Figure 1. Drawings of bacteria from Antoni van Leeuwenhoek’s 1683 letter to the Royal Society (left; Source) and one of Robert Koch’s photographs of Bacillus anthracis from 1877 (right; Source). Wikimedia Commons/Wellcome Images.
Robert Koch published the first photographs of individual bacteria in 1877, nearly 200 years after Antoni van Leeuwenhoek sent drawings of bacteria in a letter to the Royal Society. Long before cameras were linked with microscopes, generations of microscopists relied on their own eyes, pencil, and paper to record what microbes looked like and what they were doing. What happened during that centuries-long lag period between hand-drawn illustrations of microbes and the true-to-life images that biologists are used to today?
When microscopes were first invented, there was no such thing as photography. After Leeuwenhoek and other microscopy pioneers like Robert Hooke (inventor of the word “cell” in the 1665 book Micrographia), scientists of the late 1700s improved light microscopes to produce images with less distortion. However, the only imaging devices at the time were camera obscuras. Camera obscuras produced focused images of a scene inside of a large box or room, but there was no method to preserve the image.
Figure 2. The basic use of a solar microscope seen in Microscopic Delights of the Mind and Eye by Martin Frobenius Ledermuller in 1760. Source (public domain due to age)
The beginnings of photography are seen in Thomas Wedgwood's experiments with photosensitive chemicals in England during the 1790s. Wedgewood and chemist Sir Humphry Davy published a paper in 1802 on ”Copying Paintings by the agency of Light upon Nitrate of Silver.” In it they explained how to copy images of small objects by using a solar microscope. Before the invention of electricity, solar microscopes fit in a window with a mirror hanging outside to reflect sunlight, projecting the image onto a wall inside. By treating paper or glass with silver nitrate, Wedgewood could capture the projected image from a solar microscope indirectly with a camera obscura device, like taking a picture of a picture. There was just one problem—he had no way of fixing the chemistry. Unless the medium was held in the absence of light, the image continued to develop, eventually turning solid black. Wedgewood and Davy came close, but no photomicrographs from their experiments survived.
The next breakthrough came in the 1830s from another scientist working in England, William Henry Fox Talbot, working with his wife Constance Fox Talbot. Like Wedgewood, Henry Fox Talbot was using solar microscopes to project an image, paper as a medium, and silver nitrate as the photosensitive chemical. Only Talbot added a crucial step: before applying silver nitrate, he wet the paper in a weak solution of table salt.
Figure 3. An calotype photograph of plant stems by William Henry Fox Talbot in 1841. Source
The salt reacted with silver nitrate to produce an even more sensitive coating of silver chloride. Then, Talbot halted the exposure after recording by adding a stronger salt solution. Talbot captured images of plant stem cross-sections at 20x magnification using this salt print technique in 1839 and using a further improved calotype process in 1841. By definition, these were world’s first photomicrographs.
But Talbot did not capture the first photograph a microbe. For that, we skip from England over to Alfred François Donné in France, a bacteriologist and doctor who discovered the human pathogen Trichomonas vaginalis in the 1830s.
Figure 4. The Leitz Panphot released in 1953. Does it begin to look familiar? Source.
Frustrated with using solar microscopes in the cloudy weather of Paris, Donné and one of his students came up with the their own photo-électrique microscope in the early 1840s: the first microscope to use an electric arc as a light source. Meanwhile, another French man named Louis-Jacques-Mandé Daguerre invented the first mainstream photographic process, the daguerreotype. By combining the photo-électrique microscope with daguerreotype photography, Donné captured an image of T. vaginalis, becoming one of the first if not the first person to truly photograph a microbe. In 1844, he published a complete atlas of 80 photomicrographs, most taken at 400x magnification.
Heading into the second half of the 1800s, a number of German companies like Zeiss and Leitz (surviving today as Leica) began to commercialize microscope-camera setups. Photomicroscopes were improved iteration by iteration by separating the different parts and eliminating vibration between the camera and the microscope lens. Most of the horizontal and vertical microscope models from 1850 through the early 1900s (including the one used by Robert Koch to take those first photos of bacteria in 1877) appear antiquated by modern standards. By 1953, the Leitz Panphot was launched, a successful model that echoes the design most biologists use today, with the camera system adjacent to an upright microscope.
Figure 5. Ernst Haeckel’s drawings of slime molds from Artforms of Nature, 1904 (left: Source) and a modern photograph of the slime mold Physarum Polycephalum (right). Photo credit: Scott Chimileski
However, for all that imaging has done and continues to do for biology, some the most beautiful and most revolutionary scientific illustrations come from that era before microscope cameras were common. Antoni van Leeuwenhoek did not make his drawings–nevertheless the drawings by the artists he worked with as seen through his microscopes are instantly recognizable icons of modern science. In the end, science is enriched by those drawings and by other masterpieces like Ernst Haeckel’s Artforms of Nature, published between 1899 and 1904. These drawings are precious. They are a window into our scientific awakening as a species—forever a part of the history of science.
Daniel P. Haeusser. 2013. Pictures Considered #4. Koch’s Development of Early InstaGram Positive Photography. Small Things Considered.
Thorburn. 1974. Alfred François Donné, 1801-1878, discoverer of Trichomonas vaginalis and of leukaemia. Br J Vener Dis. Oct; 50(5): 377–380.
Overney, N., Overney, G. 2011. The History of Photomicrography. Microscopy-UK