Fitz James O’Brien 
Diamond Lens [PDF ebook] 

In this early science fiction tale, a man so obsessed with his scientific research that he will do whatever is necessary to advance his work concocts an elaborate scheme to obtain a state-of-the-art lens for his microscope. Once he has the purloined lens in place, he finds something in a drop of water that changes his life forever — and prompts his descent into madness.