Cytophotometric analysis of nuclear DNA and histone content were made in dividing and nondividing root meristems ofTriticum durumcv. CAPPELLI. It was demonstrated that the nuclei in the pre-DNA synthesis phase of the nuclear cycle (G1), all having a 2C DNA content, show very different amounts of fast-green stainable histone. The 2C nuclei in nonproliferating meristems of caryopses at 15 days before harvest have a histone content nearly twice that of 2C nuclei in proliferating meristems of germinating caryopses.