Antoni van Leeuwenhoek. Coloured portrait of the Dutch microscopist Antoni van Leeuwenhoek (1632- 1723). Leeuwenhoek built his own microscopes, grinding the lenses himself, according to a single lens design that could magnify up to nearly 200 times. He was not the first microscopist, but his instruments enabled him to see in greater detail than was previously possible. He was the first person to observe and describe protozoa, bacteria and sperm. He also studied insect life cycles with great accuracy. This artwork formed the frontispiece of Epistolae ad Societatem Regium Anglicum (1719), a collection of letters he wrote to the Royal Society in London, England.