Wilkins drained all the blood out of a large dog and put it into a smaller dog; minutes later the smaller dog was out chasing sticks. Hooke built a new kind of clock, using the Microscope to examine some of its tiny parts. In so doing he discovered a new kind of mite living in the rags in which these parts had been wrapped. He drew pictures of them, and then performed an exhaustive three-day series of experiments to learn what would and wouldn't kill them: the most effective killer being a Florentine poison he'd been brewing out of tobacco leaves.