1851-1931 (79 years old)
Year of great discovery/work
With his discovery of the difference between bacteria and viruses, Beijerinck founded the field of virology while also realizing that viruses could only replicate in cells. He was also a botanist, which ultimately directed his work toward studying the different types of bacteria in soil. Because he tended to study more plant microorganisms rather than medical bacteriology, he was not as well know as he may have been.
Botanists study all plants—from tiny ones that you can hardly see to giant trees!