on the lining 

 cells of the auditory channels of the ears of all existing verte- 

 brates, and that, when the function is exercised in local periph- 

 eral situations in response to local stimulation, it must be 

 exercised by sympathetic action in the ear itself, and hence 

 cause the deposit in the ear of calcareous matter, either amor- 

 phous or crystalline. 



In this connection I wish to quote Hasse's observation on 

 the nerve relations to the ciliate epithelium in Petromyzon. 

 With reference to Ketel's researches on the Cyclostome ear, he 

 says : 



" Positive Beobachtungen fur den Zusammenhang der Ner- 



