What is the primary function of a cover slip when preparing a microscope slide?

The primary function of a cover slip when preparing a microscope slide is to prevent air bubbles. When a cover slip is placed over the specimen, it creates a flat surface that helps ensure an even thickness of the slide, which is critical for optimal viewing. This also allows for the immersion of the specimen in the mounting medium, improving the clarity of the image. Additionally, a cover slip reduces the likelihood of air bubbles forming, which can obstruct the view and lead to misinterpretation of the specimen's features.

While a cover slip may incidentally hold the specimen in place, that is not its primary function. The use of a cover slip does not protect the objective lens, nor does it increase magnification; instead, it maintains the integrity of the specimen's observation by enhancing the overall clarity and ensuring a better viewing experience.