This barrel of mineral oil was used by Dr. Michael Potter to induce plasma cell tumors in mice.

Potter wanted to study plasma cell tumors because each tumor makes one kind of immunoglobulin, an antibody that helps the body fight off infection and cancer. Before he could do that, however, he needed a way to induce the tumors to grow. Potter’s colleagues at the National Cancer Institute, Ruth Merwin and Glenn Algire, discovered that implanting diffusion chambers containing breast cancer cells into mice induced plasma cell tumors. Merwin then showed that plastic rings or shavings alone could induce the tumors. Luckily, they had used BALB/c mice, one of the rare inbred mouse strains that are susceptible to developing plasma cell tumors.