386 SPECIAL HISTOLOGY. 



("central planes/' Bowman) exist in each half of the lens. 

 Moreover, the tubes themselves in the neighbourhood of the 

 " stars" become less distinct, are gradually fused together, 

 and ultimately lost, without any line of demarcation, in the 

 substance in question. 



§ 229. 

 The vitreous body or humor, occupies the entire space between 

 the lens and the retina; its relations being such that excepting at 

 the point of entrance of the optic nerve, where the connexion 

 is rather more intimate, it is only in loose apposition with the 

 retina, whilst it is very closely united with the corona ciliaris 

 and the lens itself. The membrane enclosing the vitreous 

 body, or the hyaloid membrane, which behind the ora serrata 

 constitutes an extremely fine and delicate, perfectly transparent 

 membrane scarcely perceptible under the microscope, in front 

 of that part becomes rather firmer (fig. 296 t), and is continued 

 to the border of the lens as the pars ciliaris hyaloidece s. zonula 

 Zinnii (" suspensory ligament of the lens," Bowman [and Bet- 

 zius]), where it becomes blended with the capsule of that body. 

 In doing this it splits into two lamella, a posterior (v), which is 

 blended with the capsule of the lens a little behind its border, 

 and cannot be traced further, so that beyond that point the 

 posterior wall of the lenticular capsule and the vitreous body 

 are directly in contact ; and an anterior (u) connected with the 

 ciliary processes, — the zonula in the more restricted sense, — 

 which is attached to the capsule of the lens a little in front of 

 its margin. Between the two lamellae and the border of the 

 lens, there is left a space surrounding the latter in an annular 

 manner, and, in a transverse section, of a triangular form — the 

 canal of Petit ; — which, though containing a little clear watery 

 fluid, yet during life is very narrow, inasmuch as its anterior 

 wall or the zonula Zinnii so long as it is continuous with the 

 ciliary processes, like them presents the aspect of a much pli- 

 cated membrane, and consequently is brought into close ap- 

 proximation with the posterior wall, at as many points as 

 there are ciliary processes. These folds, however, are still 

 visible where the zonula, quitting the ciliary processes, is con- 

 tinued independently upon the border of the lens, as a part of 

 the posterior wall of the posterior chamber of the eye ; and it 



