Answer:
Robert Hooke and Antoni van Leeuwenhoek.
Step-by-step explanation:
Antoni van Leeuwenhoek, along with Robert Hook, was the first person to observe microorganisms. He used a microscope, which he made by himself. Before Van Leeuwenhoek's discovery, it was rather strange how grapes could be turned into wine and milk into cheese. He didn't really make a connection between these processes, but he used a microscope and he established that the forms of life, which can't be seen by an eye, exist.