The possibility that the inability of Streptococcus faecalis to utilize 5-methyltetrahydropteroylglutamate or pteroyltriglutamate might be due to permeability was investigated. Whereas the former was taken up by S. faecalis cells growing on pteroylglutamic acid, the latter was not. No subsequent conversion of the 5-methyltetrahydropteroylglutamate took place and accumulation, which was against a considerable concentration gradient, was inhibited by fluoride. It would thus appear to be an active process.
