Abstract The meiotic cells in the anthers of lily and tulip contain a unique histone which is absent or nearly so, from the somatic tissues of these plants. This histone, termed the meiotic histone, is synthesized during the premeiotic histone synthesis, persists through meiosis, microsporogenesis, and pollen maturation. Its concentration decreases during this developmental sequence indicating that it is synthesized but once and conserved thereafter. The histones of the contracted meiotic chromosomes are strikingly similar to the histones of the extended postmeiotic chromosomes. This similarity is interpreted as indicating that if the histones have a role in chromosome contraction, such a role does not require any gross changes in histone composition. During the differentiation of microspores into mature pollen grains, some of the histones decrease and other histones increase in concentration. Some of these changes occur in the absence of DNA synthesis.