Negative stains stain the background as opposed to the specimen making the organism stand out against the colorful background.

Negative  Stains

Acidic stains are negatively charged stains that repel negatively charged cells or attract positively charged structures. Some examples include: Nigrosin and Congo Red.

Austin Community College

Methods of preparation to allow us to view and distinguish different cells and their structures that were otherwise translucent through the use of ionic salts in stains/dyes. 

Staining 

https://openstax.org/details/books/microbiology/

Microbiology covers the scope and sequence requirements for a single-semester microbiology course for non-majors. The book presents the core concepts of microbiology with a focus on applications for careers in allied health. The pedagogical features of the text make the material interesting and accessible while maintaining the career-application focus and scientific rigor inherent in the subject matter. Microbiology’s art program enhances students’ understanding of concepts through clear and effective illustrations, diagrams, and photographs.

Microbiology is produced through a collaborative publishing agreement between OpenStax and the American Society for Microbiology Press. The book aligns with the curriculum guidelines of the American Society for Microbiology.

OpenStax Microbiology Textbook

Simple stains make all of the organisms in a sample appear to be one color through use of a positively charged dye. Some examples include: Crystal Violet, Methylene Blue, and Safranin.

Simple Stains

Differential staining utilizes multiple different dyes to allow us to distinguish between different types of organisms. 

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