WHEN ONIONS ARE APPLES.

Thames Star, Issue 14664, 19 April 1915, Page 3

WHEN ONIONS ARE APPLES.

SOME ILLUSIONS-AND SOME FACTS. "Never!" you reply instant—and nobody will pick a fault 'v.ith you,. For no one would for a moment imagine anyone mistaking an onion for an apple. But don't be too sure ! Some day, when you have nothing else to do, cut a small square^ onion and a square of apple of the same size, close your eyes, and hold your nose tightly, and then get • someone to hand you one o f tho squares, without telling you which one it is. You would be well advised not to wager any money on being able to tell by chewing which it is ! The explanation is that a large part of what we call taste is really smell. Altogether there arc some very peculiar illusions which we experience every day, and yet do not notice. For instance, get someone to trace a line across your wrist— which you keep perfectly, still. You will then feel as if it is your wrist that is moving—and not the pen?ilpoint ! Or touch your forehead with the fore-finger. Keep the latter, motionless, and slowly rotate your head, and you will have an irresist-' ible sensation that it is the fingertip that is moving, and not the hen,d. Next, take our power of vision. There are innumerable little illusions to which we are all susceptible. Hold up this paper at arm's length, look intently at it, and if you notice closely you will find that it appears to move to meet your eye. FIXING THE EYE. Or look round for two objects that are almost in line with your eyeonly the one nearer to you than the othsr. Fix "your eye on the object further off for a little time, and lo ! if you just note it, £he nearer object is doubled ! It is one of the most interesting! facts in psychology that objects nearer or further off than the one our attention is focusscd on appear double to our sight. But we have habitually, though unconsciously, trained ourselves not to notice this blurredness, and it is only by a sharp and constant use of our wits that we can now observe it. . There are some interesting facts, too, in connection with the brain; How many people know, for instance, that it is the right-hand side—or hemisphere of the brain—that manages, or works, the left-hand side of the body, and vice versa ? Most people know —or have heard, at any; rate —that the brain is one of the most complex little machines in the universe. The outer core of it, composed of greyish matter, is called the cortex. And a wonderful; thing it is ! It is made up of little cells, each con- ' nected by hundreds of fibres—and there are 3,000,000,000 of these cells! So that our system is infinitely more delicate 'and complex than we generally suppose. EARS AND HEARING. Even in, say, the inner ear, besides countless) other minute organisms, there is a little tunnel—for protecting dslicate, fibres—that is composed 'of 'over ten thousand rods leaned against one another, 20,000 in all for each man's hearing "machine!" Not only is the ear for hearing, but. it has been found to have another function—that of warning us when we are about to fall, or of giving as the sensation of giddiness. Hence the reason why many who are deaf and" dumb, and have their inner ears destroyed, are incapable of being made dizzy. Lastly, there is—what we might call a n illusion—colour-blindness. This may take various forms. Some of you may have it in one form or another, and yet actually not be aware, of it, so little do we think of those common everyday experiences ! For instance, one i'airly common kind of colour-blindness is that of seeing red as green, and vice versa. It is perhaps not known that many people are afflicted with this defect. Normally, of course, it does not matter very much ; but one can easily imagine how dangerous it might be in. the case, say, of a signalman, or an engine-driver on the railway. It might be worth our whiile, after all, to test the matter with your friends.—"Answers."