This document provides instructions for examining plant cells under a microscope using an onion bulb. The bulb is cut in half and a thin section is placed in blue methyl dye between a glass slide and cover slip. When viewed under a microscope, the cell membrane, cytoplasm, and nucleus can be observed in the onion skin cells. The conclusion is that plants are composed of cells that can have different shapes and contain a membrane, cytoplasm, and nucleus.