This document introduces an experiment to test hemagglutination and complement-mediated lysis. Red blood cells (RBCs) are incubated with serum containing antibody and complement, or with heated serum lacking complement. Hemagglutination occurs when RBCs bind to antibody alone. Hemolysis occurs when RBCs bind antibody and complement, leading to complement activation and cell lysis. The experiment uses sheep RBCs (antigen) with rabbit antibody and serum (from immunized or normal rabbits) to test these reactions.