372 



HITCHCOCK'S ANATOMY 



it presents in different persons — and it is the color of tins 

 which we mean when we speak of the color of the eye — cor- 

 responds in position to the cornea lying immediately under it. 



FiG. 342. 



Era. 343. 



External View of the Iris. Anterior Segment of a Transverse Section 



of the Globe of the Eye seen from within. 

 1, Divided edge of the three Tunics ; Sclerotic, Choroid (the dark layer), and 

 Eetina. 2, Pupil. 3, Iris, the surface presented to view in this section being 

 the Uvea. 4, Ciliary Processes. 5, Scalloped Anterior Border of the Retina* 



It is circular in form, containing a few muscular fibers, with 

 a circular opening through its center, from one third to one 

 twentieth of an inch in diameter, which is known as the pupil. 

 The Ciliary processes are minute triangular folds of the Cho- 

 roid coat, which lie upon the interior surface of the iris, with 

 their bases directed toward the pupil. They are aJbout sixty 

 in number, and are divided into large and small, the latter 

 being placed between the former. The Pigmentum Nigrum, 

 or black paint, is an extremely tenuous membrane, which 

 lines the inside of the choroid coat. It is of a jet black color, 

 and is easily destroyed merely by allowing a stream of water 

 to fall upon it. 



683. Retina. — The inner membrane of the eye is the Re- 

 tina, which is merely an expansion of the optic nerve, upon 



What is the diameter of the iris? What are the ciliary processes? How many are 

 there? What is the pigmentum nigrum ? 688. Describe the retina. 



