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Why is it that we often cannot remember names, addresses, telephone numbers and ideas even when we try our hardest? We 'sense' that what we are looking for is hidden somewhere in the grey cells of our brain and is only waiting to be rediscovered. Where has the memory of something we know perfectly well gone to? Why cannot we make use of our store of knowledge as and when we require? Robert Thompson and James McConnell of Texas spent fifteen years tracking down the secret of memories and their whereabouts. Having carried out all kinds of experiments, they finally made flatworms from the family with the sonorous name Dugesia Dorotocephala the stars of an experiment that was to lead to fantastic results. These creatures are among the most primitive organisms that possess cerebral substance, but at the same time they have a complicated structure which can be completely regenerated by cell division. If one of these little worms is cut in pieces, each single piece renews itself and becomes a complete and absolutely intact flatworm. Thompson and McConnell let their starlets crawl about in a plastic trough, to which they connected a weak electric circuit. In addition, they installed their desk lamp with a sixty watt bulb above the trough. As flatworms are very aphotic (averse to light), they curled up every time the lamp was switched on. After the two scientists had repeated this game of ‘light on, light off’ for a few hours, the worms no longer took any notice of the constant changes. They had realised that no deadly peril threatened them, that darkness followed light and vice-versa. Now Thompson and McConnell combined the light stimulus with a weak electric shock, which affected the creatures a second after the light went on. Whereas the worms had ignored the light stimulus before, now they curled up again when they felt the electric current. The worms were allowed a break of two hours before they were put on the rack again. Then it turned out that they had not forgotten that they must expect an electric shock after the light came on. They curled up after it was switched on even if the expected shock did not come. Next the two patient investigators cut the worms into small pieces and waited for a month until the parts had regenerated to complete worms. Then they were returned to the test trough and the desk lamp was switched on at irregular intervals. Thompson and McConnell made the astounding discovery that not only the heads which had regenerated a new tail, but also the tail pieces which had built up a new brain curled up for fear of the expected electric shock! Had chemical processes taken place in the cells which had stored the 'old' memories and transmitted the past experiences to the newly formed cells? That was exactly what had happened. When an 'unskilled' flatworm devours a 'skilled' fellow creature, he takes over the abilities his victim has acquired. Experiments in other laboratories confirmed that if the cells from an animal that had been taught certain skills were inserted into the body of another animal the same skills continued to function. For example, rats were taught to press a specially coloured key if they wanted to reach their food. When the animals had completely mastered their lesson they were killed, an extract was taken from their brains and injected into the abdominal cavities of untrained rats. After only a few hours the untrained rats were already using the same coloured key. 4 - Mankind's Storehouse Of Memory