This document analyzes blood typing results for 4 patients: Mr. Jones, Mr. Green, Ms. Brown, and a new patient X. It summarizes that for Mr. Jones: his blood type is B, as anti-B serum was cloudy while the others were clear; he has B antigens on his red blood cells and B antibodies in his plasma; he can safely receive type O or B blood; and types B and AB can safely receive his blood. It also defines erythroblastosis fetalis as a condition where the mother and baby have incompatible blood types, causing the mother's antibodies to attack the baby's red blood cells in utero. Finally, it suggests that the next important breakthrough in blood research