John Mayall and Reproductions of Early Microscopes

In the 19th century John Mayall made copies of many early microscopes, showing both a good understanding of the instruments, and a high level of craftsmanship himself. Among the small collection of these reproductions in the collections of the Whipple Museum there are two made after the design of Antoni van Leeuwenhoek.

Models of the animal body began to be mass-produced during the 18th century, and the market for them grew alongside the 19th century expansion of universities and their new, experimental scientific disciplines. Frogs played an especially prominent role in the study of animal reproduction. Our wax models from the Ziegler studio represent two uses of frogs in developmental biology and point to the role that frogs, and the artisans who modelled them, played in 19th century biological controversies.

Adolf Ziegler (1820-1889) was the 19th century's pre-eminent wax modeller in developmental physiology and anatomy. His clients were the growing number of researchers who studied the forms and transformations of animal embryos and their internal anatomy. Ziegler's enlarged wax models provided one especially vivid and illuminating way of conveying knowledge of physical structures in otherwise microscopically small, changing, and complex embryonic forms. The Whipple Museum contains many wax models from the Ziegler studio, two sets of which contain representations of the frog.

The Whipple Museum's 'primordial skull' collection contains Ziegler models of the structure found in the heads of three vertebrate embryos during early embryonic formation. This structure, made of cartilage was understood to shape the later growth of the mature skull's solid bone. The 'higher' the vertebrate, the earlier the mature skull replaced its 'primordial' predecessor, as biologists understood it. The models were sold in a display case that includes labelled representations of frog, salmon, and axolotl embryos.

In 1889, Adolf Ziegler died and left his business to his son, Friedrich. The Ziegler studio weathered its founder's death with ease; strong international reputation ensured continued prosperity throughout Friedrich's management. The 're-publication' of some of his father's earliest models, like our series charting the development of a frog embryo, attests to that continued prosperity. This series, made in 1892, follows the transformation of a single fertilized embryo as it multiplies and transforms into a mature tadpole.

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Frogs Models, Artisans, and Academic Controversy

Techniques of Observing and Modelling

Knowledge of frog anatomy could be distributed in several ways, many of which required the assistance of artisans like Adolf Ziegler or his son, Friedrich. Academic agendas and commercial interests shaped the relationships between such craftsmen and scholars.

During Ziegler's time, comparative developmental anatomy was a thriving field of research into the animal world, and a home for heated debates about Darwin's new evolutionary theories. From the 1870s, the discipline was riven by controversies over ideas proposed by Ernst Haeckel, a zoologist at the University of Jena. He held that the embryonic development of organisms recapitulates the evolutionary transformations of their ancestors. Common evolutionary origins could therefore be observed in the structural similarities of early embryos. Opponents sought to discredit Haeckel's lofty theorisations by questioning the accuracy of his published images. This placed the quality of formal representations - image and models - at the center of scientific conflicts. As a producer of scientific images in wax, Ziegler found himself in the middle of this melee. But he maintained a cautionary intellectual posture that ensured him the commercial patronage of each side.

Though Adolf Ziegler developed his own reputation for scientific sophistication, most models were produced in tandem with the university professors that conducted these debates. Ziegler had based his original frog embryo series on a set of prints published in 1851 by Alexander Ecker, a professor of physiology and comparative anatomy from the University of Freiburg. Ecker also wrote a textbook on the anatomy of frogs due to their widespread use. He aimed to better inform those researchers that sustained the frog's position as "a commonplace on the altar of science" by using it in their experimental or anatomical work (1). For the primordial skulls, the elder Ziegler worked with a Professor Philipp Stöhr, specialist in histology, evolution, and embryology at the University of Würzburg.

These partnerships assured clients of the models' accuracy, for many believed that a mere artisan (as Ziegler and his colleagues were often perceived) could not be trusted to see and represent the embryo with adequate skill or discernment. Some academic researchers, however, such as Wilhelm His, questioned this division between the work of the hand and the work of the mind: "Just as I regard complicated spatial relations as only really understood when they are available as plastic representations, so too I consider the model, even more than the written word, the decisive record of the understanding of form of the researcher concerned," he wrote (2). Models, like Ziegler's of frog embryos and primordial skulls, were not only for teaching, but also for producing, communicating, standardizing, and laying claim to the frontiers of biological knowledge.

Accurate formal representation of frogs was of central importance to 19th century anatomists and their artisan collaborators. Different types of observing and modelling demanded different sorts of expertise from all involved, and transformed the purposes of studios like Ziegler's along with their relation to academic patrons.

The primordial skulls seen here are in fact models of models. Work was often performed within the universities by researchers or technicians who would then send their models to Ziegler for 'publication'. By the 1880s, Ziegler's studio was receiving many such models from all over Germany. University researchers, including Stöhr, who produced the original models for these primordial skulls, had then begun to use a new technique. They built section-based models of embryos using microtomes, which would cut extremely thin slices off a specimen. The modeller would then project and trace those sections onto a thin layer of wax before cutting that section out. Multiple wax sections would then be stacked into a three-dimensional model.

Scarcity of Early Microscopes

As public interest in contemporary microscopy grew in Victorian England so did interest in the history of microscopy. This in turn led to the formation a small number of private collections. Unfortunately for collectors very few of the earliest microscopes survived.

Among the most highly prized microscopes were those made by Antoni van Leeuwenhoek, the famous Dutch pioneer of microscopy. After Leeuwenhoek's death in 1723, 26 of his silver microscopes were given to the Royal Society of London and were described by the Vice-President Martin Folkes. Their magnification powers were later examined in 1741 by Henry Baker, who also provides us with an illustration of their appearance in 1753 (Image 1). It is unclear when, but at some stage in the 19th century, all 26 of the microscopes were lost.

John Mayall and the 1886 replicas

John Mayall (Junior) was a prominent member of both the Queckett Microcsopical Club and the Royal Microscopical Society. He was a friend of the lawyer and microscopist Sir Frank Crisp and helped him to acquire microscopes for his extensive collection. Notably Mayall was involved in the acquisition by Crisp of microscopes from Kings College London, including several items which had been part of the King George III collection.

In 1886 a professor from Utrecht, while in London, paid a visit to the Royal Microscopical Society, bringing with him one of Leeuwenhoek's original microscopes belonging to the Zoological Laboratories at the University of Utrecht. He allowed Mayall, then a secretary to the Society, to "make careful drawings and models of the instrument" (Images 2 & 3).(1)

Lost microscopes

No illustrations were made of the Royal Society's Leeuwenhoek microscopes until 1753 and Mayall reports that even then "they do not give a clear idea of the construction of the instruments".(2) As one of the earliest 'microscopists', Leeuwenhoek was seen as a heroic figure and there was a history of speculation into how he was able to achieve his magnifications with such seemingly basic microscopes.

Mayall writes that "the general impression during his [Leeuwenhoek's] lifetime seems to have been that he utilized lenses consisting of spherules of blown glass", and that it was Henry Baker who in 1740 discovered that "the magnifiers were not spherules of blown-glass, but bi-convex lenses".(3)

Mayall is critical of Folkes' earlier report and claims it to have been done "somewhat vaguely" and appeared "not to have directed his attention minutely to their construction". Interestingly he misses that it was Folkes, not Baker, that first noticed Leeuwenhoek's lenses were bi-convex:

"For the construction of these Instruments, it is the same in them all, and the Apparatus is very simple and convenient: They are all single Microscopes, consisting each of a very small double Convex-Glass." (4)

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