The image is a cyanotype plate (Plate II.2) featuring a collection of microscopic images of diatoms. The background is a uniform cyan blue, and the diatoms are depicted in a lighter shade of blue, creating a stark contrast. The diatoms are various shapes, including triangles, irregular polygons, and curved forms. They are covered in tiny dots, representing their intricate surface texture. Each diatom is labeled with a number (1 through 22) for identification. The plate has a decorative border and a title at the top. The overall aesthetic is reminiscent of a scientific illustration from the 19th or early 20th century.