57° 



STRUCTURE OF THE 



[sect. 228. 



M. 



restricted sense of the term, and is inserted into the capsule some- 

 what in front of the border of the lens. Between the two lamellae 

 and the border of the lens there is seen on transverse sections a 

 triangular space, completely encircling the lens — the canalis Petiti. 

 This canal contains a little clear fluid, but is very narrow during 

 life; for the zonule of Zinn, which forms its anterior wall, follows 

 the plications of the ciliary processes in the form of a much-folded 

 membrane, by which means it approaches very closely to the pos- 

 terior wall in as many places as there are ciliary processes. These 



folds are also visible at the part 

 where the zonula, after leaving 

 the processes, passes over to the 

 border of the lens as a part of the 

 posterior wall of the camera oculi 

 posterior; and thus we find that 

 the zonula is attached, not in a 

 straight but in a slightly wavy 

 line, to the capsule of the lens, 

 partly in front and partly behind 

 the equator. According to Fink- 

 beiner, the fine fibres, into which 

 this membrane spreads itself out, 

 may be followed in certain cases 

 over the whole anterior wall of 

 the capsule of the lens. 



With regard to the structure of 

 the parts mentioned, much pains 

 have been lately devoted to the 

 examination of the proper vitreous 

 body ; and the truth has, perhaps, 

 been pretty nearly arrived at. 

 Briicke's opinion was, that the 

 vitreous body consists of con- 

 centric lamellae, like an onion, 

 separated by a gelatinous fluid; but this view has been refuted by 

 Boivman, who showed that the concentrated solution of acetate of 

 lead, employed by Br'ucke for the exposition of these lamellae, gave 

 rise to the appearance of lamellation, not only at the surface of 

 the vitreous body, but also on the surface of any section ; but in 

 no case did this method of investigation bring true lamellae dis- 

 tinctly into view. There appear to be more facts in favour of 

 Hannover's assertion (founded on an examination of the vitreous 



Sections of the vitreous humour hardened 

 in chromic acid. A. Transverse section of a 

 human eye, perpendicular to the axis of the 

 optic nerve, with radiating striation in the 

 vitreous humour. B. Section of the eye of a 

 horse, made parallel to the axis of the optic 

 nerve, and carried horizontally, to show the 

 concentric stratification of the vitreous body. 



