Novel and astonishing as they may have been for Enlightenment readers, it is difficult for us to comprehend how the magnifications of lice, fleas, houseflies, and other vermin might have been conceived as amusements for the mind and eyes. In full hand-colored clarity, stingers, pincers, biting mouthparts, and other irksome insect organs become menacing monsters thanks to the powers of the microscope in Martin Frobenius Ledermüller’s three-volume Mikroskopische Gemüths- und Augen-Ergötzung (Microscopic Delights of the Mind and Eyes).

For all of their scientific verisimilitude, microscopes were first and foremost instruments of wonder, and Ledermüller (1718–1769) — a German polymath, physician, and keeper of the Margrave of Brandenburg’s natural history collection — extolls their virtues in illustrating the marvels of God’s Creation and also as pure entertainment. Along with the vermin, Ledermüller gave state-of-the-art descriptions of plant, animal, and human organs, fungi, plankton, and crystals that accompany more than 150 attractive colored plates, produced by Nuremberg publisher, artist, and engraver Adam Wolfgang Winterschmidt.

Ledermüller’s own delight at the scenes beneath the lens shines through in many of his descriptions. While washing some sand collected from a beach on Rimini’s Adriatic shore, Ledermüller notices unidentified “globules” (he guesses that they are snail eggs), and places them beneath his “Oeconomical Glass”: “It is by this means that I discovered a real Firework on Water; that is to say that my Globules made on Water the same Effect as lit Grenades do, with the only Difference, that instead of Sparks of Fire, it was only Vapors & Particles of Water that they vomited.” Lederüller is similarly enchanted by all manner of Nature’s prodigies — a bee’s tongue, fish spawn, a drop of urine, the scales of insect wings. Examining the ocellus on a butterfly wing, he finds that “no painter, however skilful he may be, will ever succeed in rendering with his Brush, the Radiance & the Fire of the red, which this Mirror spreads”.

Much of the microscope’s allure was communicated to the public through salon demonstrations coupling the new solar microscope — whose improved imaging capacity came from a rotating mirror that directed light into the eyepiece — with the camera obscura, transforming the (formerly) private affair of observation into a social event. Accordingly, the visual power of microscopy raised both scientific and social questions in the late-eighteenth century. Based on the evidence given by the microscope, Ledermüller dismisses the theory of spontaneous generation; he also argues that microscopy is a suitably edifying occupation for young women. Occasionally Ledermüller’s observations lead him to claim even the authority to name new species:

Among the swampy water insects, there is a creature, which resembles in many respects the grotesque figure of a Harlequin. His black head, his body of various colors, his jumps, his bounces, his swings, his ridiculous tricks, have much in common with those of this jester of the Italian theater. For sometimes he stands on his Head, or rather on this red Tongue or Valve, which one sees appearing underneath; sometimes he stands perfectly on his Tail furnished with two large Fins; sometimes he stretches out quietly all the way, then gathering himself all of a sudden, he springs forward by a Snake’s Jump. Sometimes he puts himself in a Peloton, looking maliciously like Scapin from under his Coat, & then makes a Leap in the air; finally he bends like a banded Bow, & swims in this Posture on Water with the step of a Caterpillar; knowing as well how to keep his Balance as a Fish, so much so that he is as able on the surface of the water as in its depth. All this has led me to compare it to a Harlequin & to give it the Name.

Across the three volumes, Ledermüller graciously concurs with the scientific opinions of a wide range of aristocratic correspondents, yet the final volume concludes with a testy reply to a German naturalist who had pointed out his error in mistaking the female housefly’s ovipositor for the male’s reproductive organ. Coming to Ledermüller’s defense, the artist Winterschmidt contributes a magnificent engraving of the housefly as the work’s final plate.

Below you can browse images from a later French edition (1764–68) of Ledermüller’s work, courtesy of the Smithsonian Libraries and Biodiversity Heritage Library.