No. I.] THE VERTEBRATE EAR. ^^ 



though it is occasionally true here that the otoliths are second- 

 arily dissolved out by the sea-water : such dissolution is usually 

 prevented by the plugging up of the entrance to the ear by a 

 mass of calcareous matter imbedded in mucus. 



The presence of otoliths over the area occupied by the 

 maculae utriculse and sacculi in all vertebrates, and the assumed 

 universal presence of these structures in the auditory organs of 

 all invertebrates, has led P. Meyer into a speculation as to their 

 significance. He starts with the assumption that Johannes 

 Miiller had proved that the otoliths in fishes were of service to 

 the animal in audition by reinforcing sound by resonance, 

 whereas this was merely a supposition of Mtiller's. Meyer 

 also points out that the membrana tectoria of the cochlear 

 papilla basilaris is free from the otolithic structures present in 

 the other cochlear organ of the Sauropsids, the papilla lagenae. 

 The speculations offered by this author are simply repetitions 

 of some of the views already offered, and with the exception of 

 those referring to the otoliths themselves are treated of in 

 another place. The functions of the otoliths are entirely un- 

 known ; but, for my own part, I consider them foreign bodies, 

 which, if now of functional value to the vertebrate ear, have 

 acquired that value, or rather have forced the sensory structures 

 to which they adhere with great readiness and in large num- 

 bers, to accommodate themselves to their presence. It is pos- 

 sible that they now perform their functions with the aid of the 

 otoliths, though it is diflficult to see what possible service the 

 otoliths can render the auditory percipient elements, and their 

 presence can be shown to be detrimental to the action of the 

 percipient elements, as they execute their function in their 

 primal state. Hence I may say that, so far as the otoliths are 

 concerned, I am not in possession at present of facts enough 

 to deny that they may play a role in auditory physiology. It 

 is true, however, that they are not primarily necessary struc- 

 tures, for they are absent from the canal sense organs. They 

 are produced in the greatest relative and absolute abundance in 

 the lower vertebrate forms, whose ears retain connection with 

 the sea-water, and whose blood is surcharged with calcareous 

 matter; e.g. sharks. In bony fishes the separate particles, which 

 in sharks always remain discrete, are united together, forming 

 the ear stones. 



