'"II i.l.KM-I \ 



:\ 



It 1.x dltlicult to tollou tin 



ease, which i-'.,i. 



developed 1>N an epithelial cell in the wall of the vehicle. The 



ma 11 calcareous ism> becomes 



enlarged in Consequence, and 



'ndolymph. \\'hen it ha- hecoi in-a\i!y loaded \\ . 



>alts. it i^ c..nne-ted with the wall l.\ means of a stalk . 



linai; Mies entiielv deta. the wall ai.d fall 



cavity of th*- ve-icle. in 

 which it i- k. 

 in^ and rotating 1 

 ciliate cell.-. 



In Vertebrates th. 

 otocyst, which, as wo 

 have .-oen. airives in its 

 fundament with 

 tiie orpin of he. 

 in Invertel.raie- is con- 

 '1 into a very com- 

 plicated structure. the 



membranous labyrinth, 



the evolution of which 



I -hall de- 

 some detail. 

 metal 



in which tli-- 

 of ftilil* 



* pla\- the 

 principal 1 



The audit nr\ -a.- d. 

 taehed from the ej.i 

 dermi.-. and lyin- at the 

 side of the aft er I .rain, so< m e\!. -ally directed pi 



jectioll. ! i 



Prohahly we have to do in thi- with the n-min 

 stalk hy mean- of which the auditory vehicle was connected witl. 

 t-pitlcriiii.x. AccordiiiLf t<> Minn- iii\- . on the , 



.-talk lixappe:irs entirely and thi- e\ a-inat i. .n is a new strut" ' 

 The lir.-t a-sumption i^ t a vorcd especially hy the pn-viin; '>neil 



condition in the Selachians tlu. presence of a long tube, which 

 maintains a permanent connection l>etwe.-n lahyri:. 



in 



M-rilu 



It 



n 



X ^ .-- y 



Fig. TO. -Membranous labyrinth of the left side of a 

 [human] embryo, afU-r fci 



hlearis ; A&, pocket 

 ; liur canal U formed; 



an>i * com- 



Mmkftnolar 



canals are dev i 1,0), enlargement of the 



i of the an- 

 t ical canal arisra. An opening (o) has been 



raoestus labyrinthi. Region of the jiuckct - 



becomes the common arm of the two vertical 



: he common pocket 



