Van Leeuwenhoek's rich legacy endures three centuries on

We microscopists live a long time. It’s because we understand the microbe world; we use our knuckles on press buttons, and wash our hands before we go to the toilet. Antony van Leeuwenhoek is a classical example of microscopical longevity. He first looked through a microscope aged 40 – yet he went on to give half a century to laying the groundwork for today’s biosciences era.

When Leeuwenhoek died, on 26 August 1723, he was in the middle of a microscopical investigation. A member of the East-India Company had sent him a sample of sand, asking him to check it for particles of gold. Leeuwenhoek had his close friend, the bookseller and publisher Reinier Boitet, make notes for a reply though, as Boitet recalled, Leeuwenhoek’s limbs were already growing numb as death approached. He still had his microscopes to hand, even when approaching his 91st birthday.

His specimens were assumed to be lost, though In 1981 I discovered nine specimen packets he’d sent to London, and undertook an extensive programme of research using light and electron microscopy. The most memorable was to take photographs of Leeuwenhoek’s fine, hand-cut sections through his original microscope at Utrecht. The results were astonishing; the lens could resolve down to 0.7µm.

He first looked through a microscope aged 40 – yet he went on to give half a century to laying the groundwork for today’s biosciences era

This made international headlines, and journalists said it was like Tutankhamun’s tomb (only smaller). My discovery became an item on the BBC’s ’News Quiz’, Robin Day interviewed me about it in London, and I was asked to appear on French television. Since then we have had TV crews from as far away as SE Asia, all keen to know what I’d found out about Leeuwenhoek’s research in the 1600s. 

During his life Leeuwenhoek made over 500 tiny single-lensed microscopes, often leaving a favourite specimen attached for later scrutiny. Almost all were lost (a set presented to the Royal Society went missing) and only nine were held by museums. Another was in private hands and was put up for auction in 2009. I bid for it up to £90,000, though the new owner paid almost half a million dollars for this tiny instrument and promptly disappeared with it.

Another Leeuwenhoek microscope was brought into the Boerhaave Museum in the Netherlands by a local resident in 1982 so the museum took it as a donation and locked it away, They only released a description twenty years later, published in an obscure Dutch journal that shortly afterwards went out of print. They tell me nobody remembers who had brought it in.

I decided on a new protocol for examining scientific instruments – scanning electron microscopy

Then – within the space of a single year – I was invited to inspect two more. Both were auction lots, though neither went to public sale. The first was a silver microscope found in a box of doll’s-house toys and taken to Christie’s for appraisal. They asked me to go and take a look, and it was clear to me that this was an original Leeuwenhoek microscope. It never went to auction; a Dutch collector purchased it privately for a fraction of its true value. He brought it to show me in Cambridge and we took it to the same pub where James Watson had celebrated cracking the code of DNA with Francis Crick.

Just a few months later, another was offered for auction on ebay. The vendor had found it in mud dredged from a Delft canal, and he described it as a “weird kind of drawing object”. I wanted to enter a bid, but the sale was suddenly cancelled. A Spanish collector had contacted the seller personally and bought it at a very low price without it ever going to auction. He sent it to me by courier and I decided on a new protocol for examining scientific instruments – scanning electron microscopy (SEM).

This was a revolution; for the first time we could scrutinise the details of manufacture. Television news came along to film the research. My detailed SEM image of the microscope is some two metres long, showing a microscope the size of a Christmas postage stamp. The details we can now study are incredible.

Ever since I first heard about Leeuwenhoek at school, I wondered whether some of his microscopes might one day be discovered. Finding his original specimens was something nobody could have anticipated – and being handed two unknown Leeuwenhoek microscopes within the space of a single year was an extraordinary surprise.

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