Antony van Leeuwenhoek

Antony van Leeuwenhoek

1632-1723

In the 1600s, the Dutch Republic was in its Golden Age.  Dutch ships traded with far-off ports feeding the coffers of the world’s first modern economy.  The robust business climate allowed a class of artists and intellectuals to develop like never before in this little lowland country.  In prosperous Delft, two such people were born in the same year, 1632.  One was Jan Vermeer who captured the times in his exquisite paintings with startling use of light and perspective.  The other was Antony van Leeuwenhoek, a curious haberdasher who changed our world by discovering one that was so tiny, no one even suspected it was there.

Van Leeuwenhoek had simple schooling and no formal training in the sciences.  He was apprenticed to a Scottish draper at the age of 16.  At the age of 22, he opened his own retail linen shop in Delft and married his first wife.  They had five children, only one of which lived beyond babyhood.   His business success led to his appointment as City Chamberlain.  In his 30’s, his wife died but he remarried a few years later.  Around this time he was certified as a land surveyor, a profession that gave him valuable mathematical tools for calculating distance and angles.  Around the time that Vermeer died at the age of 43, Van Leeuwenhoek was just beginning his scientific career.

He became fascinated with microscopes.  Early 1600’s microscopes used two convex lenses and could only magnify twenty to thirty times with a resolution of about 8 microns.  Van Leeuwenhoek and others discovered that a single, very small spherical lens could have magnifications well beyond this.  He set about painstakingly grinding extremely tiny lenses. Since the focal length of a tiny lens is very short, he mounted the lens and a specimen in a handheld device that could be held right up to the eye.  The result was the first microscope that could magnify as much as 266 times to a resolution of one micron. 

With his little microscopes, Van Leeuwenhoek studied anything he could stick on the end of a pin: salt crystals, animal organs, and insect parts.  He made detailed drawings of what he saw and began to write a series of letters to the Royal Society in London to report his observations.  In these letters, he reports his discovery of red blood cells, something that had never been seen before. But it was a drop of pond water that really changed everything; it was teeming with tiny “animalcules.” 

“.. among all which there crawled abundance of little animals, some of which were roundish; those that were somewhat bigger than others were of an Oval figure: On these latter I saw two legs near the head and two little fins on the other end of their body.”

At first the Royal Society didn’t believe it.  The budding scientific method required repeatability.  Since no one could create a microscope with the resolution of Van Leeuwenhoek’s microscopes, replication was a problem.  It took many years before the Society finally asked Robert Hooke to replicate the experiments.  On his third try, Hooke discovered:

 “great numbers of exceedingly small animals swimming to and fro dis discovered great numbers of exceedingly small animals swimming to and fro…They were observed to have all manner of motions to and fro in the water; and by all, who saw them, they were verily believed to be animals; and that there could be no fallacy in the appearance …. there was no longer any doubt of Mr. Leeuwenhoek’s discovery.”

Vindicated at last, Van Leeuwenhoek was made a fellow in the Royal Society in 1680.

During the remainder of his life, Van Leeuwenhoek would describe a whole new world of microbiology.  He would make over 300 microscopes, one for each specimen (only nine of his microscopes survive today).  He experimented with blowing glass rather than grinding to make even more powerful lenses.  He was extremely protective of his technical methods so little is known about just how he did it.  But his publication of his biological discoveries cataloged dozens of individual microorganisms.  He also estimated their size and number using the techniques learned as a land surveyor.  Imagine the reaction when he estimated that there were more of these tiny animals in a glass of water than there were humans on earth.

Though revolutionary in its day, Van Leeuwenhoek’s microscope technology would prove to be a dead-end.  It would be 100 years before the invention of compound microscopes would allow microbiology to advance.  It would be almost 200 years before Lister and Pasteur put microorganisms into a medical context.  Clearly, Van Leeuwenhoek was a scientific pioneer way ahead of his time.  

Question of the Day: In 1981, who found some of Van Leeuwenhoek's original specimens in the collections of the Royal Society of London?