Antonie van Leeuwenhoek

Antonie van Leeuwenhoek, born in Delft in 1632, was a Dutch microbiologist and microscopist during the Golden Age. Largely self-taught in science, he is remembered as the Father of Microbiology and one of the first microscopists. His pioneering microscopy work helped establish microbiology as a scientific field.

Raised in Delft after his father, a basket maker, died when Antonie was five, his mother came from a brewer’s family. After his stepfather died, he lived with an uncle and at 16 became a bookkeeper’s apprentice at a linen-draper’s shop in Amsterdam. In 1654 he married Barbara de Mey, and they had one surviving daughter, Maria; four other children died in infancy. He opened a draper’s shop selling linen, yarn, and ribbon. Over time, he gained municipal roles: chamberlain for the sheriffs (a job he held for nearly 40 years), land surveyor, and official wine-gauger in Delft. His first wife died in 1666; he remarried in 1671 to Cornelia Swalmius, with whom he had no children. He was a contemporary of painter Johannes Vermeer, likely knew him, and acted as executor of Vermeer’s will. His religion was Dutch Reformed and Calvinist, and he saw his discoveries as proof of divine creation.

Van Leeuwenhoek developed an interest in lensmaking while running his draper shop, wanting to see thread quality better. He made single-lensed microscopes of his own design, creating lenses by heating a small rod of soda lime glass and pulling it apart, then reinserting the end into a flame to form a tiny, high-quality lens. For lower magnifications he also ground lenses. He kept his methods confidential, perhaps encouraging others to think grinding was his main technique.

In the 1670s, he began exploring microbial life with his microscopes. He was the first to observe and experiment with microbes, which he called dierkens, diertgens, or diertjes, and was the first to roughly determine their size. Most of these “animalcules” are now known as unicellular organisms, though he also saw multicellular ones in pond water. He was the first to document microscopic observations of muscle fibers, bacteria, spermatozoa, red blood cells, and crystals in gouty tophi, and among the first to see blood flow in capillaries. He did not write books but described his discoveries in chaotic letters to the Royal Society, which published many in their Philosophical Transactions.

His work reached the Royal Society through physician Reinier de Graaf, who praised his microscopes as far surpassing any seen before. In 1673, the society published a letter from Van Leeuwenhoek on mold, bees, and lice.