Variations in the Vitamin B 12 Content of Selected Samples of Pork and Beef Muscle. *

Abstract

In a recent paper¹ a fairly quantitative assay procedure for a growth factor in liver preparations was described. This assay procedure involves placing rats on the basal ration for a 2 week depletion period and following the growth response during another 2 week period when the material to be tested is given. Further work has shown that crystalline vitamin B₁₂ will give a quantitative response in this assay (Fig. 1).