Anton von Leeuwenhoek
24 October 1632 – 26 August 1723) was a Dutch microbiologist and microscopist . commonly known as "the Father of Microbiology",.He was the first to relatively determine their size. Most of the "animalcules" are now referred to as unicellular organisms, although he observed multicellular organisms in pond water. He was also the first to document microscopic observations of muscle fibers, bacteria, spermatozoa, red blood cells, and crystals in gouty tophi, and was among the first to see blood flow in capillaries.-PKK