Engraving from Micrographia, 1665, by Robert Hooke.

Engraving, magnified view of a piece of stinging nettle leaf, a beard of wild oat and a transverse section of the top of wild oat, and Hooke's hygrometer; Schem. 15. From 'Micrographia: or some physiological descriptions of minute bodies made by magnifying glasses with observations and Inquiries thereupon' by Robert Hooke, Fellow of the Royal Society, 1665.