Antonie van Leeuwenhoek

History

Anthony van Leeuwenhoek was born in 1632. He was the first son of Philips Antonyszoon ( a Delft basket maker) and Margaretha Bel van den Berch (from a brewery firm). On 4 November 1632 he was baptized as ‘Thonis Philipszoon’, however, he called himself ‘van Leeuwenhoek’ because his parental house in Delft was on the corner (is “hoek” in Dutch) next to the Leeuwenpoort.

The father of van Leeuwenhoek died in 1638, whereupon his mother remarried. Ten year later also his stepfather died. Van Leeuwenhoek went to school in Warmond, during this time he lived by an uncle in Benthuizen. After his school, van Leeuwenhoek learned for the first time to work with a magnifying glass when he was apprenticed to a Scottisch cloth merchant, William Davidson, in Amsterdam. In this time, the quality of clothing was judged by thread-counting, for which of course magnification is essential.

Van Leeuwenhoek married Barbara de Meij and moved to Delft in 1953 or 1954, where he opened his own drapery business. Together they had five children, unfortunately his wife died in 1666. In 1660 he became the Chamberlain of the Council Chamber of the Sheriffs of Delft, which ensured him of income. Van Leeuwenhoek got therefore the so called “sinecure”, this means that he was an office with salary but he has no fundamental obligations. In 1671 van Leeuwenhoek remarried with Cornelia Swalmius, progeny of a pastor family. In 1679 he became an inspector of wine measures, which required a certain amount of mathematical knowledge. In 1694 his wife Cornelia died, whereupon he remained with his daughter Maria – his other children already died.

Van Leeuwenhoek was a rich man. This became obvious from the capital he left for his daughter when he died: ninety thousand guilders. On 26 August 1723 Van Leeuwenhoek died in his hometown Delft, he was almost 91 years old. There are stories which claim that on his death bed he dictated a letter to the Royal Society in London. In this letter he explained the condition of his diaphragm so thoroughly, that this disease is now known as the Van Leeuwenhoek’s disease. Van Leeuwenhoek was buried in the “Oude Kerk” (The Old Church) in Delft.

In his spare time, van Leeuwenhoek became interested in lens making, and had also become familiar with Robert Hooke’s Micrographia (1665) which probably encouraged him to try his lenses on materials other than fabric. In 1673, a friend of van Leeuwenhoek, the famous Dutch physician Reinier de Graaf wrote to Henry Oldenburg. Henry Oldenburg was the secretary of the Royal Society in London at that time. Reinier de Graaf introduced him to the Society as a maker of microscopes better than any other and enclosing the first letter from van Leeuwenhoek to the Society. This was the beginning of a series or around 560 letters that continued throughout van Leeuwenhoek’s life, to the bitter end. Despite the fact that van Leeuwenhoek – by the use of his handmade microscopes – observed cell structures and later little animals (bacteria, yeast) and thus “inventing” microbiology, he was not a teacher and had no followers in the city. Luckily for history he made a lot of drawings of what he saw and there was the letter correspondence with The Royal Society.

The microscope & The Royal Society

Van Leeuwenhoek’s interest in glass processing and his interest in microscopes has led to one of the most significant and simultaneously well-hidden, technical insight in the history of science. He placed the middle of a small rod of soda lime glass in a hot flame, he could pull the hot section apart to create two long whiskers of glass.

The end of one whisker was reinserted by the use of the flame, in this way he could create a very small, high quality glass sphere. Eventually these spheres became the lenses of his microscope; the smaller the sphere, the higher the magnification. Since his technique wasn’t very complicated, he realised it was critical that no one would know how he did it. If the scientific community knew his simple method for creating the critically important lens, they would disregard or might even forget his role in microscopy. Therefore he allowed others to believe that he was laboriously spending most of his nights and free time grinding increasingly tiny lenses to use in microscopes. However, the fact remains that van Leeuwenhoek made hundreds of microscopes.

The discoveries of van Leeuwenhoek began in 1674, when he examined samples from the cloudy water of the Berkelse Meer. (a lake near Delft which no longer exists). Nowadays van Leeuwenhoek is generally mentioned in connection with the discovery of microorganisms. However, his studies were much broader than microorganisms He dissected insects and examined anything that would fit on his microscope.
The first letter to the Royal Society illustrates this clearly, as it covers the sting, head and eye of a bee, and the structure of a louse as well as his observations of fungus that he said grew on leather, meat and other things. In 1673 his earliest observations were published by the Royal Society in its journal: Philosophical Transactions. Despite the initial success of Van Leeuwenhoek’s relationship with the Royal Society, this relationship was soon severely strained. In 1676 his credibility was questioned when he sent a copy of his first observations of microscopic single-celled organisms. Since previously no one had ever seen single-celled microorganisms, his observations of microscopic life were initially met with scepticism. Eventually, in the face of Van Leeuwenhoek’s insistence, the Royal Society sent an English vicar together with a team of respected judges and doctors. Finally in 1680 the observations of Van Leeuwenhoek were fully vindicated by the society.

Using a Microscope

Nowadays the van Leeuwenhoek microscopes usually end up as curiosities in musea, while many of them could still be used. One enthusiast, [http://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-uk.org.uk/mag/artjul07/hl-loncke2.html Hans Loncke], aims to make exact copies of the existing authentic AvL microscopes. He makes his own microscopes by methods that would have been available to van Leeuwenhoek. Using of one of Loncke’s facsimiles, Lesley Robertson has spent many hours trying to repeat Van Leeuwenhoek’s experiments, and photographing and filming the results.

Many film fragments, photos, different light sources, an set-up spanning over 300 years and lots of patience has led to fascinating results. We are very grateful that we are allowed to show the following three movies, illustrating what Anthonie van Leeuwenhoek saw 300 years ago. </br> The movie below shows a clump of Vorticella feeding on bacteria. The animals are attached to sediment particles by their spring-like stalks which extend when the animal is ready to feed. When the mouth opens, the cilia around it can be seen beating to generate a vortex that traps the prey (usually bacteria) and carries it into the mouth for digestion.

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The second movie, see below, shows an unknown worm that appeared during filming intended to prove that van Leeuwenhoek could work with a single candle for illumination. Protozoa can be seen swimming around the algae in the background.