Not a Paul Klee
acid (80x), Polarized Light ~ © Lars BechNaarden, The Netherlands.
This hardly is my primary interest among the various uses of photography, but at Wired you can find this cool collection ~ "35 Years of the World's Best Microscopic Photography." The images are the winners, over the years, of Nikon’s annual Small World photomicrography competition. Note that you can link to the runners-up for each year too. The direct link to the Nikon page is here. The source of my interest? My son Douglas is a biology major and a budding photographer.