510 



THE HUMAN BODY. 



between the eyelids as the ivliite of the eye. Both are tough 

 and strong, being composed of dense connective tissue. The 

 white of the eye and the cornea are covered by a thin layer of 

 the conjunctiva, 4 and 5. Behind the proper connective- 

 tissue layer, 3, of the cornea is a thin structureless membrane, 



FIG. 142. The left eyeball in horizontal section from before back. 1, sclerotic; 

 2, junction of sclerotic and cornea; 3, cornea: 4. 5, conjunctiva; 6, posterior 

 elastic layer of cornea; 7. ciliary muscle; 10, choroid; 11, 13, ciliary processes; 

 14, iris; 15, retina; 16, optic nerve; IT, artery entering retina in optic nerve; 18, 

 fovea centralis; 19, region where sensory part of retina ends; 22, suspensory 

 ligament; 23 is placed in the canal of Petit and the line from 25 points to it; 24, 

 the anterior part of the hyaloid membrane; 26, 27, 28 are placed on the lens; 28 

 points to the line of attachment around it of the suspensory ligament; 29, vitreous 

 humor; 30, anterior chamber of aqueous humor; 31, posterior chamber of aqueous 

 humor. 



6, lined inside by a single layer of epithelial cells; it is the 

 membrane of Descemet, or the posterior elastic layer. 



The second coat consists of the choroid, 9, 10, the ciliary 

 processes, 11, 13, and the iris, 14. The choroid is made 

 up of blood-vessels supported by loose connective tissue 

 containing numerous corpuscles, which in its inner layers 

 .are richly rilled with dark-brown or black pigment granules. 

 Towards the front of the eyeball, where it begins to diminish 

 in diameter, the choroid is thrown into plaits, the ciliary 

 processes, 11, 13. Beyond these it continues as the iris, 

 which forms the colored part of the eye seen through the 

 cornea; and in the centre of the iris is a circular aperture, 



