Final answer:
The question is pertaining to negative staining, a microscopy technique used in Biology for visualizing encapsulated cells like yeast, where substances like India ink create a halo effect around the cells.
Step-by-step explanation:
The student is likely asking about a technique in microbiology known as negative staining used to visualize structures like capsules surrounding cells. One common example of this is India ink staining of encapsulated yeast like Cryptococcus neoformans, resulting in a halo effect around the cells. The supravital stain for an inclusion that looks like a ring might refer to the nuclear lamina when cells are stained for fluorescence microscopy, highlighting structures like intermediate filaments, DNA, and various cell organelles.
Negative staining enhances the contrast in microscopic images without staining the actual structure of interest, thus forming a 'halo' or clear ring around the structure due to the surrounding stained background. It's commonly employed in conjunction with other staining methods to offer a comprehensive view of the microscopic specimen. A typical application involves the visualization of bacterial capsules, which do not absorb the negative stain, creating a stark contrast against the stained background.