Freshwater and Marine Diatoms, w.m. Microscope Slide

In 1703, an anonymous Englishman, known to history only as Mr. C, wrote to the Royal Society of London to report on a peculiar observation he’d made using only a simple microscope. He’d been looking at the roots of pond-weed, but as he looked closer, he found attached to the roots, “‘many pretty branches, compos’d of rectangular oblongs and exact squares.’” At first, he assumed these geometric attachments must be salt crystals. But the more he experimented and looked through his microscope, the more he realized there might be something amazing going on here. These tiny, beautiful shapes seemed kind of plant-like. Today, with the benefit of many, many more observations, and far superior equipment, we know that this 18th century letter is one of the earliest descriptions of a diatom, a photosynthetic, unicellular algae that can become so plentiful that oceanic blooms of these organisms, w