Robert Hooke published Micrographia in 1665. It is his most famous work and is notable for the stunning illustrations, drawn by Hooke himself. Microphagia presents several accounts of Hooke's observations through the use of the microscope. He looked at all sorts of things (snow, a needle, a razor, etc.) with a primitive compound microscope, but his most significant observations were done on fleas and cork. He observed the fleas under the microscope and was able to observe the tiny hairs on the fleas' bodies. On the cork he saw pores. Upon examination of the pores, he decided to call them "cells"; however, he did not know he had just discovered plant cells. Despite these great achievements in microscopy, microscopes didn't change much over the next 200 years, even though there were imperfections when viewing an object due to the different refraction of light.