THE LENS 



1063 



formed by the front part of the vitreous, while its anterior capsule is in contact 

 with the aqueous fluid and lies close against the back of the pupillary margin of 

 the iris. When in position the lens measures nine millimetres across, and about 

 four millimetres between its poles. 



On each surface a series of fine, sinuous, grey lines can be seen radiating from the pole to- 

 ward the equator, called respectively the anterior and posterior stellate figures. The lines 

 observable on the posterior are always so placed as to be intermediate with those on the anterior 

 surface, so that on viewing them through the lens they occupy a position corresponding to the 



Fig. 806. — Diagrammatic Representation of the Blood-vessels of the Eyeball. 



(Parsons, after Leber.) 



Arteries red; veins blue. 



s.p., Short posterior ciliary arteries. Lp.c, Long posterior ciliary artery, a.c, Anterior 



ciliary vessels. C of S., Canal of Schlemm. c.a.i.ma., Circulus arteriosus iridis rnajor. v.v,. 



Venae vorticosae. a. conj., Anterior conjunctival vessels, p. conj., Posterior conjunctival vessels. 



(t.caiy 



C.ofS 



intervals between the lines on the anterior surface. The lens-capsule is comparatively brittle, 

 and can be readily cut through when scraped with a sharp-pointed instrument; on doing so the 

 divided edges curl outward, away 'from the lenticular substance. When removed from its 

 capsule, the outer portion of the lens is found to be soft and glutinous, but its substance gets 

 progressively firmer as we approach the centre. This harder central part is known as the 

 nucleus [nucleus lentis], and the surrounding softer matter as cortex [substantia corticahsl. 

 The cortical part shows a tendency to peel off in successive layers. It consists of long fibres, 

 the ends of which meet in front and behind at the anterior and posterior stellate figures. 



