. A treatise on anatomy, physiology, and hygiene : designed for colleges, academies, and families. fractory power of any transparent medium. Itis found, on examination, that the cornea, the vitreous, the 922. What is the use of the cornea, aqueous, crystalline, and vitreoushumors? 923. What is the office of the retina? 924. What is thefunction of the optic nerve ? How is sensibility conferred on this organ ?Give the 1st observation in this connection. The 2d observation. PHYSIOLOGY OF THE ORGANS OF VISION. 407 crystalline, and the aqueous humors, have each, severally,various degrees of density
. A treatise on anatomy, physiology, and hygiene : designed for colleges, academies, and families. fractory power of any transparent medium. Itis found, on examination, that the cornea, the vitreous, the 922. What is the use of the cornea, aqueous, crystalline, and vitreoushumors? 923. What is the office of the retina? 924. What is thefunction of the optic nerve ? How is sensibility conferred on this organ ?Give the 1st observation in this connection. The 2d observation. PHYSIOLOGY OF THE ORGANS OF VISION. 407 crystalline, and the aqueous humors, have each, severally,various degrees of density; and that the crystalline lens, atits circumference, is more dense than at its centre. Thesecircumstances modify the direction of the refraction of therays of light, in their passage from the cornea to the retina. 926. The refracting powers of the plane, convex, concave,plano-convex, plano-concave, and concavo-convex lenses,*are different. The cornea and aqueous humors are convexo-concave, the vitreous humor is concavo-convex, while thecrystalline humor is a convexo-convex medium. (Fig. 139.). Fig. 142. The forms of the different lenses. 1, A plane lens. 2, A globe , A convexo-convex lens. 4, A plano-convex lens. 5, A concavo-concave , A plano-concave lens. 7, Meniscus. 8, A concavo-convex lens. 927. The different degrees of convexity or concavity alsomodify the refracting character of transparent crystalline lens is of different degrees of convexity onits two sides. The convex surfaces of the aqueous andvitreous humors are segments of circles, of different diame-ters from their concave surfaces. (Fig. 139.) AH these * The rcfractin- character of differently-formed lenses is illustratedin the works on Natural Philosophy, to which the pupil is referred. 925. Have the cornea and the humors of the eye different degree, ofdensity > What is said of the crystalline lens? What effect has the£ density of the parts of the eye upon the light^mUted to thisor-a
Size: 2595px × 963px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bo, booksubjectanatomy, booksubjecthygiene, booksubjectphysiology
