Accommodation is that function of the visual organ whereby it is able to adjust itself so that rays of light coming from different distances may all be focused upon the retina consecutively. In other words, it is that power of the eye whereby the refraction of the organ may be increased or decreased within certain limits at will.
''The contraction of the ciliary muscles causes the zone of Zinn to advance, and thus diminishes the traction exerted by the latter upon the crystalline. The lens, abandoned to itself, assumes the form which the elasticity of its fibers naturally gives it, and becomes more convex, especially its anterior surface.
''When the innervation ceases, the ciliary muscles are relaxed; the ciliary processes become tense, and stretch the zone of Zinn, which, in turn, flattens the crystalline by exerting upon it a traction in the direction of its equator." Thus during a large