, Iji 13. TV~ enliaus and HZ ich. Uti., 65B, NI i I fI< j321 about 50%. The barium salt of N- diazoacetyl-L-serine (11) was isolated as a crude yellow-green powder, Et,%. 448 at X 252 mp (pH 7.0). A paper chromatographic strip run on this material gave two very faint ninhydrin zones indicating relatively complete migration with a small amount of hydrolysis to free serine. This salt possessed little or no microbiological activity.