Dissection of Eye of the Ox, 265 



terior termination of the Choroid coat. The plications of the 

 Ciliary processes of the Choroid coat fit into, or interdigitate 

 with corresponding plications of the suspensory ligament of 

 the Lens : this the Student should note carefully before 

 making the following 



Reflection of the Circle contained within the Ciliary 

 Ring. Let the Student divide the Choroid coat, and the 

 Retina which lies beneath it, circularly, with the scissors, about 

 i-in.behind the white ring of the Ciliary muscle, being specially 

 careful not to cut the Hyaloid* membrane ; and raise this 

 piece of Retina and Choroid coat, together with the Ciliary 

 ligament and the attached Iris in one piece ; detaching the 

 Ciliary processes of the Choroid coat from the digitations 

 which they form with the plications (also called Ciliary pro- 

 cesses) of the suspensory ligament of the Lens ; and float this 

 in water over a piece of whitened cork or wax : then gently 

 wash the pigment from the back of the Iris. Great care is 

 necessary to leave the Lens, its capsule, and its suspensory 

 ligament, and the Hyaloid membrane, in situ : but it is of the 

 utmost importance in order to the right understanding of this 

 middle section of the Eye. 



We by this means obtain a posterior view of the same 

 ciliary processes of which we have just examined the anterior 

 aspect beneath the Iris. 



The posterior surface of the Iris is covered with a deep 

 tinted pigment, called the Uvea {uvea, a cluster of grapes) 

 from the purple colour it assumes in man : after removing 

 this, the membrane of the Iris should be treated with acetic 

 acid, and then there may be seen (under the microscope) at 

 the margin of the pupil a narrow circular band of non-striated 

 m,uscular fibre {Sphincter muscle of Pupil) with which, lines 

 radiating from the centre to the circumference {Dilator mus- 



* Vide infra, Hyaloid membrane, p. 266. 



M M 



