1665: Hooke shows mould under the microscope

In Micrographia, published in London in 1665, Robert Hooke described observations made with a microscope and a lighting system of his own. One of the parts most significant for the history of mycology concerned an unremarkable bloom of mould. On plate XII he presented magnified structures growing out of the substrate: branching threads and spherical heads. The Harvard University Herbaria describes this engraving as the first illustration of microfungi, and the book also as the first description of the internal structure of cap fungi.

Hooke had no concept of a fungal cell, no modern taxonomy and no germ theory. His identification therefore does not correspond to a present-day species diagnosis. The breakthrough lay in the method of presentation. The author described the preparation of the object, the capabilities of the instrument and what he actually saw, and then published a detailed engraving. A reader could compare the image with their own sample instead of taking on trust a description of an invisible substance.

Micrographia reached a wider public and showed that everyday materials — cork, cloth, a needle, an insect or mould — contain structures inaccessible to the naked eye. For the study of fungi this meant opening up a level at which spores, hyphae and reproductive organs would later begin to be distinguished. It was not the beginning of all microscopy, nor a complete mycology, but a legible point at which the scale of observation changed.

The significance of the event does not lie in priority alone. Hooke's plate shows how a scientific image can be at once a document and an interpretation. Today's micrographs require similar care: a scale, information about the preparation, and awareness of the instrument's limits. Without them even an excellent image becomes an illustration that cannot be checked.

The plate records an observation, not a modern diagnosis

The Royal Society catalogue identifies Schem XII as a microscopic study of blue mould growing on a leather binding. The circular frame at the top of the plate imitates a lens’s field of view, while Hooke’s accompanying text interprets the hairy growths as different tiny “mushrooms.” Harvard University Herbaria describes this plate as the first illustration of microfungi. The image-making process also matters: the Royal Society lists an unknown engraver and states that the copperplate was made after Hooke’s drawing—it is neither a photograph nor a direct instrumental record. Wellcome’s complete copy confirms the London edition of 1665 and allows the plate to be checked within Micrographia and its 38 plates.