S.B. from Cardiff

In his third talk, last week, Professor Tattersall told how man, by upsetting the balance of Nature, has laid himself open to attack by all sorts of disease. This evening he will describe how in the same way man breeds countless races of animals and plants for his own special purposes - horses for speed and strength, flowers for colour and scent, and so on - without any consideration of what ultimate effects this special development may have. So he has filled his world with domestic animals and plants highly susceptible, because over-bred, and terribly vulnerable to the attacks of parasites; and at the same time his domestic animals introduce their own parasites into parts of the world where, in the normal scheme of Nature, they would never be.