\ YER. 1 7 1 



' cord, with the ;;. traverses 



endowed \\ithiii the stalk, which is in.\v :i i|iiite compact structure. 



l-'inally tin- ti tin* intermediate layer, apart tn.m it^ 



producing the vitreous body, takes a fu: vo Hhare in the de- 



velopment of the whol" eye. inasmuch as tha <h i. 



adjacent to the optic cup is dill'.Tentiat. d into tin- choroid nn-mhrane 



<ti. -(')' </') ami tin- sd.M the eye. 



After having thus delineated hrietly tho source of the most 

 important components of the eye, ii will !> my purpose in what 

 {'..Hows to pursue in detail the development of ea< "parately. 



I shall Infill with the lens and vitreous body, then pass to the optic 



au.l at that point a. 11 an ac, :uation of the 



choroid membrane ami th ii-a, as well as the opti 



in a final M-i-tion I shall treat of the organs that are accessory to the- 



optic cup the eye-lid . rymal irlamls and their ducts. 



(a) The Dei- of the Lens. 



When the lens- reside has been completely 00 



primitive epidermis (fig. 264 B Is), it possesses a thick wall, which i-> 

 composed of two or thiv- layers "i epiilielial c.-lls. ami encloses a 

 cavity that in Jirls is part inly tilled with tluid, Imt in the case of 

 Mammals by a mass of small cells. The mass of cells is the result 

 of a proliferation of the ino>; sup -rticial flattened sheet of the primitive 

 epidermis; it is without importance in the further development a 

 transient mass, that soon degenerates and is absorbed when the 1 

 til ros are developed. (ARNOLD, MIIIALKOVICS, GorrsniAi:. K 



rnally the epithelial vesicle is sharply limited by a thin 

 membrane, which is afterwards thickened int<> '//e of the lens 



ila lentis). There are two opposing views in regard t. 

 develo].m"nt. According to one, the capsule is a cut icular -true 

 that is to sa y, a structure secivt<-d by tin* celK of the lens at t 



ording to the u it is the product of a co 



tissue lay. r. to be described more fully hereafter, enveloping 

 lens-vesicle. 



In latei ierable (h o in the developn 



of the anterior and posterior walls (fi<r. 266). In the region of the 

 anterior wall the epithelium (le) becomes more and more flattened; 

 the cylindrical ivlls are ronv.-rt ! into e inents, which are 



preserved throughout life in a Mnirle layer and constitute the so-called 

 lens-ejnf heli' >nn in the L adult ifiLT. -'!> A 1 '). In the posterior 



