PHI GROANS <> ITBB GEln 



he epithelial ] ui -. in tin- pi. 



produc. .1 Mm e with lli 



former cases, as has already .;.,!,, ml 



al..l ..th. 



comparison may be cairi.d i Is. The j 



from the primitive an litory vesicle are at first surrounded by a 

 \ .iM-ular n.nij. et i v -t i ne layer, as the neural t uhe ami tin* epit ! 

 optir cup .i!-. Ho the pit in.- ! -I '.. brain pom pondi the 

 Mar inemlirane of tlio eye and the soft ear-capsule, or the 

 connect ive ti ue wall <>f tin- m'ml>ranou> lal.s rint h. Around all 

 thre i linn envelope has been developed for the purpose of 



protection; around tin- hrain tin- <lun niat.-r \\irh rh- cranial 

 capMili'. around tin- >yr the >rl. i'ot ica. ami around the orgin 



hearing the bony labyrinth with it> hese is to be 



a-ltled >till a third iu)trw.>;-thy agreement. In all three cases tin- 

 soft ami firm -nvrloj. -N ar.- > ; -v more or less considerable 

 ti-Mire-like spaces, which belong to tin- IvmphaMc >y>' 

 the neural tuh.- th suli.lural and the siiharachnoid >paces are fo 

 around the eye the j. i-iclior.tid ti-> IT6, ai 



the {)erilyinp! which liave r.-e. ived in the cochlea 



.1 nani.-> of scahe (ii_ L r. 233 AST and .ST i. 



The detail- of th- formation of th- - around 



the epithelial auditory \r-icle are as follows: 



Soon after the auditory > ;i e i- OeQgfcrietod :!' from the i-j.id.-i n. 

 is enveloj"d on all >ide, l.y a richly cellular me>etichyme, theindi\i- 

 dual cells of which lie in an extremely >caniy. soft 

 intercellular sulwtance, and possess each a large nucl us with a thin 

 protopla.-mic covering ha\in.i: short processes. Gradually the envelope 

 is differentiated into two layers (tigs. 279, 2> :i- \i-inity of 



the epithelial canaU the > ( ,ft intercellular substance increases in 

 amount . la become either stellate or i.ap d, m the 



former case sendiiu 



i> form, d here th.it im -diiic.it ion of connective substance known as 

 mttoout a <$ue (figs. 281 and 283 </), in which there are 



-ide of tlii> tl. main smalh-r ami : 



!\ crowded together, and are separated from one another by thin 

 j'artitions of a tirm ii.' ito substance. With an increase of 



the latter the ti>-ue BOOD aoqoim the ch iractei- - 

 cartilage (M). 



The further changes mu-t l>e foi :n the semi- 



circular canal-, the utriculu> and sacculus ami the diutu- cn.-hlearis. 



