Jan Swammerdam (12 February 1637 – 17 February 1680) was a Dutch biologist and microscopist. His work on insects showed that the stages an insect life – egg, larva, pupa, and adult – are different forms of the same animal. He did experiments on muscle contraction. In 1658, he was the first to observe and describe red blood cells. He was one of the first people to use the microscope in dissections, and his techniques remained useful for hundreds of years.