in crystalline form of a substance (I) active for Leuconostoc citrovomm, and the chick; furthermore, i t competitively reverses the toxicity of 4aminopteroylglutamic acid (11)for the mouse. When pteroylglutamic acid (PGA) or its XIoformyl derivative was reduced catalytically over platinum in formic acid a t 0 to 30', two moles of hydrogen were absorbed. Isolation oi thc crystalline substance ( I ) was accomplished by adsorption of impurities on 3Iagnesol d t PH 7. adsorption oE dctivity 0x1 Ilarco W 5 0 ,it PET -1, elution, fractional crystallizatioii of the barium salt, and finally chromatographic separation on JIagnesol colurnns. Anal. Calcd. ior C:OH,,N707RaGH20: C, RJ. 1; 11, Ba, 19.i, CHO, 1. i5. Found 4.31; N , 14.1; Ra, 20.3; CHO, 3.hO. Cxlctl. for C2oH2SN?07,3H20: C, 45.2; H , 3.54; S , iS.Ci, CHO, 5.50; HzO, 10.8. Found: (3, 43.2; 11, +-j.(Yi; N , 18.S; CHO, 5.0'7; HzO, 11.2. I n 0.1 -Ir sodium hydroxide solutiuti I ( 10 mg. 1.) Pxhibiterl
