268 



THE ANATOMY OF THE HORSE. 



■i 



y 

 t 



d 



% 



f pupil. 

 in the 



the scissors. Another incision may then be made parallel to ttsf'''® ' 

 and about half an inch from it. The piece of sclerotic betwio* ; , 

 incisions may then be raised and turned backwards by destroyed ^'j^y 

 slender processes, nerves, and vessels that connect it to the chore li T'ji^ 

 the anterior edge of the piece of choroid thus exposed, and imm^ '-'^ ^ 

 behind the rim of the iris, there will be seen a whitish zone — the 

 bodi/, or anmdus alhidus. \ 



The Aqueous Humour occupies a chamber which is bounded i 

 by the posterior surface of the cornea ; and behind by the capsu 

 suspensory ligament of the lens, and by the ends of the ciliary prfcesi ^-^ ^--.^ 

 It is across this chamber that the iris extends, and the chamber il sofnne- 

 times described as being divided by the iris into two compartmens, M'iz-, 

 an anterior, in front of the iris ; and a posterior, behind it. kn V^he 

 living eye, however, the posterior surface of the iris contacts with the 

 lens-capsule, so as to leave only a narrow chink behind the attaichm^nt 

 of the curtain to which the term posterior chamber may be kppVied. 

 The aqueous humour is composed of water with a small propolrtion of 

 common salt in solution. j\ 



The Iris is a muscular pigmented curtain extended across the ifcaterior 

 of the eye, and having about its centre an aperture termed the 



By va,riations , 

 size of this aj k'erture 

 the amount ofa ' lig^*' 

 transmitted to e ! the re- 

 tina is regulatfoied. It 

 varies somew ia. hat in 

 colour, but is n usoost fre- 

 quently of a yesedllowish- 

 brown tint. broilts an- 

 terior surface, ove which 

 shows some linljunes con- 

 verging to the p upil, is 

 bathed by the an-e queous 

 humour, as is anesilso its 

 posterior surfacased imme- 

 diately internal^ siito its 

 attachment. ' is The 

 greater part oik. f the 

 posterior surface] , how- 

 ever, is in contac[ cct with 

 the capsule of th^pea lens, 

 glides on it during the movements of the curtain. The ciiye.rcum- 

 ferential border is attached within the junction of the scleroti(dia: and 

 The inner border circumscribes the pupil, which variinnes in 



Fig. 37. 

 Choroid Membrane and Iris exposed bv the kemoyal 

 OF THE ScLEROTit AND CORNEA (Qiuii.t after Zinn). 

 a. One of the segments of the sclerotic thrown back ; b. Ciliary 

 muscle ; c. Iris ; e. One of the ciliary nerves ; /. One of the vasa 

 vorticosa or choroidal veins. 



and 



cornea. 



