Swammerdam, Jan (1637–1680)

Dutch naturalist who is considered a founder of both comparative anatomy and entomology. Based on their metamorphic development, he classified insects into four main groups, three of which are still used in a modified form in insect classification. He was also probably the first to discover red blood cells when he observed oval particles in frog's blood in 1658.

Swammerdam was born in Amsterdam and studied medicine at Leiden but never practised as a physician. From 1673 he was under the influence of a religious zealot.

Swammerdam accurately described and illustrated the life cycles and anatomies of many insect species, including bees, mayflies, and dragonflies.

Swammerdam also provided a substantial body of new knowledge about vertebrates. He anticipated the discovery of the role of oxygen in respiration by postulating that air contained a volatile element that could pass from the lungs to the heart and then to the muscles, providing the energy for muscle contraction.

In his work on human and mammalian anatomy, Swammerdam discovered valves in the lymphatic system (now called Swammerdam valves). He also investigated the human reproductive system and was one of the first to show that female mammals produce eggs, analogous to birds' eggs.

Swammerdam's manuscripts were not published in full until 1737, when Hermann Boerhaave published Biblia naturae/Bible of Nature, a two-volume Latin translation of Swammerdam's Dutch text, with illustrations engraved from Swammerdam's drawings.