560 



COMPARATIVE PHYSIOLOGY. 



upon one another, experiment has shown that they vibrate in 

 response to the movements of the drum-head en masse ; though 

 the stapes has by no means the range of movement of the han- 

 dle of the malleus; in other words, there is loss in amplitude. 



Fig. 403.— Section of auditory organ of horse (after Chanveau). A, auditory canal; 

 B, membrana tympanl; C, malleue; D, incus; F, stapes; (?, mastoid cells; H, 

 fenestra ovalis; /, vestibule: J, K, L, outline of semicucular canals; M, cochlea; 

 JV/ commencement of scala tympanl. 



but gain in intensity. A glance at Fig. 404 will show that the 

 end attained by this arrangement of membrane and bony levers, 

 which may be virtually reduced to one (as it is in the frog, etc.), 

 is the transmission of the vibrations to the membrane of the 

 fenestra ovalis, through the stapes finally, and so to the fluids 

 within the internal ear. But it might be supposed that, for the 

 avoidance of shocks and the better adaptation of the apparatus 



