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The forces of reproduction. Meta/physics and insect sex in eighteenth-century entomology

Thursday, 15 October, 2020

In the early modern era, popular opinion on insect reproduction was largely based on the Aristotelian concept of ‘spontaneous generation’. Yet, in the seventeenth century, natural historians began to challenge this longstanding concept, which held that insects came into being out of mud, manure and other decaying matter. This theory was eventually discarded fully in the eighteenth century when a growing number of naturalists argued that copulation and functioning reproductive organs were indeed necessary for the creation of new insect life.

Lesser, Insecto-theologia

‘Insecto-theologia’ (1738), title page.

Through microscopic observation and ‘experimental’ methods, scholars studied insect behaviour and reproductive cycles, and thereby altered understandings of sexual activity beyond the insect world. As many users of these techniques discovered reproductive organs and observed female and male insects actually engaging ‘in the act’, ‘spontaneous generation’ slowly vanished as an explanation for how ‘creepy crawlies’ came into the world. The recent work of Mary Terrall, Matthew Cobb, Erik Jorink, Brian Ogilvie, Marc Ratcliff and Thomas Ruhland among others has shown how the discussion on spontaneous generation is part and parcel of a more general history of observation in the emergent sciences.

Lesser, Insecto-theologia

Title page of the French edition (1752).

Not surprisingly for scholars of the early modern world, theologians were an important group of actors in these processes (see Blair and von Greyerz). As is widely acknowledged, insects played an important role in physico-theology – or natural theology – and other religious texts around 1700. This has been studied comprehensively in the German context most recently by Anne-Charlott Trepp and Brian Ogilvie (both in Blair and von Greyerz, above). One central text in both authors’ work is Friedrich Christian Lesser’s Insecto-theologia from 1738. The text received widespread attention in the German-speaking lands, prompting a second edition in 1742. In the same year a French edition appeared with remarks by Pierre Lyonnet. This was then translated into Italian in 1751. Building on Trepp’s and Ogilvie’s œuvre, I will add a further perspective on natural theology, insects and science in the Enlightenment by focusing on how mating practices were described and reproductive organs depicted. The additional analysis of notions of force/power (Kraft) within these texts will further explain how the physical (in all senses of the word) was so important for the metaphysics of Enlightenment natural theology.

Lesser based his book to a great extent on Dutch scholars, like Jan Swammerdam, and used Baconian ‘new science’ for his argument for design – to use a slightly anachronistic term. As Anne-Charlott Trepp has shown, physico-theology replaced some of the dominant eschatological arguments of the seventeenth century with a new concern to prove God’s omnipotence and benevolence by looking at natural objects and finding order in nature. Jorink asserts that Swammerdam ‘was primarily guided by a prioris of a philosophical and theological kind’. One of these was that everything in nature, including the generation of insects, obeys God's laws.

Lesser, Insecto-theologia

‘Insecto-theologia’, frontispiece.

As with many of his fellow theologians in the eighteenth century, the study of the natural world became central to Lesser’s everyday life. The frontispiece clearly shows a naturalist at work in the familiar setting of the home.

It also already contains the important ‘maxima in minimis’ argument. He was of course certain that God’s power can be seen in the smallest worms as in the largest elephants. However, Lesser was convinced that this notion had not yet been sufficiently recognised among his fellow scholars in the republic of letters. Here he referred to the contemporary emphasis on physical experimentation in the creation of new knowledge, but made an interesting point regarding the social life of knowledge. According to him the above-mentioned attention deficit was not so contemptible in ‘people with untrained senses’ (‘Leute von ungeübten Sinnen’) but certainly scholars should not shy away from learned attention to the minuscule.

Friedrich Christian Lesser

Engraving of Friedrich Christian Lesser with an inscription by Johann Eustachius Goldhagen. (National Library of Denmark)

Lesser explicitly spoke of the creator’s ‘artistry’ in generating insects, such that even the smallest worm is made with such unattainable art that even the finest artist could not imitate it (Lesser, p.2), thereby echoing his Dutch predecessors and explicitly referring to William Derham in the corresponding footnote. Not surprisingly for a German author, the erudition is in the footnotes. He of course acknowledged previous work in his footnotes, and indeed most of the pages of the introduction are bibliographical references. Lesser’s description of Swammerdam’s scholarly practices are of special importance here because Lesser saw these as instrumental in the processes of knowledge formation. He went out himself to catch insects, collecting and nourishing them carefully. He constantly observed them, investigated their anatomy and had all their parts illustrated by an artist (p.27).

As in other realms of natural history, book learning and practical experience went hand in hand. Interestingly Lesser also specifically mentioned instruments and collections as the main tools of research in his introduction to Insecto-theologia. All these aspects are of course no surprise to historians of early modern science, but why did Lesser focus on generation to connect religion and natural history?

Swammerdam, The Book of Nature: Five reproductive organs of the bee

Swammerdam, ‘The Book of Nature’: Five reproductive organs of the bee. (Wellcome Collection. Attribution 4.0 International, CC BY 4.0)

Lesser took his inspiration from scripture and literally the beginning of the creation myth. Referring to Genesis, Lesser claimed: ‘The almighty being that created insects through his almighty word, has given them the power through ordinary procreation to multiply and reproduce the species’ (p.37). In the following paragraph, he also recounted the ‘generationem aequivocam’ theory but refuted it clearly by confirming that the notion of insects generating from decaying matter was only formed because the ancient philosophers had not observed nature with enough attention to detail and so had not realised that insects did lay small eggs in such things as manure, flesh, etc. Modern philosophers (‘Neue Welt-Weise’) however had observed things with sharper eyes. He then described his predecessors’ observations in great detail, starting with Francesco Redi who conducted experiments in the 1660s. Revisiting Redi’s work, Emily C. Parke has recently shown that seventeenth-century ‘spontaneous generation’ was ‘not a single theory but rather a landscape of possible views’. This is also clearly visible in Lesser’s text. Accordingly, it exhibits the range of arguments and refutations in a variety of ways. Next to observation was reason of course spiced with long-standing conventions like the important ‘chain of being’ assumption. For Lesser it would be ‘against all reason’ if plants, which are on a lower scale than animals, could bring forth insects.

Clearly, not only observation but also tradition, especially classical authors and scripture itself, was proof that the sexual act was indeed necessary. Returning to Genesis, Lesser maintained that God had given every living organism the power (Kraft) to procreate and this was true for insects too: ‘that this almighty word was extended to the insects’ procreation through insemination, as in all other animals’ (Lesser, p.41). The power/force (Kraft) metaphor recurs persistently in Lesser’s work and certainly has some connection to the important concept of force in Newtonian physics, connecting early modern natural history to natural philosophy or physics.

Combining this with observation again, Lesser stressed that one can see the ‘proper body-parts for siring and giving birth’ in insects as well as the eggs from which they spring. He described the basics of animal mating in a distinct chapter on proliferation and started this with a definition on how procreation works. Lesser clearly favoured the sperm over the egg. He also compared insects to human beings and other animals and described the two practices of mating he knew about: either insects mated belly to belly or from behind. But as the observation of insect copulation was one of the main problems in eighteenth-century entomology, as Mary Terrall has recently shown, it is not surprising that Lesser did speak at lengths about eggs when writing about what was actually observed: the generation of insects from ova.

He provides lots of details, and describes male and female organs thus: ‘The male member can be found mostly at the rump but sometimes also on the abdomen. They also have their rod and testicles. The size of those vary according to the size of the insects themselves. The vulva on the female insect is rough in order to prevent chafing of this tender element during intercourse. Ordinarily it is placed at the rump but sometimes also at the upper parts of the abdomen’ (p.268-69). Lesser’s detailed description of genitalia is astounding not only because of the religious nature of his text, but also because 65 years later one of the most important entomologists of the later eighteenth century rejected any attention to genitalia in natural history. In 1803 Johann Christian Fabricius – often called the Linnaeus of insects – wrote an important article in one of the earliest specialised entomology journals (‘Vertheidigung des fabricischen Systems’, Magazin für Insektenkunde 2 (1803), p.1-13).

Addressing his critics, he explained why his taxonomic system that was based on the mouthparts of insects was the best despite its flaws. First, genitalia are often too small to observe properly and second, echoing Linnaeus, he argued that inquiry into genitals was abominable and displeasing (‘Genitalium disquisitio abominabilis displicet’, Fabricius, p.5). This may come as a surprise to historians of eighteenth-century botany who are fully aware that Linnaeus based his plant taxonomy on the reproductive organs of plants. It is very difficult to ascertain why both Linnaeus and Fabricius made this statement, but one explanation might be a differentiation between flora and fauna where the morphology of the former was different enough from human reproductive organs. And although anthropomorphism was popular in botany and Linnaeus’s sexual system was severely criticised precisely for its attention to reproduction, non-human animals seem to have been more closely connected to a discussion of human sexuality.

Again, insects are used for understanding human behaviour. Apparently Linnaeus’s ‘nosce te ipsum’ had put humans firmly in the animal kingdom. Of course this was further developed in the nineteenth century. We know that the Victorians were obsessed with sex – as was the Enlightenment. In 1820 Johannes Jacob Hegetschweiler could publish a dissertation in Zurich that was concerned with insect genitalia (‘Dissertatio inauguralis zootomica de insectorum genitalibus’). Hence Fabricius’s dictum about genitals being abominable did not hold for long. Genitals are indeed one of the important characteristics of differentiating between insect species today.

Dominik Hünniger, Universität Hamburg

Dominik is author of the chapter ‘Inveterate travellers and travelling invertebrates’, in the edited volume ‘Interspecies Interactions: Animals and Humans between the Middle Ages and Modernity’, ed. Sarah Cockram and Andrew Wells (Routledge, 2017).

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