Fragments of spleen of chickens previously injected with Salmonella paratyphi B vaccine were incubated in chem. defined medium M-199 with various additions, and the medium assayed for antibody agglutinating the test organism.With M-199 containing 50% horse serum, 1 mg./ml. D-glucosamine, chondroitin sulfate, or hyaluronic acid, antibody appeared, but none with M-199 alone.The substances tested were decreasingly effective in the order named.