FIGURE 4-8 Development of the light microscope. (a) Early microscopes, like the ones used by Robert Hooke in the 1660s, used lenses or a mirror to illuminate the specimen. (b) Optics in general, and light microscopes in particular, developed enormously during the nineteenth century. By the middle of the twentieth century, highly sophisticated microscopes limited only by the resolution of light were common. (c) In the second half of the twentieth century, fluorescence microscopy and digital imaging, together with confocal techniques, were developed to yield the versatile microscopes of today.

[Part (a) SSPL/Getty Images; parts (b) and (c) courtesy of A. Bretscher.]