Not all specimens have to be stained before magnification under a light microscope. However, since cells are mainly composed of water, their organelles may be difficult to view without stain. Some cells have pigments that may enable them to be viewed, while others may be very hard to see well. Lugol's solution, is an excellent stain to use when viewing onion cells. Areas such as the nucleus and cell wall become very apparent after adding a drop of stain to the slide. Since Lugol's solution contains iodine, any starch granules will stain blue black within the cell. Other stains exist such as methyl green which dyes chromatin to make viewing easy. Nile blue stains nuclei blue. These are just a few examples of the many stains used to view different parts of cells.