Final answer:
The Wright-Giemsa stain is used for a peripheral blood smear to perform a WBC count, which involves staining white blood cells for identification and counting under a microscope.
Step-by-step explanation:
For conducting a white blood cell (WBC) count using a peripheral blood smear, the most commonly used additive is a stain. Specifically, the Wright-Giemsa stain is utilized for this purpose. It differentiates the WBCs by staining the nucleus and cytoplasm of white blood cells different shades of purple and the red blood cells a pinkish-red color. Once the blood smear is stained, leukocytes can be counted and identified microscopically with the oil immersion objective lens. Scanning the entire slide systematically, often using a scanning pattern, allows for accurate counting and classification of WBC types. This process is crucial for medical diagnoses and to check for any abnormal cell counts or the presence of disease-associated pathogens.