visual purple 名詞
 視紫質,視紫紅質
 Op·tog·ra·phy n.  Physiol. The production of an optogram on the retina by the photochemical action of light on the visual purple; the fixation of an image in the eye.  The object so photographed shows white on a purple or red background.  See Visual purple, under Visual.
 ◄ ►
 Pur·pu·rog·e·nous a.  Biol. Having the power to produce a purple color; as, the purpurogenous membrane, or choroidal epithelium, of the eye. See Visual purple, under Visual.
 ◄ ►
 Vi·sion n.
 1. The act of seeing external objects; actual sight.
    Faith here is turned into vision there.   --Hammond.
 2. Physiol. The faculty of seeing; sight; one of the five senses, by which colors and the physical qualities of external objects are appreciated as a result of the stimulating action of light on the sensitive retina, an expansion of the optic nerve.
 3. That which is seen; an object of sight.
 4. Especially, that which is seen otherwise than by the ordinary sight, or the rational eye; a supernatural, prophetic, or imaginary sight; an apparition; a phantom; a specter; as, the visions of Isaiah.
    The baseless fabric of this vision.   --Shak.
    No dreams, but visions strange.   --Sir P. Sidney.
 5. Hence, something unreal or imaginary; a creation of fancy.
 Arc of vision Astron., the arc which measures the least distance from the sun at which, when the sun is below the horizon, a star or planet emerging from his rays becomes visible.
 Beatific vision Theol., the immediate sight of God in heaven.
 Direct vision Opt., vision when the image of the object falls directly on the yellow spot (see under Yellow); also, vision by means of rays which are not deviated from their original direction.
 Field of vision, field of view.  See under Field.
 Indirect vision Opt., vision when the rays of light from an object fall upon the peripheral parts of the retina.
 Reflected vision, or Refracted vision, vision by rays reflected from mirrors, or refracted by lenses or prisms, respectively.
 Vision purple. Physiol. See Visual purple, under Visual.
 Vis·u·al a.
 1. Of or pertaining to sight; used in sight; serving as the instrument of seeing; as, the visual nerve.
 The air,
 Nowhere so clear, sharpened his visual ray.   --Milton.
 2. That can be seen; visible.  [R.]
 Visual angle. Opt. See under Angle.
 Visual cone Persp., a cone whose vertex is at the point of sight, or the eye.
 Visual plane, any plane passing through the point of sight.
 Visual point, the point at which the visual rays unite; the position of the eye.
 Visual purple Physiol., a photochemical substance, of a purplish red color, contained in the retina of human eyes and in the eyes of most animals. It is quickly bleached by light, passing through the colors, red, orange, and yellow, and then disappearing.  Also called rhodopsin, and vision purple.  See Optography.
 Visual ray, a line from the eye, or point of sight.
 Visual white Physiol., the final product in the action of light on visual purple. It is reconverted into visual purple by the regenerating action of the choroidal epithelium.
 Visual yellow Physiol., a product intermediate between visual purple and visual white, formed in the photochemical action of light on visual purple.
 ◄ ►
 visual purple
      n : a red photopigment in the retinal rods of vertebrates;
          dissociates into retinene by light [syn: rhodopsin, retinal
          purple]