Endospores do not stain easily Perhaps you have seen them as

Endospores do not stain easily: Perhaps you have seen them as unstained white objects inside Bacillus species in other staining procedures. If they are visible as unstained objects in other stains, of what use is the endospore stain?

Solution

A staining procedure is performed not to always provide a color to the desired target, but it aims to generate a visible contrast between objects which can help them to visibly identify as different. Although most of the bio-polymers/organisms uptake colors by easy diffusion or harsh chemical-based methods such as acid-fuschin stain, some bio-molecules/organisms do not uptake stains at all. However, since an organism always resides on a background, it remains necessary to either stain the target object or the background in order to clearly identify the target as a separate entity. This is termed as negative staining.

According to the question, the endospores do not uptake any stain and appear as opaque white objects under microscope. However, although they do not uptake any stain, a staining procedure is still performed in order to stain the background. This kind of staining procedure where the target remains unstained and only the background is stained to provide a visible contrast is termed as negative staining.

Hence, though endospores do not uptake any stain, a staining procedure is still performed.