Exploring our archives

On a recent visit to the excellent Boerhaave Museum in Leiden I noticed several of the Royal Society’s members represented among its collection. For example, on display was a copy of John Flamsteed’s beautiful Atlas coelestis, published posthumously in 1729 by his wife and amanuensis Margaret. Most prominent, however, was the work of Antoni van Leeuwenhoek of Delft, who is credited, along with Robert Hooke with the discovery of micro-organisms, a process which, as Jenni noted in her earlier post, can be traced more clearly using the Hooke folio. Leeuwenhoek was elected a member of the Royal Society in 1680 and clearly relished this recognition of his achievements: a 1686 portrait by J. Verkolje shows the former shopkeeper leaning proudly on a copy of the Society’s charter. One of Leeuwenhoek’s letters, published in the Philosophical Transactions of 1708/9, discusses the circulation of blood in fishes, a topic on which he had first corresponded with the Society in 1688. His observations and sketches decisively proved the theory that had been first advanced by William Harvey in 1628. Leeuwenhoek’s finding was illustrated by an incredibly detailed drawing of the circulation in the tail of a tadpole in the Boerhaave Museum.

Given the growing acceptance in this period that the blood did flow around the body, two important topic of discussion for the Society arose: namely, was how this was achieved and what purpose it served. Hooke tried to demonstrate in a series of experiments of 1669 that the circulation of the blood was caused by the beating of the heart. During the next year, discussion of the circulation of the blood in animals prompted some comparisons with the ongoing microscopical observations of the pores in plants, some being described as shaped like tiny drawers or ‘letter boxes’. The Society discussed whether a similar system to the circulation of the blood operated with the movement of the sap in plants and trees, providing their nourishment from the roots, or whether ‘ambient air’ was responsible for sustaining the plant. These speculations may have encouraged the curator of plants, Grew, in his 1675 publication on the ‘Comparative anatomy of trunks’.

Some interesting ideas about the relationship of air to the circulation of the blood were also put forward by Hooke at a meeting of 1672, when during a discussion of the purpose of respiration he argued ‘that by the air something essentiall to life might be conveyed into the blood, and something that was noysome to it be discharged back into the air’. He suggested that in order to discover whether ‘there are not Valves in the arterys, by which the air may passe into the parts of the Blood’ a representation could be made by injecting wax into the arteries.

Both the discussion of valves and the suggestion of injecting wax to produce accurate anatomical models echo the work of a Dutch contemporary of Leeuwenhoek’s based in Leiden. Jan Swammerdam was a pioneer in both microscopy and anatomy and had, also in 1672, presented the Society with a uterus filled with wax so as to show its anatomical structure more clearly. Swammerdam and Leeuwenhoek both observed red blood cells, the latter reporting the presence of ‘globules’ in his microscopical observations. It would be some time before these ‘globules’ could be decisively connected with Hooke’s conjectures about the purpose of the blood’s circulation through the lungs. However, the circulation of ideas between London and Leiden, which also included De Graaf and Constantin Huygens - both of whom helped Leeuwenhoek in his translation of his works and letters - would prove influential in advancing the understanding of the mechanism and purpose of the circulation of the blood.

Image: L0013035 Credit: Wellcome Library, London Photomontage From: Arcana naturae, ope & beneficio exquistissimorum microscopiorum detecta By: Leeuwenhoek, Anthony van Published: C. Boutesteyn Leyden 1708 3 figures Collection: Rare Books Full Bibliographic Record Link to Wellcome Library Catalogue

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