ILLUSTRATIONS 



FIGURE PACE 



B. Diagram section of the cochlea, showing the 

 ascending and descending spiral duct and the cochlear 

 duct containing the organ of Corti or true organ of 

 hearing. 



C. Greatly enlarged view of the cochlear duct, 

 showing the organ of Corti with its damper, hair cells 

 and hearing nerves. 



104. — Series Showing the Membranous Labyrinth 



OR Inner Ear from Fish to Man . . 205 



(After Retzius.) Right side; outer view. 



A. Shark (Acanthias). 



B. Ganoid fish {Lepidosteus). 



C. Primitive reptile (Hatteria). 



D. Alligator. 



E. Primitive mammal (Rabbit). 



F. Man. 



105. — Development of the Labyrinth or Inner 



Ear of Man 206 



(After Streeter.) 



106. — Transverse Section of the Head in a 

 Frog, Showing the Relations of the 

 Middle Ear (there is no Outer Ear) 

 to the Inner Ear and of the Latter to 

 the Brain ...... 208 



(After T. J. Parker and W. N. Parker.) 



107. — Embryo Sturgeon, Showing Gill Clefts 209 

 (After W. K. Parker.) 



108. — Human (A) and Macaque (B) Embryos, 

 Showing Origin of the External Ear 

 FROM Six Tubercles . . . .211 



A. From Leche, after Selenka. 



B. From Leche, after His, Keibel. 



(A, B, from Der Mcnsch, Gustav Fischer.) 

 xxxviii 



