3i8 AVERS. [Vol. VI. 



tions to the brain shows us that the semicircular canals do not 

 now and never have possessed any special relations to the 

 equilibrative function. In any case we cannot lose sight of the 

 primitive function of the organs which gave rise to the ear 

 organs. For the functions have probably not suffered greater 

 alterations than the structure of the organs, and the changes in 

 the latter have not been excessive, much less fundamental. 



33. From all the evidence it appears that a vertebrate may 

 live in perfect equilibrium without an internal ear. This is 

 proven beyond question by Amphioxus, which has no ear, and 

 by many forms among the lower vertebrates which may be 

 deprived of their ears without destroying or even disturbing the 

 powers of equilibration ; e.g. Boettcher's Frog, Tomascewicz's 

 Carp, and Steiner's Sharks. 



34. If there are still those who cling to the old idea of a 

 localization of the equilibrative function in the semicircular 

 canals of the ear, it should suffice for their conversion to remind 

 them that in low vertebrates, canal organs are placed on the sur- 

 face of the body in all three planes of space and in planes 

 oblique to these, and that these canals and their inclosed sense 

 organs are subject to much greater motion in the planes of space, 

 owing to their greater distance from the axis about which the 

 motions which affect them and the ear canals alike are executed, 

 and further, the surface organs are more subject to external 

 sensory impressions than the inclosed ear canals (not consider- 

 ing the probably greatly heightened sensitiveness of the latter), 

 so that these forms would not need the ear canals as equilibra- 

 tive organs ; but they are the very ones wJiich have the ear canals 

 the best developed ! 



35. As regards the canals themselves, they are not known to 

 have any other function than the one inherited from their 

 ancestors, viz. that of serving as mechanical protectors of the 

 sense organs. The ear canals belong in the list of organs 

 which continue to appear in ontogeny after the need which 

 they were originated to fill has passed away. They are to be 

 classed with such structures as valves in the horizontal veins 

 of man's body, the vermiform appendix, coccygeal bones, atavis- 

 tic muscles, and the rest of the considerable number of " nor- 

 mally " present but antiquated and functionless organs. 



36. As a good example of how simple tactile corpuscles may 



