SECT. 228.] THE VITREOUS BODY. 569 



nevertheless, the essential points of the course of the fibres just 

 described remain completely the same, seeing that in these more 

 complex stars the rays of the anterior and posterior aspects do not 

 correspond, and that no fibre goes from one pole to the other. In 

 the stars, the substance of the lens is not formed of tubes as else- 

 where, but consists of a material which is in part finely granular, 

 in part homogeneous; and, therefore, it happens that, as the stars 

 pass through all the laminae, there exist three or more perpendicular, 

 non-fibrillatcd planes (central planes, Bowman) in each half of the 

 lens. The tubes of the lens become broader in the neighbourhood 

 of the stars, but do not here coalesce with each other, for they 

 terminate in clavate and fusiform enlargements of most diverse 

 form, which often appear polygonal when seen from the surface 

 (see my Micr. Anat., ii. 2, fig. 416). 



The fibres of the lena are sometimes finely striated longitudinally, and fur- 

 nished with delicate, transverse lines, which cannot be referred either to fibres 

 or to cells. — The superficial fibres of the lens are each provided, in the region 

 of the equator of the lens, with a single, beautiful nucleus, which, the further 

 we proceed inwards, becomes smaller and smaller, and at last disappears. 

 Thomas found, on sections of dried lenses, two or three systems of concentric 

 lines, which Gzermak has recently explained in a way reconcileable with the 

 structure of the lens. 



§ 228. The vitreous body {corpus vitreum) completely fills the 

 space between the lens and the retina, lying only loosely upon the 

 proper retina, except at the place of entrance of the optic nerve, 

 where the connection is somewhat more intimate; but, on the 

 other hand, being very firmly connected with the corona ciliaris 

 and the lens itself. The membrane enveloping the vitreous body 

 (the membrana hyaloided) occurs behind the ora serrata in the 

 form of an extremely fine and delicate, clear pellicle, scarcely per- 

 ceptible under the microscope; it is more readily visible at the 

 bottom of the eye-ball, where it measures o 004 of a millimetre 

 (0002'"), according to II. Muller. In front of the ora serrata, the 

 hyaloid membrane becomes somewhat firmer, and proceeds, under 

 the name pars ciliaris Jii/aloieleos s. zonula Zlnnii (lig. suspensorium 

 h ntis, Bowman), to the border of the lens, in order to coalesce 

 with the capsule of it. During this course, it divides into an 

 anterior and a posterior lamella, the latter of which coalesces with 

 the capsule of the lens somewhat behind its border, but continues 

 to be recognisable (Arlt, H. Muller) throughout the whole extent 

 of the circular fossa of the vitreous body. The anterior lamella, 

 connected with the ciliary processes, forms the zonula, in the more 



