CHAP, vi DIOPTRIC MECHANISM OF THE EYE 



267 



The outer or fibrous coat (known to the ancients indifferently 

 as solera, cornea, or dura) consists of two distinct parts : an 

 anterior, transparent portion, tho cornea, and a posterior, opaque 

 part, the sclerotic. The middle coat, or uvea (from its likeness 



Epithelium 

 con/unctivae 



Can at is 

 Schlemmii 



Musculus 

 ciliaris 



Arteria ciliaris ant. 





gamenrum 

 suspensorium 

 lent is 



Vena uorticosa 



^p^r 0///c 



c / '^>^^ i -'""> 

 Sc/era S3|S&&;j 





-* miiis> 

 'fj'iimy 



\Mc. 

 amina cribrosa 



^li'^m-Dural sheath 



Arteria cent rails 

 retinae 



}'['.. 10i;. Diagram of the adult right human eye, horizontal section. Magniticil li \ imcs. (Luciuni 

 I'rfiin A. E. Schiifer.) The line a b passes through the c(|uatcir, .< y through the "i>tic axis of 

 1 he eye; A. c.p., posterior ciliary art ery ; .1. >."., anlfi inr i-iliai-y artery ; N.c., one of the ciliary 

 in-iAvs ; F.i'., vena vorticosa ; e.r.m., external rectus muscle; a.c., anterior, p.i\, posteriui 

 chamber of the eye; /'.<., Pel it's canal. 



to a black grape from which the stalk has been torn away), is 

 now subdivided into three portions a posterior, pigmented part, 

 the choroid ; a middle region which is muscular and bears 

 papillae, the zona ciliaris ; and an anterior diaphragm formed by 

 the iris, the aperture in its centre being the pupil. The inner 

 coat, known as the retina, arachnea, or arachnoid, because it 



