354 THE VITREOUS HUMOUR, BY PROF. A. IWANOFF. 



this latter, and, lying at first beneath the surface of the vitreous, 

 ascend towards the ora serrata, and become applied in the 

 form of extremely fine fibrils to the membrana limitans retinae, 

 -with which they are in close contact ; in this way the vitreous 

 and limitans are so intimately connected at the ora serrata that 

 it is impossible to separate the retina from the vitreous, por- 

 tions of the vitreous remaining constantly adherent at the ora. 

 But just as on the one hand it may be clearly demonstrated 

 that the zonula-fibres arise from the substance of the vitreous 

 behind the ora serrata, so, on the other hand, it may be shown 

 that the territory of origin of the zonula does not terminate at 

 this line. The origin of the zonula-fibres from the corpus 

 vitreum may also be shown to take place for some distance in 

 front of the ora, and consequently towards the ciliary processes, 

 so that here also the zonula and the vitreous do not form 

 isolated structures. 



The zonula Zinnii first appears to be completely differentiated 

 from the vitreous at a distance of from four to five millime- 

 ters from the ora. As it passes towards the lens it is separated 

 from the pigment layers of the smooth portion of the corpus 

 <ciliare, as well as from that of the processus ciliaris, by the pars 

 ciliaris retinae and by the eve^where demonstrable membrana 

 limitans. Nevertheless, the zonula is not prolonged to the 

 apices of those ciliary processes that project furthest forwards, 

 but speedily separates itself from them in order to pass to the 

 sequator of the lens. Having arrived at this point, the fibres 

 of the zonula break up in the form of a brush, and by means 

 of these brush -like processes the zonula becomes attached to 

 the anterior and posterior capsule of the lens. 



The first appearance of the fibres of the zonula in the vitre- 

 ous is in the form of wavy fasciculi of extremely fine fibrils. 

 At the surface of the vitreous the several fibrils composing 

 each fasciculus coalesce to form a single fibre ; and the fibres 

 thus composed are the finest of those forming the zonula pro- 

 per. At their point of emergence from the vitreous, the fibrils 

 (which have not yet coalesced) are intimately connected with 

 the limitans. Thus it happens that if an attempt be made to 

 strip off the zonula in a backward direction from the corpus 

 ciliare, it tears through at this point of the limitans. This is 



