Purpose: To determine the presence/absence and location of flagella on various microorganisms
Principle: Because bacterial flagella are very thin and fragile a special stain (flagella stain) is prepared that contains a mordant. This mordant allows piling of the stain on the flagella, increasing the thickness until they become visible. Various arrangements of flagella are seen on different cells.
The stain to the right shows a typical flagella stain. The arrow indicates lophotrichous flagella (tufts of flagella at one end).