Tin: oi;<:ANB OF TH 177 



tute of cells; tl>>. I.-,-. ; ig chemical metamorphosis, 



i,- n-.pccti\ely the ineml.i 

 lira ne of DESCEMET. 



The internal ondot helium of il loped at an e.v 



;>rdinarily early ej>och in tin- ( 'liirk. For as soon as the structureless 

 -heet piv\iou>ly mentioned (fig. 200 /<) has attained a certain thick 

 noss. mosenchymatie cells proceeding fn m tin- margin spread them 



i out nn its inner rarfaoe aaa -ingle-layered thin cell-membrane. 



With this hegin- also i ../ the anterior chamber of the eye. 



l-'or tin- thin fun. lament of the cornea, which at first lay in immediate 



(t with tlu- front >urface of the lens, now becomes somewhat 

 elevated from the latter, ami -eparatod tVom it ly a fissure-like space 

 tilled with tluid (humor aqueus). Tin- fissure is first observable at 

 the margin of the secondary opt i cup. and spreads out from this 



ii toward the anterior pole of the lens. The anterior chamber 

 of the eye doe> not, however, acquire a greater size and its definite 

 form until the development of the iris. 



Two opposing \itws xist concerning the origin of the .structureless 



h has been described as constiti; irst fundament of the cornea in 



the Chick. According to KESSLER it is a (product of the secretion of the 



cj'i.lcrmi.s, \vlu-ivas the conical corpusch-s migrate in from t!.c im-scnchyma. 

 In his opinion, therefore, the composed of two entirely <li:T 



fundaments. According to Koi.LiKi:!:, on the contrary, all its parts are 

 devrlojied out of the mesenchyma, a:,d the homogeneous matrix simply out 

 the cells in its growth and extei.- 



In Mi inn' '//.v < ii_u r . 266) the oonditiona ditl'er som- \\hat from those 

 of the Chick ; for as soon as the lens-vesicle in Mammals is fully 



const rioted oil', it is already enveloped l>y a thin sheet of nn-mchyma 

 (Jt) with few rells. which separates it from the epid- -rini-. Tlie thin 

 layer is rapidly thickened by tlie immigration <!' cells from the 

 vicinity. Then it is >ej ai'ated int.. twolajen (tii:. *J''7), the pupillar 

 nieinl'i-aiie (//) ;u:d the fundament of the cornea (h). The form* 

 a thiii. very \a-cular memhrane lying on the ant . ace of the 



lens; its network of Hood "inmiuiicates on the one hand 



posteriorly with the vessels of the vif ly, together witli wliich 



it constitutes the tunica vasculosa lent is. and on the other anastomoses 

 at tlie margin of the optic cup with tin- va>cu!ar network ot 

 latter. The fiun lament of the corne. diarply delimited from 



the pupillary ineinl-rane at the tin..- when the anterior chamber of 

 the eye (A-) is forme 1 a> a narrow fissure, w] ; illy increase* 



in extent with the appa :ance of the iri^. 



