This is a vintage cyanotype plate from A. Schmidt's Diatom Atlas, labeled 'Plate 117'. It features detailed illustrations of various diatoms, microscopic single-celled algae. The illustrations are rendered in a delicate, intricate style, showcasing the radial symmetry and ornate patterns characteristic of diatom shells. The plate contains eleven numbered illustrations of diatoms, each with a unique shape and pattern. Some are circular, others are more elongated or irregular. The patterns within the diatoms consist of radial lines, dots, and intricate designs. One illustration (number 5) depicts a fragment of a diatom structure, showing its layered composition. The illustrations are arranged on a pale blue background, typical of cyanotype prints. The overall aesthetic is reminiscent of scientific illustrations from the 19th or early 20th century, emphasizing detail and accuracy. The print has a slightly aged appearance, with some subtle imperfections and variations in tone.