In the 19^th century the scope of biology was divided between medicine – which investigated questioned of form and function through physiology – and natural history – which was concerned with the diversity of life and the interaction between forms of life and non-life. By the beginning of the 20^th century these two domains overlapped, giving way to specialised scientific disciplines such as geology, embryology and bacteriology. Technological advancement boosted scientific experimentation. Microscopy, for instance, impacted directly on biological thinking in so far as the ever-sharper focus on the basic units of an organism afforded by microscopes and cameras, pointed to the importance of the cell. This led to the cohering of nascent disciplines such bacteriology and to the fomentation of debates such as that around vitalism vs. mechanism, which had been going on since the time of Aristotle.

Darwin’s On the Origin of Species (1859) brought a definitive order to the world of organisms promptly after Theodor Schwann’s and Matthias Schleiden’s 1838 cell theory. The later was made possible by the improvements in the microscope that took place in the 19^th century to lay bare the basic structure of cells. A radical shift in biology came with the germ theory championed by Louis Pasteur, who demonstrated that most diseases were caused by bacteria. The human condition improved together with the refinement of technology, which sharpened the view of the world and its tiniest details escaping human vision. Further complications came with the introduction of X rays, which revealed unexpected complexities in the structure of atoms. The final element of disruption came with Albert Einstein’s theory of relativity in 1905, which redefined physics as the study of relations between observers and events rather than of events themselves. 

The progressive infiltration of the human eye into the folds of the natural world gave rise to a series of inventions and deductions, which turned reality into a function of the observer’s location and motion relative to other naturally occurring external events. The aid of photography in magnifying the minutiae of the smallest elements of reality was fundamental. It does not seem an overstatement to say that the lens became de facto a proxy of the eye, filling in for the shortcomings of human anatomy. Such was the dependence on technology between the 19^th and the early 20^th century, that both scientists and photographers claimed that photomicrography could cure the world’s ills.

There are too many places of amusement in our cities, too many trashy and pernicious novels in our free libraries ... We do not suggest photography through the microscope as the remedy for existing defects, but we think that the more our young men take up intellectual pastimes the better it will be for the nation. This is one of those pastimes. It is not a selfish one. One enthusiast is a centre of usefulness to others, for he cannot keep to himself the enjoyment he receives from the study of Nature's beauties and wonders.

Thus, spoke Richard Kerr in his Nature through Microscope and Camera (1909), a book showing pictures of animals and plants taken with “the microscope and the camera combined in one instrument”, with the negatives “receiving no touching-up whatever”. The photographs contained in the book were taken by Arthur E. Smith, about whom little to no information survives, and exhibited at the British Royal Society in 1904. Sixty-five photomicrographs of a spruce stem, a rattan cane, a lily bud, a wheat-stem, a butterfly’s tongue and a mosquito are shown as ailments to the universal pains of contemporary humankind.

Photomicrography is the process of using a microscope to photograph a magnified image of microscopic specimens. In its most basic form, an image of a specimen viewed through a microscope is illuminated by a light source onto a screen or paper. The projected image is then photographed. The technique was invented in the 19^th century for the furtherment of scientific research. Even though it was a scientist who first experimented with the process, it was not until photographer William Henry Fox Talbot captured the first plant sections in the 1930s that it became a full-fledged technique. 

An evocative study in photomicrography is that of Arthur Mason Worthington on the physics of splashes. “The splash of a drop”, Mason affirmed, “is a transaction which is accomplished in the twinkling of an eye, and it may seem to some that a man who proposes to discourse on the matter for an hour must have lost all sense of proportion. If that opinion exists, I hope this evening to be able to remove it, and to convince you that we have to deal with an exquisitely regulated phenomenon, and one which very happily illustrates some of the fundamental properties of fluids.”

In 1894, Worthington presented the result of his research on the dissolution stages of the splash of a drop of water falling into milk and other surfaces at the Royal Institution of Great Britain. The photographic technology that Worthington made use of was not advanced enough to reveal the tiniest details of the drop’s descent. To obviate the shortcomings, Worthington developed his own device, which was able, through a more sophisticated flash than those available on the market, to illuminate falling drops in a darkened room. Worthington repeated the operation until he captured all the different stages of the fall. Other than the mesmerising beauty of the single shots, what is striking is the style of Worthington’s prose. His descriptions of dripping drops reveal the enthusiasm of a child in a candy store, marveling at the shapes and colours of the tidbits he yearns to bite into. And it is so that the central mass of Worthington’s drop rises in a column which just fails itself to break into drops and falls back into the middle of the circle of satellites”. Or still, we see the “drop of a milk falling onto smoked glass”, “tracing lobes” and riding “triumphantly on the top of an emerging column.”

Furthering the scientific use of microscopy, the German surgeon and botanist Heinrich Anton de Bary contributed a chapter in biology through his microphotographs of diseased potatoes in his book Mikro-Photographien nach botanischen Präparaten (1878). Settling the role of the cell in living things, de Bary examined the concepts of parasites and then straightened them out through photography. His interest in the matter was sparked by the potato blight that ravished in Ireland when he was still a child, causing panic and famine. 

Other than on objects and on fluids, early film tests were made on trotting horses. The most significant achievements in this sense were obtained by Eadweard Muybridge in the United States. In the second half of the 19^th century, much controversy prevailed among horsemen whether all four feet of a trotting horse were ever clear of the ground at the same instant. Muybridge, who at the time was director of photographic surveys for the United States Government, secured photographs of Occident, a celebrated horse owned by Leland Stanford, founder of Stanford University, California, and president of the Central Pacific Railroad. The original photographs were taken on a racetrack in Sacramento, and though blurred, were sufficient to show the trotting horse with all feet off the ground. Muybridge employed a method of his invention based on stop-action photography. A battery of twenty-four cameras triggered either at timed intervals or as the horse’s legs tripped a wire suspended above the ground, generated a sequence of photographs capturing postures previously invisible to the human eye.

Muybridge showed his photographs with a zoöpraxiscope, an early device for displaying moving images, which is considered a predecessor to the movie projector. Muybridge commissioned an artist to paint the shots of Occident as silhouettes, which were then illuminated from the back, canceling the background and producing fanciful visual effects. After the successful demonstration that horses’ hoofs come off the ground all at once, Muybridge turned his camera towards other subjects. His studies were compiled in Animals in Motion, where, among other things, he demonstrated the law governing the consecutive action of the limbs in the primitive method of terrestrial progressive motion by vertebrates – essentially the study of a baby crawling on all fours – some phases of bucking and kicking and some phases in the flight of a cockatoo.

Muybridge’s case testifies to the blurring divide between science and art that wavered through the development of microscopy. Relevant in this sense is the example of Gustav Klimt’s The Kiss (1907). The oval forms of the frees of the female figure in the painting are disposed inside circle-like areas, as if seen through a microscope. We know that Klimt was a regular at scientific lectures in Vienna, where he saw the same microscopic images that he added to his painterly vocabulary.

Photomicrography escaped the confines of the laboratory and entered the house of commoners. The Handbook of Photomicrography by Hind Lloyd and Brough Randles provides an account of microphotography for amateurs and beginners. Full explanations are given about the principles governing the images contained in the book and the methods for obtaining them. The authors explain how to make lantern slides, colour photography and how to mount various photographic objects to obtain photomicrographs of fruits, animals, shells, seaweeds, insects, snowflakes and butterflies. Forty-four plates reproduced from direct colour photography illustrate the accompanying text. 

To conclude, photomicrography became a paramount scientific tool to show the visible face of the invisible. Bringing new knowledge to the mind and conspicuously new aesthetic elements to the eye, microscopy opened up to previously unknown forms, transparencies, patterns, curves, colours, lines and lights, bringing science and art closer than ever before.