Abstract
Actinomycin D inhibits vitamin K induced formation of prothrombin in chicks deficient in vitamin K. The administration of actinomycin in doses which inhibit prothrombin formation also inhibits synthesis in the liver of RNA from adenosine triphosphate as detected with adenine-8-C14. The results are consistent with a genetic action of vitamin K in inducing RNA formation for the synthesis of clotting proteins