680 



DISEASES AND THEIR -TREATMENT. 



The humors are three in number, and they serve as reflectors 

 of the light. They are : the aqueous humor, crystalline lens, and 

 vitreous humor. The last is the largest, and occupies about four 

 fifths of the whole interior of the globe, or eyeball. The appendages 



" Figs. 892, 893, 894, 895.— Different Types of the Eye in Health. 



of the eye are the 'eyelids, eyelashes, and the membrana nictitaris, 

 generally called the haw, which is situated in the inner or lower 

 angle of the eye. It is connected with the different muscles of the 

 eyeball. By the contraction of the straight muscle of the eye, the 

 haw is forced outward, and us one, of the beautiful arrangements that 

 nature has provided for the protection of so delicate and sensitive 



Fig. 896. 



a, Optic nerve ; b, Sclerotic; e, Choroid; d, Retina; e, Cornea; f, Iris; g, h, Ciliary circle; 

 i, Insertion on crystalline lens; j, Crystalline lens; k, Crystalline capsule; 1, Vitreous body; m, 

 n, Anterior and posterior chambers ; u, Membrane of aqueous humor ; p, p, Tarsi ; q, q, Fi- 

 brous membrane of eyelids; r, Elevator muscle of upper eyelid; s, s, Orbicularis muscle of eye- 

 lids; t, t, Skin of Eyelids; u, Conjunctiva ;' v, Membrane covering cornea; x, Posterior rectus 

 muscle ; y, Superior rectus muscle; z, Inferior rectus muscle; w, Orbital membrane. 



