546 BULBUS OCULI 



are firmly cemented, and it presents for study an anterior 

 surface, a posterior surface, and a circumference or equator. 



The anterior surface is not so highly curved as the posterior 

 surface. Its central part, which corresponds with the pupillary 

 aperture of the iris, looks, through the pupil, into the anterior 

 chamber of the eye. Around that part the margin of the 

 pupillary orifice of the iris is in contact with the lens, whilst 

 nearer the equator the anterior surface of the lens is separated 

 from the iris by the fluid in the posterior chamber of the eyeball. 

 The posterior surface of the lens presents a higher degree of 

 curvature than the anterior surface, and is received into the 

 fossa hyaloidea of the vitreous body. The equator or circum- 

 ference is rounded. It forms one of the boundaries of the 

 spatia zonularia. The manner in which the zonula ciliaris is 

 attached to the capsule in this vicinity has been described 

 already. 



Faint radiating lines may be seen on both surfaces of the 

 lens, and they give a clue to its structure. They indicate 

 the planes along which the extremities of the lens - fibres 

 come into apposition with each other. 



The capsule of the lens is a resistant glassy membrane, 

 which is considerably thicker anteriorly than posteriorly. 



Dissection. The anterior wall of the capsule may now be 

 divided with a sharp knife. A little pressure will cause the 

 body of the lens to escape through the opening. The stained 

 capsule can be very advantageously studied whilst floating in 

 water. 



If the lens body is compressed between the finger and thumb, 

 it will be noted that the outer portion or cortical part is soft, 

 whilst the central part or nucleus is distinctly firmer. When 

 the lens is hardened in alcohol it can easily be proved that it is 

 composed of numerous concentrically arranged laminae. 



Chambers of the Eyeball. The anterior chamber of the 

 eyeball is the space between the cornea, anteriorly, and the 

 iris and central part of the lens, posteriorly. At the irido- 

 corneal angle it is bounded by the ligamentum pectinatum 

 iridis, and there the aqueous humour which fills this chamber 

 finds access to the spatia anguli iridis. 



The posterior chamber is a circular space or interval which 

 is bounded, anteriorly, by the posterior surface of the iris, and, 

 posteriorly, by the circumferential part of the anterior face of 

 the lens. Peripherally, the posterior chamber is closed by 

 the thick anterior projecting ends of the ciliary processes. 

 It also is filled with aqueous humour. 



