Ocular refraction and the shadow test . This small sphere is attached to the largerin much the same manner as the crystal is attached to an open-facedwatch. The axes of the eyes are parallel to each other. The eye is composed of three ineinbranes that enclose the refract-ing media or humors The membranes are the Sclerotic, the Choroidand the Retina. The humors are the Aqueous, the Crystalline Lensand the Vitreous. The outer membrane is the sclerotic and is a tough fibrous mem-brane that gives form to the eye, it is what is commonly called the white of the eye. The Cornea is a part of the scler
Ocular refraction and the shadow test . This small sphere is attached to the largerin much the same manner as the crystal is attached to an open-facedwatch. The axes of the eyes are parallel to each other. The eye is composed of three ineinbranes that enclose the refract-ing media or humors The membranes are the Sclerotic, the Choroidand the Retina. The humors are the Aqueous, the Crystalline Lensand the Vitreous. The outer membrane is the sclerotic and is a tough fibrous mem-brane that gives form to the eye, it is what is commonly called the white of the eye. The Cornea is a part of the sclerotic, formingabout one filth of its area, and is transparent. Looking at an eyeobliquely the form of the cornea may easily be seen elevated abovethe larger sphere of the eye. The form of the cornea is similar to aconvex lens. Where it joins the white portion of the sclerotic it formsa circular outline. The motor muscles are attached to the cornea is made up of four layers, the outer of which is the con- OCULAR REFRACTION. A (liagramniitic representationS.—The —Tlie —The aqueous —The vitreous —The optic —The —The centre of rotation of the eye. The straight line through the centre of lotation lo the yellow spotvision. The clotted circle shows the relative departure ftoni spherical formnormal eye e 9t. tical cross section of the humai Ch.—The choroid C.—The cornea. L.—The crystalline lens. Y.—The yellow spot, or niacu P.—The pupil. M.—The ciliary muscle. indi le ofately The crystalline lens is shownThe havigiven in this cut are notcipal parts of the eye. nucle and surrounding to be exact, it is merely 1 II V S I O L O G V AND A X A T O M V. 103 junctiva. The portion of the conjunctiva covering the cornea is verythin and is free from vessels, it is the mucous membrane of the eyeand covers the whole of the outer surface, also extending continuouslyand forming the inner coating of the
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