Who discovered virus in microorganism?

Answer 1

The first person to use the word "virus" to describe unknown toxins smaller than bacteria was Martinus Beijerinck, although the existence of toxins of this type had been observed earlier through the use of unique bacteria filtration devices. He used the word "virus" because he assumed the toxin was a soluble fluid of some type ("virus" is Latin for poison/venom). It was not until later that Wendell Stanley proved that viruses were solids, and much later the electron microscope was able to show that they had complicated structures.