1) Jan swammerdam 2) Microscopist 3) Natural scientist 4) Naturalist 
[n] - Dutch naturalist and microscopist who proposed a classification of insects and who was among the first to recognize cells in animals and was the first to see red blood cells (1637-1680)
Jan Swammerdam noun Dutch naturalist and microscopist who proposed a classification of insects and who was among the first to recognize cells in animals and was the first to see red blood cells (1637-1680)
1637–80, Dutch anatomist and entomologist.