The doctors would also carry canes to poke bodies to test if they were still alive and to remind them to stay the correct distance away. The doctors could also examine patients using the cane. The doctors would wear large masks that looked like birds' beaks. This was because people believed the plague spread on bad air. The beaks of the masks were filled with plants, vinegar sponges, or perfume to protect the doctor from the bad air. Plague doctors wore robes covered in wax so body fluids would not stick to it. They wore glass goggles over their eyes. They would wear goggles if they could.