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a natural incompatibility between midges of different origin. Midges from North Germany showed themselves willing to mate with members of their species from Schwaben, but the midge offspring produced were not viable. If the midges from different German provinces had an antipathy for each other, then midges from different continents would surely produce offspring that were unviable. So they bred a race from California and French midges. When they were released in the town of Okpo, the males of the Mainz bastard race proved to be great lovers and competed successfully with the Burmese males, but the eggs laid by the wives they had mated with did not produce any new midges. The chromosome count of the different species of midge did not tally and genetic destruction took place. The advantage of this way of destroying midges is obvious—the risk of contaminating food and plants by spraying them with insecticides disappears. Professor Laven is continuing his researches on the basis of the most recent genetic discoveries. He radiates male midges with about 4,000 r X-rays. This does not cause the creatures any organic damage, but the chromosome chain between the genes is damaged. The chromosome household is disturbed, the genes are changed and insects develop in an unprogrammed sequence. They are still capable of reproduction, but their offspring are reduced in every way i.e. in number, size, etc. Of some midge generations treated in this way who continue to hand down their planned disability, Laven said: 'There is no cure for semi-sterility, because it is hereditary.’ Laven is convinced that in a comparatively short time it will be possible to use his model experiment against other harmful insects; he even thinks that the plagues of rats in many parts of the world can be tackled in this way. The tremendous possibilities of manipulating the genetic code are no visionary dream. We are dealing with scientific facts. Of course between yesterday and tomorrow lies the 'abyss' that will be crossed. Most probably we shall only rediscover something that has already happened. One day new knowledge and techniques will create a human organism suited for interstellar flight, one that will not fall sick and will be equal to all the burdens and stresses imposed on it. Medical science has been performing transplants of organs for more than twenty years, but unproductive and unpleasant sensation-mongering about these important scientific operations did not begin until after the first heart transplant. When pieces of skin were transplanted in the 1940's, when bones were changed in 1948 and when a kidney was transplanted in 1950, there was not a murmur. In 1954 the first transplant of a limb on to a dog was successful. In 1955 somebody else's lung was inserted into a man. In 1967 a pancreas was transplanted and in 1969 doctors risked the transplant of a It was the heart transplant which first unleashed lively discussions and violent opposition in all the newspapers in the world—probably because there is an unspoken feeling that it fulfills more than the function of a simple pump. Strangely enough, man, who enjoys living and is terrified of death, has not welcomed this advance of medical science with open arms. Yet the prospect of being able to save a man's life by changing a defective organ is an important one. Many teams of surgeons know how to perform the surgical operation. As soon as the threshold of the immune reaction can be lowered without the body's own defences against infection being endangered, transplants should take place as a matter of course, just like operations for appendicitis. But that is the moment when the supply of spare liver. There were successful transplants of other organs besides these.