Overlay Data Paper
depositor: E. Jorink


Jan Swammerdam was a seventeenth century Dutch microscopist and naturalist who is most famous for his microscopic observations and descriptions of insect development that were published posthumously as The Bible of Nature, but is more often referred to as The Book of Nature due to a mistranslation of the title. Swammerdam pioneered the use of the microscope for zoological purposes, and is considered a founder of both comparative anatomy and entomology.

Born in Amsterdam in 1637, Swammerdam was the son of a pharmacist who always wanted him to earn his living either as a practicing physician or as a member of the Calvinist ministry. Although, he trained as a medical doctor at the prestigious University of Leiden, Swammerdam preferred scientific research to the medical practice and was supported by his father for the majority of his life. In his later years, Swammerdam fell under the influence of a religious mystic, Antoinette Bourignon, and abandoned his scientific work for a time. He died in 1680 at the age of 43 from a recurrence of malaria with much of his work largely unknown and unacknowledged. Ownership rights, translation difficulties, and other complications prevented the publication of Swammerdam's collective papers until 1737, when Dutch doctor Herman Boerhaave finished translating the opus into Latin.

Swammerdam A 19th century fantasy portrait of Swammerdam,
based on the face of Hartman Hartmanzoon (1591–1659)
from Rembrandt's The Anatomy Lesson of Dr. Nicolaes Tulp.
No genuine portrait of Jan Swammerdam is known.

Source: Cobb, Swammerdam.


During his medical and anatomical studies, Swammerdam examined the heart, lungs, and muscles and is believed to be the first person to describe red blood cells. He also conducted important observations on how nerves function, described the anatomy of the human reproductive system, and discovered valves in the lymphatic system, which are now called Swammerdam valves. Anticipating the role of oxygen in respiration, Swammerdam suggested that air contained a volatile element that could pass from the lungs to the heart and then to the muscles, providing energy for muscle contraction.

Swammerdam's entomological work involved the life history of insects and the anatomy of mayflies, butterflies, beetles, dragonflies and bees. The first to describe the queen bee, which had previously been incorrectly referred to by scientists as the king bee, Swammerdam developed a classification of insects based on their type of development. Three of the five major groups he described are still retained in modern classification schemes. His detailed study of the development of flies via delicate dissections led him to the revolutionary conclusion that insects undergo metamorphosis through various life stages.

To aid him in his observations, Swammerdam developed a variety of original and highly effective microscopic techniques. For instance, he injected wax into specimens to hold blood vessels firm, dissected fragile structures under water to avoid destroying them, and used micropipettes to inject and inflate organisms under the microscope. Swammerdam preferred simple microscopes to compound ones and used small bead-like lenses that he made himself. He also preferred to only observe specimens under direct natural light, and his research was occasionally delayed in the fall and winter months when sunlight was scarce. Without a camera to capture images, Swammerdam made detailed drawings of his specimens and his collective microscopic work is often considered to be the most comprehensive of any single person.

Microscope Single-lens microscope (circa 1670).

In his book, Swammerdam indicated that he only observed specimens visible under direct natural light, generally outdoors on summer mornings. Prior to his microscopic observation of specimens, Swammerdam carried on painstaking dissections with a variety of tools including fine pairs of scissors, a saw made from a small section of watch spring, a fine sharp-pointed pen-knife, feathers, glass tubes, small tweezers, needles and forceps. He utilized a variety of original and highly effective techniques to clean the specimen and to dissolve unwanted tissues and highlight those of interest. Without a camera to capture images, Swammerdam made drawings of his specimens, first in red crayon, then completed in black ink or pencil. Many of the drawings were ultimately transferred to copper plates for printing.

Source: Cobb, Swammerdam.


Circulation of knowledge

The scientific revolution of the 17th century was driven by countless discoveries in the observatory, at sea, in the workshop, in society at large and in the library. There was a dramatic increase in the amount of information, giving rise to new knowledge, theories and world views. But how did the 17th-century scientific information system actually work? How were new elements of knowledge picked up, processed, disseminated and -- ultimately -- accepted in broad circles of the educated community? In short: how did knowledge circulate? The Dutch Republic played a key role in this “information society” avant la lettre. Its global trade network, prosperity and relative tolerance made the Republic a refuge for intellectuals from around Europe. Not only did the book trade in the territory of the Republic account for more than half of Europe’s production of scientific works, but the Republic was also the cradle of the modern scientific journal. The basis of this information system lay in the correspondence between intellectuals.

There is a long tradition in the Netherlands of studying the scientific revolution, starting with E.J. Dijksterhuis in the 1940s and 1950s and continuing today (e.g. K. van Berkel and H.F. Cohen). In recent decades, historians of science and scholarship have become increasingly aware of the pivotal role the 17th-century Dutch Republic played in the international network of humanists and scholars before and during the “scientific revolution”. Important developments in disciplines such as philology, natural philosophy and natural history were fostered in or nurtured by the dynamic intellectual atmosphere of the Dutch Golden Age. Institutions such as universities and publishing houses were instrumental in the production and dissemination of knowledge. Intellectuals from all over Europe visited the Netherlands, which was then considered “the storehouse of the intellectual world” and which is now increasingly studied as such. The 17th-century Republic offers an ideal case for exploring the answers to the above-mentioned question, and correspondence between scholars is the ideal research subject. Until the publication of the first scientific journals in the 1660s, scholarly letters were by far the most direct and important means of communication between intellectuals abroad and at home.

Swammerdam's letters

Swammerdam's letters contain a great deal of information about his life and his work. For example, in a number of letters he explains that he stopped his observations in the autumn and winter, for want of light. Elsewhere, he complains about the cost, accuracy and efficiency of engravers with regard to the production of his plates. The results of his work were initially incorporated into separate treatises and letters to friends, such as Thévenot, although it was Swammerdam's intention to collect these into one volume. The tracts and letters are not of an argumentative kind. On the contrary, they are purely descriptive, setting out in painstaking detail the life cycle and behaviour of the various animals, and the arrangement and function of their external and internal parts.

Source: Circulation of Knowledge; other.


The website of the Circulation of Knowledge project, in particular its Epistolarium web page, provides ample opportunities for querying the letter collections. It is designed to answer the basic questions: "Who sends what to whom and when?" In addition it comes with an interesting option of similarity search. When Swammerdam is selected as sender, several data visualizations become available, such as a Google map showing the spatial coverage of the correspondence, a clickable time line with markers linked to individual letters, a diagram of the correspondent network (in which the names' font size indicates the number of letters to this recipient -- but unfortunately not linked) and a co-citation graph of person names.

Epistolarium Epistolarium page with Swammerdam selected.

Spatial coverage Spatial coverage of Swammerdam's correspondence.

Network Swammerdam's correspondence network.

As the network graph already suggests the letters are quite unevenly distributed over the recipients, as becomes more clear from the pie chart below:

Recipients The recipients of Swammerdam's letters.

The largest share goes to Thévenot. Melchisédech Thévenot (c. 1620 – 29 October 1692) was a French author, scientist, traveler, cartographer, orientalist, inventor, and diplomat. He was also famous for his popular 1696 book The Art of Swimming, one of the first books on the subject and widely read during the 18th century (Benjamin Franklin, an avid swimmer in his youth, is known to have read it). From about September 1664, Swammerdam lived in Paris as the guest of Thévenot. He was an active member, as was his friend Steno, of Thévenot’s scientific academy, an informal club that met to watch experiments and dispute over Cartesian ideas.

The second in the list is Antoinette Bourignon de la Porte (13 January 1616 – 30 October 1680). She was a French-Flemish mystic and adventurer. She taught that the end times would come soon and that the Last Judgment would then be felled. Her belief was that she was chosen by God to restore true Christianity on earth and became the central figure of a spiritual network that extended beyond the borders of the Dutch Republic, including Holstein and Scotland. The Antoinette was accompanied in her exile by a friend of Swammerdam’s. Jan wrote to her for spiritual comfort on 29 April 1674, and asked her permission before publishing his researches on the mayfly. He visited her in Schleswig–Holstein, between September 1675 and June 1676.

Although the collection is exceptionally well made ​​accessible, the subject(s) of the letters cannot be easily looked up and may be even difficult to indentify; a mixture of things are often mentioned in a single letter. The Epistolarium relies on keyword search and topic modeling. However, the list of keywords added to each letter does not cover the subjects in a way that is sufficient for a user who wants to get an overview of the content. Would he nevertheless get an idea of ​​what is discussed in these documents, then a study of the vocabulary may be a good idea. Because the majority of Swammerdam's letters is in Dutch, we have added a word list and list of n-grams (i.e. a contiguous sequence of n words in the text) for this part of the collection (both created with a stoplist of most frequent with no substantive meaning), both of them can be explored online.

Vocabulary Swammerdam's vocabulary of Dutch letters.
Left: word list; right: N-grams. Stoplist used.
Click on image to explore the vocabulary.

The usage of specific words can be further analyzed by a look-up in the concordance (Key Word In Context format), which can be dowloaded as a PDF file (5.5 Mb). Both, wordlist and concordance are based on screen copies of the Dutch letters, currently published in the Epistolarium. The files consist of plain text and are available as supplement (zip file, 85 Kb).

KWIC KWIC index of Swammerdam's vocabulary of Dutch letters.