“The Diamond Lens” is a short story published by the Irish writer Fitz-James O’Brien in 1858. It describes the quest of an obsessed amateur microscopist for ever greater degrees of magnification, a goal for which he is willing to go to exceptional lengths. O’Brien was apparently known for mixing scientific themes with mysticism, and “The Diamond Lens” certainly fits this description. I won’t spoil it any further; interested readers can download the story for free (in several formats) from The Gutenberg Project.
As the narrator and protagonist becomes a proficient microscopist, he encounters Volvox: