Maternal Inheritance and Interspecific Hybrids of the Liverwort Sphaerocarpos

Abstract

SEX determination in Sphaerocarpos, a genus of diœcious liverworts, is genetically controlled¹. When the spores of a tetrad derived from a single spore mother cell are germinated, two of the sporelings develop into male and two into female gametophytes. Cytological studies have shown that there are eight chromosomes in the complement of each sex. Of these, seven of the eight chromosomes in the female are similar to seven in the male. The eighth chromosome of the female, the X chromosome, is larger than the seven autosomes ; the eighth chromosome of the male, the Y chromosome, is smaller than the autosomes^2–4.