AbstractThe isolated interphase chromosomes or chromatin of higher plants and animals can act as template for the conduct of DNA‐dependent RNA synthesis catalyzed by RNA polymerase. Such polymerase may be either the endogenous enzyme present in the chromatin or added exogenous enzyme purified from a different organism, asE. coli.Only a portion of the DNA of chromatin is available for transcription by RNA polymerase, the remainder being inert, repressed. The physical agents of repression are proteins of the class known as histones. Removal of histone from chromosomal DNA causes derepression of genetic material previously repressed. Analysis of a particular gene, that which supervises the synthesis of pea seed globulin, shows that the state of repression characteristic of the chromatin in life is preserved in the isolated material. That hormones which bring about increases in rate of RNA and protein synthesis in life do so by causing derepression of previously repressed genes is indicated by the fact that the template activity for RNA synthesis of chromatin isolated from organs after appropriate hormone treatment is greater than is the case without such treatmen