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.

Spore staining solution (Moeller method) is mainly composed of carbolic acid staining solution, Moeller methylene blue staining solution, Moeller decolorizing solution, the spores will be stained red, the bacterial body is red, the operation is simple, the results of the judgment is more reliable, but it should be noted that the observation of the spores should be in the maturation period, but it can't be too long, otherwise you can only see the spores, and nutrient body has disappeared.