Bacteria .................. .

The story of the biological relationship between man and micro-organisms is one of evolution. Although there is fossilised evidence of the existence of bacteria thousands of years ago, we know that mutation of strains of bacteria has occurred and
altered their properties. Even in the last hundred years the bacterium which made scarlet fever, a deadly disease in the 19th century has ceased to be an organism of high strength. However, nowadays the viruses are much more active and of far greater significance than formerly, as the widespread use of antibiotics has resulted in some strains of organisms developing a resistance to the antibiotics.