water model of the human eye
Date: 1954
Inventory Number: 2001-1-0003
Classification: Eye Model
Subject:
Maker: George Wald (1906 - 1997)
Maker: Biological Laboratories, Harvard University (founded 1932)
Donor: Ruth Hubbard (born 1924)
Cultural Region:
Place of Origin:
Dimensions:
19.8 × 5.1 × 3.3 cm (7 13/16 × 2 × 1 5/16 in.)
Accessories: absorption cell with a solution of rhodopsin
DescriptionThis shop-built apparatus consists of a blown-glass flask with a removable stopper. The flask (13 mm radius) is shaped like a human eyeball, having a spherical bulge (6 mm radius) shaped like the cornea on the front surface and a slightly flattened rear surface. The size of the eyeball is also similar to that of a real eyeball so that it mimics closely the optical sytem of the human eye. In use, the replica of the human eyeball is filled with water.
The front of the "water eye" is placed behind a metal screen, which has a rotating disk pierced with three circular holes of differing sizes. This diaphragm mimicked the pupil of the eye.
The flattened rear of the "water eye" was set up against a clip holding a small absorption cell (10 x 2 x 2 mm). The cell contained a solution of cattle rhodopsin to which hydroxylamine had been added.
The metal screen and rhodopsin cell clip were are attached to the front and rear of a metal bracket with a clip to hold the "water eye." The assemblage is mounted an a brass rod.
The front of the "water eye" is placed behind a metal screen, which has a rotating disk pierced with three circular holes of differing sizes. This diaphragm mimicked the pupil of the eye.
The flattened rear of the "water eye" was set up against a clip holding a small absorption cell (10 x 2 x 2 mm). The cell contained a solution of cattle rhodopsin to which hydroxylamine had been added.
The metal screen and rhodopsin cell clip were are attached to the front and rear of a metal bracket with a clip to hold the "water eye." The assemblage is mounted an a brass rod.
In Collection(s)
Signedunsigned
FunctionTesting the loss and restoration of light sensitivity, by the bleaching and resynthesis of the visual pigment rhodopsin.
Historical AttributesThis instrument, which George Wald called a "water eye," was a "replica of a human eyeball ...blown from glass." Professor Wald had the eye built in Harvard's Biological Laboratories in order to study the phenomena of light and dark adaptation of the human eye. These were commonly ascribed to the bleaching and resynthesis of visual pigments in the cones of the eye. Wald used the water model of the eye to study the bleaching rhodopsin when exposed to diffuse white light. He found that a "high degree of light adaptation can be achieved with very little bleaching of rhodopsin." Further study led him to a photochemical view of vision in which the microstructure of the eye's receptors were sensitive to a single quantum of light and the relationship had to be considered on a molecular level.
Primary SourcesGeorge Wald, "On the Mechanism of the Visual Threshold and Visual Adaptation," Science, 119, no. 3104 (June 25, 1954): 887-892.
ProvenanceGeorge Wald, Biological Laboratories, Harvard University, 1954-1997; Ruth Hubbard, wife of George Wald, Biological Laboratories, Harvard University, 1997-2001; transfer to CHSI, 2001.