228 MARINE BIOLOGICAL LABORATORY. 



In closing, allow me to recapitulate the more impor- 

 tant features of oto-phylogeny, past, present, and to 

 come. 



In the PAST the ear of man was a canal organ of the 

 lateral line system of sense-organs. A system which 

 has disappeared from the surface of the adult human 

 body; but which still occurs in a reduced condition 

 during embryonic development. All its organs regu- 

 larly produced protective canals, and the auditory organ 

 came to differ from the neighboring organs merely in 

 size and the greater depth of its ampullar pit. At first 

 its functions were identical with those organs of the 

 same system, having the same nerve supply ; but 

 as it was more and more removed from the surface 

 of the body, it acquired greater protection against 

 injuries and concomitantly greater sensitiveness. It 

 increased in size and began the process of division, 

 which has resulted in the organ as it exists at the 

 present day. 



These changes required untold millions of years for 

 their perfection ; for, since palaeontological science tells 

 us that this same Amia or ganoid Dog-fish which has 

 retained its surface organs in such a primitive condition, 

 existed in its present form, at the very least, twelve mil- 

 lions of years ago, you will readily conclude that the 

 human mind can form no adequate conception of the 

 period of time which elapsed since the ancestors of 

 the Dog-fish were like the Cyclostome fishes in the 

 structure of their ears. 



For we know that at the present time Amia has an 

 internal ear of greater complication than the Torpedo, 



