Show Fluid That Continually Spreads Over Retina Gives Us the Ability to See I The elaborate mechanism for vision vision vision vi vi- sion would fail to give ability to see if it were not for a fluid that continually continually continually contin contin- spreads over the retina the viewing plate in the back of the eyeball eyeball eye eye- ball on which the objects seen are projected as a picture according to toa toa toa a writer in the New York Herald- Herald Tribune This plate is covered with witha a structure of oC rods and cones which appear to be the elements clements from which the picture is transmitted to the sight center in the thc brain These rods and cones would be unable to transmit their picture unless they were covered with a fluid called visual visual visual vis vis- vis- vis ual purple The chemical nature ot of this suo- suo stance has been unknown Dr Selig He Hecht ht of Columbia university has ascertained that it is a protein by establishing its size by passing it through a porous porcelain filter This test showed it has a molecular lar weight of about which indicates it is a highly complex molecule and a protein since no DO other class of substances possess such high molecular weights Visual purple has been extracted from animals animals' eyes and has been found sensitive to light In its natural natural natural nat nat- ural state it is a pinkish color but when it has been exposed to light it changes to a yellow and finally becomes colorless By leaving it inthe in inthe inthe the dark it will return to its original pink color and regain its sensitivity to light When the eye looks at too strong a light the thc visual purple is changed to its inactive state and when the eye is plunged into a dark area from one too strongly illuminated illuminated illuminated it is unable to see well until the visual purple has been regenerated regenerated regenerated regen regen- or a new supply spread on the retina Carotene a parent substance from which the body makes vitamin vitamin vitamin vita vita- min A seems to be necessary for forthe forthe forthe the body when it is manufacturing visual purple Lack of vitamin A leads to u i s. s |