Whether bacteria have spores as well as the shape and location of the spores are important characteristics of bacteria, the bacterial spore wall is more complex than the cell wall of nutrient cells, dense, low permeability, coloring and decoloration are more difficult than nutrient cells. Spores have strong resistance to heat and chemicals, when using alkaline dyes and heating or prolonged staining time, so that the bacterial body and spores can be colored, and then rinsed with distilled water to remove the color of the bacterial body, but the color of the spores can still be retained, and can be clearly differentiated under the microscope between the morphology of the spores and nutrient body.