image EL_L3_49_Fig
Image number: RS.15795
Credit: ©The Royal Society

Microscopic image of the colony-forming flagellate Anthophysa vegetans and observations of the forms of precipitated gold


5 February 1703


Unknown, Artist

Object type

Archive reference number

Manuscript page number




height (page): 225mm
width (page): 175mm



11 figures in a letter by Antoni van Leeuwenhoek to the Royal Society. The images were made by a draftsman.

Leeuwenhoek was experimenting with water from the canal in front of his house in Delft. He collected some water in a glass tube and observed the growth of small tree-like particles that would stick to and grow on the inside of the glass tube.

Fig. 1: Having let out the water from the tube, the draftsman could draw this branched particle that stuck to the inside of the glass tube.

Figs 2-3: slightly less regular branched particles.

Figs. 4-4a: the glass bulb Leeuwenhoek developed for this experiment on silver and aqua fortis, and the tree of silver that appeared on the inside of the glass (a so-called 'arbor philosophica').

Figs 5-9: salt crystals Leeuwenhoek found in a solution of gold in aqua regia.

Fig. 10: a little glass bulb, with which Leeuwenhoek experiments and shows that it is not weird (according to him) that duckweed is sometimes at the top of the water and sometimes at the bottom. He explains that with warm water the glass bulb (with air inside) will float on the water, but with colder water, some air will go out, water comes in and the bulb sinks to the bottom, and once the weather and water gets warmer, the water is pushed out and the bulb rises to the surface again.

Object history

The Journal Book mentions on 17 March 1702/3, 'A Letter was Read from Mr Leewenhoeck, containing many Observations made upon Waters viewed in a Tube; about Gold dissolv'd in Aqua Regia, &c.' (JBO/11/015).

The letter and images were printed in:
A. Leeuwenhoek, ‘Containing his observations on some animalcula in water, the dissolution of silver, etc.’, Phil. Trans. vol. 23, no. 286 (July and August 1703), pp. 1430-43. Figs 1-10.

Related Fellows

Antoni van Leeuwenhoek (1632-1723, Dutch), Naturalist

Associated place

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