Colour Blind People Can Never See a Ghost.

Kaipara and Waitemata Echo, 15 May 1914, Page 8

Colour Blind People Can Never See a Ghost.

Science has discovered that colour blind persons never see ghosts. Their eyes are not made the right way for it. The scientist who has made this discovery is Dr. August Lummer, head of the Physical Institute of the great University of Breslau in Germany. He holds that it is proved that persons who honestly believe that they see ghosts are victims of optical illusions. The effort to see in an almost dark place creates the effect of very strange apparitions and hence the subject, being probably also in a nervous condition, imagines that he sees ghosts. The normal eye has an arrangement of tiny rods -and bones in the retina. The rods perceive light and the cones colour. When a person with a normal eye tries to see in a half dark place the cones, which are useless, interfere with the effective action of the rods and the confusion creates the effect of apparitions that come and go and change their shapes. The colour blind person lacks the cones and his rods act with extraordinary efficiency in the dark. The colour blind person sees a clear, permanent outline of things as long as there is the least amount of li.ijht present. That means that he never sees ghosts. In order to understand this interesting fact or theory, it is necessary to study the intricate structure of the eye. /The retina of the eye consists of ten layers, v of which only the second layer, containing the rods and cones, interests us. The function of • the rods and cones is very different, one from the other. "With the cones wte perceive colour, with the rods we perceive light and fociis. The normal eye has about an equal num-, her of cones and rods. In the totally colour blind eye, however, the cones are absent. In the eye that ■is partially colour blind there are some cones, but the set" of nerves communicating red and green, or yellow and blue to the brain, are atrophied. A person who is redblind, is always green blind, both sol ours appearing black or grey ; the person who is blue blind is always yellow blind, both colours appearing luminously white or grey. To the person who is totally colour blind daylight is extremely disagreeable. This is due to the fact that beinjf equipped only with a light-seeing apparatus, untempered, and not toned down by the colour which, is everywhere apparent, a sunlit landscape makes the impression of a snow-clad landscapo, and we all know how trying snow is to the eyes. However, in the dark the colour blind person, equipped with an apparatus very much more sensitive for glimpsing at feeble light than the normal person.: A speck of paper so tiny as to be unperceived in the dark by the normal* eye, will be readily perceived and correctly located by the colour-blind eye, which is able to focus in the dark, a feat which the normal eye can never accomplish, because in the normal eye only cones—the colour-see-ing instruments—are contained in that spot of the eye which brings into focus all objects apprehended by vision, while in the colour-blind eye this spot is equipped with rods. Upon this fact, the inability of the normal eyes to focus even such objects in the dark which are sufficiently luminous and large of area to be seen, depends the seeing of ghosts and spooks. x No room is entirely dark. Through some slit in the shutter, some crack in the wall a ray of light is certain to find its way into a room. Falling iipon a large surface, say a nightgown hung against the wall, .or a petticoat thrown over a chair, it attracts tlie- attention of the person who has been awakened with a shock by some slight noise, the nibbling of a mouse, or the flipflapping of a bat or bird. Sitting up in bed, with heart beating, the person who has been rudely aroused from slumber stares at the object which confronts him. Nowi another peculiarity of the cones is that they look at objects in a straight line, while the rods see things sideways. Accustomed as the normal eye is to focus with the cones at play, it tries to look straight at the object which it sees. But wa can*aot see colours in the dark, for the sense of colour is due to the absorption of some rays of the sun's spectrum and the reflection or transmission of others, and the . cones, consequently are entirely powerless to" help* their owner in determining not only the colour and nature of the object, but even its exact location. The rods try valiantly to do their work. They glance sideways at the object, and the object is seen not very plainly, but in an uncertain flickering <eort of way. Determined to make out what it is the eye strains hard to look at the strange thing in a straight line. In doing this the acteon of the rods is suspended for the moment, and the helpless cones are turned upon it instead. Of course, i they see nothing, and the object in consequence seems to disappear. This is repeated in rnpid .succession. The nerves, irritated by being rudely awakened, aj.^t'aMitiii , y u,r elusiveness of the object which extinguishes itself and reappears with will-o'-the-wisp ease, help the eye in investing its tormentor with shape I and substance of a ghost. The illusion of a spook is perfect, and it will take a man with strong I cerves,. indeed, to resist the hallu- I

cination that he is actually entertaining a visitor from another world. On the other hand, the colourblind man, as we have seen, is furnished only with rods, the organs which give perception of light and dark and the form of objects. His sight in a dark place is not hampered by the presence of cones in his retina. If he sees anything at all he sees a permanent, dark object, not a wavering, fluctuating, ghost-like object.