 But in the 1930s, the proof that bacteriophages were viruses was provided by Christopher Andrewes (1896–1988) and others.They showed that these viruses differed in size and in their chemical and serological properties.In 1940, the first electron micrograph of a bacteriophage was published and this silenced sceptics who had argued that bacteriophages were relatively simple enzymes and not viruses.